78 lines
1.6 KiB
C
78 lines
1.6 KiB
C
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#include <defs.h>
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#include <wait.h>
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#include <atomic.h>
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#include <kmalloc.h>
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#include <sem.h>
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#include <proc.h>
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#include <sync.h>
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#include <assert.h>
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void
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sem_init(semaphore_t *sem, int value) {
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sem->value = value;
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wait_queue_init(&(sem->wait_queue));
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}
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static __noinline void __up(semaphore_t *sem, uint32_t wait_state) {
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bool intr_flag;
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local_intr_save(intr_flag);
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{
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wait_t *wait;
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if ((wait = wait_queue_first(&(sem->wait_queue))) == NULL) {
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sem->value ++;
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}
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else {
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assert(wait->proc->wait_state == wait_state);
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wakeup_wait(&(sem->wait_queue), wait, wait_state, 1);
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}
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}
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local_intr_restore(intr_flag);
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}
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static __noinline uint32_t __down(semaphore_t *sem, uint32_t wait_state) {
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bool intr_flag;
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local_intr_save(intr_flag);
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if (sem->value > 0) {
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sem->value --;
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local_intr_restore(intr_flag);
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return 0;
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}
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wait_t __wait, *wait = &__wait;
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wait_current_set(&(sem->wait_queue), wait, wait_state);
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local_intr_restore(intr_flag);
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schedule();
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local_intr_save(intr_flag);
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wait_current_del(&(sem->wait_queue), wait);
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local_intr_restore(intr_flag);
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if (wait->wakeup_flags != wait_state) {
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return wait->wakeup_flags;
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}
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return 0;
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}
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void
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up(semaphore_t *sem) {
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__up(sem, WT_KSEM);
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}
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void
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down(semaphore_t *sem) {
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uint32_t flags = __down(sem, WT_KSEM);
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assert(flags == 0);
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}
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bool
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try_down(semaphore_t *sem) {
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bool intr_flag, ret = 0;
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local_intr_save(intr_flag);
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if (sem->value > 0) {
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sem->value --, ret = 1;
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}
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local_intr_restore(intr_flag);
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return ret;
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}
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