Merge #97

97: v0.4.0 r=japaric a=japaric

closes #32
closes #33

Co-authored-by: Jorge Aparicio <jorge@japaric.io>

.cargo/config

@@ -1,31 +1,13 @@
 [target.thumbv6m-none-eabi]
-runner = 'arm-none-eabi-gdb'
-rustflags = [
-  "-C", "link-arg=-Tlink.x",
-  "-C", "linker=true",
-  "-Z", "linker-flavor=ld",
-]
+runner = "qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel"
 
 [target.thumbv7m-none-eabi]
-runner = 'arm-none-eabi-gdb'
+runner = "qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel"
+
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
 rustflags = [
   "-C", "link-arg=-Tlink.x",
-  "-C", "linker=arm-none-eabi-ld",
-  "-Z", "linker-flavor=ld",
 ]
 
-[target.thumbv7em-none-eabi]
-runner = 'arm-none-eabi-gdb'
-rustflags = [
-  "-C", "link-arg=-Tlink.x",
-  "-C", "linker=arm-none-eabi-ld",
-  "-Z", "linker-flavor=ld",
-]
-
-[target.thumbv7em-none-eabihf]
-runner = 'arm-none-eabi-gdb'
-rustflags = [
-  "-C", "link-arg=-Tlink.x",
-  "-C", "linker=arm-none-eabi-ld",
-  "-Z", "linker-flavor=ld",
-]
+[build]
+target = "thumbv7m-none-eabi"

.gdbinit

@@ -1,6 +0,0 @@
-target remote :3333
-
-monitor arm semihosting enable
-
-load
-step

.github/bors.toml

@@ -1,3 +1,4 @@
+delete_merged_branches = true
 status = [
   "continuous-integration/travis-ci/push",
 ]

.gitignore

@@ -1,6 +1,6 @@
 **/*.rs.bk
-*.org
 .#*
 .gdb_history
+/book/book
+/target
 Cargo.lock
-target/

.travis.yml

@@ -2,38 +2,48 @@ language: rust
 
 matrix:
   include:
+    # NOTE used to build docs on successful merges to master
+    - env: TARGET=x86_64-unknown-linux-gnu
+      rust: beta
+
+    - env: TARGET=thumbv6m-none-eabi
+      rust: beta
+      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+
+    - env: TARGET=thumbv7m-none-eabi
+      rust: beta
+      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+
     - env: TARGET=x86_64-unknown-linux-gnu
       rust: nightly
+      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv6m-none-eabi
       rust: nightly
-      if: branch != master
+      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
     - env: TARGET=thumbv7m-none-eabi
       rust: nightly
-      if: branch != master
-
-    - env: TARGET=thumbv7em-none-eabi
-      rust: nightly
-      if: branch != master
-
-    - env: TARGET=thumbv7em-none-eabihf
-      rust: nightly
-      if: branch != master
+      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
 before_install: set -e
 
 install:
   - bash ci/install.sh
-  - export PATH="$PATH:$PWD/gcc/bin"
+  - export PATH="$PATH:$PWD/qemu"
 
 script:
   - bash ci/script.sh
 
+after_script: set +e
+
 after_success:
   - bash ci/after-success.sh
 
-after_script: set +e
+cache: cache
+
+before_cache:
+  - chmod -R a+r $HOME/.cargo;
 
 branches:
   only:

Cargo.toml

@@ -4,33 +4,62 @@ authors = [
   "Per Lindgren <per.lindgren@ltu.se>",
 ]
 categories = ["concurrency", "embedded", "no-std"]
-description = "Real Time For the Masses (RTFM) framework for ARM Cortex-M microcontrollers"
-documentation = "https://japaric.github.io/cortex-m-rtfm/cortex_m_rtfm/"
+description = "Real Time For the Masses (RTFM): a concurrency framework for building real time systems"
+documentation = "https://japaric.github.io/cortex-m-rtfm/book/"
+edition = "2018"
 keywords = ["arm", "cortex-m"]
 license = "MIT OR Apache-2.0"
 name = "cortex-m-rtfm"
+readme = "README.md"
 repository = "https://github.com/japaric/cortex-m-rtfm"
-version = "0.3.4"
+version = "0.4.0-beta.1"
+
+[lib]
+name = "rtfm"
+
+[[example]]
+name = "baseline"
+required-features = ["timer-queue"]
+
+[[example]]
+name = "periodic"
+required-features = ["timer-queue"]
+
+[[example]]
+name = "schedule"
+required-features = ["timer-queue"]
+
+[[example]]
+name = "types"
+required-features = ["timer-queue"]
 
 [dependencies]
-cortex-m = "0.4.0"
-cortex-m-rtfm-macros = { path = "macros", version = "0.3.2" }
-rtfm-core = "0.2.0"
-untagged-option = "0.1.1"
+cortex-m = "0.5.8"
+cortex-m-rt = "0.6.5"
+cortex-m-rtfm-macros = { path = "macros", version = "0.4.0-beta.1" }
+heapless = "0.4.0"
+owned-singleton = "0.1.0"
 
-[target.'cfg(target_arch = "x86_64")'.dev-dependencies]
-compiletest_rs = "0.3.5"
+[dev-dependencies]
+alloc-singleton = "0.1.0"
+cortex-m-semihosting = "0.3.1"
+lm3s6965 = "0.1.3"
+panic-halt = "0.2.0"
 
-[dev-dependencies.cortex-m-rt]
-features = ["abort-on-panic"]
-version = "0.3.9"
-
-[dev-dependencies.stm32f103xx]
-features = ["rt"]
-version = "0.8.0"
+[dev-dependencies.panic-semihosting]
+features = ["exit"]
+version = "0.5.1"
 
 [features]
-cm7-r0p1 = ["cortex-m/cm7-r0p1"]
+timer-queue = ["cortex-m-rtfm-macros/timer-queue"]
+
+[target.x86_64-unknown-linux-gnu.dev-dependencies]
+compiletest_rs = "0.3.16"
+tempdir = "0.3.7"
 
 [profile.release]
+codegen-units = 1
 lto = true
+
+[workspace]
+members = ["macros"]

LICENSE-CC-BY-SA

@@ -0,0 +1,428 @@
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+

LICENSE-MIT

@@ -1,4 +1,4 @@
-Copyright (c) 2017 Jorge Aparicio
+Copyright (c) 2017-2018 Jorge Aparicio
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated

README.md

@@ -1,25 +1,104 @@
-[![crates.io](https://img.shields.io/crates/v/cortex-m-rtfm.svg)](https://crates.io/crates/cortex-m-rtfm)
-[![crates.io](https://img.shields.io/crates/d/cortex-m-rtfm.svg)](https://crates.io/crates/cortex-m-rtfm)
+# Real Time For the Masses
 
-# `cortex-m-rtfm`
+A concurrency framework for building real time systems.
 
-> Real Time For the Masses (RTFM) framework for ARM Cortex-M microcontrollers
+**IMPORTANT** This crate is currently in pre-release (beta) state . We reserve
+the right to make breaking changes in the syntax or to patch memory safety holes
+before the v0.4.0 release, which is planned for 2018-12-07. When v0.4.0 is
+released *all the pre-releases will be yanked*. If you run into a panic message
+or an unhelpful error message (e.g. misleading span), or if something doesn't
+behave the way you expect please open [an issue]!
 
-# [Documentation](https://japaric.github.io/cortex-m-rtfm/cortex_m_rtfm/)
+[an issue]: https://github.com/japaric/cortex-m-rtfm/issues
 
-# License
+## Features
 
-Licensed under either of
+- **Tasks** as the unit of concurrency [^1]. Tasks can be *event triggered*
+  (fired in response to asynchronous stimuli) or spawned by the application on
+  demand.
+
+- **Message passing** between tasks. Specifically, messages can be passed to
+  software tasks at spawn time.
+
+- **A timer queue** [^2]. Software tasks can be scheduled to run at some time
+  in the future. This feature can be used to implement periodic tasks.
+
+- Support for prioritization of tasks and, thus, **preemptive multitasking**.
+
+- **Efficient and data race free memory sharing** through fine grained *priority
+  based* critical sections [^1].
+
+- **Deadlock free execution** guaranteed at compile time. This is an stronger
+  guarantee than what's provided by [the standard `Mutex`
+  abstraction][std-mutex].
+
+[std-mutex]: https://doc.rust-lang.org/std/sync/struct.Mutex.html
+
+- **Minimal scheduling overhead**. The task scheduler has minimal software
+  footprint; the hardware does the bulk of the scheduling.
+
+- **Highly efficient memory usage**: All the tasks share a single call stack and
+  there's no hard dependency on a dynamic memory allocator.
+
+- **All Cortex-M devices are fully supported**.
+
+- This task model is amenable to known WCET (Worst Case Execution Time) analysis
+  and scheduling analysis techniques. (Though we haven't yet developed Rust
+  friendly tooling for that.)
+
+## Requirements
+
+- Rust 1.31.0+
+
+- Applications must be written using the 2018 edition.
+
+## [User documentation](https://japaric.github.io/cortex-m-rtfm/book/index.html)
+
+## [API reference](https://japaric.github.io/cortex-m-rtfm/api/rtfm/index.html)
+
+## Acknowledgments
+
+This crate is based on [the RTFM language][rtfm-lang] created by the Embedded
+Systems group at [Luleå University of Technology][ltu], led by [Prof. Per
+Lindgren][per].
+
+[rtfm-lang]: http://www.rtfm-lang.org/
+[ltu]: https://www.ltu.se/?l=en
+[per]: https://www.ltu.se/staff/p/pln-1.11258?l=en
+
+## References
+
+[^1]: Eriksson, J., Häggström, F., Aittamaa, S., Kruglyak, A., & Lindgren, P.
+   (2013, June). Real-time for the masses, step 1: Programming API and static
+   priority SRP kernel primitives. In Industrial Embedded Systems (SIES), 2013
+   8th IEEE International Symposium on (pp. 110-113). IEEE.
+
+[^2]: Lindgren, P., Fresk, E., Lindner, M., Lindner, A., Pereira, D., & Pinho,
+   L. M. (2016). Abstract timers and their implementation onto the arm cortex-m
+   family of mcus. ACM SIGBED Review, 13(1), 48-53.
+
+## License
+
+All source code (including code snippets) is licensed under either of
 
 - Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
-  http://www.apache.org/licenses/LICENSE-2.0)
+  [https://www.apache.org/licenses/LICENSE-2.0][L1])
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or
+  [https://opensource.org/licenses/MIT][L2])
 
-- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+[L1]: https://www.apache.org/licenses/LICENSE-2.0
+[L2]: https://opensource.org/licenses/MIT
 
 at your option.
 
-## Contribution
+The written prose contained within the book is licensed under the terms of the
+Creative Commons CC-BY-SA v4.0 license ([LICENSE-CC-BY-SA](LICENSE-CC-BY-SA) or
+[https://creativecommons.org/licenses/by-sa/4.0/legalcode][L3]).
+
+[L3]: https://creativecommons.org/licenses/by-sa/4.0/legalcode
+
+### Contribution
 
 Unless you explicitly state otherwise, any contribution intentionally submitted
 for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
-dual licensed as above, without any additional terms or conditions.
+licensed as above, without any additional terms or conditions.

book/book.toml

@@ -0,0 +1,5 @@
+[book]
+authors = ["Jorge Aparicio"]
+multilingual = false
+src = "src"
+title = "Real Time For the Masses"

book/src/SUMMARY.md

@@ -0,0 +1,16 @@
+# Summary
+
+[Preface](./preface.md)
+- [RTFM by example](./by-example.md)
+  - [The `app` attribute](./by-example/app.md)
+  - [Resources](./by-example/resources.md)
+  - [Tasks](./by-example/tasks.md)
+  - [Timer queue](./by-example/timer-queue.md)
+  - [Singletons](./by-example/singletons.md)
+  - [Types, Send and Sync](./by-example/types-send-sync.md)
+  - [Starting a new project](./by-example/new.md)
+  - [Tips & tricks](./by-example/tips.md)
+- [Under the hood](./internals.md)
+  - [Ceiling analysis](./internals/ceilings.md)
+  - [Task dispatcher](./internals/tasks.md)
+  - [Timer queue](./internals/timer-queue.md)

book/src/by-example.md

@@ -0,0 +1,16 @@
+# RTFM by example
+
+This part of the book introduces the Real Time For the Masses (RTFM) framework
+to new users by walking them through examples of increasing complexity.
+
+All examples in this part of the book can be found in the GitHub [repository] of
+the project, and most of the examples can be run on QEMU so no special hardware
+is required to follow along.
+
+[repository]: https://github.com/japaric/cortex-m-rtfm
+
+To run the examples on your laptop / PC you'll need the `qemu-system-arm`
+program. Check [the embedded Rust book] for instructions on how to set up an
+embedded development environment that includes QEMU.
+
+[the embedded Rust book]: https://rust-embedded.github.io/book/intro/install.html

book/src/by-example/app.md

@@ -0,0 +1,105 @@
+# The `app` attribute
+
+This is the smallest possible RTFM application:
+
+``` rust
+{{#include ../../../examples/smallest.rs}}
+```
+
+All RTFM applications use the [`app`] attribute (`#[app(..)]`). This attribute
+must be applied to a `const` item that contains items. The `app` attribute has
+a mandatory `device` argument that takes a *path* as a value. This path must
+point to a *device* crate generated using [`svd2rust`] **v0.14.x**. The `app`
+attribute will expand into a suitable entry point so it's not required to use
+the [`cortex_m_rt::entry`] attribute.
+
+[`app`]: ../../api/cortex_m_rtfm_macros/attr.app.html
+[`svd2rust`]: https://crates.io/crates/svd2rust
+[`cortex_m_rt::entry`]: ../../api/cortex_m_rt_macros/attr.entry.html
+
+> **ASIDE**: Some of you may be wondering why we are using a `const` item as a
+> module and not a proper `mod` item. The reason is that using attributes on
+> modules requires a feature gate, which requires a nightly toolchain. To make
+> RTFM work on stable we use the `const` item instead. When more parts of macros
+> 1.2 are stabilized we'll move from a `const` item to a `mod` item and
+> eventually to a crate level attribute (`#![app]`).
+
+## `init`
+
+Within the pseudo-module the `app` attribute expects to find an initialization
+function marked with the `init` attribute. This function must have signature
+`[unsafe] fn()`.
+
+This initialization function will be the first part of the application to run.
+The `init` function will run *with interrupts disabled* and has exclusive access
+to Cortex-M and device specific peripherals through the `core` and `device`
+variables, which are injected in the scope of `init` by the `app` attribute. Not
+all Cortex-M peripherals are available in `core` because the RTFM runtime takes
+ownership of some of them -- for more details see the [`rtfm::Peripherals`]
+struct.
+
+`static mut` variables declared at the beginning of `init` will be transformed
+into `&'static mut` references that are safe to access.
+
+[`rtfm::Peripherals`]: ../../api/rtfm/struct.Peripherals.html
+
+The example below shows the types of the `core` and `device` variables and
+showcases safe access to a `static mut` variable.
+
+``` rust
+{{#include ../../../examples/init.rs}}
+```
+
+Running the example will print `init` to the console and then exit the QEMU
+process.
+
+```  console
+$ cargo run --example init
+{{#include ../../../ci/expected/init.run}}```
+
+## `idle`
+
+A function marked with the `idle` attribute can optionally appear in the
+pseudo-module. This function is used as the special *idle task* and must have
+signature `[unsafe] fn() - > !`.
+
+When present, the runtime will execute the `idle` task after `init`. Unlike
+`init`, `idle` will run *with interrupts enabled* and it's not allowed to return
+so it runs forever.
+
+When no `idle` function is declared, the runtime sets the [SLEEPONEXIT] bit and
+then sends the microcontroller to sleep after running `init`.
+
+[SLEEPONEXIT]: https://developer.arm.com/products/architecture/cpu-architecture/m-profile/docs/100737/0100/power-management/sleep-mode/sleep-on-exit-bit
+
+Like in `init`, `static mut` variables will be transformed into `&'static mut`
+references that are safe to access.
+
+The example below shows that `idle` runs after `init`.
+
+``` rust
+{{#include ../../../examples/idle.rs}}
+```
+
+``` console
+$ cargo run --example idle
+{{#include ../../../ci/expected/idle.run}}```
+
+## `interrupt` / `exception`
+
+Just like you would do with the `cortex-m-rt` crate you can use the `interrupt`
+and `exception` attributes within the `app` pseudo-module to declare interrupt
+and exception handlers. In RTFM, we refer to interrupt and exception handlers as
+*hardware* tasks.
+
+``` rust
+{{#include ../../../examples/interrupt.rs}}
+```
+
+``` console
+$ cargo run --example interrupt
+{{#include ../../../ci/expected/interrupt.run}}```
+
+So far all the RTFM applications we have seen look no different that the
+applications one can write using only the `cortex-m-rt` crate. In the next
+section we start introducing features unique to RTFM.

book/src/by-example/new.md

@@ -0,0 +1,67 @@
+# Starting a new project
+
+Now that you have learned about the main features of the RTFM framework you can
+try it out on your hardware by following these instructions.
+
+1. Instantiate the [`cortex-m-quickstart`] template.
+
+[`cortex-m-quickstart`]: https://github.com/rust-embedded/cortex-m-quickstart#cortex-m-quickstart
+
+``` console
+$ # for example using `cargo-generate`
+$ cargo generate \
+    --git https://github.com/rust-embedded/cortex-m-quickstart \
+    --name app
+
+$ # follow the rest of the instructions
+```
+
+2. Add a device crate that was generated using [`svd2rust`] **v0.14.x**, or a
+   board support crate that depends on one such device crate as a dependency.
+   Make sure that the `rt` feature of the crate is enabled.
+
+[`svd2rust`]: https://crates.io/crates/svd2rust
+
+In this example, I'll use the [`lm3s6965`] device crate. This device crate
+doesn't have an `rt` Cargo feature; that feature is always enabled.
+
+[`lm3s6965`]: https://crates.io/crates/lm3s6965
+
+This device crate provides a linker script with the memory layout of the target
+device so `memory.x` and `build.rs` need to be removed.
+
+``` console
+$ cargo add lm3s6965 --vers 0.1.3
+
+$ rm memory.x build.rs
+```
+
+3. Add the `cortex-m-rtfm` crate as a dependency and, if you need it, enable the
+   `timer-queue` feature.
+
+``` console
+$ cargo add cortex-m-rtfm --allow-prerelease --upgrade=none
+```
+
+4. Write your RTFM application.
+
+Here I'll use the `init` example from the `cortex-m-rtfm` crate.
+
+``` console
+$ curl \
+    -L https://github.com/japaric/cortex-m-rtfm/raw/v0.4.0-beta.1/examples/init.rs \
+    > src/main.rs
+```
+
+That example depends on the `panic-semihosting` crate:
+
+``` console
+$ cargo add panic-semihosting
+```
+
+5. Build it, flash it and run it.
+
+``` console
+$ # NOTE: I have uncommented the `runner` option in `.cargo/config`
+$ cargo run
+{{#include ../../../ci/expected/init.run}}```

book/src/by-example/resources.md

@@ -0,0 +1,119 @@
+## Resources
+
+One of the limitations of the attributes provided by the `cortex-m-rt` crate is
+that sharing data (or peripherals) between interrupts, or between an interrupt
+and the `entry` function, requires a `cortex_m::interrupt::Mutex`, which
+*always* requires disabling *all* interrupts to access the data. Disabling all
+the interrupts is not always required for memory safety but the compiler doesn't
+have enough information to optimize the access to the shared data.
+
+The `app` attribute has a full view of the application thus it can optimize
+access to `static` variables. In RTFM we refer to the `static` variables
+declared inside the `app` pseudo-module as *resources*. To access a resource the
+context (`init`, `idle`, `interrupt` or `exception`) must first declare the
+resource in the `resources` argument of its attribute.
+
+In the example below two interrupt handlers access the same resource. No `Mutex`
+is required in this case because the two handlers run at the same priority and
+no preemption is possible. The `SHARED` resource can only be accessed by these
+two handlers.
+
+``` rust
+{{#include ../../../examples/resource.rs}}
+```
+
+``` console
+$ cargo run --example resource
+{{#include ../../../ci/expected/resource.run}}```
+
+## Priorities
+
+The priority of each handler can be declared in the `interrupt` and `exception`
+attributes. It's not possible to set the priority in any other way because the
+runtime takes ownership of the `NVIC` peripheral; it's also not possible to
+change the priority of a handler / task at runtime. Thanks to this restriction
+the framework has knowledge about the *static* priorities of all interrupt and
+exception handlers.
+
+Interrupts and exceptions can have priorities in the range `1..=(1 <<
+NVIC_PRIO_BITS)` where `NVIC_PRIO_BITS` is a constant defined in the `device`
+crate. The `idle` task has a priority of `0`, the lowest priority.
+
+Resources that are shared between handlers that run at different priorities
+require critical sections for memory safety. The framework ensures that critical
+sections are used but *only where required*: for example, no critical section is
+required by the highest priority handler that has access to the resource.
+
+The critical section API provided by the RTFM framework (see [`Mutex`]) is
+based on dynamic priorities rather than on disabling interrupts. The consequence
+is that these critical sections will prevent *some* handlers, including all the
+ones that contend for the resource, from *starting* but will let higher priority
+handlers, that don't contend for the resource, run.
+
+[`Mutex`]: ../../api/rtfm/trait.Mutex.html
+
+In the example below we have three interrupt handlers with priorities ranging
+from one to three. The two handlers with the lower priorities contend for the
+`SHARED` resource. The lowest priority handler needs to [`lock`] the
+`SHARED` resource to access its data, whereas the mid priority handler can
+directly access its data. The highest priority handler is free to preempt
+the critical section created by the lowest priority handler.
+
+[`lock`]: ../../api/rtfm/trait.Mutex.html#method.lock
+
+``` rust
+{{#include ../../../examples/lock.rs}}
+```
+
+``` console
+$ cargo run --example lock
+{{#include ../../../ci/expected/lock.run}}```
+
+## Late resources
+
+Unlike normal `static` variables, which need to be assigned an initial value
+when declared, resources can be initialized at runtime. We refer to these
+runtime initialized resources as *late resources*. Late resources are useful for
+*moving* (as in transferring ownership) peripherals initialized in `init` into
+interrupt and exception handlers.
+
+Late resources are declared like normal resources but that are given an initial
+value of `()` (the unit value). Late resources must be initialized at the end of
+the `init` function using plain assignments (e.g. `FOO = 1`).
+
+The example below uses late resources to stablish a lockless, one-way channel
+between the `UART0` interrupt handler and the `idle` function. A single producer
+single consumer [`Queue`] is used as the channel. The queue is split into
+consumer and producer end points in `init` and then each end point is stored
+in a different resource; `UART0` owns the producer resource and `idle` owns
+the consumer resource.
+
+[`Queue`]: ../../api/heapless/spsc/struct.Queue.html
+
+``` rust
+{{#include ../../../examples/late.rs}}
+```
+
+``` console
+$ cargo run --example late
+{{#include ../../../ci/expected/late.run}}```
+
+## `static` resources
+
+`static` variables can also be used as resources. Tasks can only get `&`
+(shared) references to these resources but locks are never required to access
+their data. You can think of `static` resources as plain `static` variables that
+can be initialized at runtime and have better scoping rules: you can control
+which tasks can access the variable, instead of the variable being visible to
+all the functions in the scope it was declared in.
+
+In the example below a key is loaded (or created) at runtime and then used from
+two tasks that run at different priorities.
+
+``` rust
+{{#include ../../../examples/static.rs}}
+```
+
+``` console
+$ cargo run --example static
+{{#include ../../../ci/expected/static.run}}```

