Merge #741

741: Docs 2 r=korken89 a=datdenkikniet

Working on the migration guide and other docs

TODO:
- [x] Migration guide
- [x] Hardcoded examples should link to example code that is tested (this was already done, AFAICT)
- [x] Address #699 
- [x] Discuss: should we remove references to non-v2, apart from the migration guide and link to the book for v1? (Off-github conclusion: yes)
- [x] RTIC {vs,and} Embassy (important: distinction between embassy runtime & HALs)
- [x] More descriptive docs on how to implement & PR implementations of `Monotonic` to `rtic-monotonics` 


Co-authored-by: datdenkikniet <jcdra1@gmail.com>

3 files changed, 0 insertions, 669 deletions

diff --git a/book/en/src/migration/migration_rtic.md b/book/en/src/migration/migration_rtic.md
deleted file mode 100644
index c027da3..0000000
--- a/book/en/src/migration/migration_rtic.md
+++ /dev/null
@@ -1,50 +0,0 @@
-# Migrating from RTFM to RTIC
-
-This section covers how to upgrade an application written against RTFM v0.5.x to
-the same version of RTIC. This applies since the renaming of the framework as per [RFC #33].
-
-**Note:** There are no code differences between RTFM v0.5.3 and RTIC v0.5.3, it is purely a name
-change.
-
-[RFC #33]: https://github.com/rtic-rs/rfcs/pull/33
-
-## `Cargo.toml`
-
-First, the `cortex-m-rtfm` dependency needs to be updated to
-`cortex-m-rtic`.
-
-``` toml
-[dependencies]
-# change this
-cortex-m-rtfm = "0.5.3"
-
-# into this
-cortex-m-rtic = "0.5.3"
-```
-
-## Code changes
-
-The only code change that needs to be made is that any reference to `rtfm` before now need to point
-to `rtic` as follows:
-
-``` rust
-//
-// Change this
-//
-
-#[rtfm::app(/* .. */, monotonic = rtfm::cyccnt::CYCCNT)]
-const APP: () = {
-    // ...
-
-};
-
-//
-// Into this
-//
-
-#[rtic::app(/* .. */, monotonic = rtic::cyccnt::CYCCNT)]
-const APP: () = {
-    // ...
-
-};
-```
diff --git a/book/en/src/migration/migration_v4.md b/book/en/src/migration/migration_v4.md
deleted file mode 100644
index d1a7ebe..0000000
--- a/book/en/src/migration/migration_v4.md
+++ /dev/null
@@ -1,247 +0,0 @@
-# Migrating from v0.4.x to v0.5.0
-
-This section covers how to upgrade an application written against RTFM v0.4.x to
-the version v0.5.0 of the framework.
-
-## Project name change RTFM -> RTIC
-
-With release [v0.5.2][rtic0.5.2] the name was change to Real-Time Interrupt-driven Concurrency
-
-All occurrences of `RTFM` needs to change to `RTIC`.
-
-See [migration guide RTFM to RTIC](./migration_rtic.md)
-
-[rtic0.5.2]: https://crates.io/crates/cortex-m-rtic/0.5.2
-
-## `Cargo.toml`
-
-Change the version of `cortex-m-rtfm` to
-`"0.5.0"`, change `rtfm` to `rtic`.
-Remove the `timer-queue` feature.
-
-``` toml
-[dependencies.cortex-m-rtfm]
-# change this
-version = "0.4.3"
-
-# into this
-[dependencies.cortex-m-rtic]
-version = "0.5.0"
-
-# and remove this Cargo feature
-features = ["timer-queue"]
-#           ^^^^^^^^^^^^^
-```
-
-## `Context` argument
-
-All functions inside the `#[rtfm::app]` item need to take as first argument a
-`Context` structure. This `Context` type will contain the variables that were
-magically injected into the scope of the function by version v0.4.x of the
-framework: `resources`, `spawn`, `schedule` -- these variables will become
-fields of the `Context` structure. Each function within the `#[rtfm::app]` item
-gets a different `Context` type.
-
-``` rust
-#[rtfm::app(/* .. */)]
-const APP: () = {
-    // change this
-    #[task(resources = [x], spawn = [a], schedule = [b])]
-    fn foo() {
-        resources.x.lock(|x| /* .. */);
-        spawn.a(message);
-        schedule.b(baseline);
-    }
-
-    // into this
-    #[task(resources = [x], spawn = [a], schedule = [b])]
-    fn foo(mut cx: foo::Context) {
-        // ^^^^^^^^^^^^^^^^^^^^
-
-        cx.resources.x.lock(|x| /* .. */);
-    //  ^^^
-
-        cx.spawn.a(message);
-    //  ^^^
-
-        cx.schedule.b(message, baseline);
-    //  ^^^
-    }
-
-    // change this
-    #[init]
-    fn init() {
-        // ..
