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#![feature(asm)]
#![feature(const_fn)]
#![feature(optin_builtin_traits)]
#![no_std]
extern crate cortex_m;
extern crate static_ref;
use core::cell::UnsafeCell;
pub use cortex_m::asm::{bkpt, wfi};
pub use cortex_m::interrupt::CriticalSection;
pub use cortex_m::interrupt::free as atomic;
pub use static_ref::Static;
#[cfg(not(armv6m))]
use cortex_m::register::{basepri_max, basepri};
#[cfg(not(armv6m))]
macro_rules! barrier {
() => {
asm!("" ::: "memory" : "volatile");
}
}
#[inline(always)]
unsafe fn claim<T, U, R, F, G>(
data: T,
ceiling: u8,
nvic_prio_bits: u8,
t: &mut Threshold,
f: F,
g: G,
) -> R
where
F: FnOnce(U, &mut Threshold) -> R,
G: FnOnce(T) -> U,
{
let max_priority = 1 << nvic_prio_bits;
if ceiling > t.0 {
match () {
#[cfg(armv6m)]
() => {
atomic(|_| f(g(data), &mut Threshold::new(max_priority)))
}
#[cfg(not(armv6m))]
() => {
if ceiling == max_priority {
atomic(|_| f(g(data), &mut Threshold::new(max_priority)))
} else {
let old = basepri::read();
let hw = (max_priority - ceiling) << (8 - nvic_prio_bits);
basepri_max::write(hw);
barrier!();
let ret = f(g(data), &mut Threshold(ceiling));
barrier!();
basepri::write(old);
ret
}
}
}
} else {
f(g(data), t)
}
}
pub struct Peripheral<P>
where
P: 'static,
{
// FIXME(rustc/LLVM bug?) storing the ceiling in the resource de-optimizes
// claims (the ceiling value gets loaded at runtime rather than inlined)
// ceiling: u8,
peripheral: cortex_m::peripheral::Peripheral<P>,
}
impl<P> Peripheral<P> {
pub const fn new(peripheral: cortex_m::peripheral::Peripheral<P>) -> Self {
Peripheral { peripheral }
}
#[inline(always)]
pub unsafe fn claim<R, F>(
&'static self,
ceiling: u8,
nvic_prio_bits: u8,
t: &mut Threshold,
f: F,
) -> R
where
F: FnOnce(&P, &mut Threshold) -> R,
{
claim(
&self.peripheral,
ceiling,
nvic_prio_bits,
t,
f,
|peripheral| &*peripheral.get(),
)
}
pub fn get(&self) -> *mut P {
self.peripheral.get()
}
}
unsafe impl<P> Sync for Peripheral<P>
where
P: Send,
{
}
pub struct Resource<T> {
// FIXME(rustc/LLVM bug?) storing the ceiling in the resource de-optimizes
// claims (the ceiling value gets loaded at runtime rather than inlined)
// ceiling: u8,
data: UnsafeCell<T>,
}
impl<T> Resource<T> {
pub const fn new(value: T) -> Self {
Resource { data: UnsafeCell::new(value) }
}
#[inline(always)]
pub unsafe fn claim<R, F>(
&'static self,
ceiling: u8,
nvic_prio_bits: u8,
t: &mut Threshold,
f: F,
) -> R
where
F: FnOnce(&Static<T>, &mut Threshold) -> R,
{
claim(&self.data, ceiling, nvic_prio_bits, t, f, |data| {
Static::ref_(&*data.get())
})
}
#[inline(always)]
pub unsafe fn claim_mut<R, F>(
&'static self,
ceiling: u8,
nvic_prio_bits: u8,
t: &mut Threshold,
f: F,
) -> R
where
F: FnOnce(&mut Static<T>, &mut Threshold) -> R,
{
claim(&self.data, ceiling, nvic_prio_bits, t, f, |data| {
Static::ref_mut(&mut *data.get())
})
}
pub fn get(&self) -> *mut T {
self.data.get()
}
}
unsafe impl<T> Sync for Resource<T>
where
T: Send,
{
}
pub struct Threshold(u8);
impl Threshold {
pub unsafe fn new(value: u8) -> Self {
Threshold(value)
}
}
impl !Send for Threshold {}
#[macro_export]
macro_rules! task {
($NAME:ident, $body:path) => {
#[allow(non_snake_case)]
#[no_mangle]
pub unsafe extern "C" fn $NAME() {
let f: fn($crate::Threshold, ::$NAME::Resources) = $body;
f(
$crate::Threshold::new(::$NAME::$NAME),
::$NAME::Resources::new(),
);
}
};
($NAME:ident, $body:path, $local:ident {
$($var:ident: $ty:ty = $expr:expr;)+
}) => {
struct $local {
$($var: $ty,)+
}
#[allow(non_snake_case)]
#[no_mangle]
pub unsafe extern "C" fn $NAME() {
let f: fn(
$crate::Threshold,
&mut $local,
::$NAME::Resources,
) = $body;
static mut LOCAL: $local = $local {
$($var: $expr,)+
};
f(
$crate::Threshold::new(::$NAME::$NAME),
&mut LOCAL,
::$NAME::Resources::new(),
);
}
};
}
#[allow(non_camel_case_types)]
#[doc(hidden)]
pub enum Exception {
/// System service call via SWI instruction
SVCALL,
/// Pendable request for system service
PENDSV,
/// System tick timer
SYS_TICK,
}
impl Exception {
#[doc(hidden)]
pub fn nr(&self) -> usize {
match *self {
Exception::SVCALL => 11,
Exception::PENDSV => 14,
Exception::SYS_TICK => 15,
}
}
}
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