book/src/by-example/singletons.md

@@ -0,0 +1,26 @@
+# Singletons
+
+The `app` attribute is aware of [`owned-singleton`] crate and its [`Singleton`]
+attribute. When this attribute is applied to one of the resources the runtime
+will perform the `unsafe` initialization of the singleton for you, ensuring that
+only a single instance of the singleton is ever created.
+
+[`owned-singleton`]: ../../api/owned_singleton/index.html
+[`Singleton`]: ../../api/owned_singleton_macros/attr.Singleton.html
+
+Note that when using the `Singleton` attribute you'll need to have the
+`owned_singleton` in your dependencies.
+
+Below is an example that uses the `Singleton` attribute on a chunk of memory
+and then uses the singleton instance as a fixed-size memory pool using one of
+the [`alloc-singleton`] abstractions.
+
+[`alloc-singleton`]: https://crates.io/crates/alloc-singleton
+
+``` rust
+{{#include ../../../examples/singleton.rs}}
+```
+
+``` console
+$ cargo run --example singleton
+{{#include ../../../ci/expected/singleton.run}}```

book/src/by-example/tasks.md

@@ -0,0 +1,63 @@
+# Software tasks
+
+RTFM treats interrupt and exception handlers as *hardware* tasks. Hardware tasks
+are invoked by the hardware in response to events, like pressing a button. RTFM
+also supports *software* tasks which can be spawned by the software from any
+execution context.
+
+Software tasks can also be assigned priorities and are dispatched from interrupt
+handlers. RTFM requires that free interrupts are declared in an `extern` block
+when using software tasks; these free interrupts will be used to dispatch the
+software tasks. An advantage of software tasks over hardware tasks is that many
+tasks can be mapped to a single interrupt handler.
+
+Software tasks are declared by applying the `task` attribute to functions. To be
+able to spawn a software task the name of the task must appear in the `spawn`
+argument of the context attribute (`init`, `idle`, `interrupt`, etc.).
+
+The example below showcases three software tasks that run at 2 different
+priorities. The three tasks map to 2 interrupts handlers.
+
+``` rust
+{{#include ../../../examples/task.rs}}
+```
+
+``` console
+$ cargo run --example task
+{{#include ../../../ci/expected/task.run}}```
+
+## Message passing
+
+The other advantage of software tasks is that messages can be passed to these
+tasks when spawning them. The type of the message payload must be specified in
+the signature of the task handler.
+
+The example below showcases three tasks, two of them expect a message.
+
+``` rust
+{{#include ../../../examples/message.rs}}
+```
+
+``` console
+$ cargo run --example message
+{{#include ../../../ci/expected/message.run}}```
+
+## Capacity
+
+Task dispatchers do *not* use any dynamic memory allocation. The memory required
+to store messages is statically reserved. The framework will reserve enough
+space for every context to be able to spawn each task at most once. This is a
+sensible default but the "inbox" capacity of each task can be controlled using
+the `capacicy` argument of the `task` attribute.
+
+The example below sets the capacity of the software task `foo` to 4. If the
+capacity is not specified then the second `spawn.foo` call in `UART0` would
+fail.
+
+``` rust
+{{#include ../../../examples/capacity.rs}}
+```
+
+``` console
+$ cargo run --example capacity
+{{#include ../../../ci/expected/capacity.run}}```

book/src/by-example/timer-queue.md

@@ -0,0 +1,89 @@
+# Timer queue
+
+When the `timer-queue` feature is enabled the RTFM framework includes a *global
+timer queue* that applications can use to *schedule* software tasks to run some
+time in the future.
+
+To be able to schedule a software task the name of the task must appear in the
+`schedule` argument of the context attribute. When scheduling a task the
+[`Instant`] at which the task should be executed must be passed as the first
+argument of the `schedule` invocation.
+
+[`Instant`]: ../../api/rtfm/struct.Instant.html
+
+The RTFM runtime includes a monotonic, non-decreasing, 32-bit timer which can be
+queried using the `Instant::now` constructor. A [`Duration`] can be added to
+`Instant::now()` to obtain an `Instant` into the future. The monotonic timer is
+disabled while `init` runs so `Instant::now()` always returns the value
+`Instant(0 /* clock cycles */)`; the timer is enabled right before the
+interrupts are re-enabled and `idle` is executed.
+
+[`Duration`]: ../../api/rtfm/struct.Duration.html
+
+The example below schedules two tasks from `init`: `foo` and `bar`. `foo` is
+scheduled to run 8 million clock cycles in the future. Next, `bar` is scheduled
+to run 4 million clock cycles in the future. `bar` runs before `foo` since it
+was scheduled to run first.
+
+> **IMPORTANT**: The examples that use the `schedule` API or the `Instant`
+> abstraction will **not** properly work on QEMU because the Cortex-M cycle
+> counter functionality has not been implemented in `qemu-system-arm`.
+
+``` rust
+{{#include ../../../examples/schedule.rs}}
+```
+
+Running the program on real hardware produces the following output in the console:
+
+``` text
+{{#include ../../../ci/expected/schedule.run}}
+```
+
+## Periodic tasks
+
+Software tasks have access to the `Instant` at which they were scheduled to run
+through the `scheduled` variable. This information and the `schedule` API can be
+used to implement periodic tasks as shown in the example below.
+
+``` rust
+{{#include ../../../examples/periodic.rs}}
+```
+
+This is the output produced by the example. Note that there is zero drift /
+jitter even though `schedule.foo` was invoked at the *end* of `foo`. Using
+`Instant::now` instead of `scheduled` would have resulted in drift / jitter.
+
+``` text
+{{#include ../../../ci/expected/periodic.run}}
+```
+
+## Baseline
+
+For the tasks scheduled from `init` we have exact information about their
+`scheduled` time. For hardware tasks there's no `scheduled` time because these
+tasks are asynchronous in nature. For hardware task the runtime provides a
+`start` time, which indicates the time at which the task handler started
+executing.
+
+Note that `start` is **not** equal to the arrival time of the event that fired
+the task. Depending on the priority of the task and the load of the system the
+`start` time could be very far off from the event arrival time.
+
+What do you think will be the value of `scheduled` for software tasks that are
+*spawned* instead of scheduled? The answer is that spawned tasks inherit the
+*baseline* time of the context that spawned it. The baseline of hardware tasks
+is `start`, the baseline of software tasks is `scheduled` and the baseline of
+`init` is `start = Instant(0)`. `idle` doesn't really have a baseline but tasks
+spawned from it will use `Instant::now()` as their baseline time.
+
+The example below showcases the different meanings of the *baseline*.
+
+``` rust
+{{#include ../../../examples/baseline.rs}}
+```
+
+Running the program on real hardware produces the following output in the console:
+
+``` text
+{{#include ../../../ci/expected/baseline.run}}
+```

book/src/by-example/tips.md

@@ -0,0 +1,43 @@
+# Tips & tricks
+
+## Running tasks from RAM
+
+The main goal of moving the specification of RTFM applications to attributes in
+RTFM v0.4.x was to allow inter-operation with other attributes. For example, the
+`link_section` attribute can be applied to tasks to place them in RAM; this can
+improve performance in some cases.
+
+> **IMPORTANT**: In general, the `link_section`, `export_name` and `no_mangle`
+> attributes are very powerful but also easy to misuse. Incorrectly using any of
+> these attributes can cause undefined behavior; you should always prefer to use
+> safe, higher level attributes around them like `cortex-m-rt`'s `interrupt` and
+> `exception` attributes.
+>
+> In the particular case of RAM functions there's no
+> safe abstraction for it in `cortex-m-rt` v0.6.5 but there's an [RFC] for
+> adding a `ramfunc` attribute in a future release.
+
+[RFC]: https://github.com/rust-embedded/cortex-m-rt/pull/100
+
+The example below shows how to place the higher priority task, `bar`, in RAM.
+
+``` rust
+{{#include ../../../examples/ramfunc.rs}}
+```
+
+Running this program produces the expected output.
+
+``` console
+$ cargo run --example ramfunc
+{{#include ../../../ci/expected/ramfunc.run}}```
+
+One can look at the output of `cargo-nm` to confirm that `bar` ended in RAM
+(`0x2000_0000`), whereas `foo` ended in Flash (`0x0000_0000`).
+
+``` console
+$ cargo nm --example ramfunc --release | grep ' foo::'
+{{#include ../../../ci/expected/ramfunc.grep.foo}}```
+
+``` console
+$ cargo nm --example ramfunc --release | grep ' bar::'
+{{#include ../../../ci/expected/ramfunc.grep.bar}}```

book/src/by-example/types-send-sync.md

@@ -0,0 +1,60 @@
+# Types, Send and Sync
+
+The `app` attribute injects a context, a collection of variables, into every
+function. All these variables have predictable, non-anonymous types so you can
+write plain functions that take them as arguments.
+
+The API reference specifies how these types are generated from the input. You
+can also generate documentation for you binary crate (`cargo doc --bin <name>`);
+in the documentation you'll find `Context` structs (e.g. `init::Context` and
+`idle::Context`) whose fields represent the variables injected into each
+function.
+
+The example below shows the different types generates by the `app` attribute.
+
+``` rust
+{{#include ../../../examples/types.rs}}
+```
+
+## `Send`
+
+[`Send`] is a marker trait for "types that can be transferred across thread
+boundaries", according to its definition in `core`. In the context of RTFM the
+`Send` trait is only required where it's possible to transfer a value between
+tasks that run at *different* priorities. This occurs in a few places: in message
+passing, in shared `static mut` resources and in the initialization of late
+resources.
+
+[`Send`]: https://doc.rust-lang.org/core/marker/trait.Send.html
+
+The `app` attribute will enforce that `Send` is implemented where required so
+you don't need to worry much about it. It's more important to know where you do
+*not* need the `Send` trait: on types that are transferred between tasks that
+run at the *same* priority. This occurs in two places: in message passing and in
+shared `static mut` resources.
+
+The example below shows where a type that doesn't implement `Send` can be used.
+
+``` rust
+{{#include ../../../examples/not-send.rs}}
+```
+
+## `Sync`
+
+Similarly, [`Sync`] is a marker trait for "types for which it is safe to share
+references between threads", according to its definition in `core`. In the
+context of RTFM the `Sync` trait is only required where it's possible for two,
+or more, tasks that run at different priority to hold a shared reference to a
+resource. This only occurs with shared `static` resources.
+
+[`Sync`]: https://doc.rust-lang.org/core/marker/trait.Sync.html
+
+The `app` attribute will enforce that `Sync` is implemented where required but
+it's important to know where the `Sync` bound is not required: in `static`
+resources shared between tasks that run at the *same* priority.
+
+The example below shows where a type that doesn't implement `Sync` can be used.
+
+``` rust
+{{#include ../../../examples/not-sync.rs}}
+```

book/src/internals.md

@@ -0,0 +1,6 @@
+# Under the hood
+
+This section describes the internals of the RTFM framework at a *high level*.
+Low level details like the parsing and code generation done by the procedural
+macro (`#[app]`) will not be explained here. The focus will be the analysis of
+the user specification and the data structures used by the runtime.

book/src/internals/ceilings.md

@@ -0,0 +1,3 @@
+# Ceiling analysis
+
+**TODO**

book/src/internals/tasks.md

@@ -0,0 +1,3 @@
+# Task dispatcher
+
+**TODO**

book/src/internals/timer-queue.md

@@ -0,0 +1,3 @@
+# Timer queue
+
+**TODO**

book/src/preface.md

@@ -0,0 +1,12 @@
+<h1 align="center">Real Time For the Masses</h1>
+
+<p align="center">A concurrency framework for building real time systems</p>
+
+# Preface
+
+This book contains user level documentation for the Real Time For the Masses
+(RTFM) framework. The API reference can be found [here](../api/rtfm/index.html).
+
+{{#include ../../README.md:5:53}}
+
+{{#include ../../README.md:59:}}

build.rs

@@ -3,8 +3,8 @@ use std::env;
 fn main() {
     let target = env::var("TARGET").unwrap();
 
-    if target.starts_with("thumbv6m-") {
-        println!("cargo:rustc-cfg=armv6m");
+    if target.starts_with("thumbv7m") | target.starts_with("thumbv7em") {
+        println!("cargo:rustc-cfg=armv7m")
     }
 
     println!("cargo:rerun-if-changed=build.rs");

ci/after-success.sh

@@ -1,20 +1,27 @@
 set -euxo pipefail
 
 main() {
-    cargo doc
+    rm -f .cargo/config
+    cargo doc --features timer-queue
+    ( cd book && mdbook build )
+
+    local td=$(mktemp -d)
+    cp -r target/doc $td/api
+    cp -r book/book $td/
+    cp LICENSE-* $td/book/
 
     mkdir ghp-import
-
     curl -Ls https://github.com/davisp/ghp-import/archive/master.tar.gz |
         tar --strip-components 1 -C ghp-import -xz
 
-    ./ghp-import/ghp_import.py target/doc
+    ./ghp-import/ghp_import.py $td
 
     set +x
     git push -fq https://$GH_TOKEN@github.com/$TRAVIS_REPO_SLUG.git gh-pages && echo OK
+
+    rm -rf $td
 }
 
-# only publish on successful merges to master
-if [ $TRAVIS_BRANCH = master ] && [ $TRAVIS_PULL_REQUEST = false ] && [ $TARGET = x86_64-unknown-linux-gnu ]; then
+if [ $TRAVIS_BRANCH = master ] && [ $TRAVIS_PULL_REQUEST = false ]; then
     main
 fi

ci/expected/baseline.run

@@ -0,0 +1,4 @@
+init(baseline = Instant(0))
+foo(baseline = Instant(0))
+UART0(baseline = Instant(904))
+foo(baseline = Instant(904))

ci/expected/capacity.run

@@ -0,0 +1,5 @@
+foo(0)
+foo(1)
+foo(2)
+foo(3)
+bar

ci/expected/idle.run

@@ -0,0 +1,2 @@
+init
+idle

ci/expected/init.run

@@ -0,0 +1 @@
+init

ci/expected/interrupt.run

@@ -0,0 +1,4 @@
+init
+UART0 called 1 time
+idle
+UART0 called 2 times

ci/expected/late.run

@@ -0,0 +1 @@
+received message: 42

ci/expected/lock.run

@@ -0,0 +1,5 @@
+A
+B - SHARED = 1
+C
+D - SHARED = 2
+E

ci/expected/message.run

@@ -0,0 +1,6 @@
+foo
+bar(0)
+baz(1, 2)
+foo
+bar(1)
+baz(2, 3)

ci/expected/periodic.run

@@ -0,0 +1,3 @@
+foo(scheduled = Instant(8000000), now = Instant(8000196))
+foo(scheduled = Instant(16000000), now = Instant(16000196))
+foo(scheduled = Instant(24000000), now = Instant(24000196))

ci/expected/ramfunc.grep.bar

@@ -0,0 +1,3 @@
+20000100 B bar::FREE_QUEUE::lk14244m263eivix
+200000dc B bar::INPUTS::mi89534s44r1mnj1
+20000000 T bar::ns9009yhw2dc2y25

ci/expected/ramfunc.grep.foo

@@ -0,0 +1,3 @@
+20000100 B foo::FREE_QUEUE::ujkptet2nfdw5t20
+200000dc B foo::INPUTS::thvubs85b91dg365
+000002c6 T foo::sidaht420cg1mcm8

ci/expected/ramfunc.run

@@ -0,0 +1 @@
+foo

ci/expected/resource.run

@@ -0,0 +1,2 @@
+UART0: SHARED = 1
+UART1: SHARED = 2

ci/expected/schedule.run

@@ -0,0 +1,3 @@
+init @ Instant(0)
+bar  @ Instant(4000236)
+foo  @ Instant(8000173)

ci/expected/singleton.run

@@ -0,0 +1,2 @@
+bar(2)
+foo(1)

ci/expected/static.run

@@ -0,0 +1,2 @@
+UART1(KEY = 0xdeadbeef)
+UART0(KEY = 0xdeadbeef)

ci/expected/task.run

@@ -0,0 +1,3 @@
+foo
+baz
+bar

ci/install.sh

@@ -5,9 +5,11 @@ main() {
         rustup target add $TARGET
     fi
 
-    mkdir gcc
-
-    curl -L https://developer.arm.com/-/media/Files/downloads/gnu-rm/7-2018q2/gcc-arm-none-eabi-7-2018-q2-update-linux.tar.bz2?revision=bc2c96c0-14b5-4bb4-9f18-bceb4050fee7?product=GNU%20Arm%20Embedded%20Toolchain,64-bit,,Linux,7-2018-q2-update | tar --strip-components=1 -C gcc -xj
+    mkdir qemu
+    curl -L https://github.com/japaric/qemu-bin/raw/master/14.04/qemu-system-arm-2.12.0 > qemu/qemu-system-arm
+    chmod +x qemu/qemu-system-arm
 }
 
-main
+if [ $TRAVIS_BRANCH != master ] || [ $TRAVIS_PULL_REQUEST != false ]; then
+    main
+fi

ci/script.sh

@@ -1,23 +1,95 @@
 set -euxo pipefail
 
 main() {
-    if [ $TARGET = x86_64-unknown-linux-gnu ]; then
-        cargo build
-        cargo test --test cfail
+    local T=$TARGET
+
+    if [ $T = x86_64-unknown-linux-gnu ]; then
+        # compile-fail and compile-pass tests
+        if [ $TRAVIS_RUST_VERSION = nightly ]; then
+            # TODO how to run a subset of these tests when timer-queue is disabled?
+            cargo test --features timer-queue --test compiletest --target $T
+        fi
+
+        cargo check --target $T
+        cargo check --features timer-queue --target $T
         return
     fi
 
-    case $TARGET in
-        thumbv7em-none-eabi*)
-            cargo check --target $TARGET --features cm7-r0p1
-            cargo check --target $TARGET --features cm7-r0p1 --examples
-        ;;
-    esac
+    cargo check --target $T --examples
+    cargo check --features timer-queue --target $T --examples
 
-    cargo check --target $TARGET
-    cargo check --target $TARGET --examples
+    # run-pass tests
+    case $T in
+        thumbv6m-none-eabi | thumbv7m-none-eabi)
+            local exs=(
+                idle
+                init
+                interrupt
+
+                resource
+                lock
+                late
+                static
+
+                task
+                message
+                capacity
+
+                singleton
+
+                types
+                not-send
+                not-sync
+
+                ramfunc
+            )
+
+            for ex in ${exs[@]}; do
+                if [ $ex = ramfunc ] && [ $T = thumbv6m-none-eabi ]; then
+                    # LLD doesn't support this at the moment
+                    continue
+                fi
+
+                if [ $ex != types ]; then
+                    cargo run --example $ex --target $T | \
+                        diff -u ci/expected/$ex.run -
+
+                    cargo run --example $ex --target $T --release | \
+                        diff -u ci/expected/$ex.run -
+                fi
+
+                cargo run --features timer-queue --example $ex --target $T | \
+                    diff -u ci/expected/$ex.run -
+
+                cargo run --features timer-queue --example $ex --target $T --release | \
+                    diff -u ci/expected/$ex.run -
+            done
+    esac
 }
 