-    }
-
-    // into this
-    #[init]
-    fn init(cx: init::Context) {
-        //  ^^^^^^^^^^^^^^^^^
-        // ..
-    }
-
-    // ..
-};
-```
-
-## Resources
-
-The syntax used to declare resources has changed from `static mut`
-variables to a `struct Resources`.
-
-``` rust
-#[rtfm::app(/* .. */)]
-const APP: () = {
-    // change this
-    static mut X: u32 = 0;
-    static mut Y: u32 = (); // late resource
-
-    // into this
-    struct Resources {
-        #[init(0)] // <- initial value
-        X: u32, // NOTE: we suggest changing the naming style to `snake_case`
-
-        Y: u32, // late resource
-    }
-
-    // ..
-};
-```
-
-## Device peripherals
-
-If your application was accessing the device peripherals in `#[init]` through
-the `device` variable then you'll need to add `peripherals = true` to the
-`#[rtfm::app]` attribute to continue to access the device peripherals through
-the `device` field of the `init::Context` structure.
-
-Change this:
-
-``` rust
-#[rtfm::app(/* .. */)]
-const APP: () = {
-    #[init]
-    fn init() {
-        device.SOME_PERIPHERAL.write(something);
-    }
-
-    // ..
-};
-```
-
-Into this:
-
-``` rust
-#[rtfm::app(/* .. */, peripherals = true)]
-//                    ^^^^^^^^^^^^^^^^^^
-const APP: () = {
-    #[init]
-    fn init(cx: init::Context) {
-        //  ^^^^^^^^^^^^^^^^^
-        cx.device.SOME_PERIPHERAL.write(something);
-    //  ^^^
-    }
-
-    // ..
-};
-```
-
-## `#[interrupt]` and `#[exception]`
-
-Remove the attributes `#[interrupt]` and `#[exception]`.
-To declare hardware tasks in v0.5.x use the `#[task]`
-attribute with the `binds` argument instead.
-
-Change this:
-
-``` rust
-#[rtfm::app(/* .. */)]
-const APP: () = {
-    // hardware tasks
-    #[exception]
-    fn SVCall() { /* .. */ }
-
-    #[interrupt]
-    fn UART0() { /* .. */ }
-
-    // software task
-    #[task]
-    fn foo() { /* .. */ }
-
-    // ..
-};
-```
-
-Into this:
-
-``` rust
-#[rtfm::app(/* .. */)]
-const APP: () = {
-    #[task(binds = SVCall)]
-    //     ^^^^^^^^^^^^^^
-    fn svcall(cx: svcall::Context) { /* .. */ }
-    // ^^^^^^ we suggest you use a `snake_case` name here
-
-    #[task(binds = UART0)]
-    //     ^^^^^^^^^^^^^
-    fn uart0(cx: uart0::Context) { /* .. */ }
-
-    #[task]
-    fn foo(cx: foo::Context) { /* .. */ }
-
-    // ..
-};
-```
-
-## `schedule`
-
-The `schedule` API no longer requires the `timer-queue` cargo feature.
-To use the `schedule` API one must first define the monotonic timer the
-runtime will use using the `monotonic` argument of the `#[rtfm::app]` attribute.
-To continue using the cycle counter (CYCCNT) as the monotonic timer,
-and match the behavior of version v0.4.x, add the `monotonic = rtfm::cyccnt::CYCCNT`
-argument to the `#[rtfm::app]` attribute.
-
-Also, the `Duration` and `Instant` types and the `U32Ext` trait moved
-into the `rtfm::cyccnt` module.
-This module is only available on ARMv7-M+ devices.
-The removal of the `timer-queue` also brings back the `DWT` peripheral
-inside the core peripherals struct, if `DWT` is required,
-ensure it is enabled by the application inside `init`.
-
-Change this:
-
-``` rust
-use rtfm::{Duration, Instant, U32Ext};
-
-#[rtfm::app(/* .. */)]
-const APP: () = {
-    #[task(schedule = [b])]
-    fn a() {
-        // ..
-    }
-};
-```
-
-Into this:
-
-``` rust
-use rtfm::cyccnt::{Duration, Instant, U32Ext};
-//        ^^^^^^^^
-
-#[rtfm::app(/* .. */, monotonic = rtfm::cyccnt::CYCCNT)]
-//                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-const APP: () = {
-    #[init]
-    fn init(cx: init::Context) {
-        cx.core.DWT.enable_cycle_counter();
-        // optional, configure the DWT run without a debugger connected
-        cx.core.DCB.enable_trace();
-    }
-    #[task(schedule = [b])]
-    fn a(cx: a::Context) {
-        // ..
