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#include <mutex.h>
/* Internal use only. This function is atomic, meaning it cannot be interrupted by a system task switch. */
static uint32_t atomic_exchange(uint32_t* ptr, uint32_t newval) {
uint32_t r;
asm volatile("xchg (%%ecx), %%eax" : "=a"(r) : "c"(ptr), "a"(newval));
return r;
}
void mutex_lock(uint32_t* mutex) {
while (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) {
yield();
}
}
int mutex_try_lock(uint32_t* mutex) {
if (atomic_exchange(mutex, MUTEX_LOCKED) == MUTEX_LOCKED) {
return 0;
}
return 1;
}
void mutex_unlock(uint32_t* mutex) {
*mutex = MUTEX_UNLOCKED;
}
/* vim: set ts=4 sw=4 tw=0 noet :*/
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