-if [ $TRAVIS_BRANCH != master ]; then
+# fake Travis variables to be able to run this on a local machine
+if [ -z ${TRAVIS_BRANCH-} ]; then
+    TRAVIS_BRANCH=auto
+fi
+
+if [ -z ${TRAVIS_PULL_REQUEST-} ]; then
+    TRAVIS_PULL_REQUEST=false
+fi
+
+if [ -z ${TRAVIS_RUST_VERSION-} ]; then
+    case $(rustc -V) in
+        *nightly*)
+            TRAVIS_RUST_VERSION=nightly
+            ;;
+        *beta*)
+            TRAVIS_RUST_VERSION=beta
+            ;;
+        *)
+            TRAVIS_RUST_VERSION=stable
+            ;;
+    esac
+fi
+
+if [ $TRAVIS_BRANCH != master ] || [ $TRAVIS_PULL_REQUEST != false ]; then
     main
 fi

examples/baseline.rs

@@ -0,0 +1,61 @@
+//! examples/baseline.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+// NOTE: does NOT properly work on QEMU
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init(spawn = [foo])]
+    fn init() {
+        println!("init(baseline = {:?})", start);
+
+        // `foo` inherits the baseline of `init`: `Instant(0)`
+        spawn.foo().unwrap();
+    }
+
+    #[task(schedule = [foo])]
+    fn foo() {
+        static mut ONCE: bool = true;
+
+        println!("foo(baseline = {:?})", scheduled);
+
+        if *ONCE {
+            *ONCE = false;
+
+            rtfm::pend(Interrupt::UART0);
+        } else {
+            debug::exit(debug::EXIT_SUCCESS);
+        }
+    }
+
+    #[interrupt(spawn = [foo])]
+    fn UART0() {
+        println!("UART0(baseline = {:?})", start);
+
+        // `foo` inherits the baseline of `UART0`: its `start` time
+        spawn.foo().unwrap();
+    }
+
+    extern "C" {
+        fn UART1();
+    }
+};

examples/capacity.rs

@@ -0,0 +1,57 @@
+//! examples/capacity.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init(spawn = [foo])]
+    fn init() {
+        rtfm::pend(Interrupt::UART0);
+    }
+
+    #[interrupt(spawn = [foo, bar])]
+    fn UART0() {
+        spawn.foo(0).unwrap();
+        spawn.foo(1).unwrap();
+        spawn.foo(2).unwrap();
+        spawn.foo(3).unwrap();
+
+        spawn.bar().unwrap();
+    }
+
+    #[task(capacity = 4)]
+    fn foo(x: u32) {
+        println!("foo({})", x);
+    }
+
+    #[task]
+    fn bar() {
+        println!("bar");
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    // Interrupt handlers used to dispatch software tasks
+    extern "C" {
+        fn UART1();
+    }
+};

examples/custom-type.rs

@@ -1,49 +0,0 @@
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::{app, Threshold};
-
-pub struct Foo;
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        static CO_OWNED: Foo = Foo;
-        static ON: Foo = Foo;
-        static OWNED: Foo = Foo;
-        static SHARED: Foo = Foo;
-    },
-
-    idle: {
-        resources: [OWNED, SHARED],
-    },
-
-    tasks: {
-        SYS_TICK: {
-            path: sys_tick,
-            resources: [CO_OWNED, ON, SHARED],
-        },
-
-        TIM2: {
-            enabled: false,
-            path: tim2,
-            priority: 1,
-            resources: [CO_OWNED],
-        },
-    },
-}
-
-fn init(_p: ::init::Peripherals, _r: ::init::Resources) {}
-
-fn idle(_t: &mut Threshold, _r: ::idle::Resources) -> ! {
-    loop {}
-}
-
-fn sys_tick(_t: &mut Threshold, _r: SYS_TICK::Resources) {}
-
-fn tim2(_t: &mut Threshold, _r: TIM2::Resources) {}

examples/full-syntax.rs

@@ -1,83 +0,0 @@
-//! A showcase of the `app!` macro syntax
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::{app, Threshold};
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        static CO_OWNED: u32 = 0;
-        static ON: bool = false;
-        static OWNED: bool = false;
-        static SHARED: bool = false;
-    },
-
-    init: {
-        // This is the path to the `init` function
-        //
-        // `init` doesn't necessarily has to be in the root of the crate
-        path: main::init,
-    },
-
-    idle: {
-        // This is a path to the `idle` function
-        //
-        // `idle` doesn't necessarily has to be in the root of the crate
-        path: main::idle,
-        resources: [OWNED, SHARED],
-    },
-
-    tasks: {
-        SYS_TICK: {
-            path: sys_tick,
-            // If omitted priority is assumed to be 1
-            // priority: 1,
-            resources: [CO_OWNED, ON, SHARED],
-        },
-
-        TIM2: {
-            // Tasks are enabled, between `init` and `idle`, by default but they
-            // can start disabled if `false` is specified here
-            enabled: false,
-            path: tim2,
-            priority: 1,
-            resources: [CO_OWNED],
-        },
-    },
-}
-
-mod main {
-    use rtfm::{self, Resource, Threshold};
-
-    pub fn init(_p: ::init::Peripherals, _r: ::init::Resources) {}
-
-    pub fn idle(t: &mut Threshold, mut r: ::idle::Resources) -> ! {
-        loop {
-            *r.OWNED = !*r.OWNED;
-
-            if *r.OWNED {
-                if r.SHARED.claim(t, |shared, _| *shared) {
-                    rtfm::wfi();
-                }
-            } else {
-                r.SHARED.claim_mut(t, |shared, _| *shared = !*shared);
-            }
-        }
-    }
-}
-
-fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-    *r.ON = !*r.ON;
-
-    *r.CO_OWNED += 1;
-}
-
-fn tim2(_t: &mut Threshold, mut r: TIM2::Resources) {
-    *r.CO_OWNED += 1;
-}

examples/generics.rs

@@ -1,73 +0,0 @@
-//! Working with resources in a generic fashion
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::{app, Resource, Threshold};
-use stm32f103xx::{GPIOA, SPI1};
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        static GPIOA: GPIOA;
-        static SPI1: SPI1;
-    },
-
-    tasks: {
-        EXTI0: {
-            path: exti0,
-            priority: 1,
-            resources: [GPIOA, SPI1],
-        },
-
-        EXTI1: {
-            path: exti1,
-            priority: 2,
-            resources: [GPIOA, SPI1],
-        },
-    },
-}
-
-fn init(p: init::Peripherals) -> init::LateResources {
-    init::LateResources {
-        GPIOA: p.device.GPIOA,
-        SPI1: p.device.SPI1,
-    }
-}
-
-fn idle() -> ! {
-    loop {
-        rtfm::wfi();
-    }
-}
-
-// A generic function that uses some resources
-fn work<G, S>(t: &mut Threshold, gpioa: &G, spi1: &S)
-where
-    G: Resource<Data = GPIOA>,
-    S: Resource<Data = SPI1>,
-{
-    gpioa.claim(t, |_gpioa, t| {
-        // drive NSS low
-
-        spi1.claim(t, |_spi1, _| {
-            // transfer data
-        });
-
-        // drive NSS high
-    });
-}
-
-// This task needs critical sections to access the resources
-fn exti0(t: &mut Threshold, r: EXTI0::Resources) {
-    work(t, &r.GPIOA, &r.SPI1);
-}
-
-// This task has direct access to the resources
-fn exti1(t: &mut Threshold, r: EXTI1::Resources) {
-    work(t, &r.GPIOA, &r.SPI1);
-}

examples/idle.rs

@@ -0,0 +1,43 @@
+//! examples/idle.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init]
+    fn init() {
+        println!("init");
+    }
+
+    #[idle]
+    fn idle() -> ! {
+        static mut X: u32 = 0;
+
+        // Safe access to local `static mut` variable
+        let _x: &'static mut u32 = X;
+
+        println!("idle");
+
+        debug::exit(debug::EXIT_SUCCESS);
+
+        loop {}
+    }
+};

examples/init.rs

@@ -0,0 +1,44 @@
+//! examples/init.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use rtfm::app;
+
+// NOTE: This convenience macro will appear in all the other examples and
+// will always look the same
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init]
+    fn init() {
+        static mut X: u32 = 0;
+
+        // Cortex-M peripherals
+        let _core: rtfm::Peripherals = core;
+
+        // Device specific peripherals
+        let _device: lm3s6965::Peripherals = device;
+
+        // Safe access to local `static mut` variable
+        let _x: &'static mut u32 = X;
+
+        println!("init");
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+};

examples/interrupt.rs

@@ -0,0 +1,61 @@
+//! examples/interrupt.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init]
+    fn init() {
+        // Pends the UART0 interrupt but its handler won't run until *after*
+        // `init` returns because interrupts are disabled
+        rtfm::pend(Interrupt::UART0);
+
+        println!("init");
+    }
+
+    #[idle]
+    fn idle() -> ! {
+        // interrupts are enabled again; the `UART0` handler runs at this point
+
+        println!("idle");
+
+        rtfm::pend(Interrupt::UART0);
+
+        debug::exit(debug::EXIT_SUCCESS);
+
+        loop {}
+    }
+
+    #[interrupt]
+    fn UART0() {
+        static mut TIMES: u32 = 0;
+
+        // Safe access to local `static mut` variable
+        *TIMES += 1;
+
+        println!(
+            "UART0 called {} time{}",
+            *TIMES,
+            if *TIMES > 1 { "s" } else { "" }
+        );
+    }
+};

examples/late-resources.rs

@@ -1,86 +0,0 @@
-//! Demonstrates initialization of resources in `init`.
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::{app, Threshold};
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        // Usually, resources are initialized with a constant initializer:
-        static ON: bool = false;
-
-        // However, there are cases where this is not possible or not desired.
-        // For example, there may not be a sensible value to use, or the type may
-        // not be constructible in a constant (like `Vec`).
-        //
-        // While it is possible to use an `Option` in some cases, that requires
-        // you to properly initialize it and `.unwrap()` it at every use. It
-        // also consumes more memory.
-        //
-        // To solve this, it is possible to defer initialization of resources to
-        // `init` by omitting the initializer. Doing that will require `init` to
-        // return the values of all "late" resources.
-        static IP_ADDRESS: u32;
-
-        // PORT is used by 2 tasks, making it a shared resource. This just tests
-        // another internal code path and is not important for the example.
-        static PORT: u16;
-    },
-
-    idle: {
-        // Test that late resources can be used in idle
-        resources: [IP_ADDRESS],
-    },
-
-    tasks: {
-        SYS_TICK: {
-            priority: 1,
-            path: sys_tick,
-            resources: [IP_ADDRESS, PORT, ON],
-        },
-
-        EXTI0: {
-            priority: 2,
-            path: exti0,
-            resources: [PORT],
-        }
-    }
-}
-
-// The signature of `init` is now required to have a specific return type.
-fn init(_p: init::Peripherals, _r: init::Resources) -> init::LateResources {
-    // `init::Resources` does not contain `IP_ADDRESS`, since it is not yet
-    // initialized.
-    //_r.IP_ADDRESS;     // doesn't compile
-
-    // ...obtain value for IP_ADDRESS from EEPROM/DHCP...
-    let ip_address = 0x7f000001;
-
-    init::LateResources {
-        // This struct will contain fields for all resources with omitted
-        // initializers.
-        IP_ADDRESS: ip_address,
-        PORT: 0,
-    }
-}
-
-fn sys_tick(_t: &mut Threshold, r: SYS_TICK::Resources) {
-    // Other tasks can access late resources like any other, since they are
-    // guaranteed to be initialized when tasks are run.
-
-    r.IP_ADDRESS;
-}
-
-fn exti0(_t: &mut Threshold, _r: EXTI0::Resources) {}
-
-fn idle(_t: &mut Threshold, _r: idle::Resources) -> ! {
-    loop {
-        rtfm::wfi();
-    }
-}

examples/late.rs

@@ -0,0 +1,65 @@
+//! examples/late.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use heapless::{
+    consts::*,
+    spsc::{Consumer, Producer, Queue},
+};
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    // Late resources
+    static mut P: Producer<'static, u32, U4> = ();
+    static mut C: Consumer<'static, u32, U4> = ();
+
+    #[init]
+    fn init() {
+        // NOTE: we use `Option` here to work around the lack of
+        // a stable `const` constructor
+        static mut Q: Option<Queue<u32, U4>> = None;
+
+        *Q = Some(Queue::new());
+        let (p, c) = Q.as_mut().unwrap().split();
+
+        // Initialization of late resources
+        P = p;
+        C = c;
+    }
+
+    #[idle(resources = [C])]
+    fn idle() -> ! {
+        loop {
+            if let Some(byte) = resources.C.dequeue() {
+                println!("received message: {}", byte);
+
+                debug::exit(debug::EXIT_SUCCESS);
+            } else {
+                rtfm::pend(Interrupt::UART0);
+            }
+        }
+    }
+
+    #[interrupt(resources = [P])]
+    fn UART0() {
+        resources.P.enqueue(42).unwrap();
+    }
+};

examples/lock.rs

@@ -0,0 +1,71 @@
+//! examples/lock.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    static mut SHARED: u32 = 0;
+
+    #[init]
+    fn init() {
+        rtfm::pend(Interrupt::GPIOA);
+    }
+
+    // when omitted priority is assumed to be `1`
+    #[interrupt(resources = [SHARED])]
+    fn GPIOA() {
+        println!("A");
+
+        // the lower priority task requires a critical section to access the data
+        resources.SHARED.lock(|shared| {
+            // data can only be modified within this critical section (closure)
+            *shared += 1;
+
+            // GPIOB will *not* run right now due to the critical section
+            rtfm::pend(Interrupt::GPIOB);
+
+            println!("B - SHARED = {}", *shared);
+
+            // GPIOC does not contend for `SHARED` so it's allowed to run now
+            rtfm::pend(Interrupt::GPIOC);
+        });
+
+        // critical section is over: GPIOB can now start
+
+        println!("E");
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[interrupt(priority = 2, resources = [SHARED])]
+    fn GPIOB() {
+        // the higher priority task does *not* need a critical section
+        *resources.SHARED += 1;
+
+        println!("D - SHARED = {}", *resources.SHARED);
+    }
+
+    #[interrupt(priority = 3)]
+    fn GPIOC() {
+        println!("C");
+    }
+};

examples/message.rs

@@ -0,0 +1,61 @@
+//! examples/message.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init(spawn = [foo])]
+    fn init() {
+        spawn.foo(/* no message */).unwrap();
+    }
+
+    #[task(spawn = [bar])]
+    fn foo() {
+        static mut COUNT: u32 = 0;
+
+        println!("foo");
+
+        spawn.bar(*COUNT).unwrap();
+        *COUNT += 1;
+    }
+
+    #[task(spawn = [baz])]
+    fn bar(x: u32) {
+        println!("bar({})", x);
+
+        spawn.baz(x + 1, x + 2).unwrap();
+    }
+
+    #[task(spawn = [foo])]
+    fn baz(x: u32, y: u32) {
+        println!("baz({}, {})", x, y);
+
+        if x + y > 4 {
+            debug::exit(debug::EXIT_SUCCESS);
+        }
+
+        spawn.foo().unwrap();
+    }
+
+    extern "C" {
+        fn UART0();
+    }
+};

examples/nested.rs

@@ -1,128 +0,0 @@
-//! Nesting claims and how the preemption threshold works
-//!
-//! If you run this program you'll hit the breakpoints as indicated by the
-//! letters in the comments: A, then B, then C, etc.
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::{app, Resource, Threshold};
-use stm32f103xx::Interrupt;
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        static LOW: u64 = 0;
-        static HIGH: u64 = 0;
-    },
-
-    tasks: {
-        EXTI0: {
-            path: exti0,
-            priority: 1,
-            resources: [LOW, HIGH],
-        },
-
-        EXTI1: {
-            path: exti1,
-            priority: 2,
-            resources: [LOW],
-        },
-
-        EXTI2: {
-            path: exti2,
-            priority: 3,
-            resources: [HIGH],
-        },
-    },
-}
-
-fn init(_p: init::Peripherals, _r: init::Resources) {}
-
-fn idle() -> ! {
-    // A
-    rtfm::bkpt();
-
-    // Sets task `exti0` as pending
-    //
-    // Because `exti0` has higher priority than `idle` it will be executed
-    // immediately
-    rtfm::set_pending(Interrupt::EXTI0); // ~> exti0
-
-    loop {
-        rtfm::wfi();
-    }
-}
-
-#[allow(non_snake_case)]
-fn exti0(
-    t: &mut Threshold,
-    EXTI0::Resources {
-        LOW: mut low,
-        HIGH: mut high,
-    }: EXTI0::Resources,
-) {
-    // Because this task has a priority of 1 the preemption threshold `t` also
-    // starts at 1
-
-    // B
-    rtfm::bkpt();
-
-    // Because `exti1` has higher priority than `exti0` it can preempt it
-    rtfm::set_pending(Interrupt::EXTI1); // ~> exti1
-
-    // A claim creates a critical section
-    low.claim_mut(t, |_low, t| {
-        // This claim increases the preemption threshold to 2
-        //
-        // 2 is just high enough to not race with task `exti1` for access to the
-        // `LOW` resource
-
-        // D
-        rtfm::bkpt();
-
-        // Now `exti1` can't preempt this task because its priority is equal to
-        // the current preemption threshold
-        rtfm::set_pending(Interrupt::EXTI1);
-
-        // But `exti2` can, because its priority is higher than the current
-        // preemption threshold
-        rtfm::set_pending(Interrupt::EXTI2); // ~> exti2
-
-        // F
-        rtfm::bkpt();
-
-        // Claims can be nested
-        high.claim_mut(t, |_high, _| {
-            // This claim increases the preemption threshold to 3
-
-            // Now `exti2` can't preempt this task
-            rtfm::set_pending(Interrupt::EXTI2);
-
-            // G
-            rtfm::bkpt();
-        });
-
-        // Upon leaving the critical section the preemption threshold drops back
-        // to 2 and `exti2` immediately preempts this task
-        // ~> exti2
-    });
-
-    // Once again the preemption threshold drops but this time to 1. Now the
-    // pending `exti1` task can preempt this task
-    // ~> exti1
-}
-
-fn exti1(_t: &mut Threshold, _r: EXTI1::Resources) {
-    // C, I
-    rtfm::bkpt();
-}
-
-fn exti2(_t: &mut Threshold, _r: EXTI2::Resources) {
-    // E, H
-    rtfm::bkpt();
-}

examples/not-send.rs

@@ -0,0 +1,58 @@
+//! `examples/not-send.rs`
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_halt;
+
+use core::marker::PhantomData;
+
+use cortex_m_semihosting::debug;
+use rtfm::app;
+
+pub struct NotSend {
+    _0: PhantomData<*const ()>,
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    static mut SHARED: Option<NotSend> = None;
+
+    #[init(spawn = [baz, quux])]
+    fn init() {
+        spawn.baz().unwrap();
+        spawn.quux().unwrap();
+    }
+
+    #[task(spawn = [bar])]
+    fn foo() {
+        // scenario 1: message passed to task that runs at the same priority
+        spawn.bar(NotSend { _0: PhantomData }).ok();
+    }
+
+    #[task]
+    fn bar(_x: NotSend) {
+        // scenario 1
+    }
+
+    #[task(priority = 2, resources = [SHARED])]
+    fn baz() {
+        // scenario 2: resource shared between tasks that run at the same priority
+        *resources.SHARED = Some(NotSend { _0: PhantomData });
+    }
+
+    #[task(priority = 2, resources = [SHARED])]
+    fn quux() {
+        // scenario 2
+        let _not_send = resources.SHARED.take().unwrap();
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    extern "C" {
+        fn UART0();
+        fn UART1();
+    }
+};

examples/not-sync.rs

@@ -0,0 +1,41 @@
+//! `examples/not-sync.rs`
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_halt;
+
+use core::marker::PhantomData;
+
+use cortex_m_semihosting::debug;
+use rtfm::app;
+
+pub struct NotSync {
+    _0: PhantomData<*const ()>,
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    static SHARED: NotSync = NotSync { _0: PhantomData };
+
+    #[init]
+    fn init() {
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[task(resources = [SHARED])]
+    fn foo() {
+        let _: &NotSync = resources.SHARED;
+    }
+
+    #[task(resources = [SHARED])]
+    fn bar() {
+        let _: &NotSync = resources.SHARED;
+    }
+
+    extern "C" {
+        fn UART0();
+    }
+};

examples/one-task.rs

@@ -1,96 +0,0 @@
-//! An application with one task
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m;
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use cortex_m::peripheral::syst::SystClkSource;
-use rtfm::{app, Threshold};
-use stm32f103xx::GPIOC;
-
-app! {
-    device: stm32f103xx,
-
-    // Here data resources are declared
-    //
-    // Data resources are static variables that are safe to share across tasks
-    resources: {
-        // Declaration of resources looks exactly like declaration of static
-        // variables
-        static ON: bool = false;
-    },
-
-    // Here tasks are declared
-    //
-    // Each task corresponds to an interrupt or an exception. Every time the
-    // interrupt or exception becomes *pending* the corresponding task handler
-    // will be executed.
-    tasks: {
-        // Here we declare that we'll use the SYS_TICK exception as a task
-        SYS_TICK: {
-            // Path to the task handler
-            path: sys_tick,
-
-            // These are the resources this task has access to.
-            //
-            // The resources listed here must also appear in `app.resources`
-            resources: [ON],
-        },
-    }
-}
-
-fn init(mut p: init::Peripherals, r: init::Resources) {
-    // `init` can modify all the `resources` declared in `app!`
-    r.ON;
-
-    // power on GPIOC
-    p.device.RCC.apb2enr.modify(|_, w| w.iopcen().enabled());
-
-    // configure PC13 as output
-    p.device.GPIOC.bsrr.write(|w| w.bs13().set());
-    p.device
-        .GPIOC
-        .crh
-        .modify(|_, w| w.mode13().output().cnf13().push());
-
-    // configure the system timer to generate one interrupt every second
-    p.core.SYST.set_clock_source(SystClkSource::Core);
-    p.core.SYST.set_reload(8_000_000); // 1s
-    p.core.SYST.enable_interrupt();
-    p.core.SYST.enable_counter();
-}
-
-fn idle() -> ! {
-    loop {
-        rtfm::wfi();
-    }
-}
-
-// This is the task handler of the SYS_TICK exception
-//
-// `_t` is the preemption threshold token. We won't use it in this program.
-//
-// `r` is the set of resources this task has access to. `SYS_TICK::Resources`
-// has one field per resource declared in `app!`.
-#[allow(unsafe_code)]
-fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-    // toggle state
-    *r.ON = !*r.ON;
-
-    if *r.ON {
-        // set the pin PC13 high
-        // NOTE(unsafe) atomic write to a stateless register
-        unsafe {
-            (*GPIOC::ptr()).bsrr.write(|w| w.bs13().set());
-        }
-    } else {
-        // set the pin PC13 low
-        // NOTE(unsafe) atomic write to a stateless register
-        unsafe {
-            (*GPIOC::ptr()).bsrr.write(|w| w.br13().reset());
-        }
-    }
-}

