cosmopolitan/third_party/nsync/mu_semaphore_win32.c

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/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi
Copyright 2016 Google Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0 │
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "libc/errno.h"
#include "libc/nt/enum/wait.h"
#include "libc/nt/synchronization.h"
#include "libc/runtime/runtime.h"
#include "third_party/nsync/mu_semaphore.h"
#include "third_party/nsync/mu_semaphore.internal.h"
#include "third_party/nsync/time.h"
asm(".ident\t\"\\n\\n\
*NSYNC (Apache 2.0)\\n\
Copyright 2016 Google, Inc.\\n\
https://github.com/google/nsync\"");
// clang-format off
/* Initialize *s; the initial value is 0. */
void nsync_mu_semaphore_init_win32 (nsync_semaphore *s) {
int64_t *h = (int64_t *) s;
*h = CreateSemaphore(NULL, 0, 1, NULL);
if (!*h) notpossible;
}
/* Wait until the count of *s exceeds 0, and decrement it. */
void nsync_mu_semaphore_p_win32 (nsync_semaphore *s) {
int64_t *h = (int64_t *) s;
WaitForSingleObject(*h, -1u);
}
/* Wait until one of:
the count of *s is non-zero, in which case decrement *s and return 0;
or abs_deadline expires, in which case return ETIMEDOUT. */
int nsync_mu_semaphore_p_with_deadline_win32 (nsync_semaphore *s, nsync_time abs_deadline) {
int64_t *h = (int64_t *) s;
int result;
if (nsync_time_cmp (abs_deadline, nsync_time_no_deadline) == 0) {
result = WaitForSingleObject(*h, -1u);
} else {
nsync_time now;
now = nsync_time_now ();
do {
if (nsync_time_cmp (abs_deadline, now) <= 0) {
result = WaitForSingleObject (*h, 0);
} else {
nsync_time delay;
delay = nsync_time_sub (abs_deadline, now);
if (NSYNC_TIME_SEC (delay) > 1000*1000) {
result = WaitForSingleObject (*h, 1000*1000);
} else {
result = WaitForSingleObject (*h,
(unsigned) (NSYNC_TIME_SEC (delay) * 1000 +
(NSYNC_TIME_NSEC (delay) + 999999) / (1000 * 1000)));
}
}
if (result == kNtWaitTimeout) {
now = nsync_time_now ();
}
} while (result == kNtWaitTimeout && /* Windows generates early wakeups. */
nsync_time_cmp (abs_deadline, now) > 0);
}
return (result == kNtWaitTimeout ? ETIMEDOUT : 0);
}
/* Ensure that the count of *s is at least 1. */
void nsync_mu_semaphore_v_win32 (nsync_semaphore *s) {
int64_t *h = (int64_t *) s;
ReleaseSemaphore(*h, 1, NULL);
}