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|
use crate::mem::MaybeUninit;
use crate::time::Duration;
use super::{
abi,
error::{expect_success, fail},
time::with_tmos,
};
const CLEAR: abi::FLGPTN = 0;
const RAISED: abi::FLGPTN = 1;
/// A thread parking primitive that is not susceptible to race conditions,
/// but provides no atomic ordering guarantees and allows only one `raise` per wait.
pub struct WaitFlag {
flag: abi::ID,
}
impl WaitFlag {
/// Creates a new wait flag.
pub fn new() -> WaitFlag {
let flag = expect_success(
unsafe {
abi::acre_flg(&abi::T_CFLG {
flgatr: abi::TA_FIFO | abi::TA_WSGL | abi::TA_CLR,
iflgptn: CLEAR,
})
},
&"acre_flg",
);
WaitFlag { flag }
}
/// Wait for the wait flag to be raised.
pub fn wait(&self) {
let mut token = MaybeUninit::uninit();
expect_success(
unsafe { abi::wai_flg(self.flag, RAISED, abi::TWF_ORW, token.as_mut_ptr()) },
&"wai_flg",
);
}
/// Wait for the wait flag to be raised or the timeout to occur.
///
/// Returns whether the flag was raised (`true`) or the operation timed out (`false`).
pub fn wait_timeout(&self, dur: Duration) -> bool {
let mut token = MaybeUninit::uninit();
let res = with_tmos(dur, |tmout| unsafe {
abi::twai_flg(self.flag, RAISED, abi::TWF_ORW, token.as_mut_ptr(), tmout)
});
match res {
abi::E_OK => true,
abi::E_TMOUT => false,
error => fail(error, &"twai_flg"),
}
}
/// Raise the wait flag.
///
/// Calls to this function should be balanced with the number of successful waits.
pub fn raise(&self) {
expect_success(unsafe { abi::set_flg(self.flag, RAISED) }, &"set_flg");
}
}
impl Drop for WaitFlag {
fn drop(&mut self) {
expect_success(unsafe { abi::del_flg(self.flag) }, &"del_flg");
}
}
|