examples/periodic.rs

@@ -0,0 +1,43 @@
+//! examples/periodic.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use rtfm::{app, Instant};
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+const PERIOD: u32 = 8_000_000;
+
+// NOTE: does NOT work on QEMU!
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init(schedule = [foo])]
+    fn init() {
+        schedule.foo(Instant::now() + PERIOD.cycles()).unwrap();
+    }
+
+    #[task(schedule = [foo])]
+    fn foo() {
+        let now = Instant::now();
+        println!("foo(scheduled = {:?}, now = {:?})", scheduled, now);
+
+        schedule.foo(scheduled + PERIOD.cycles()).unwrap();
+    }
+
+    extern "C" {
+        fn UART0();
+    }
+};

examples/preemption.rs

@@ -1,67 +0,0 @@
-//! Two tasks running at *different* priorities with access to the same resource
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::{app, Resource, Threshold};
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        static COUNTER: u64 = 0;
-    },
-
-    tasks: {
-        // The `SYS_TICK` task has higher priority than `TIM2`
-        SYS_TICK: {
-            path: sys_tick,
-            priority: 2,
-            resources: [COUNTER],
-        },
-
-        TIM2: {
-            path: tim2,
-            priority: 1,
-            resources: [COUNTER],
-        },
-    },
-}
-
-fn init(_p: init::Peripherals, _r: init::Resources) {
-    // ..
-}
-
-fn idle() -> ! {
-    loop {
-        rtfm::wfi();
-    }
-}
-
-fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-    // ..
-
-    // This task can't be preempted by `tim2` so it has direct access to the
-    // resource data
-    *r.COUNTER += 1;
-
-    // ..
-}
-
-fn tim2(t: &mut Threshold, mut r: TIM2::Resources) {
-    // ..
-
-    // As this task runs at lower priority it needs a critical section to
-    // prevent `sys_tick` from preempting it while it modifies this resource
-    // data. The critical section is required to prevent data races which can
-    // lead to undefined behavior.
-    r.COUNTER.claim_mut(t, |counter, _t| {
-        // `claim_mut` creates a critical section
-        *counter += 1;
-    });
-
-    // ..
-}

examples/ramfunc.rs

@@ -0,0 +1,53 @@
+//! examples/ramfunc.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init(spawn = [bar])]
+    fn init() {
+        spawn.bar().unwrap();
+    }
+
+    #[inline(never)]
+    #[task]
+    fn foo() {
+        println!("foo");
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    // run this task from RAM
+    #[inline(never)]
+    #[link_section = ".data.bar"]
+    #[task(priority = 2, spawn = [foo])]
+    fn bar() {
+        spawn.foo().unwrap();
+    }
+
+    extern "C" {
+        fn UART0();
+
+        // run the task dispatcher from RAM
+        #[link_section = ".data.UART1"]
+        fn UART1();
+    }
+};

examples/resource.rs

@@ -0,0 +1,60 @@
+//! examples/resource.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    // A resource
+    static mut SHARED: u32 = 0;
+
+    #[init]
+    fn init() {
+        rtfm::pend(Interrupt::UART0);
+        rtfm::pend(Interrupt::UART1);
+    }
+
+    #[idle]
+    fn idle() -> ! {
+        debug::exit(debug::EXIT_SUCCESS);
+
+        // error: `SHARED` can't be accessed from this context
+        // SHARED += 1;
+
+        loop {}
+    }
+
+    // `SHARED` can be access from this context
+    #[interrupt(resources = [SHARED])]
+    fn UART0() {
+        *resources.SHARED += 1;
+
+        println!("UART0: SHARED = {}", resources.SHARED);
+    }
+
+    // `SHARED` can be access from this context
+    #[interrupt(resources = [SHARED])]
+    fn UART1() {
+        *resources.SHARED += 1;
+
+        println!("UART1: SHARED = {}", resources.SHARED);
+    }
+};

examples/safe-static-mut-ref.rs

@@ -1,31 +0,0 @@
-//! Safe creation of `&'static mut` references
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::app;
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        static BUFFER: [u8; 16] = [0; 16];
-    },
-
-    init: {
-        resources: [BUFFER],
-    },
-}
-
-fn init(_p: init::Peripherals, r: init::Resources) {
-    let _buf: &'static mut [u8; 16] = r.BUFFER;
-}
-
-fn idle() -> ! {
-    loop {
-        rtfm::wfi();
-    }
-}

examples/schedule.rs

@@ -0,0 +1,51 @@
+//! examples/schedule.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use rtfm::{app, Instant};
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+// NOTE: does NOT work on QEMU!
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init(schedule = [foo, bar])]
+    fn init() {
+        let now = Instant::now();
+
+        println!("init @ {:?}", now);
+
+        // Schedule `foo` to run 8e6 cycles (clock cycles) in the future
+        schedule.foo(now + 8_000_000.cycles()).unwrap();
+
+        // Schedule `bar` to run 4e6 cycles in the future
+        schedule.bar(now + 4_000_000.cycles()).unwrap();
+    }
+
+    #[task]
+    fn foo() {
+        println!("foo  @ {:?}", Instant::now());
+    }
+
+    #[task]
+    fn bar() {
+        println!("bar  @ {:?}", Instant::now());
+    }
+
+    extern "C" {
+        fn UART0();
+    }
+};

examples/singleton.rs

@@ -0,0 +1,69 @@
+//! examples/singleton.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use alloc_singleton::stable::pool::{Box, Pool};
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[Singleton(Send)]
+    static mut M: [u32; 2] = [0; 2];
+
+    static mut P: Pool<M> = ();
+
+    #[init(resources = [M])]
+    fn init() {
+        rtfm::pend(Interrupt::I2C0);
+
+        P = Pool::new(resources.M);
+    }
+
+    #[interrupt(
+        priority = 2,
+        resources = [P],
+        spawn = [foo, bar],
+    )]
+    fn I2C0() {
+        spawn.foo(resources.P.alloc(1).unwrap()).unwrap();
+        spawn.bar(resources.P.alloc(2).unwrap()).unwrap();
+    }
+
+    #[task(resources = [P])]
+    fn foo(x: Box<M>) {
+        println!("foo({})", x);
+
+        resources.P.lock(|p| p.dealloc(x));
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[task(priority = 2, resources = [P])]
+    fn bar(x: Box<M>) {
+        println!("bar({})", x);
+
+        resources.P.dealloc(x);
+    }
+
+    extern "C" {
+        fn UART0();
+        fn UART1();
+    }
+};

examples/smallest.rs

@@ -0,0 +1,17 @@
+//! examples/smallest.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+// panic-handler crate
+extern crate panic_semihosting;
+
+use rtfm::app;
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init]
+    fn init() {}
+};

examples/static.rs

@@ -0,0 +1,47 @@
+//! examples/static.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    static KEY: u32 = ();
+
+    #[init]
+    fn init() {
+        rtfm::pend(Interrupt::UART0);
+        rtfm::pend(Interrupt::UART1);
+
+        KEY = 0xdeadbeef;
+    }
+
+    #[interrupt(resources = [KEY])]
+    fn UART0() {
+        println!("UART0(KEY = {:#x})", resources.KEY);
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[interrupt(priority = 2, resources = [KEY])]
+    fn UART1() {
+        println!("UART1(KEY = {:#x})", resources.KEY);
+    }
+};

examples/task.rs

@@ -0,0 +1,61 @@
+//! examples/task.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use rtfm::app;
+
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init(spawn = [foo])]
+    fn init() {
+        spawn.foo().unwrap();
+    }
+
+    #[task(spawn = [bar, baz])]
+    fn foo() {
+        println!("foo");
+
+        // spawns `bar` onto the task scheduler
+        // `foo` and `bar` have the same priority so `bar` will not run until
+        // after `foo` terminates
+        spawn.bar().unwrap();
+
+        // spawns `baz` onto the task scheduler
+        // `baz` has higher priority than `foo` so it immediately preempts `foo`
+        spawn.baz().unwrap();
+    }
+
+    #[task]
+    fn bar() {
+        println!("bar");
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[task(priority = 2)]
+    fn baz() {
+        println!("baz");
+    }
+
+    // Interrupt handlers used to dispatch software tasks
+    extern "C" {
+        fn UART0();
+        fn UART1();
+    }
+};

examples/two-tasks.rs

@@ -1,58 +0,0 @@
-//! Two tasks running at the *same* priority with access to the same resource
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm;
-extern crate stm32f103xx;
-
-use rtfm::{app, Threshold};
-
-app! {
-    device: stm32f103xx,
-
-    resources: {
-        static COUNTER: u64 = 0;
-    },
-
-    // Both SYS_TICK and TIM2 have access to the `COUNTER` data
-    tasks: {
-        SYS_TICK: {
-            path: sys_tick,
-            resources: [COUNTER],
-        },
-
-        TIM2: {
-            path: tim2,
-            resources: [COUNTER],
-        },
-    },
-}
-
-fn init(_p: init::Peripherals, _r: init::Resources) {
-    // ..
-}
-
-fn idle() -> ! {
-    loop {
-        rtfm::wfi();
-    }
-}
-
-// As both tasks are running at the same priority one can't preempt the other.
-// Thus both tasks have direct access to the resource
-fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-    // ..
-
-    *r.COUNTER += 1;
-
-    // ..
-}
-
-fn tim2(_t: &mut Threshold, mut r: TIM2::Resources) {
-    // ..
-
-    *r.COUNTER += 1;
-
-    // ..
-}

examples/types.rs

@@ -0,0 +1,54 @@
+//! examples/types.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use rtfm::{app, Instant};
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    static mut SHARED: u32 = 0;
+
+    #[init(schedule = [foo], spawn = [foo])]
+    fn init() {
+        let _: Instant = start;
+        let _: rtfm::Peripherals = core;
+        let _: lm3s6965::Peripherals = device;
+        let _: init::Schedule = schedule;
+        let _: init::Spawn = spawn;
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[exception(schedule = [foo], spawn = [foo])]
+    fn SVCall() {
+        let _: Instant = start;
+        let _: SVCall::Schedule = schedule;
+        let _: SVCall::Spawn = spawn;
+    }
+
+    #[interrupt(resources = [SHARED], schedule = [foo], spawn = [foo])]
+    fn UART0() {
+        let _: Instant = start;
+        let _: resources::SHARED = resources.SHARED;
+        let _: UART0::Schedule = schedule;
+        let _: UART0::Spawn = spawn;
+    }
+
+    #[task(priority = 2, resources = [SHARED], schedule = [foo], spawn = [foo])]
+    fn foo() {
+        let _: Instant = scheduled;
+        let _: foo::Resources = resources;
+        let _: foo::Schedule = schedule;
+        let _: foo::Spawn = spawn;
+    }
+
+    extern "C" {
+        fn UART1();
+    }
+};

examples/zero-tasks.rs

@@ -1,43 +0,0 @@
-//! Minimal example with zero tasks
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_std]
-
-extern crate cortex_m_rtfm as rtfm; // IMPORTANT always do this rename
-extern crate stm32f103xx; // the device crate
-
-// import the procedural macro
-use rtfm::app;
-
-// This macro call indicates that this is a RTFM application
-//
-// This macro will expand to a `main` function so you don't need to supply
-// `main` yourself.
-app! {
-    // this is the path to the device crate
-    device: stm32f103xx,
-}
-
-// The initialization phase.
-//
-// This runs first and within a *global* critical section. Nothing can preempt
-// this function.
-fn init(p: init::Peripherals) {
-    // This function has access to all the peripherals of the device
-    p.core.SYST;
-    p.device.GPIOA;
-    p.device.RCC;
-    // ..
-}
-
-// The idle loop.
-//
-// This runs after `init` and has a priority of 0. All tasks can preempt this
-// function. This function can never return so it must contain some sort of
-// endless loop.
-fn idle() -> ! {
-    loop {
-        // This puts the processor to sleep until there's a task to service
-        rtfm::wfi();
-    }
-}

gen-examples.sh

@@ -1,57 +0,0 @@
-# Converts the examples in the `examples` directory into documentation in the
-# `examples` module (`src/examples/*.rs`)
-
-set -ex
-
-main() {
-    local examples=(
-        zero-tasks
-        one-task
-        two-tasks
-        preemption
-        nested
-        late-resources
-        safe-static-mut-ref
-        generics
-        full-syntax
-    )
-
-    rm -rf src/examples
-
-    mkdir src/examples
-
-    cat >src/examples/mod.rs <<'EOF'
-//! Examples
-// Auto-generated. Do not modify.
-EOF
-
-    local i=0 out=
-    for ex in ${examples[@]}; do
-        name=_${i}_${ex//-/_}
-        out=src/examples/${name}.rs
-
-        echo "pub mod $name;" >> src/examples/mod.rs
-
-        grep '//!' examples/$ex.rs > $out
-        echo '//!' >> $out
-        echo '//! ```' >> $out
-        grep -v '//!' examples/$ex.rs | (
-            IFS=''
-
-            while read line; do
-                echo "//! $line" >> $out;
-            done
-        )
-        echo '//! ```' >> $out
-        echo '// Auto-generated. Do not modify.' >> $out
-
-
-        chmod -x $out
-
-        i=$(( i + 1 ))
-    done
-
-    chmod -x src/examples/mod.rs
-}
-
-main

macros/Cargo.toml

@@ -2,19 +2,28 @@
 authors = ["Jorge Aparicio <jorge@japaric.io>"]
 categories = ["concurrency", "embedded", "no-std"]
 description = "Procedural macros of the cortex-m-rtfm crate"
-documentation = "https://docs.rs/cortex-m-rtfm-macros"
+documentation = "https://japaric.github.io/cortex-m-rtfm/api/cortex_m_rtfm"
 keywords = ["arm", "cortex-m"]
 license = "MIT OR Apache-2.0"
 name = "cortex-m-rtfm-macros"
+readme = "../README.md"
 repository = "https://github.com/japaric/cortex-m-rtfm"
-version = "0.3.2"
-
-[dependencies]
-failure = "0.1.1"
-proc-macro2 = "0.4.6"
-quote = "0.6.3"
-rtfm-syntax = "0.3.4"
-syn = "0.14.2"
+version = "0.4.0-beta.1"
 
 [lib]
 proc-macro = true
+
+[dependencies]
+quote = "0.6.8"
+proc-macro2 = "0.4.20"
+
+[dependencies.syn]
+features = ["extra-traits", "full"]
+version = "0.15.6"
+
+[dependencies.rand]
+default-features = false
+version = "0.5.5"
+
+[features]
+timer-queue = []

macros/src/analyze.rs

@@ -1,77 +1,243 @@
-use std::cmp;
-use std::collections::HashMap;
+use std::{
+    cmp,
+    collections::{HashMap, HashSet},
+};
 
-use syn::Ident;
+use syn::{Attribute, Ident, Type};
 
-use check::App;
+use syntax::{App, Idents};
 
 pub type Ownerships = HashMap<Ident, Ownership>;
 
+pub struct Analysis {
+    /// Capacities of free queues
+    pub capacities: Capacities,
+    pub dispatchers: Dispatchers,
+    // Ceilings of free queues
+    pub free_queues: HashMap<Ident, u8>,
+    pub resources_assert_send: HashSet<Box<Type>>,
+    pub tasks_assert_send: HashSet<Ident>,
+    /// Types of RO resources that need to be Sync
+    pub assert_sync: HashSet<Box<Type>>,
+    // Resource ownership
+    pub ownerships: Ownerships,
+    // Ceilings of ready queues
+    pub ready_queues: HashMap<u8, u8>,
+    pub timer_queue: TimerQueue,
+}
+
+#[derive(Clone, Copy, PartialEq)]
 pub enum Ownership {
-    /// Owned or co-owned by tasks that run at the same priority
+    // NOTE priorities and ceilings are "logical" (0 = lowest priority, 255 = highest priority)
     Owned { priority: u8 },
-    /// Shared by tasks that run at different priorities.
-    ///
-    /// `ceiling` is the maximum value across all the task priorities
     Shared { ceiling: u8 },
 }
 
 impl Ownership {
-    pub fn ceiling(&self) -> u8 {
+    pub fn needs_lock(&self, priority: u8) -> bool {
         match *self {
-            Ownership::Owned { priority } => priority,
-            Ownership::Shared { ceiling } => ceiling,
-        }
-    }
+            Ownership::Owned { .. } => false,
+            Ownership::Shared { ceiling } => {
+                debug_assert!(ceiling >= priority);
 
-    pub fn is_owned(&self) -> bool {
-        match *self {
-            Ownership::Owned { .. } => true,
-            _ => false,
+                priority < ceiling
+            }
         }
     }
 }
 
-pub fn app(app: &App) -> Ownerships {
-    let mut ownerships = HashMap::new();
+pub struct Dispatcher {
+    /// Attributes to apply to the dispatcher
+    pub attrs: Vec<Attribute>,
+    pub interrupt: Ident,
+    /// Tasks dispatched at this priority level
+    pub tasks: Vec<Ident>,
+    // Queue capacity
+    pub capacity: u8,
+}
 
-    for resource in &app.idle.resources {
-        ownerships.insert(resource.clone(), Ownership::Owned { priority: 0 });
-    }
+/// Priority -> Dispatcher
+pub type Dispatchers = HashMap<u8, Dispatcher>;
 
-    for task in app.tasks.values() {
-        for resource in task.resources.iter() {
-            if let Some(ownership) = ownerships.get_mut(resource) {
-                match *ownership {
-                    Ownership::Owned { priority } => {
-                        if priority == task.priority {
-                            *ownership = Ownership::Owned { priority };
-                        } else {
-                            *ownership = Ownership::Shared {
-                                ceiling: cmp::max(priority, task.priority),
-                            };
-                        }
-                    }
-                    Ownership::Shared { ceiling } => {
-                        if task.priority > ceiling {
-                            *ownership = Ownership::Shared {
-                                ceiling: task.priority,
-                            };
+pub type Capacities = HashMap<Ident, u8>;
+
+pub fn app(app: &App) -> Analysis {
+    // Ceiling analysis of R/W resource and Sync analysis of RO resources
+    // (Resource shared by tasks that run at different priorities need to be `Sync`)
+    let mut ownerships = Ownerships::new();
+    let mut resources_assert_send = HashSet::new();
+    let mut tasks_assert_send = HashSet::new();
+    let mut assert_sync = HashSet::new();
+
+    for (priority, res) in app.resource_accesses() {
+        if let Some(ownership) = ownerships.get_mut(res) {
+            match *ownership {
+                Ownership::Owned { priority: ceiling } | Ownership::Shared { ceiling } => {
+                    if priority != ceiling {
+                        *ownership = Ownership::Shared {
+                            ceiling: cmp::max(ceiling, priority),
+                        };
+
+                        let res = &app.resources[res];
+                        if res.mutability.is_none() {
+                            assert_sync.insert(res.ty.clone());
                         }
                     }
                 }
-
-                continue;
             }
 
-            ownerships.insert(
-                resource.clone(),
-                Ownership::Owned {
-                    priority: task.priority,
-                },
-            );
+            continue;
+        }
+
+        ownerships.insert(res.clone(), Ownership::Owned { priority });
+    }
+
+    // Compute sizes of free queues
+    // We assume at most one message per `spawn` / `schedule`
+    let mut capacities: Capacities = app.tasks.keys().map(|task| (task.clone(), 0)).collect();
+    for (_, task) in app.spawn_calls().chain(app.schedule_calls()) {
+        *capacities.get_mut(task).expect("BUG: capacities.get_mut") += 1;
+    }
+
+    // Override computed capacities if user specified a capacity in `#[task]`
+    for (name, task) in &app.tasks {
+        if let Some(cap) = task.args.capacity {
+            *capacities.get_mut(name).expect("BUG: capacities.get_mut") = cap;
         }
     }
 
