mirror of
https://github.com/jart/cosmopolitan.git
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61 lines
2.9 KiB
C
61 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2024 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/fds.h"
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#include "libc/runtime/runtime.h"
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#include "libc/thread/posixthread.internal.h"
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struct Cursor *__cursor_new(void) {
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struct Cursor *c;
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if ((c = _mapanon(sizeof(struct Cursor)))) {
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if ((c->shared = _mapshared(sizeof(struct CursorShared)))) {
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c->shared->lock = (pthread_mutex_t)PTHREAD_SHARED_MUTEX_INITIALIZER_NP;
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} else {
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munmap(c, sizeof(struct Cursor));
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c = 0;
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}
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}
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return c;
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}
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void __cursor_ref(struct Cursor *c) {
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if (!c)
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return;
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unassert(atomic_fetch_add_explicit(&c->refs, 1, memory_order_relaxed) >= 0);
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}
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int __cursor_unref(struct Cursor *c) {
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if (!c)
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return 0;
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if (atomic_fetch_sub_explicit(&c->refs, 1, memory_order_release))
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return 0;
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atomic_thread_fence(memory_order_acquire);
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int rc = munmap(c->shared, sizeof(struct CursorShared));
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rc |= munmap(c, sizeof(struct Cursor));
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return rc;
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}
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void __cursor_lock(struct Cursor *c) {
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_pthread_mutex_lock(&c->shared->lock);
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}
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void __cursor_unlock(struct Cursor *c) {
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_pthread_mutex_unlock(&c->shared->lock);
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}
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