-    }
-};
-```
diff --git a/book/en/src/migration/migration_v5.md b/book/en/src/migration/migration_v5.md
deleted file mode 100644
index 5a8fabc..0000000
--- a/book/en/src/migration/migration_v5.md
+++ /dev/null
@@ -1,372 +0,0 @@
-# Migrating from v0.5.x to v1.0.0
-
-This section describes how to upgrade from v0.5.x to v1.0.0 of the RTIC framework.
-
-## `Cargo.toml` - version bump
-
-Change the version of `cortex-m-rtic` to `"1.0.0"`.
-
-## `mod` instead of `const`
-
-With the support of attributes on modules the `const APP` workaround is not needed.
-
-Change
-
-``` rust
-#[rtic::app(/* .. */)]
-const APP: () = {
-  [code here]
-};
-```
-
-into
-
-``` rust
-#[rtic::app(/* .. */)]
-mod app {
-  [code here]
-}
-```
-
-Now that a regular Rust module is used it means it is possible to have custom
-user code within that module.
-Additionally, it means that `use`-statements for resources used in user
-code must be moved inside `mod app`, or be referred to with `super`. For
-example, change:
-
-```rust
-use some_crate::some_func;
-
-#[rtic::app(/* .. */)]
-const APP: () = {
-    fn func() {
-        some_crate::some_func();
-    }
-};
-```
-
-into
-
-```rust
-#[rtic::app(/* .. */)]
-mod app {
-    use some_crate::some_func;
-
-    fn func() {
-        some_crate::some_func();
-    }
-}
-```
-
-or
-
-```rust
-use some_crate::some_func;
-
-#[rtic::app(/* .. */)]
-mod app {
-    fn func() {
-        super::some_crate::some_func();
-    }
-}
-```
-
-## Move Dispatchers from `extern "C"` to app arguments
-
-Change
-
-``` rust
-#[rtic::app(/* .. */)]
-const APP: () = {
-    [code here]
-
-    // RTIC requires that unused interrupts are declared in an extern block when
-    // using software tasks; these free interrupts will be used to dispatch the
-    // software tasks.
-    extern "C" {
-        fn SSI0();
-        fn QEI0();
-    }
-};
-```
-
-into
-
-``` rust
-#[rtic::app(/* .. */, dispatchers = [SSI0, QEI0])]
-mod app {
-  [code here]
-}
-```
-
-This works also for ram functions, see examples/ramfunc.rs
-
-
-## Resources structs - `#[shared]`, `#[local]`
-
-Previously the RTIC resources had to be in in a struct named exactly "Resources":
-
-``` rust
-struct Resources {
-    // Resources defined in here
-}
-```
-
-With RTIC v1.0.0 the resources structs are annotated similarly like
-`#[task]`, `#[init]`, `#[idle]`: with the attributes `#[shared]` and `#[local]`
-
-``` rust
-#[shared]
-struct MySharedResources {
-    // Resources shared between tasks are defined here
-}
-
-#[local]
-struct MyLocalResources {
-    // Resources defined here cannot be shared between tasks; each one is local to a single task
-}
-```
-
-These structs can be freely named by the developer.
-
-## `shared` and `local` arguments in `#[task]`s
-
-In v1.0.0 resources are split between `shared` resources and `local` resources.
-`#[task]`, `#[init]` and `#[idle]` no longer have a `resources` argument; they must now use the `shared` and `local` arguments.
-
-In v0.5.x:
-
-``` rust
-struct Resources {
-    local_to_b: i64,
-    shared_by_a_and_b: i64,
-}
-
-#[task(resources = [shared_by_a_and_b])]
-fn a(_: a::Context) {}
-
-#[task(resources = [shared_by_a_and_b, local_to_b])]
-fn b(_: b::Context) {}
-```
-
-In v1.0.0:
-
-``` rust
-#[shared]
-struct Shared {
-    shared_by_a_and_b: i64,
-}
-
-#[local]
-struct Local {
-    local_to_b: i64,
-}
-
-#[task(shared = [shared_by_a_and_b])]
-fn a(_: a::Context) {}
-
-#[task(shared = [shared_by_a_and_b], local = [local_to_b])]
-fn b(_: b::Context) {}
-```
-
-## Symmetric locks
-
-Now RTIC utilizes symmetric locks, this means that the `lock` method need
-to be used for all `shared` resource access.