-    ownerships
+    // Compute the size of the timer queue
+    // Compute the priority of the timer queue, which matches the priority of the highest
+    // `schedule`-able task
+    let mut tq_capacity = 0;
+    let mut tq_priority = 1;
+    let mut tq_tasks = Idents::new();
+    for (_, task) in app.schedule_calls() {
+        tq_capacity += capacities[task];
+        tq_priority = cmp::max(tq_priority, app.tasks[task].args.priority);
+        tq_tasks.insert(task.clone());
+    }
+
+    // Compute dispatchers capacities
+    // Determine which tasks are dispatched by which dispatcher
+    // Compute the timer queue priority which matches the priority of the highest priority
+    // dispatcher
+    let mut dispatchers = Dispatchers::new();
+    let mut free_interrupts = app.free_interrupts.iter();
+    let mut tasks = app.tasks.iter().collect::<Vec<_>>();
+    tasks.sort_by(|l, r| l.1.args.priority.cmp(&r.1.args.priority));
+    for (name, task) in tasks {
+        let dispatcher = dispatchers.entry(task.args.priority).or_insert_with(|| {
+            let (name, fi) = free_interrupts
+                .next()
+                .expect("BUG: not enough free_interrupts");
+
+            Dispatcher {
+                attrs: fi.attrs.clone(),
+                capacity: 0,
+                interrupt: name.clone(),
+                tasks: vec![],
+            }
+        });
+
+        dispatcher.capacity += capacities[name];
+        dispatcher.tasks.push(name.clone());
+    }
+
+    // All messages sent from `init` need to be `Send`
+    for task in app.init.args.spawn.iter().chain(&app.init.args.schedule) {
+        tasks_assert_send.insert(task.clone());
+    }
+
+    // All late resources need to be `Send`, unless they are owned by `idle`
+    for (name, res) in &app.resources {
+        let owned_by_idle = Ownership::Owned { priority: 0 };
+        if res.expr.is_none()
+            && ownerships
+                .get(name)
+                .map(|ship| *ship != owned_by_idle)
+                .unwrap_or(false)
+        {
+            resources_assert_send.insert(res.ty.clone());
+        }
+    }
+
+    // All resources shared with init need to be `Send`, unless they are owned by `idle`
+    // This is equivalent to late initialization (e.g. `static mut LATE: Option<T> = None`)
+    for name in &app.init.args.resources {
+        let owned_by_idle = Ownership::Owned { priority: 0 };
+        if ownerships
+            .get(name)
+            .map(|ship| *ship != owned_by_idle)
+            .unwrap_or(false)
+        {
+            resources_assert_send.insert(app.resources[name].ty.clone());
+        }
+    }
+
+    // Ceiling analysis of free queues (consumer end point) -- first pass
+    // Ceiling analysis of ready queues (producer end point)
+    // Also compute more Send-ness requirements
+    let mut free_queues: HashMap<_, _> = app.tasks.keys().map(|task| (task.clone(), 0)).collect();
+    let mut ready_queues: HashMap<_, _> = dispatchers.keys().map(|level| (*level, 0)).collect();
+    for (priority, task) in app.spawn_calls() {
+        if let Some(priority) = priority {
+            // Users of `spawn` contend for the to-be-spawned task FREE_QUEUE
+            let c = free_queues.get_mut(task).expect("BUG: free_queue.get_mut");
+            *c = cmp::max(*c, priority);
+
+            let c = ready_queues
+                .get_mut(&app.tasks[task].args.priority)
+                .expect("BUG: ready_queues.get_mut");
+            *c = cmp::max(*c, priority);
+
+            // Send is required when sending messages from a task whose priority doesn't match the
+            // priority of the receiving task
+            if app.tasks[task].args.priority != priority {
+                tasks_assert_send.insert(task.clone());
+            }
+        } else {
+            // spawns from `init` are excluded from the ceiling analysis
+        }
+    }
+
+    // Ceiling analysis of free queues (consumer end point) -- second pass
+    // Ceiling analysis of the timer queue
+    let mut tq_ceiling = tq_priority;
+    for (priority, task) in app.schedule_calls() {
+        if let Some(priority) = priority {
+            // Users of `schedule` contend for the to-be-spawned task FREE_QUEUE (consumer end point)
+            let c = free_queues.get_mut(task).expect("BUG: free_queue.get_mut");
+            *c = cmp::max(*c, priority);
+
+            // Users of `schedule` contend for the timer queu
+            tq_ceiling = cmp::max(tq_ceiling, priority);
+        } else {
+            // spawns from `init` are excluded from the ceiling analysis
+        }
+    }
+
+    Analysis {
+        capacities,
+        dispatchers,
+        free_queues,
+        tasks_assert_send,
+        resources_assert_send,
+        assert_sync,
+        ownerships,
+        ready_queues,
+        timer_queue: TimerQueue {
+            capacity: tq_capacity,
+            ceiling: tq_ceiling,
+            priority: tq_priority,
+            tasks: tq_tasks,
+        },
+    }
+}
+
+pub struct TimerQueue {
+    pub capacity: u8,
+    pub ceiling: u8,
+    pub priority: u8,
+    pub tasks: Idents,
 }

macros/src/check.rs

@@ -1,95 +1,115 @@
-use std::collections::HashMap;
+use std::{collections::HashSet, iter};
 
-use syn::{Ident, Path};
-use syntax::check::{self, Idents, Idle, Init, Statics};
-use syntax::{self, Result};
+use proc_macro2::Span;
+use syn::parse;
 
-pub struct App {
-    pub device: Path,
-    pub idle: Idle,
-    pub init: Init,
-    pub resources: Statics,
-    pub tasks: Tasks,
-}
+use syntax::App;
 
-pub type Tasks = HashMap<Ident, Task>;
+pub fn app(app: &App) -> parse::Result<()> {
+    // Check that all referenced resources have been declared
+    for res in app
+        .idle
+        .as_ref()
+        .map(|idle| -> Box<Iterator<Item = _>> { Box::new(idle.args.resources.iter()) })
+        .unwrap_or_else(|| Box::new(iter::empty()))
+        .chain(&app.init.args.resources)
+        .chain(app.exceptions.values().flat_map(|e| &e.args.resources))
+        .chain(app.interrupts.values().flat_map(|i| &i.args.resources))
+        .chain(app.tasks.values().flat_map(|t| &t.args.resources))
+    {
+        if !app.resources.contains_key(res) {
+            return Err(parse::Error::new(
+                res.span(),
+                "this resource has NOT been declared",
+            ));
+        }
+    }
 
-#[allow(non_camel_case_types)]
-pub enum Exception {
-    PENDSV,
-    SVCALL,
-    SYS_TICK,
-}
+    // Check that late resources have not been assigned to `init`
+    for res in &app.init.args.resources {
+        if app.resources.get(res).unwrap().expr.is_none() {
+            return Err(parse::Error::new(
+                res.span(),
+                "late resources can NOT be assigned to `init`",
+            ));
+        }
+    }
 
-impl Exception {
-    pub fn from(s: &str) -> Option<Self> {
-        Some(match s {
-            "PENDSV" => Exception::PENDSV,
-            "SVCALL" => Exception::SVCALL,
-            "SYS_TICK" => Exception::SYS_TICK,
-            _ => return None,
+    // Check that all late resources have been initialized in `#[init]`
+    for res in app
+        .resources
+        .iter()
+        .filter_map(|(name, res)| if res.expr.is_none() { Some(name) } else { None })
+    {
+        if app.init.assigns.iter().all(|assign| assign.left != *res) {
+            return Err(parse::Error::new(
+                res.span(),
+                "late resources MUST be initialized at the end of `init`",
+            ));
+        }
+    }
+
+    // Check that all referenced tasks have been declared
+    for task in app
+        .idle
+        .as_ref()
+        .map(|idle| -> Box<Iterator<Item = _>> {
+            Box::new(idle.args.schedule.iter().chain(&idle.args.spawn))
         })
-    }
-
-    pub fn nr(&self) -> usize {
-        match *self {
-            Exception::PENDSV => 14,
-            Exception::SVCALL => 11,
-            Exception::SYS_TICK => 15,
+        .unwrap_or_else(|| Box::new(iter::empty()))
+        .chain(&app.init.args.schedule)
+        .chain(&app.init.args.spawn)
+        .chain(
+            app.exceptions
+                .values()
+                .flat_map(|e| e.args.schedule.iter().chain(&e.args.spawn)),
+        )
+        .chain(
+            app.interrupts
+                .values()
+                .flat_map(|i| i.args.schedule.iter().chain(&i.args.spawn)),
+        )
+        .chain(
+            app.tasks
+                .values()
+                .flat_map(|t| t.args.schedule.iter().chain(&t.args.spawn)),
+        ) {
+        if !app.tasks.contains_key(task) {
+            return Err(parse::Error::new(
+                task.span(),
+                "this task has NOT been declared",
+            ));
         }
     }
-}
 
-pub enum Kind {
-    Exception(Exception),
-    Interrupt { enabled: bool },
-}
+    // Check that there are enough free interrupts to dispatch all tasks
+    let ndispatchers = app
+        .tasks
+        .values()
+        .map(|t| t.args.priority)
+        .collect::<HashSet<_>>()
+        .len();
+    if ndispatchers > app.free_interrupts.len() {
+        return Err(parse::Error::new(
+            Span::call_site(),
+            &*format!(
+                "{} free interrupt{} (`extern {{ .. }}`) {} required to dispatch all soft tasks",
+                ndispatchers,
+                if ndispatchers > 1 { "s" } else { "" },
+                if ndispatchers > 1 { "are" } else { "is" },
+            ),
+        ));
+    }
 
-pub struct Task {
-    pub kind: Kind,
-    pub path: Path,
-    pub priority: u8,
-    pub resources: Idents,
-}
-
-pub fn app(app: check::App) -> Result<App> {
-    let app = App {
-        device: app.device,
-        idle: app.idle,
-        init: app.init,
-        resources: app.resources,
-        tasks: app.tasks
-            .into_iter()
-            .map(|(k, v)| {
-                let v = ::check::task(&k.to_string(), v)?;
-
-                Ok((k, v))
-            })
-            .collect::<Result<_>>()?,
-    };
-
-    Ok(app)
-}
-
-fn task(name: &str, task: syntax::check::Task) -> Result<Task> {
-    let kind = match Exception::from(name) {
-        Some(e) => {
-            ensure!(
-                task.enabled.is_none(),
-                "`enabled` field is not valid for exceptions"
-            );
-
-            Kind::Exception(e)
+    // Check that free interrupts are not being used
+    for int in app.interrupts.keys() {
+        if app.free_interrupts.contains_key(int) {
+            return Err(parse::Error::new(
+                int.span(),
+                "free interrupts (`extern { .. }`) can't be used as interrupt handlers",
+            ));
         }
-        None => Kind::Interrupt {
-            enabled: task.enabled.unwrap_or(true),
-        },
-    };
+    }
 
-    Ok(Task {
-        kind,
-        path: task.path,
-        priority: task.priority.unwrap_or(1),
-        resources: task.resources,
-    })
+    Ok(())
 }

macros/src/lib.rs

@@ -1,185 +1,312 @@
-//! Procedural macros of the `cortex-m-rtfm` crate
 // #![deny(warnings)]
 #![recursion_limit = "128"]
 
-#[macro_use]
-extern crate failure;
 extern crate proc_macro;
 extern crate proc_macro2;
-extern crate syn;
-#[macro_use]
 extern crate quote;
-extern crate rtfm_syntax as syntax;
+extern crate rand;
+extern crate syn;
 
 use proc_macro::TokenStream;
-use syntax::{App, Result};
+use syn::parse_macro_input;
 
 mod analyze;
 mod check;
-mod trans;
+mod codegen;
+mod syntax;
 
-/// The `app!` macro, a macro used to specify the tasks and resources of a RTFM application.
+/// Attribute used to declare a RTFM application
 ///
-/// The contents of this macro uses a `key: value` syntax. All the possible keys are shown below:
+/// This attribute must be applied to a `const` item of type `()`. The `const` item is effectively
+/// used as a `mod` item: its value must be a block that contains items commonly found in modules,
+/// like functions and `static` variables.
 ///
-/// ``` text
-/// app! {
-///     device: ..,
+/// The `app` attribute has one mandatory argument:
 ///
-///     resources: { .. },
+/// - `device = <path>`. The path must point to a device crate generated using [`svd2rust`]
+/// **v0.14.x**.
 ///
-///     init: { .. },
+/// [`svd2rust`]: https://crates.io/crates/svd2rust
 ///
-///     idle: { .. },
+/// The items allowed in the block value of the `const` item are specified below:
 ///
-///     tasks: { .. },
-/// }
-/// ```
+/// # 1. `static [mut]` variables
 ///
-/// # `device`
+/// These variables are used as *resources*. Resources can be owned by tasks or shared between them.
+/// Tasks can get `&mut` (exclusives) references to `static mut` resources, but only `&` (shared)
+/// references to `static` resources. Lower priority tasks will need a [`lock`] to get a `&mut`
+/// reference to a `static mut` resource shared with higher priority tasks.
 ///
-/// The value of this key is a Rust path, like `foo::bar::baz`, that must point to a *device crate*,
-/// a crate generated using `svd2rust`.
+/// [`lock`]: ../rtfm/trait.Mutex.html#method.lock
 ///
-/// # `resources`
+/// `static mut` resources that are shared by tasks that run at *different* priorities need to
+/// implement the [`Send`] trait. Similarly, `static` resources that are shared by tasks that run at
+/// *different* priorities need to implement the [`Sync`] trait.
 ///
-/// This key is optional. Its value is a list of `static` variables. These variables are the data
-/// that can be safely accessed, modified and shared by tasks.
+/// [`Send`]: https://doc.rust-lang.org/core/marker/trait.Send.html
+/// [`Sync`]: https://doc.rust-lang.org/core/marker/trait.Sync.html
 ///
-/// ``` text
-/// resources: {
-///     static A: bool = false;
-///     static B: i32 = 0;
-///     static C: [u8; 16] = [0; 16];
-///     static D: Thing = Thing::new(..);
-///     static E: Thing;
-/// }
-/// ```
+/// Resources can be initialized at runtime by assigning them `()` (the unit value) as their initial
+/// value in their declaration. These "late" resources need to be initialized an the end of the
+/// `init` function.
 ///
-/// The initial value of a resource can be omitted. This means that the resource will be runtime
-/// initialized; these runtime initialized resources are also known as *late resources*.
+/// The `app` attribute will inject a `resources` module in the root of the crate. This module
+/// contains proxy `struct`s that implement the [`Mutex`] trait. The `struct` are named after the
+/// `static mut` resources. For example, `static mut FOO: u32 = 0` will map to a `resources::FOO`
+/// `struct` that implements the `Mutex<Data = u32>` trait.
 ///
-/// If this key is omitted its value defaults to an empty list.
+/// [`Mutex`]: ../rtfm/trait.Mutex.html
 ///
-/// # `init`
+/// # 2. `fn`
 ///
-/// This key is optional. Its value is a set of key values. All the possible keys are shown below:
+/// Functions must contain *one* of the following attributes: `init`, `idle`, `interrupt`,
+/// `exception` or `task`. The attribute defines the role of the function in the application.
 ///
-/// ``` text
-/// init: {
-///     path: ..,
-/// }
-/// ```
+/// ## a. `#[init]`
 ///
-/// ## `init.path`
+/// This attribute indicates that the function is to be used as the *initialization function*. There
+/// must be exactly one instance of the `init` attribute inside the `app` pseudo-module. The
+/// signature of the `init` function must be `[unsafe] fn ()`.
 ///
-/// This key is optional. Its value is a Rust path, like `foo::bar::baz`, that points to the
-/// initialization function.
+/// The `init` function runs after memory (RAM) is initialized and runs with interrupts disabled.
+/// Interrupts are re-enabled after `init` returns.
 ///
-/// If the key is omitted its value defaults to `init`.
+/// The `init` attribute accepts the following optional arguments:
 ///
-/// ## `init.resources`
+/// - `resources = [RESOURCE_A, RESOURCE_B, ..]`. This is the list of resources this function has
+/// access to.
 ///
-/// This key is optional. Its value is a set of resources the `init` function *owns*. The resources
-/// in this list must be a subset of the resources listed in the top `resources` key. Note that some
-/// restrictions apply:
+/// - `schedule = [task_a, task_b, ..]`. This is the list of *software* tasks that this function can
+/// schedule to run in the future. *IMPORTANT*: This argument is accepted only if the `timer-queue`
+/// feature has been enabled.
 ///
-/// - The resources in this list can't be late resources.
-/// - The resources that appear in this list can't appear in other list like `idle.resources` or
-/// `tasks.$TASK.resources`
+/// - `spawn = [task_a, task_b, ..]`. This is the list of *software* tasks that this function can
+/// immediately spawn.
 ///
-/// If this key is omitted its value is assumed to be an empty list.
+/// The `app` attribute will injected a *context* into this function that comprises the following
+/// variables:
 ///
-/// # `idle`
+/// - `core: rtfm::Peripherals`. Exclusive access to core peripherals. See [`rtfm::Peripherals`] for
+/// more details.
 ///
-/// This key is optional. Its value is a set of key values. All the possible keys are shown below:
+/// [`rtfm::Peripherals`]: ../rtfm/struct.Peripherals.html
 ///
-/// ``` text
-/// idle: {
-///     path: ..,
-///     resources: [..],
-/// }
-/// ```
+/// - `device: <device-path>::Peripherals`. Exclusive access to device-specific peripherals.
+/// `<device-path>` is the path to the device crate declared in the top `app` attribute.
 ///
-/// ## `idle.path`
+/// - `start: rtfm::Instant`. The `start` time of the system: `Instant(0 /* cycles */)`. **NOTE**:
+/// only present if the `timer-queue` feature is enabled.
 ///
-/// This key is optional. Its value is a Rust path, like `foo::bar::baz`, that points to the idle
-/// loop function.
+/// - `resources: _`. An opaque `struct` that contains all the resources assigned to this function.
+/// The resource maybe appear by value (`impl Singleton`), by references (`&[mut]`) or by proxy
+/// (`impl Mutex`).
 ///
-/// If the key is omitted its value defaults to `idle`.
+/// - `schedule: init::Schedule`. A `struct` that can be used to schedule *software* tasks.
+/// **NOTE**: only present if the `timer-queue` feature is enabled.
 ///
-/// ## `idle.resources`
+/// - `spawn: init::Spawn`. A `struct` that can be used to spawn *software* tasks.
 ///
-/// This key is optional. Its value is a list of resources the `idle` loop has access to. The
-/// resources in this list must be a subset of the resources listed in the top `resources` key.
+/// Other properties / constraints:
 ///
-/// If omitted its value defaults to an empty list.
+/// - The `init` function can **not** be called from software.
 ///
-/// # `tasks`
+/// - The `static mut` variables declared at the beginning of this function will be transformed into
+/// `&'static mut` references that are safe to access. For example, `static mut FOO: u32 = 0` will
+/// become `FOO: &'static mut u32`.
 ///
-/// This key is optional. Its value is a list of tasks. Each task itself is a set of key value pair.
-/// The full syntax is shown below:
+/// - Assignments (e.g. `FOO = 0`) at the end of this function can be used to initialize *late*
+/// resources.
 ///
-/// ``` text
-/// tasks: {
-///     $TASK: {
-///         enabled: ..,
-///         path: ..,
-///         priority: ..,
-///         resources: [..],
-///     },
-/// }
-/// ```
+/// ## b. `#[idle]`
 ///
-/// If this key is omitted its value is assumed to be an empty list.
+/// This attribute indicates that the function is to be used as the *idle task*. There can be at
+/// most once instance of the `idle` attribute inside the `app` pseudo-module. The signature of the
+/// `idle` function must be `fn() -> !`.
 ///
-/// ## `tasks.$TASK`
+/// The `idle` task is a special task that always runs in the background. The `idle` task runs at
+/// the lowest priority of `0`. If the `idle` task is not defined then the runtime sets the
+/// [SLEEPONEXIT] bit after executing `init`.
 ///
-/// The key must be either a Cortex-M exception or a device specific interrupt. `PENDSV`, `SVCALL`,
-/// `SYS_TICK` are considered as exceptions. All other names are assumed to be interrupts.
+/// [SLEEPONEXIT]: https://developer.arm.com/products/architecture/cpu-architecture/m-profile/docs/100737/0100/power-management/sleep-mode/sleep-on-exit-bit
 ///
-/// ## `tasks.$TASK.enabled`
+/// The `idle` attribute accepts the following optional arguments:
 ///
-/// This key is optional for interrupts and forbidden for exceptions. Its value must be a boolean
-/// and indicates whether the interrupt will be enabled (`true`) or disabled (`false`) after `init`
-/// ends and before `idle` starts.
+/// - `resources = (..)`. Same meaning / function as [`#[init].resources`](#a-init).
 ///
-/// If this key is omitted its value defaults to `true`.
+/// - `schedule = (..)`. Same meaning / function as [`#[init].schedule`](#a-init).
 ///
-/// ## `tasks.$TASK.path`
+/// - `spawn = (..)`. Same meaning / function as [`#[init].spawn`](#a-init).
 ///
-/// The value of this key is a Rust path, like `foo::bar::baz`, that points to the handler of this
-/// task.
+/// The `app` attribute will injected a *context* into this function that comprises the following
+/// variables:
 ///
-/// ## `tasks.$TASK.priority`
+/// - `resources: _`. Same meaning / function as [`init.resources`](#a-init).
 ///
-/// This key is optional. Its value is an integer with type `u8` that specifies the priority of this
-/// task. The minimum valid priority is 1. The maximum valid priority depends on the number of the
-/// NVIC priority bits the device has; if the device has 4 priority bits the maximum allowed value
-/// would be 16.
+/// - `schedule: idle::Schedule`. Same meaning / function as [`init.schedule`](#a-init).
 ///
-/// If this key is omitted its value defaults to `1`.
+/// - `spawn: idle::Spawn`. Same meaning / function as [`init.spawn`](#a-init).
 ///
-/// ## `tasks.$TASK.resources`
+/// Other properties / constraints:
 ///
-/// This key is optional. Its value is a list of resources this task has access to. The resources in
-/// this list must be a subset of the resources listed in the top `resources` key.
+/// - The `idle` function can **not** be called from software.
 ///
-/// If omitted its value defaults to an empty list.
-#[proc_macro]
-pub fn app(ts: TokenStream) -> TokenStream {
-    match run(ts) {
-        Err(e) => panic!("error: {}", e),
-        Ok(ts) => ts,
+/// - The `static mut` variables declared at the beginning of this function will be transformed into
+/// `&'static mut` references that are safe to access. For example, `static mut FOO: u32 = 0` will
+/// become `FOO: &'static mut u32`.
+///
+/// ## c. `#[exception]`
+///
+/// This attribute indicates that the function is to be used as an *exception handler*, a type of
+/// hardware task. The signature of `exception` handlers must be `[unsafe] fn()`.
+///
+/// The name of the function must match one of the Cortex-M exceptions that has [configurable
+/// priority][system-handler].
+///
+/// [system-handler]: ../cortex_m/peripheral/scb/enum.SystemHandler.html
+///
+/// The `exception` attribute accepts the following optional arguments.
+///
+/// - `priority = <integer>`. This is the static priority of the exception handler. The value must
+/// be in the range `1..=(1 << <device-path>::NVIC_PRIO_BITS)` where `<device-path>` is the path to
+/// the device crate declared in the top `app` attribute. If this argument is omitted the priority
+/// is assumed to be 1.
+///
+/// - `resources = (..)`. Same meaning / function as [`#[init].resources`](#a-init).
+///
+/// - `schedule = (..)`. Same meaning / function as [`#[init].schedule`](#a-init).
+///
+/// - `spawn = (..)`. Same meaning / function as [`#[init].spawn`](#a-init).
+///
+/// The `app` attribute will injected a *context* into this function that comprises the following
+/// variables:
+///
+/// - `start: rtfm::Instant`. The time at which this handler started executing. **NOTE**: only
+/// present if the `timer-queue` feature is enabled.
+///
+/// - `resources: _`. Same meaning / function as [`init.resources`](#a-init).
+///
+/// - `schedule: <exception-name>::Schedule`. Same meaning / function as [`init.schedule`](#a-init).
+///
+/// - `spawn: <exception-name>::Spawn`.  Same meaning / function as [`init.spawn`](#a-init).
+///
+/// Other properties / constraints:
+///
+/// - `exception` handlers can **not** be called from software.
+///
+/// - The `static mut` variables declared at the beginning of this function will be transformed into
+/// `&mut` references that are safe to access. For example, `static mut FOO: u32 = 0` will
+/// become `FOO: &mut u32`.
+///
+/// ## d. `#[interrupt]`
+///
+/// This attribute indicates that the function is to be used as an *interrupt handler*, a type of
+/// hardware task. The signature of `interrupt` handlers must be `[unsafe] fn()`.
+///
+/// The name of the function must match one of the device specific interrupts. See your device crate
+/// documentation (`Interrupt` enum) for more details.
+///
+/// The `interrupt` attribute accepts the following optional arguments.
+///
+/// - `priority = (..)`. Same meaning / function as [`#[exception].priority`](#b-exception).
+///
+/// - `resources = (..)`. Same meaning / function as [`#[init].resources`](#a-init).
+///
+/// - `schedule = (..)`. Same meaning / function as [`#[init].schedule`](#a-init).
+///
+/// - `spawn = (..)`. Same meaning / function as [`#[init].spawn`](#a-init).
+///
+/// The `app` attribute will injected a *context* into this function that comprises the following
+/// variables:
+///
+/// - `start: rtfm::Instant`. Same meaning / function as [`exception.start`](#b-exception).
+///
+/// - `resources: _`. Same meaning / function as [`init.resources`](#a-init).
+///
+/// - `schedule: <interrupt-name>::Schedule`. Same meaning / function as [`init.schedule`](#a-init).
+///
+/// - `spawn: <interrupt-name>::Spawn`.  Same meaning / function as [`init.spawn`](#a-init).
+///
+/// Other properties / constraints:
+///
+/// - `interrupt` handlers can **not** be called from software, but they can be [`pend`]-ed by the
+/// software from any context.
+///
+/// [`pend`]: ../rtfm/fn.pend.html
+///
+/// - The `static mut` variables declared at the beginning of this function will be transformed into
+/// `&mut` references that are safe to access. For example, `static mut FOO: u32 = 0` will
+/// become `FOO: &mut u32`.
+///
+/// ## e. `#[task]`
+///
+/// This attribute indicates that the function is to be used as a *software task*. The signature of
+/// software `task`s must be `[unsafe] fn(<inputs>)`.
+///
+/// The `task` attribute accepts the following optional arguments.
+///
+/// - `capacity = <integer>`. The maximum number of instances of this task that can be queued onto
+/// the task scheduler for execution. The value must be in the range `1..=255`. If the `capacity`
+/// argument is omitted then the capacity will be inferred.
+///
+/// - `priority = <integer>`. Same meaning / function as [`#[exception].priority`](#b-exception).
+///
+/// - `resources = (..)`. Same meaning / function as [`#[init].resources`](#a-init).
+///
+/// - `schedule = (..)`. Same meaning / function as [`#[init].schedule`](#a-init).
+///
+/// - `spawn = (..)`. Same meaning / function as [`#[init].spawn`](#a-init).
+///
+/// The `app` attribute will injected a *context* into this function that comprises the following
+/// variables:
+///
+/// - `scheduled: rtfm::Instant`. The time at which this task was scheduled to run. **NOTE**: Only
+/// present if `timer-queue` is enabled.
+///
+/// - `resources: _`. Same meaning / function as [`init.resources`](#a-init).
+///
+/// - `schedule: <interrupt-name>::Schedule`. Same meaning / function as [`init.schedule`](#a-init).
+///
+/// - `spawn: <interrupt-name>::Spawn`.  Same meaning / function as [`init.spawn`](#a-init).
+///
+/// Other properties / constraints:
+///
+/// - Software `task`s can **not** be called from software, but they can be `spawn`-ed and
+/// `schedule`-d by the software from any context.
+///
+/// - The `static mut` variables declared at the beginning of this function will be transformed into
+/// `&mut` references that are safe to access. For example, `static mut FOO: u32 = 0` will
+/// become `FOO: &mut u32`.
+///
+/// # 3. `extern` block
+///
+/// This `extern` block contains a list of interrupts which are *not* used by the application as
+/// hardware tasks. These interrupts will be used to dispatch software tasks. Each interrupt will be
+/// used to dispatch *multiple* software tasks *at the same priority level*.
+///
+/// This `extern` block must only contain functions with signature `fn ()`. The names of these
+/// functions must match the names of the target device interrupts.
+///
+/// Importantly, attributes can be applied to the functions inside this block. These attributes will
+/// be forwarded to the interrupt handlers generated by the `app` attribute.
+#[proc_macro_attribute]
+pub fn app(args: TokenStream, input: TokenStream) -> TokenStream {
+    // Parse
+    let args = parse_macro_input!(args as syntax::AppArgs);
+    let items = parse_macro_input!(input as syntax::Input).items;
+
+    let app = match syntax::App::parse(items, args) {
+        Err(e) => return e.to_compile_error().into(),
+        Ok(app) => app,
+    };
+
+    // Check the specification
+    if let Err(e) = check::app(&app) {
+        return e.to_compile_error().into();
     }
-}
-
-fn run(ts: TokenStream) -> Result<TokenStream> {
-    let app = App::parse(ts)?.check()?;
-    let app = check::app(app)?;
-
-    let ownerships = analyze::app(&app);
-    let tokens = trans::app(&app, &ownerships);
-
-    Ok(tokens.into())
+
+    // Ceiling analysis
+    let analysis = analyze::app(&app);
+
+    // Code generation
+    codegen::app(&app, &analysis)
 }

