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Diffstat (limited to 'book/en/src/by-example/app_priorities.md')
| -rw-r--r-- | book/en/src/by-example/app_priorities.md | 30 |
1 files changed, 9 insertions, 21 deletions
diff --git a/book/en/src/by-example/app_priorities.md b/book/en/src/by-example/app_priorities.md index 8cee749..f03ebf7 100644 --- a/book/en/src/by-example/app_priorities.md +++ b/book/en/src/by-example/app_priorities.md @@ -4,23 +4,18 @@ The `priority` argument declares the static priority of each `task`. -For Cortex-M, tasks can have priorities in the range `1..=(1 << NVIC_PRIO_BITS)` -where `NVIC_PRIO_BITS` is a constant defined in the `device` crate. +For Cortex-M, tasks can have priorities in the range `1..=(1 << NVIC_PRIO_BITS)` where `NVIC_PRIO_BITS` is a constant defined in the `device` crate. -Omitting the `priority` argument the task priority defaults to `1`. -The `idle` task has a non-configurable static priority of `0`, the lowest priority. +Omitting the `priority` argument the task priority defaults to `1`. The `idle` task has a non-configurable static priority of `0`, the lowest priority. > A higher number means a higher priority in RTIC, which is the opposite from what > Cortex-M does in the NVIC peripheral. > Explicitly, this means that number `10` has a **higher** priority than number `9`. -The highest static priority task takes precedence when more than one -task are ready to execute. +The highest static priority task takes precedence when more than one task are ready to execute. The following scenario demonstrates task prioritization: -Spawning a higher priority task A during execution of a lower priority task B suspends -task B. Task A has higher priority thus preempting task B which gets suspended -until task A completes execution. Thus, when task A completes task B resumes execution. +Spawning a higher priority task A during execution of a lower priority task B pends task A. Task A has higher priority thus preempting task B which gets suspended until task A completes execution. Thus, when task A completes task B resumes execution. ```text Task Priority @@ -39,23 +34,17 @@ Task Priority The following example showcases the priority based scheduling of tasks: ``` rust -{{#include ../../../../examples/preempt.rs}} +{{#include ../../../../rtic/examples/preempt.rs}} ``` ``` console $ cargo run --target thumbv7m-none-eabi --example preempt -{{#include ../../../../ci/expected/preempt.run}} +{{#include ../../../../rtic/ci/expected/preempt.run}} ``` -Note that the task `bar` does *not* preempt task `baz` because its priority -is the *same* as `baz`'s. The higher priority task `bar` runs before `foo` -when `baz`returns. When `bar` returns `foo` can resume. +Note that the task `bar` does *not* preempt task `baz` because its priority is the *same* as `baz`'s. The higher priority task `bar` runs before `foo` when `baz`returns. When `bar` returns `foo` can resume. -One more note about priorities: choosing a priority higher than what the device -supports will result in a compilation error. - -The error is cryptic due to limitations in the Rust language -if `priority = 9` for task `uart0_interrupt` in `example/common.rs` this looks like: +One more note about priorities: choosing a priority higher than what the device supports will result in a compilation error. The error is cryptic due to limitations in the Rust language, if `priority = 9` for task `uart0_interrupt` in `example/common.rs` this looks like: ```text error[E0080]: evaluation of constant value failed @@ -68,5 +57,4 @@ if `priority = 9` for task `uart0_interrupt` in `example/common.rs` this looks l ``` -The error message incorrectly points to the starting point of the macro, but at least the -value subtracted (in this case 9) will suggest which task causes the error. +The error message incorrectly points to the starting point of the macro, but at least the value subtracted (in this case 9) will suggest which task causes the error. |