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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "runtime.h"
void
runtime_initlock(Lock *l)
{
l->key = 0;
if(sem_init(&l->sem, 0, 0) != 0)
runtime_throw("sem_init failed");
}
static uint32
runtime_xadd(uint32 volatile *val, int32 delta)
{
uint32 oval, nval;
for(;;){
oval = *val;
nval = oval + delta;
if(runtime_cas(val, oval, nval))
return nval;
}
}
// noinline so that runtime_lock doesn't have to split the stack.
static void runtime_lock_full(Lock *l) __attribute__ ((noinline));
static void
runtime_lock_full(Lock *l)
{
if(sem_wait(&l->sem) != 0)
runtime_throw("sem_wait failed");
}
void
runtime_lock(Lock *l)
{
if(m != nil) {
if(m->locks < 0)
runtime_throw("lock count");
m->locks++;
}
if(runtime_xadd(&l->key, 1) > 1) // someone else has it; wait
runtime_lock_full(l);
}
static void runtime_unlock_full(Lock *l) __attribute__ ((noinline));
static void
runtime_unlock_full(Lock *l)
{
if(sem_post(&l->sem) != 0)
runtime_throw("sem_post failed");
}
void
runtime_unlock(Lock *l)
{
if(m != nil) {
m->locks--;
if(m->locks < 0)
runtime_throw("lock count");
}
if(runtime_xadd(&l->key, -1) > 0) // someone else is waiting
runtime_unlock_full(l);
}
void
runtime_destroylock(Lock *l)
{
sem_destroy(&l->sem);
}
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