macros/src/trans.rs

@@ -1,631 +0,0 @@
-use proc_macro2::{TokenStream, Span};
-use syn::{Ident, LitStr};
-
-use analyze::Ownerships;
-use check::{App, Kind};
-
-fn krate() -> Ident {
-    Ident::new("rtfm", Span::call_site())
-}
-
-pub fn app(app: &App, ownerships: &Ownerships) -> TokenStream {
-    let mut root = vec![];
-    let mut main = vec![quote!(#![allow(path_statements)])];
-
-    ::trans::tasks(app, ownerships, &mut root, &mut main);
-    ::trans::init(app, &mut main, &mut root);
-    ::trans::idle(app, ownerships, &mut main, &mut root);
-    ::trans::resources(app, ownerships, &mut root);
-
-    root.push(quote! {
-        #[allow(unsafe_code)]
-        fn main() {
-            #(#main)*
-        }
-    });
-
-    quote!(#(#root)*)
-}
-
-fn idle(app: &App, ownerships: &Ownerships, main: &mut Vec<TokenStream>, root: &mut Vec<TokenStream>) {
-    let krate = krate();
-
-    let mut mod_items = vec![];
-    let mut tys = vec![];
-    let mut exprs = vec![];
-
-    if !app.idle.resources.is_empty() {
-        tys.push(quote!(&mut #krate::Threshold));
-        exprs.push(quote!(unsafe { &mut #krate::Threshold::new(0) }));
-    }
-
-    if !app.idle.resources.is_empty() {
-        let mut needs_reexport = false;
-        for name in &app.idle.resources {
-            if ownerships[name].is_owned() {
-                if app.resources.get(name).is_some() {
-                    needs_reexport = true;
-                    break;
-                }
-            }
-        }
-
-        let super_ = if needs_reexport {
-            None
-        } else {
-            Some(Ident::new("super", Span::call_site()))
-        };
-        let mut rexprs = vec![];
-        let mut rfields = vec![];
-        for name in &app.idle.resources {
-            if ownerships[name].is_owned() {
-                let resource = app.resources.get(name).expect(&format!(
-                    "BUG: resource {} assigned to `idle` has no definition",
-                    name
-                ));
-                let ty = &resource.ty;
-
-                rfields.push(quote! {
-                    pub #name: &'static mut #ty,
-                });
-
-                let _name = Ident::new(&name.to_string(), Span::call_site());
-                rexprs.push(if resource.expr.is_some() {
-                    quote! {
-                        #name: &mut #super_::#_name,
-                    }
-                } else {
-                    quote! {
-                        #name: #super_::#_name.as_mut(),
-                    }
-                });
-            } else {
-                rfields.push(quote! {
-                    pub #name: ::idle::#name,
-                });
-
-                rexprs.push(quote! {
-                    #name: ::idle::#name { _0: ::core::marker::PhantomData },
-                });
-            }
-        }
-
-        if needs_reexport {
-            root.push(quote! {
-                #[allow(non_camel_case_types)]
-                #[allow(non_snake_case)]
-                pub struct _idleResources {
-                    #(#rfields)*
-                }
-            });
-
-            mod_items.push(quote! {
-                pub use ::_idleResources as Resources;
-            });
-        } else {
-            mod_items.push(quote! {
-                #[allow(non_snake_case)]
-                pub struct Resources {
-                    #(#rfields)*
-                }
-            });
-        }
-
-        mod_items.push(quote! {
-            #[allow(unsafe_code)]
-            impl Resources {
-                pub unsafe fn new() -> Self {
-                    Resources {
-                        #(#rexprs)*
-                    }
-                }
-            }
-        });
-
-        tys.push(quote!(idle::Resources));
-        exprs.push(quote!(unsafe { idle::Resources::new() }));
-    }
-
-    let device = &app.device;
-    for name in &app.idle.resources {
-        let ceiling = ownerships[name].ceiling();
-
-        // owned resource
-        if ceiling == 0 {
-            continue;
-        }
-
-        let _name = Ident::new(&name.to_string(), Span::call_site());
-        let resource = app.resources
-            .get(name)
-            .expect(&format!("BUG: resource {} has no definition", name));
-
-        let ty = &resource.ty;
-        let _static = if resource.expr.is_some() {
-            quote!(#_name)
-        } else {
-            quote!(#_name.some)
-        };
-
-        mod_items.push(quote! {
-            #[allow(non_camel_case_types)]
-            pub struct #name { _0: ::core::marker::PhantomData<*const ()> }
-        });
-
-        root.push(quote! {
-            #[allow(unsafe_code)]
-            unsafe impl #krate::Resource for idle::#name {
-                type Data = #ty;
-
-                fn borrow<'cs>(&'cs self, t: &'cs Threshold) -> &'cs Self::Data {
-                    assert!(t.value() >= #ceiling);
-
-                    unsafe { &#_static }
-                }
-
-                fn borrow_mut<'cs>(
-                    &'cs mut self,
-                    t: &'cs Threshold,
-                ) -> &'cs mut Self::Data {
-                    assert!(t.value() >= #ceiling);
-
-                    unsafe { &mut #_static }
-                }
-
-                fn claim<R, F>(&self, t: &mut Threshold, f: F) -> R
-                where
-                    F: FnOnce(&Self::Data, &mut Threshold) -> R
-                {
-                    unsafe {
-                        #krate::claim(
-                            &#_static,
-                            #ceiling,
-                            #device::NVIC_PRIO_BITS,
-                            t,
-                            f,
-                        )
-                    }
-                }
-
-                fn claim_mut<R, F>(&mut self, t: &mut Threshold, f: F) -> R
-                where
-                    F: FnOnce(&mut Self::Data, &mut Threshold) -> R
-                {
-                    unsafe {
-                        #krate::claim(
-                            &mut #_static,
-                            #ceiling,
-                            #device::NVIC_PRIO_BITS,
-                            t,
-                            f,
-                        )
-                    }
-                }
-            }
-        });
-    }
-
-    if !mod_items.is_empty() {
-        root.push(quote! {
-            #[allow(unsafe_code)]
-            mod idle {
-                #(#mod_items)*
-            }
-        });
-    }
-
-    let idle = &app.idle.path;
-    main.push(quote! {
-        // type check
-        let idle: fn(#(#tys),*) -> ! = #idle;
-
-        idle(#(#exprs),*);
-    });
-}
-
-fn init(app: &App, main: &mut Vec<TokenStream>, root: &mut Vec<TokenStream>) {
-    let device = &app.device;
-    let krate = krate();
-
-    let mut tys = vec![quote!(init::Peripherals)];
-    let mut exprs = vec![
-        quote!{
-            init::Peripherals {
-                core: ::#device::CorePeripherals::steal(),
-                device: ::#device::Peripherals::steal(),
-            }
-        },
-    ];
-    let mut ret = None;
-    let mut mod_items = vec![];
-
-    let (init_resources, late_resources): (Vec<_>, Vec<_>) = app.resources
-        .iter()
-        .partition(|&(_, res)| res.expr.is_some());
-
-    if !init_resources.is_empty() {
-        let mut fields = vec![];
-        let mut lifetime = None;
-        let mut rexprs = vec![];
-
-        for (name, resource) in init_resources {
-            let ty = &resource.ty;
-
-            if app.init.resources.contains(name) {
-                fields.push(quote! {
-                    pub #name: &'static mut #ty,
-                });
-
-                let expr = &resource.expr;
-                rexprs.push(quote!(#name: {
-                    static mut #name: #ty = #expr;
-                    &mut #name
-                },));
-            } else {
-                let _name = Ident::new(&name.to_string(), Span::call_site());
-                lifetime = Some(quote!('a));
-
-                fields.push(quote! {
-                    pub #name: &'a mut #ty,
-                });
-
-                rexprs.push(quote! {
-                    #name: &mut ::#_name,
-                });
-            }
-        }
-
-        root.push(quote! {
-            #[allow(non_camel_case_types)]
-            #[allow(non_snake_case)]
-            pub struct _initResources<#lifetime> {
-                #(#fields)*
-            }
-        });
-
-        mod_items.push(quote! {
-            pub use ::_initResources as Resources;
-
-            #[allow(unsafe_code)]
-            impl<#lifetime> Resources<#lifetime> {
-                pub unsafe fn new() -> Self {
-                    Resources {
-                        #(#rexprs)*
-                    }
-                }
-            }
-        });
-
-        tys.push(quote!(init::Resources));
-        exprs.push(quote!(init::Resources::new()));
-    }
-
-    // Initialization statements for late resources
-    let mut late_resource_init = vec![];
-
-    if !late_resources.is_empty() {
-        // `init` must initialize and return resources
-
-        let mut fields = vec![];
-
-        for (name, resource) in late_resources {
-            let _name = Ident::new(&name.to_string(), Span::call_site());
-
-            let ty = &resource.ty;
-
-            fields.push(quote! {
-                pub #name: #ty,
-            });
-
-            late_resource_init.push(quote! {
-                #_name = #krate::UntaggedOption { some: _late_resources.#name };
-            });
-        }
-
-        root.push(quote! {
-            #[allow(non_camel_case_types)]
-            #[allow(non_snake_case)]
-            pub struct _initLateResources {
-                #(#fields)*
-            }
-        });
-
-        mod_items.push(quote! {
-            pub use ::_initLateResources as LateResources;
-        });
-
-        // `init` must return the initialized resources
-        ret = Some(quote!( -> ::init::LateResources));
-    }
-
-    root.push(quote! {
-        #[allow(unsafe_code)]
-        mod init {
-            pub struct Peripherals {
-                pub core: ::#device::CorePeripherals,
-                pub device: ::#device::Peripherals,
-            }
-
-            #(#mod_items)*
-        }
-    });
-
-    let mut exceptions = vec![];
-    let mut interrupts = vec![];
-    for (name, task) in &app.tasks {
-        match task.kind {
-            Kind::Exception(ref e) => {
-                if exceptions.is_empty() {
-                    exceptions.push(quote! {
-                        let scb = &*#device::SCB::ptr();
-                    });
-                }
-
-                let nr = e.nr();
-                let priority = task.priority;
-                exceptions.push(quote! {
-                    let prio_bits = #device::NVIC_PRIO_BITS;
-                    let hw = ((1 << prio_bits) - #priority) << (8 - prio_bits);
-                    scb.shpr[#nr - 4].write(hw);
-                });
-            }
-            Kind::Interrupt { enabled } => {
-                // Interrupt. These are enabled / disabled through the NVIC
-                if interrupts.is_empty() {
-                    interrupts.push(quote! {
-                        use #device::Interrupt;
-
-                        let mut nvic: #device::NVIC = core::mem::transmute(());
-                    });
-                }
-
-                let priority = task.priority;
-                interrupts.push(quote! {
-                    let prio_bits = #device::NVIC_PRIO_BITS;
-                    let hw = ((1 << prio_bits) - #priority) << (8 - prio_bits);
-                    nvic.set_priority(Interrupt::#name, hw);
-                });
-
-                if enabled {
-                    interrupts.push(quote! {
-                        nvic.enable(Interrupt::#name);
-                    });
-                } else {
-                    interrupts.push(quote! {
-                        nvic.disable(Interrupt::#name);
-                    });
-                }
-            }
-        }
-    }
-
-    let init = &app.init.path;
-    main.push(quote! {
-        // type check
-        let init: fn(#(#tys,)*) #ret = #init;
-
-        #krate::atomic(unsafe { &mut #krate::Threshold::new(0) }, |_t| unsafe {
-            let _late_resources = init(#(#exprs,)*);
-            #(#late_resource_init)*
-
-            #(#exceptions)*
-            #(#interrupts)*
-        });
-    });
-}
-
-fn resources(app: &App, ownerships: &Ownerships, root: &mut Vec<TokenStream>) {
-    let krate = krate();
-
-    for name in ownerships.keys() {
-        let _name = Ident::new(&name.to_string(), Span::call_site());
-
-        // Declare the static that holds the resource
-        let resource = app.resources
-            .get(name)
-            .expect(&format!("BUG: resource {} has no definition", name));
-
-        let expr = &resource.expr;
-        let ty = &resource.ty;
-
-        root.push(match *expr {
-            Some(ref expr) => quote! {
-                static mut #_name: #ty = #expr;
-            },
-            None => quote! {
-                // Resource initialized in `init`
-                static mut #_name: #krate::UntaggedOption<#ty> =
-                    #krate::UntaggedOption { none: () };
-            },
-        });
-    }
-}
-
-fn tasks(app: &App, ownerships: &Ownerships, root: &mut Vec<TokenStream>, main: &mut Vec<TokenStream>) {
-    let device = &app.device;
-    let krate = krate();
-
-    for (tname, task) in &app.tasks {
-        let mut exprs = vec![];
-        let mut fields = vec![];
-        let mut items = vec![];
-
-        let has_resources = !task.resources.is_empty();
-
-        if has_resources {
-            for rname in &task.resources {
-                let ceiling = ownerships[rname].ceiling();
-                let _rname = Ident::new(&rname.to_string(), Span::call_site());
-                let resource = app.resources
-                    .get(rname)
-                    .expect(&format!("BUG: resource {} has no definition", rname));
-
-                let ty = &resource.ty;
-                let _static = if resource.expr.is_some() {
-                    quote!(#_rname)
-                } else {
-                    quote!(#_rname.some)
-                };
-
-                items.push(quote! {
-                    #[allow(non_camel_case_types)]
-                    pub struct #rname { _0: PhantomData<*const ()> }
-                });
-
-                root.push(quote! {
-                    #[allow(unsafe_code)]
-                    unsafe impl #krate::Resource for #tname::#rname {
-                        type Data = #ty;
-
-                        fn borrow<'cs>(&'cs self, t: &'cs Threshold) -> &'cs Self::Data {
-                            assert!(t.value() >= #ceiling);
-
-                            unsafe { &#_static }
-                        }
-
-                        fn borrow_mut<'cs>(
-                            &'cs mut self,
-                            t: &'cs Threshold,
-                        ) -> &'cs mut Self::Data {
-                            assert!(t.value() >= #ceiling);
-
-                            unsafe { &mut #_static }
-                        }
-
-                        fn claim<R, F>(&self, t: &mut Threshold, f: F) -> R
-                        where
-                            F: FnOnce(&Self::Data, &mut Threshold) -> R
-                        {
-                            unsafe {
-                                #krate::claim(
-                                    &#_static,
-                                    #ceiling,
-                                    #device::NVIC_PRIO_BITS,
-                                    t,
-                                    f,
-                                )
-                            }
-                        }
-
-                        fn claim_mut<R, F>(&mut self, t: &mut Threshold, f: F) -> R
-                        where
-                            F: FnOnce(&mut Self::Data, &mut Threshold) -> R
-                        {
-                            unsafe {
-                                #krate::claim(
-                                    &mut #_static,
-                                    #ceiling,
-                                    #device::NVIC_PRIO_BITS,
-                                    t,
-                                    f,
-                                )
-                            }
-                        }
-                    }
-                });
-
-                if ceiling <= task.priority {
-                    root.push(quote! {
-                        #[allow(unsafe_code)]
-                        impl core::ops::Deref for #tname::#rname {
-                            type Target = #ty;
-
-                            fn deref(&self) -> &Self::Target {
-                                unsafe { &#_static }
-                            }
-                        }
-
-                        #[allow(unsafe_code)]
-                        impl core::ops::DerefMut for #tname::#rname {
-                            fn deref_mut(&mut self) -> &mut Self::Target {
-                                unsafe { &mut #_static }
-                            }
-                        }
-                    })
-                }
-
-                fields.push(quote! {
-                    pub #rname: #rname,
-                });
-
-                exprs.push(quote! {
-                    #rname: #rname { _0: PhantomData },
-                });
-            }
-
-            items.push(quote! {
-                #[allow(non_snake_case)]
-                pub struct Resources {
-                    #(#fields)*
-                }
-            });
-
-            items.push(quote! {
-                #[allow(unsafe_code)]
-                impl Resources {
-                    pub unsafe fn new() -> Self {
-                        Resources {
-                            #(#exprs)*
-                        }
-                    }
-                }
-            });
-        }
-
-        let mut tys = vec![];
-        let mut exprs = vec![];
-
-        let priority = task.priority;
-        if has_resources {
-            tys.push(quote!(&mut #krate::Threshold));
-            exprs.push(quote! {
-                &mut if #priority == 1 << #device::NVIC_PRIO_BITS {
-                    #krate::Threshold::new(::core::u8::MAX)
-                } else {
-                    #krate::Threshold::new(#priority)
-                }
-            });
-        }
-
-        if has_resources {
-            tys.push(quote!(#tname::Resources));
-            exprs.push(quote!(#tname::Resources::new()));
-        }
-
-        let path = &task.path;
-        let _tname = Ident::new(&tname.to_string(), Span::call_site());
-        let export_name = LitStr::new(&tname.to_string(), Span::call_site());
-        root.push(quote! {
-            #[allow(non_snake_case)]
-            #[allow(unsafe_code)]
-            #[export_name = #export_name]
-            pub unsafe extern "C" fn #_tname() {
-                let f: fn(#(#tys,)*) = #path;
-
-                f(#(#exprs,)*)
-            }
-        });
-
-        root.push(quote!{
-            #[allow(non_snake_case)]
-            #[allow(unsafe_code)]
-            mod #tname {
-                #[allow(unused_imports)]
-                use core::marker::PhantomData;
-
-                #[allow(dead_code)]
-                #[deny(const_err)]
-                pub const CHECK_PRIORITY: (u8, u8) = (
-                    #priority - 1,
-                    (1 << ::#device::NVIC_PRIO_BITS) - #priority,
-                );
-
-                #(#items)*
-            }
-        });
-
-        // after miri landed (?) rustc won't analyze `const` items unless they are used so we force
-        // evaluation with this path statement
-        main.push(quote!(#tname::CHECK_PRIORITY;));
-    }
-}

memory.x

@@ -1,6 +0,0 @@
-/* STM32F103C8V6 */
-MEMORY
-{
-  FLASH : ORIGIN = 0x08000000, LENGTH = 64K
-  RAM : ORIGIN = 0x20000000, LENGTH = 20K
-}

src/examples/_0_zero_tasks.rs

@@ -1,47 +0,0 @@
-//! Minimal example with zero tasks
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm; // IMPORTANT always do this rename
-//! extern crate stm32f103xx; // the device crate
-//! 
-//! // import the procedural macro
-//! use rtfm::app;
-//! 
-//! // This macro call indicates that this is a RTFM application
-//! //
-//! // This macro will expand to a `main` function so you don't need to supply
-//! // `main` yourself.
-//! app! {
-//!     // this is the path to the device crate
-//!     device: stm32f103xx,
-//! }
-//! 
-//! // The initialization phase.
-//! //
-//! // This runs first and within a *global* critical section. Nothing can preempt
-//! // this function.
-//! fn init(p: init::Peripherals) {
-//!     // This function has access to all the peripherals of the device
-//!     p.core.SYST;
-//!     p.device.GPIOA;
-//!     p.device.RCC;
-//!     // ..
-//! }
-//! 
-//! // The idle loop.
-//! //
-//! // This runs after `init` and has a priority of 0. All tasks can preempt this
-//! // function. This function can never return so it must contain some sort of
-//! // endless loop.
-//! fn idle() -> ! {
-//!     loop {
-//!         // This puts the processor to sleep until there's a task to service
-//!         rtfm::wfi();
-//!     }
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_1_one_task.rs

