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86 lines
2.6 KiB
Rust
86 lines
2.6 KiB
Rust
// SPDX-License-Identifier: MIT OR Apache-2.0
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//
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// Copyright (c) 2018-2019 Andre Richter <andre.o.richter@gmail.com>
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//! Trait definitions for coupling `kernel` and `BSP` code.
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//!
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//! ```
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//! +-------------------+
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//! | Interface (Trait) |
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//! | |
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//! +--+-------------+--+
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//! ^ ^
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//! | |
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//! | |
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//! +----------+--+ +--+----------+
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//! | Kernel code | | BSP Code |
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//! | | | |
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//! +-------------+ +-------------+
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//! ```
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/// System console operations.
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pub mod console {
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use core::fmt;
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/// Console write functions.
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pub trait Write {
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fn write_fmt(&self, args: fmt::Arguments) -> fmt::Result;
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}
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/// Console read functions.
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pub trait Read {
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fn read_char(&self) -> char {
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' '
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}
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}
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/// Console statistics.
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pub trait Statistics {
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/// Return the number of characters written.
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fn chars_written(&self) -> usize {
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0
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}
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/// Return the number of characters read.
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fn chars_read(&self) -> usize {
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0
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}
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}
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/// Trait alias for a full-fledged console.
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pub trait All = Write + Read + Statistics;
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}
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/// Synchronization primitives.
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pub mod sync {
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/// Any object implementing this trait guarantees exclusive access to the data contained within
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/// the mutex for the duration of the lock.
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///
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/// The trait follows the [Rust embedded WG's
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/// proposal](https://github.com/korken89/wg/blob/master/rfcs/0377-mutex-trait.md) and therefore
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/// provides some goodness such as [deadlock
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/// prevention](https://github.com/korken89/wg/blob/master/rfcs/0377-mutex-trait.md#design-decisions-and-compatibility).
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///
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/// # Example
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///
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/// Since the lock function takes an `&mut self` to enable deadlock-prevention, the trait is
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/// best implemented **for a reference to a container struct**, and has a usage pattern that
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/// might feel strange at first:
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///
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/// ```
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/// static MUT: Mutex<RefCell<i32>> = Mutex::new(RefCell::new(0));
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///
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/// fn foo() {
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/// let mut r = &MUT; // Note that r is mutable
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/// r.lock(|data| *data += 1);
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/// }
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/// ```
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pub trait Mutex {
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/// Type of data encapsulated by the mutex.
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type Data;
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/// Creates a critical section and grants temporary mutable access to the encapsulated data.
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fn lock<R>(&mut self, f: impl FnOnce(&mut Self::Data) -> R) -> R;
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}
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}
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