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//
// critsect.c
//
// Critical sections
//
// Copyright (C) 2002 Michael Ringgaard. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// 3. Neither the name of the project nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
#include <os.h>
#include <atomic.h>
__inline tid_t threadid() {
struct tib *tib;
__asm {
mov eax, fs:[TIB_SELF_OFFSET]
mov [tib], eax
}
return tib->tid;
}
void mkcs(critsect_t cs) {
cs->count = -1;
cs->recursion = 0;
cs->owner = NOHANDLE;
cs->event = mkevent(0, 0);
}
void csfree(critsect_t cs) {
close(cs->event);
}
void enter(critsect_t cs) {
tid_t tid = threadid();
if (cs->owner == tid) {
cs->recursion++;
} else {
if (atomic_add(&cs->count, 1) > 0) while (waitone(cs->event, INFINITE) != 0);
cs->owner = tid;
}
}
void leave(critsect_t cs) {
if (cs->owner != threadid()) return;
if (cs->recursion > 0) {
cs->recursion--;
} else {
cs->owner = NOHANDLE;
if (atomic_add(&cs->count, -1) >= 0) eset(cs->event);
}
}