@@ -1,100 +0,0 @@
-//! An application with one task
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m;
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use cortex_m::peripheral::syst::SystClkSource;
-//! use rtfm::{app, Threshold};
-//! use stm32f103xx::GPIOC;
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     // Here data resources are declared
-//!     //
-//!     // Data resources are static variables that are safe to share across tasks
-//!     resources: {
-//!         // Declaration of resources looks exactly like declaration of static
-//!         // variables
-//!         static ON: bool = false;
-//!     },
-//! 
-//!     // Here tasks are declared
-//!     //
-//!     // Each task corresponds to an interrupt or an exception. Every time the
-//!     // interrupt or exception becomes *pending* the corresponding task handler
-//!     // will be executed.
-//!     tasks: {
-//!         // Here we declare that we'll use the SYS_TICK exception as a task
-//!         SYS_TICK: {
-//!             // Path to the task handler
-//!             path: sys_tick,
-//! 
-//!             // These are the resources this task has access to.
-//!             //
-//!             // The resources listed here must also appear in `app.resources`
-//!             resources: [ON],
-//!         },
-//!     }
-//! }
-//! 
-//! fn init(mut p: init::Peripherals, r: init::Resources) {
-//!     // `init` can modify all the `resources` declared in `app!`
-//!     r.ON;
-//! 
-//!     // power on GPIOC
-//!     p.device.RCC.apb2enr.modify(|_, w| w.iopcen().enabled());
-//! 
-//!     // configure PC13 as output
-//!     p.device.GPIOC.bsrr.write(|w| w.bs13().set());
-//!     p.device
-//!         .GPIOC
-//!         .crh
-//!         .modify(|_, w| w.mode13().output().cnf13().push());
-//! 
-//!     // configure the system timer to generate one interrupt every second
-//!     p.core.SYST.set_clock_source(SystClkSource::Core);
-//!     p.core.SYST.set_reload(8_000_000); // 1s
-//!     p.core.SYST.enable_interrupt();
-//!     p.core.SYST.enable_counter();
-//! }
-//! 
-//! fn idle() -> ! {
-//!     loop {
-//!         rtfm::wfi();
-//!     }
-//! }
-//! 
-//! // This is the task handler of the SYS_TICK exception
-//! //
-//! // `_t` is the preemption threshold token. We won't use it in this program.
-//! //
-//! // `r` is the set of resources this task has access to. `SYS_TICK::Resources`
-//! // has one field per resource declared in `app!`.
-//! #[allow(unsafe_code)]
-//! fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-//!     // toggle state
-//!     *r.ON = !*r.ON;
-//! 
-//!     if *r.ON {
-//!         // set the pin PC13 high
-//!         // NOTE(unsafe) atomic write to a stateless register
-//!         unsafe {
-//!             (*GPIOC::ptr()).bsrr.write(|w| w.bs13().set());
-//!         }
-//!     } else {
-//!         // set the pin PC13 low
-//!         // NOTE(unsafe) atomic write to a stateless register
-//!         unsafe {
-//!             (*GPIOC::ptr()).bsrr.write(|w| w.br13().reset());
-//!         }
-//!     }
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_2_two_tasks.rs

@@ -1,62 +0,0 @@
-//! Two tasks running at the *same* priority with access to the same resource
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use rtfm::{app, Threshold};
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     resources: {
-//!         static COUNTER: u64 = 0;
-//!     },
-//! 
-//!     // Both SYS_TICK and TIM2 have access to the `COUNTER` data
-//!     tasks: {
-//!         SYS_TICK: {
-//!             path: sys_tick,
-//!             resources: [COUNTER],
-//!         },
-//! 
-//!         TIM2: {
-//!             path: tim2,
-//!             resources: [COUNTER],
-//!         },
-//!     },
-//! }
-//! 
-//! fn init(_p: init::Peripherals, _r: init::Resources) {
-//!     // ..
-//! }
-//! 
-//! fn idle() -> ! {
-//!     loop {
-//!         rtfm::wfi();
-//!     }
-//! }
-//! 
-//! // As both tasks are running at the same priority one can't preempt the other.
-//! // Thus both tasks have direct access to the resource
-//! fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-//!     // ..
-//! 
-//!     *r.COUNTER += 1;
-//! 
-//!     // ..
-//! }
-//! 
-//! fn tim2(_t: &mut Threshold, mut r: TIM2::Resources) {
-//!     // ..
-//! 
-//!     *r.COUNTER += 1;
-//! 
-//!     // ..
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_3_preemption.rs

@@ -1,71 +0,0 @@
-//! Two tasks running at *different* priorities with access to the same resource
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use rtfm::{app, Resource, Threshold};
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     resources: {
-//!         static COUNTER: u64 = 0;
-//!     },
-//! 
-//!     tasks: {
-//!         // The `SYS_TICK` task has higher priority than `TIM2`
-//!         SYS_TICK: {
-//!             path: sys_tick,
-//!             priority: 2,
-//!             resources: [COUNTER],
-//!         },
-//! 
-//!         TIM2: {
-//!             path: tim2,
-//!             priority: 1,
-//!             resources: [COUNTER],
-//!         },
-//!     },
-//! }
-//! 
-//! fn init(_p: init::Peripherals, _r: init::Resources) {
-//!     // ..
-//! }
-//! 
-//! fn idle() -> ! {
-//!     loop {
-//!         rtfm::wfi();
-//!     }
-//! }
-//! 
-//! fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-//!     // ..
-//! 
-//!     // This task can't be preempted by `tim2` so it has direct access to the
-//!     // resource data
-//!     *r.COUNTER += 1;
-//! 
-//!     // ..
-//! }
-//! 
-//! fn tim2(t: &mut Threshold, mut r: TIM2::Resources) {
-//!     // ..
-//! 
-//!     // As this task runs at lower priority it needs a critical section to
-//!     // prevent `sys_tick` from preempting it while it modifies this resource
-//!     // data. The critical section is required to prevent data races which can
-//!     // lead to undefined behavior.
-//!     r.COUNTER.claim_mut(t, |counter, _t| {
-//!         // `claim_mut` creates a critical section
-//!         *counter += 1;
-//!     });
-//! 
-//!     // ..
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_4_nested.rs

@@ -1,132 +0,0 @@
-//! Nesting claims and how the preemption threshold works
-//!
-//! If you run this program you'll hit the breakpoints as indicated by the
-//! letters in the comments: A, then B, then C, etc.
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use rtfm::{app, Resource, Threshold};
-//! use stm32f103xx::Interrupt;
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     resources: {
-//!         static LOW: u64 = 0;
-//!         static HIGH: u64 = 0;
-//!     },
-//! 
-//!     tasks: {
-//!         EXTI0: {
-//!             path: exti0,
-//!             priority: 1,
-//!             resources: [LOW, HIGH],
-//!         },
-//! 
-//!         EXTI1: {
-//!             path: exti1,
-//!             priority: 2,
-//!             resources: [LOW],
-//!         },
-//! 
-//!         EXTI2: {
-//!             path: exti2,
-//!             priority: 3,
-//!             resources: [HIGH],
-//!         },
-//!     },
-//! }
-//! 
-//! fn init(_p: init::Peripherals, _r: init::Resources) {}
-//! 
-//! fn idle() -> ! {
-//!     // A
-//!     rtfm::bkpt();
-//! 
-//!     // Sets task `exti0` as pending
-//!     //
-//!     // Because `exti0` has higher priority than `idle` it will be executed
-//!     // immediately
-//!     rtfm::set_pending(Interrupt::EXTI0); // ~> exti0
-//! 
-//!     loop {
-//!         rtfm::wfi();
-//!     }
-//! }
-//! 
-//! #[allow(non_snake_case)]
-//! fn exti0(
-//!     t: &mut Threshold,
-//!     EXTI0::Resources {
-//!         LOW: mut low,
-//!         HIGH: mut high,
-//!     }: EXTI0::Resources,
-//! ) {
-//!     // Because this task has a priority of 1 the preemption threshold `t` also
-//!     // starts at 1
-//! 
-//!     // B
-//!     rtfm::bkpt();
-//! 
-//!     // Because `exti1` has higher priority than `exti0` it can preempt it
-//!     rtfm::set_pending(Interrupt::EXTI1); // ~> exti1
-//! 
-//!     // A claim creates a critical section
-//!     low.claim_mut(t, |_low, t| {
-//!         // This claim increases the preemption threshold to 2
-//!         //
-//!         // 2 is just high enough to not race with task `exti1` for access to the
-//!         // `LOW` resource
-//! 
-//!         // D
-//!         rtfm::bkpt();
-//! 
-//!         // Now `exti1` can't preempt this task because its priority is equal to
-//!         // the current preemption threshold
-//!         rtfm::set_pending(Interrupt::EXTI1);
-//! 
-//!         // But `exti2` can, because its priority is higher than the current
-//!         // preemption threshold
-//!         rtfm::set_pending(Interrupt::EXTI2); // ~> exti2
-//! 
-//!         // F
-//!         rtfm::bkpt();
-//! 
-//!         // Claims can be nested
-//!         high.claim_mut(t, |_high, _| {
-//!             // This claim increases the preemption threshold to 3
-//! 
-//!             // Now `exti2` can't preempt this task
-//!             rtfm::set_pending(Interrupt::EXTI2);
-//! 
-//!             // G
-//!             rtfm::bkpt();
-//!         });
-//! 
-//!         // Upon leaving the critical section the preemption threshold drops back
-//!         // to 2 and `exti2` immediately preempts this task
-//!         // ~> exti2
-//!     });
-//! 
-//!     // Once again the preemption threshold drops but this time to 1. Now the
-//!     // pending `exti1` task can preempt this task
-//!     // ~> exti1
-//! }
-//! 
-//! fn exti1(_t: &mut Threshold, _r: EXTI1::Resources) {
-//!     // C, I
-//!     rtfm::bkpt();
-//! }
-//! 
-//! fn exti2(_t: &mut Threshold, _r: EXTI2::Resources) {
-//!     // E, H
-//!     rtfm::bkpt();
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_5_late_resources.rs

@@ -1,90 +0,0 @@
-//! Demonstrates initialization of resources in `init`.
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use rtfm::{app, Threshold};
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     resources: {
-//!         // Usually, resources are initialized with a constant initializer:
-//!         static ON: bool = false;
-//! 
-//!         // However, there are cases where this is not possible or not desired.
-//!         // For example, there may not be a sensible value to use, or the type may
-//!         // not be constructible in a constant (like `Vec`).
-//!         //
-//!         // While it is possible to use an `Option` in some cases, that requires
-//!         // you to properly initialize it and `.unwrap()` it at every use. It
-//!         // also consumes more memory.
-//!         //
-//!         // To solve this, it is possible to defer initialization of resources to
-//!         // `init` by omitting the initializer. Doing that will require `init` to
-//!         // return the values of all "late" resources.
-//!         static IP_ADDRESS: u32;
-//! 
-//!         // PORT is used by 2 tasks, making it a shared resource. This just tests
-//!         // another internal code path and is not important for the example.
-//!         static PORT: u16;
-//!     },
-//! 
-//!     idle: {
-//!         // Test that late resources can be used in idle
-//!         resources: [IP_ADDRESS],
-//!     },
-//! 
-//!     tasks: {
-//!         SYS_TICK: {
-//!             priority: 1,
-//!             path: sys_tick,
-//!             resources: [IP_ADDRESS, PORT, ON],
-//!         },
-//! 
-//!         EXTI0: {
-//!             priority: 2,
-//!             path: exti0,
-//!             resources: [PORT],
-//!         }
-//!     }
-//! }
-//! 
-//! // The signature of `init` is now required to have a specific return type.
-//! fn init(_p: init::Peripherals, _r: init::Resources) -> init::LateResources {
-//!     // `init::Resources` does not contain `IP_ADDRESS`, since it is not yet
-//!     // initialized.
-//!     //_r.IP_ADDRESS;     // doesn't compile
-//! 
-//!     // ...obtain value for IP_ADDRESS from EEPROM/DHCP...
-//!     let ip_address = 0x7f000001;
-//! 
-//!     init::LateResources {
-//!         // This struct will contain fields for all resources with omitted
-//!         // initializers.
-//!         IP_ADDRESS: ip_address,
-//!         PORT: 0,
-//!     }
-//! }
-//! 
-//! fn sys_tick(_t: &mut Threshold, r: SYS_TICK::Resources) {
-//!     // Other tasks can access late resources like any other, since they are
-//!     // guaranteed to be initialized when tasks are run.
-//! 
-//!     r.IP_ADDRESS;
-//! }
-//! 
-//! fn exti0(_t: &mut Threshold, _r: EXTI0::Resources) {}
-//! 
-//! fn idle(_t: &mut Threshold, _r: idle::Resources) -> ! {
-//!     loop {
-//!         rtfm::wfi();
-//!     }
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_6_safe_static_mut_ref.rs

@@ -1,35 +0,0 @@
-//! Safe creation of `&'static mut` references
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use rtfm::app;
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     resources: {
-//!         static BUFFER: [u8; 16] = [0; 16];
-//!     },
-//! 
-//!     init: {
-//!         resources: [BUFFER],
-//!     },
-//! }
-//! 
-//! fn init(_p: init::Peripherals, r: init::Resources) {
-//!     let _buf: &'static mut [u8; 16] = r.BUFFER;
-//! }
-//! 
-//! fn idle() -> ! {
-//!     loop {
-//!         rtfm::wfi();
-//!     }
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_7_generics.rs

@@ -1,77 +0,0 @@
-//! Working with resources in a generic fashion
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use rtfm::{app, Resource, Threshold};
-//! use stm32f103xx::{GPIOA, SPI1};
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     resources: {
-//!         static GPIOA: GPIOA;
-//!         static SPI1: SPI1;
-//!     },
-//! 
-//!     tasks: {
-//!         EXTI0: {
-//!             path: exti0,
-//!             priority: 1,
-//!             resources: [GPIOA, SPI1],
-//!         },
-//! 
-//!         EXTI1: {
-//!             path: exti1,
-//!             priority: 2,
-//!             resources: [GPIOA, SPI1],
-//!         },
-//!     },
-//! }
-//! 
-//! fn init(p: init::Peripherals) -> init::LateResources {
-//!     init::LateResources {
-//!         GPIOA: p.device.GPIOA,
-//!         SPI1: p.device.SPI1,
-//!     }
-//! }
-//! 
-//! fn idle() -> ! {
-//!     loop {
-//!         rtfm::wfi();
-//!     }
-//! }
-//! 
-//! // A generic function that uses some resources
-//! fn work<G, S>(t: &mut Threshold, gpioa: &G, spi1: &S)
-//! where
-//!     G: Resource<Data = GPIOA>,
-//!     S: Resource<Data = SPI1>,
-//! {
-//!     gpioa.claim(t, |_gpioa, t| {
-//!         // drive NSS low
-//! 
-//!         spi1.claim(t, |_spi1, _| {
-//!             // transfer data
-//!         });
-//! 
-//!         // drive NSS high
-//!     });
-//! }
-//! 
-//! // This task needs critical sections to access the resources
-//! fn exti0(t: &mut Threshold, r: EXTI0::Resources) {
-//!     work(t, &r.GPIOA, &r.SPI1);
-//! }
-//! 
-//! // This task has direct access to the resources
-//! fn exti1(t: &mut Threshold, r: EXTI1::Resources) {
-//!     work(t, &r.GPIOA, &r.SPI1);
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/_8_full_syntax.rs

@@ -1,87 +0,0 @@
-//! A showcase of the `app!` macro syntax
-//!
-//! ```
-//! #![deny(unsafe_code)]
-//! #![deny(warnings)]
-//! #![no_std]
-//! 
-//! extern crate cortex_m_rtfm as rtfm;
-//! extern crate stm32f103xx;
-//! 
-//! use rtfm::{app, Threshold};
-//! 
-//! app! {
-//!     device: stm32f103xx,
-//! 
-//!     resources: {
-//!         static CO_OWNED: u32 = 0;
-//!         static ON: bool = false;
-//!         static OWNED: bool = false;
-//!         static SHARED: bool = false;
-//!     },
-//! 
-//!     init: {
-//!         // This is the path to the `init` function
-//!         //
-//!         // `init` doesn't necessarily has to be in the root of the crate
-//!         path: main::init,
-//!     },
-//! 
-//!     idle: {
-//!         // This is a path to the `idle` function
-//!         //
-//!         // `idle` doesn't necessarily has to be in the root of the crate
-//!         path: main::idle,
-//!         resources: [OWNED, SHARED],
-//!     },
-//! 
-//!     tasks: {
-//!         SYS_TICK: {
-//!             path: sys_tick,
-//!             // If omitted priority is assumed to be 1
-//!             // priority: 1,
-//!             resources: [CO_OWNED, ON, SHARED],
-//!         },
-//! 
-//!         TIM2: {
-//!             // Tasks are enabled, between `init` and `idle`, by default but they
-//!             // can start disabled if `false` is specified here
-//!             enabled: false,
-//!             path: tim2,
-//!             priority: 1,
-//!             resources: [CO_OWNED],
-//!         },
-//!     },
-//! }
-//! 
-//! mod main {
-//!     use rtfm::{self, Resource, Threshold};
-//! 
-//!     pub fn init(_p: ::init::Peripherals, _r: ::init::Resources) {}
-//! 
-//!     pub fn idle(t: &mut Threshold, mut r: ::idle::Resources) -> ! {
-//!         loop {
-//!             *r.OWNED = !*r.OWNED;
-//! 
-//!             if *r.OWNED {
-//!                 if r.SHARED.claim(t, |shared, _| *shared) {
-//!                     rtfm::wfi();
-//!                 }
-//!             } else {
-//!                 r.SHARED.claim_mut(t, |shared, _| *shared = !*shared);
-//!             }
-//!         }
-//!     }
-//! }
-//! 
-//! fn sys_tick(_t: &mut Threshold, mut r: SYS_TICK::Resources) {
-//!     *r.ON = !*r.ON;
-//! 
-//!     *r.CO_OWNED += 1;
-//! }
-//! 
-//! fn tim2(_t: &mut Threshold, mut r: TIM2::Resources) {
-//!     *r.CO_OWNED += 1;
-//! }
-//! ```
-// Auto-generated. Do not modify.