-In old code one could do the following as the high priority
-task has exclusive access to the resource:
-
-``` rust
-#[task(priority = 2, resources = [r])]
-fn foo(cx: foo::Context) {
-    cx.resources.r = /* ... */;
-}
-
-#[task(resources = [r])]
-fn bar(cx: bar::Context) {
-    cx.resources.r.lock(|r| r = /* ... */);
-}
-```
-
-And with symmetric locks one needs to use locks in both tasks:
-
-``` rust
-#[task(priority = 2, shared = [r])]
-fn foo(cx: foo::Context) {
-    cx.shared.r.lock(|r| r = /* ... */);
-}
-
-#[task(shared = [r])]
-fn bar(cx: bar::Context) {
-    cx.shared.r.lock(|r| r = /* ... */);
-}
-```
-
-Note that the performance does not change thanks to LLVM's optimizations which optimizes away unnecessary locks.
-
-## Lock-free resource access
-
-In RTIC 0.5 resources shared by tasks running at the same priority could be accessed *without* the `lock` API.
-This is still possible in 1.0: the `#[shared]` resource must be annotated with the field-level `#[lock_free]` attribute.
-
-v0.5 code:
-
-``` rust
-struct Resources {
-    counter: u64,
-}
-
-#[task(resources = [counter])]
-fn a(cx: a::Context) {
-    *cx.resources.counter += 1;
-}
-
-#[task(resources = [counter])]
-fn b(cx: b::Context) {
-    *cx.resources.counter += 1;
-}
-```
-
-v1.0 code:
-
-``` rust
-#[shared]
-struct Shared {
-    #[lock_free]
-    counter: u64,
-}
-
-#[task(shared = [counter])]
-fn a(cx: a::Context) {
-    *cx.shared.counter += 1;
-}
-
-#[task(shared = [counter])]
-fn b(cx: b::Context) {
-    *cx.shared.counter += 1;
-}
-```
-
-## no `static mut` transform
-
-`static mut` variables are no longer transformed to safe `&'static mut` references.
-Instead of that syntax, use the `local` argument in `#[init]`.
-
-v0.5.x code:
-
-``` rust
-#[init]
-fn init(_: init::Context) {
-    static mut BUFFER: [u8; 1024] = [0; 1024];
-    let buffer: &'static mut [u8; 1024] = BUFFER;
-}
-```
-
-v1.0.0 code:
-
-``` rust
-#[init(local = [
-    buffer: [u8; 1024] = [0; 1024]
-//   type ^^^^^^^^^^^^   ^^^^^^^^^ initial value
-])]
-fn init(cx: init::Context) -> (Shared, Local, init::Monotonics) {
-    let buffer: &'static mut [u8; 1024] = cx.local.buffer;
-
-    (Shared {}, Local {}, init::Monotonics())
-}
-```
-
-## Init always returns late resources
-
-In order to make the API more symmetric the #[init]-task always returns a late resource.
-
-From this:
-
-``` rust
-#[rtic::app(device = lm3s6965)]
-const APP: () = {
-    #[init]
-    fn init(_: init::Context) {
-        rtic::pend(Interrupt::UART0);
-    }
-
-    // [more code]
-};
-```
-
-to this:
-
-``` rust
-#[rtic::app(device = lm3s6965)]
-mod app {
-    #[shared]
-    struct MySharedResources {}
-
-    #[local]
-    struct MyLocalResources {}
-
-    #[init]
-    fn init(_: init::Context) -> (MySharedResources, MyLocalResources, init::Monotonics) {
-        rtic::pend(Interrupt::UART0);
-
-        (MySharedResources, MyLocalResources, init::Monotonics())
-    }
-
-    // [more code]
-}
-```
-
-## Spawn from anywhere
-
-With the new spawn/spawn_after/spawn_at interface,
-old code requiring the context `cx` for spawning such as:
-
-``` rust
-#[task(spawn = [bar])]
-fn foo(cx: foo::Context) {
-    cx.spawn.bar().unwrap();
-}
-
-#[task(schedule = [bar])]
-fn bar(cx: bar::Context) {
-    cx.schedule.foo(/* ... */).unwrap();
-}
-```
-
-Will now be written as:
-
-``` rust
-#[task]
-fn foo(_c: foo::Context) {
-    bar::spawn().unwrap();
-}
-
-#[task]
-fn bar(_c: bar::Context) {
-    // Takes a Duration, relative to “now”
-    let spawn_handle = foo::spawn_after(/* ... */);
-}
-
-#[task]
-fn bar(_c: bar::Context) {
-    // Takes an Instant
-    let spawn_handle = foo::spawn_at(/* ... */);
-}
-```
-
-Thus the requirement of having access to the context is dropped.
-
-Note that the attributes `spawn`/`schedule` in the task definition are no longer needed.
-
----
-
-## Additions
-
-### Extern tasks
-
-Both software and hardware tasks can now be defined external to the `mod app`.
-Previously this was possible only by implementing a trampoline calling out the task implementation.
-
-See examples `examples/extern_binds.rs` and `examples/extern_spawn.rs`.
-
-This enables breaking apps into multiple files.