src/examples/mod.rs

@@ -1,11 +0,0 @@
-//! Examples
-// Auto-generated. Do not modify.
-pub mod _0_zero_tasks;
-pub mod _1_one_task;
-pub mod _2_two_tasks;
-pub mod _3_preemption;
-pub mod _4_nested;
-pub mod _5_late_resources;
-pub mod _6_safe_static_mut_ref;
-pub mod _7_generics;
-pub mod _8_full_syntax;

src/export.rs

@@ -0,0 +1,84 @@
+/// IMPLEMENTATION DETAILS. DO NOT USE ANYTHING IN THIS MODULE
+use core::{hint, ptr};
+
+#[cfg(armv7m)]
+use cortex_m::register::basepri;
+pub use cortex_m::{
+    asm::wfi, interrupt, peripheral::scb::SystemHandler, peripheral::syst::SystClkSource,
+    peripheral::Peripherals,
+};
+pub use cortex_m_rt::{entry, exception};
+pub use heapless::consts;
+use heapless::spsc::Queue;
+
+#[cfg(feature = "timer-queue")]
+pub use crate::tq::{isr as sys_tick, NotReady, TimerQueue};
+
+pub type FreeQueue<N> = Queue<u8, N>;
+pub type ReadyQueue<T, N> = Queue<(T, u8), N>;
+
+#[cfg(armv7m)]
+#[inline(always)]
+pub fn run<F>(f: F)
+where
+    F: FnOnce(),
+{
+    let initial = basepri::read();
+    f();
+    unsafe { basepri::write(initial) }
+}
+
+#[cfg(not(armv7m))]
+#[inline(always)]
+pub fn run<F>(f: F)
+where
+    F: FnOnce(),
+{
+    f();
+}
+
+// TODO(MaybeUninit) Until core::mem::MaybeUninit is stabilized we use our own (inefficient)
+// implementation
+pub struct MaybeUninit<T> {
+    value: Option<T>,
+}
+
+impl<T> MaybeUninit<T> {
+    pub const fn uninitialized() -> Self {
+        MaybeUninit { value: None }
+    }
+
+    pub unsafe fn get_ref(&self) -> &T {
+        if let Some(x) = self.value.as_ref() {
+            x
+        } else {
+            hint::unreachable_unchecked()
+        }
+    }
+
+    pub unsafe fn get_mut(&mut self) -> &mut T {
+        if let Some(x) = self.value.as_mut() {
+            x
+        } else {
+            hint::unreachable_unchecked()
+        }
+    }
+
+    pub fn set(&mut self, val: T) {
+        unsafe { ptr::write(&mut self.value, Some(val)) }
+    }
+}
+
+#[inline(always)]
+pub fn assert_send<T>()
+where
+    T: Send,
+{
+}
+
+#[inline(always)]
+pub fn assert_sync<T>()
+where
+    T: Sync,
+{
+}

src/lib.rs

@@ -1,170 +1,342 @@
 //! Real Time For the Masses (RTFM) framework for ARM Cortex-M microcontrollers
 //!
-//! This crate is based on [the RTFM framework] created by the Embedded Systems
-//! group at [Luleå University of Technology][ltu], led by Prof. Per Lindgren,
-//! and uses a simplified version of the Stack Resource Policy as scheduling
-//! policy (check the [references] for details).
+//! **IMPORTANT**: This crate is published as [`cortex-m-rtfm`] on crates.io but the name of the
+//! library is `rtfm`.
 //!
-//! [the RTFM framework]: http://www.rtfm-lang.org/
-//! [ltu]: https://www.ltu.se/?l=en
-//! [per]: https://www.ltu.se/staff/p/pln-1.11258?l=en
-//! [references]: ./index.html#references
+//! [`cortex-m-rtfm`]: https://crates.io/crates/cortex-m-rtfm
 //!
-//! # Features
+//! The user level documentation can be found [here].
 //!
-//! - **Event triggered tasks** as the unit of concurrency.
-//! - Support for prioritization of tasks and, thus, **preemptive
-//!   multitasking**.
-//! - **Efficient and data race free memory sharing** through fine grained *non
-//!   global* critical sections.
-//! - **Deadlock free execution** guaranteed at compile time.
-//! - **Minimal scheduling overhead** as the scheduler has no "software
-//!   component": the hardware does all the scheduling.
-//! - **Highly efficient memory usage**: All the tasks share a single call stack
-//!   and there's no hard dependency on a dynamic memory allocator.
-//! - **All Cortex M devices are fully supported**.
-//! - This task model is amenable to known WCET (Worst Case Execution Time)
-//!   analysis and scheduling analysis techniques. (Though we haven't yet
-//!   developed Rust friendly tooling for that.)
+//! [here]: ../../book/index.html
 //!
-//! # Constraints
+//! Don't forget to check the documentation of the [`#[app]`] attribute, which is the main component
+//! of the framework.
 //!
-//! - Tasks must run to completion. That's it, tasks can't contain endless
-//!   loops. However, you can run an endless event loop in the `idle` *loop*.
+//! [`#[app]`]: ../cortex_m_rtfm_macros/attr.app.html
 //!
-//! - Task priorities must remain constant at runtime.
+//! # Cargo features
 //!
-//! # Dependencies
+//! - `timer-queue`. This opt-in feature enables the `schedule` API which can be used to schedule
+//! tasks to run in the future. Also see [`Instant`] and [`Duration`].
 //!
-//! The application crate must depend on a device crate generated using
-//! [`svd2rust`] v0.12.x and the "rt" feature of that crate must be enabled. The
-//! SVD file used to generate the device crate *must* contain [`<cpu>`]
-//! information.
-//!
-//! [`svd2rust`]: https://docs.rs/svd2rust/0.12.0/svd2rust/
-//! [`<cpu>`]: https://www.keil.com/pack/doc/CMSIS/SVD/html/elem_cpu.html
-//!
-//! # `app!`
-//!
-//! The `app!` macro is documented [here].
-//!
-//! [here]: https://docs.rs/cortex-m-rtfm-macros/0.3.0/cortex_m_rtfm_macros/fn.app.html
-//!
-//! # Important: Cortex-M7 devices
-//!
-//! If targeting a Cortex-M7 device with revision r0p1 then you MUST enable the `cm7-r0p1` Cargo
-//! feature of this crate or the `Resource.claim` and `Resource.claim_mut` methods WILL misbehave.
-//!
-//! # Examples
-//!
-//! In increasing grade of complexity. See the [examples](./examples/index.html)
-//! module.
-//!
-//! # References
-//!
-//! - Baker, T. P. (1991). Stack-based scheduling of realtime processes.
-//!   *Real-Time Systems*, 3(1), 67-99.
-//!
-//! > The original Stack Resource Policy paper. [PDF][srp].
-//!
-//! [srp]: http://www.cs.fsu.edu/~baker/papers/mstacks3.pdf
-//!
-//! - Eriksson, J., Häggström, F., Aittamaa, S., Kruglyak, A., & Lindgren, P.
-//!   (2013, June). Real-time for the masses, step 1: Programming API and static
-//!   priority SRP kernel primitives. In Industrial Embedded Systems (SIES),
-//!   2013 8th IEEE International Symposium on (pp. 110-113). IEEE.
-//!
-//! > A description of the RTFM task and resource model. [PDF][rtfm]
-//!
-//! [rtfm]: http://www.diva-portal.org/smash/get/diva2:1005680/FULLTEXT01.pdf
+//! [`Instant`]: struct.Instant.html
+//! [`Duration`]: struct.Duration.html
+
 #![deny(missing_docs)]
 #![deny(warnings)]
 #![no_std]
 
-extern crate cortex_m;
-extern crate cortex_m_rtfm_macros;
-extern crate rtfm_core;
-extern crate untagged_option;
+use core::{cell::Cell, u8};
+#[cfg(feature = "timer-queue")]
+use core::{cmp::Ordering, ops};
 
-use core::{mem, u8};
-
-pub use cortex_m::asm::{bkpt, wfi};
-pub use cortex_m_rtfm_macros::app;
-pub use rtfm_core::{Resource, Threshold};
-#[doc(hidden)]
-pub use untagged_option::UntaggedOption;
-
-use cortex_m::interrupt::{self, Nr};
-use cortex_m::peripheral::NVIC;
-#[cfg(not(armv6m))]
+#[cfg(not(feature = "timer-queue"))]
+use cortex_m::peripheral::SYST;
+#[cfg(armv7m)]
 use cortex_m::register::basepri;
+use cortex_m::{
+    interrupt::{self, Nr},
+    peripheral::{CBP, CPUID, DCB, DWT, FPB, FPU, ITM, MPU, NVIC, SCB, TPIU},
+};
+pub use cortex_m_rtfm_macros::app;
 
-pub mod examples;
+#[doc(hidden)]
+pub mod export;
+#[doc(hidden)]
+#[cfg(feature = "timer-queue")]
+mod tq;
 
-/// Executes the closure `f` in a preemption free context
+/// Core peripherals
 ///
-/// During the execution of the closure no task can preempt the current task.
-pub fn atomic<R, F>(t: &mut Threshold, f: F) -> R
-where
-    F: FnOnce(&mut Threshold) -> R,
-{
-    if t.value() == u8::MAX {
-        f(t)
-    } else {
-        interrupt::disable();
-        let r = f(&mut unsafe { Threshold::max() });
-        unsafe { interrupt::enable() };
-        r
+/// This is `cortex_m::Peripherals` minus the peripherals that the RTFM runtime uses
+///
+/// - The `NVIC` field is never present.
+/// - When the `timer-queue` feature is enabled the following fields are *not* present: `DWT` and
+/// `SYST`.
+#[allow(non_snake_case)]
+pub struct Peripherals<'a> {
+    /// Cache and branch predictor maintenance operations (not present on Cortex-M0 variants)
+    pub CBP: CBP,
+
+    /// CPUID
+    pub CPUID: CPUID,
+
+    /// Debug Control Block (by value if the `timer-queue` feature is disabled)
+    #[cfg(feature = "timer-queue")]
+    pub DCB: &'a mut DCB,
+
+    /// Debug Control Block (borrowed if the `timer-queue` feature is enabled)
+    #[cfg(not(feature = "timer-queue"))]
+    pub DCB: DCB,
+
+    /// Data Watchpoint and Trace unit (not present if the `timer-queue` feature is enabled)
+    #[cfg(not(feature = "timer-queue"))]
+    pub DWT: DWT,
+
+    /// Flash Patch and Breakpoint unit (not present on Cortex-M0 variants)
+    pub FPB: FPB,
+
+    /// Floating Point Unit (only present on `thumbv7em-none-eabihf`)
+    pub FPU: FPU,
+
+    /// Instrumentation Trace Macrocell (not present on Cortex-M0 variants)
+    pub ITM: ITM,
+
+    /// Memory Protection Unit
+    pub MPU: MPU,
+
+    // Nested Vector Interrupt Controller
+    // pub NVIC: NVIC,
+    /// System Control Block
+    pub SCB: &'a mut SCB,
+
+    /// SysTick: System Timer (not present if the `timer-queue` is enabled)
+    #[cfg(not(feature = "timer-queue"))]
+    pub SYST: SYST,
+
+    /// Trace Port Interface Unit (not present on Cortex-M0 variants)
+    pub TPIU: TPIU,
+}
+
+/// A measurement of a monotonically nondecreasing clock. Opaque and useful only with `Duration`
+///
+/// This data type is only available when the `timer-queue` feature is enabled
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[cfg(feature = "timer-queue")]
+pub struct Instant(i32);
+
+#[cfg(feature = "timer-queue")]
+impl Instant {
+    /// IMPLEMENTATION DETAIL. DO NOT USE
+    #[doc(hidden)]
+    pub fn artificial(timestamp: i32) -> Self {
+        Instant(timestamp)
+    }
+
+    /// Returns an instant corresponding to "now"
+    pub fn now() -> Self {
+        Instant(DWT::get_cycle_count() as i32)
+    }
+
+    /// Returns the amount of time elapsed since this instant was created.
+    pub fn elapsed(&self) -> Duration {
+        Instant::now() - *self
+    }
+
+    /// Returns the amount of time elapsed from another instant to this one.
+    pub fn duration_since(&self, earlier: Instant) -> Duration {
+        let diff = self.0 - earlier.0;
+        assert!(diff >= 0, "second instant is later than self");
+        Duration(diff as u32)
     }
 }
 
-#[inline]
-#[doc(hidden)]
-pub unsafe fn claim<T, R, F>(
-    data: T,
-    ceiling: u8,
-    _nvic_prio_bits: u8,
-    t: &mut Threshold,
-    f: F,
-) -> R
-where
-    F: FnOnce(T, &mut Threshold) -> R,
-{
-    if ceiling > t.value() {
-        match () {
-            #[cfg(armv6m)]
-            () => atomic(t, |t| f(data, t)),
+#[cfg(feature = "timer-queue")]
+impl ops::AddAssign<Duration> for Instant {
+    fn add_assign(&mut self, dur: Duration) {
+        debug_assert!(dur.0 < (1 << 31));
+        self.0 = self.0.wrapping_add(dur.0 as i32);
+    }
+}
 
-            #[cfg(not(armv6m))]
-            () => {
-                let max_priority = 1 << _nvic_prio_bits;
+#[cfg(feature = "timer-queue")]
+impl ops::Add<Duration> for Instant {
+    type Output = Self;
 
-                if ceiling == max_priority {
-                    atomic(t, |t| f(data, t))
+    fn add(mut self, dur: Duration) -> Self {
+        self += dur;
+        self
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl ops::SubAssign<Duration> for Instant {
+    fn sub_assign(&mut self, dur: Duration) {
+        // XXX should this be a non-debug assertion?
+        debug_assert!(dur.0 < (1 << 31));
+        self.0 = self.0.wrapping_sub(dur.0 as i32);
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl ops::Sub<Duration> for Instant {
+    type Output = Self;
+
+    fn sub(mut self, dur: Duration) -> Self {
+        self -= dur;
+        self
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl ops::Sub<Instant> for Instant {
+    type Output = Duration;
+
+    fn sub(self, other: Instant) -> Duration {
+        self.duration_since(other)
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl Ord for Instant {
+    fn cmp(&self, rhs: &Self) -> Ordering {
+        self.0.wrapping_sub(rhs.0).cmp(&0)
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl PartialOrd for Instant {
+    fn partial_cmp(&self, rhs: &Self) -> Option<Ordering> {
+        Some(self.cmp(rhs))
+    }
+}
+
+/// A `Duration` type to represent a span of time.
+///
+/// This data type is only available when the `timer-queue` feature is enabled
+#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
+#[cfg(feature = "timer-queue")]
+pub struct Duration(u32);
+
+#[cfg(feature = "timer-queue")]
+impl ops::AddAssign for Duration {
+    fn add_assign(&mut self, dur: Duration) {
+        self.0 += dur.0;
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl ops::Add<Duration> for Duration {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Duration(self.0 + other.0)
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl ops::SubAssign for Duration {
+    fn sub_assign(&mut self, rhs: Duration) {
+        self.0 -= rhs.0;
+    }
+}
+
+#[cfg(feature = "timer-queue")]
+impl ops::Sub<Duration> for Duration {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        Duration(self.0 - rhs.0)
+    }
+}
+
+/// Adds the `cycles` method to the `u32` type
+///
+/// This trait is only available when the `timer-queue` feature is enabled
+#[cfg(feature = "timer-queue")]
+pub trait U32Ext {
+    /// Converts the `u32` value into clock cycles
+    fn cycles(self) -> Duration;
+}
+
+#[cfg(feature = "timer-queue")]
+impl U32Ext for u32 {
+    fn cycles(self) -> Duration {
+        Duration(self)
+    }
+}
+
+/// Memory safe access to shared resources
+///
+/// In RTFM, locks are implemented as critical sections that prevent other tasks from *starting*.
+/// These critical sections are implemented by temporarily increasing the dynamic priority (see
+/// [BASEPRI]) of the current context.
+///
+/// [BASEPRI]: https://developer.arm.com/products/architecture/cpu-architecture/m-profile/docs/100701/latest/special-purpose-mask-registers
+pub unsafe trait Mutex {
+    /// IMPLEMENTATION DETAIL. DO NOT USE THIS CONSTANT
+    #[doc(hidden)]
+    const CEILING: u8;
+
+    /// IMPLEMENTATION DETAIL. DO NOT USE THIS CONSTANT
+    #[doc(hidden)]
+    const NVIC_PRIO_BITS: u8;
+
+    /// Data protected by the mutex
+    type Data: Send;
+
+    /// IMPLEMENTATION DETAIL. DO NOT USE THIS METHOD
+    #[doc(hidden)]
+    unsafe fn priority(&self) -> &Cell<u8>;
+
+    /// IMPLEMENTATION DETAIL. DO NOT USE THIS METHOD
+    #[doc(hidden)]
+    fn ptr(&self) -> *mut Self::Data;
+
+    /// Creates a critical section and grants temporary access to the protected data
+    #[inline(always)]
+    #[cfg(armv7m)]
+    fn lock<R, F>(&mut self, f: F) -> R
+    where
+        F: FnOnce(&mut Self::Data) -> R,
+    {
+        unsafe {
+            let current = self.priority().get();
+
+            if self.priority().get() < Self::CEILING {
+                if Self::CEILING == (1 << Self::NVIC_PRIO_BITS) {
+                    self.priority().set(u8::MAX);
+                    let r = interrupt::free(|_| f(&mut *self.ptr()));
+                    self.priority().set(current);
+                    r
                 } else {
-                    let old = basepri::read();
-                    let hw = (max_priority - ceiling) << (8 - _nvic_prio_bits);
-                    basepri::write(hw);
-                    let ret = f(data, &mut Threshold::new(ceiling));
-                    basepri::write(old);
-                    ret
+                    self.priority().set(Self::CEILING);
+                    basepri::write(logical2hw(Self::CEILING, Self::NVIC_PRIO_BITS));
+                    let r = f(&mut *self.ptr());
+                    basepri::write(logical2hw(current, Self::NVIC_PRIO_BITS));
+                    self.priority().set(current);
+                    r
                 }
+            } else {
+                f(&mut *self.ptr())
+            }
+        }
+    }
+
+    /// Creates a critical section and grants temporary access to the protected data
+    #[cfg(not(armv7m))]
+    fn lock<R, F>(&mut self, f: F) -> R
+    where
+        F: FnOnce(&mut Self::Data) -> R,
+    {
+        unsafe {
+            let current = self.priority().get();
+
+            if self.priority().get() < Self::CEILING {
+                self.priority().set(u8::MAX);
+                let r = interrupt::free(|_| f(&mut *self.ptr()));
+                self.priority().set(current);
+                r
+            } else {
+                f(&mut *self.ptr())
             }
         }
-    } else {
-        f(data, t)
     }
 }
 
-/// Sets an interrupt, that is a task, as pending
+#[cfg(armv7m)]
+#[inline]
+fn logical2hw(logical: u8, nvic_prio_bits: u8) -> u8 {
+    ((1 << nvic_prio_bits) - logical) << (8 - nvic_prio_bits)
+}
+
+/// Sets the given `interrupt` as pending
 ///
-/// If the task priority is high enough the task will be serviced immediately,
-/// otherwise it will be serviced at some point after the current task ends.
-pub fn set_pending<I>(interrupt: I)
+/// This is a convenience function around
+/// [`NVIC::pend`](../cortex_m/peripheral/struct.NVIC.html#method.pend)
+pub fn pend<I>(interrupt: I)
 where
     I: Nr,
 {
-    // NOTE(safe) atomic write
-    let mut nvic: NVIC = unsafe { mem::transmute(()) };
-    nvic.set_pending(interrupt);
+    NVIC::pend(interrupt)
 }

src/tq.rs

@@ -0,0 +1,135 @@
+use core::cmp::{self, Ordering};
+
+use cortex_m::peripheral::{SCB, SYST};
+use heapless::{binary_heap::Min, ArrayLength, BinaryHeap};
+
+use crate::{Instant, Mutex};
+
+pub struct TimerQueue<T, N>
+where
+    N: ArrayLength<NotReady<T>>,
+    T: Copy,
+{
+    pub syst: SYST,
+    pub queue: BinaryHeap<NotReady<T>, N, Min>,
+}
+
+impl<T, N> TimerQueue<T, N>
+where
+    N: ArrayLength<NotReady<T>>,
+    T: Copy,
+{
+    pub fn new(syst: SYST) -> Self {
+        TimerQueue {
+            syst,
+            queue: BinaryHeap::new(),
+        }
+    }
+
+    #[inline]
+    pub unsafe fn enqueue_unchecked(&mut self, nr: NotReady<T>) {
+        let mut is_empty = true;
+        if self
+            .queue
+            .peek()
+            .map(|head| {
+                is_empty = false;
+                nr.instant < head.instant
+            })
+            .unwrap_or(true)
+        {
+            if is_empty {
+                self.syst.enable_interrupt();
+            }
+
+            // set SysTick pending
+            (*SCB::ptr()).icsr.write(1 << 26);
+        }
+
+        self.queue.push_unchecked(nr);
+    }
+}
+
+pub struct NotReady<T>
+where
+    T: Copy,
+{
+    pub index: u8,
+    pub instant: Instant,
+    pub task: T,
+}
+
+impl<T> Eq for NotReady<T> where T: Copy {}
+
+impl<T> Ord for NotReady<T>
+where
+    T: Copy,
+{
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.instant.cmp(&other.instant)
+    }
+}
+
+impl<T> PartialEq for NotReady<T>
+where
+    T: Copy,
+{
+    fn eq(&self, other: &Self) -> bool {
+        self.instant == other.instant
+    }
+}
+
+impl<T> PartialOrd for NotReady<T>
+where
+    T: Copy,
+{
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(&other))
+    }
+}
+
+#[inline(always)]
+pub fn isr<TQ, T, N, F>(mut tq: TQ, mut f: F)
+where
+    TQ: Mutex<Data = TimerQueue<T, N>>,
+    T: Copy + Send,
+    N: ArrayLength<NotReady<T>>,
+    F: FnMut(T, u8),
+{
+    loop {
+        // XXX does `#[inline(always)]` improve performance or not?
+        let next = tq.lock(#[inline(always)]
+        |tq| {
+            if let Some(instant) = tq.queue.peek().map(|p| p.instant) {
+                let diff = instant.0.wrapping_sub(Instant::now().0);
+
+                if diff < 0 {
+                    // task became ready
+                    let m = unsafe { tq.queue.pop_unchecked() };
+
+                    Some((m.task, m.index))
+                } else {
+                    // set a new timeout
+                    const MAX: u32 = 0x00ffffff;
+
+                    tq.syst.set_reload(cmp::min(MAX, diff as u32));
+
+                    // start counting down from the new reload
+                    tq.syst.clear_current();
+
+                    None
+                }
+            } else {
+                // the queue is empty
+                tq.syst.disable_interrupt();
+                None
+            }
+        });
+
+        if let Some((task, index)) = next {
+            f(task, index)
+        } else {
+            return;
+        }
+    }
+}