70 lines
1.3 KiB
C
70 lines
1.3 KiB
C
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/*
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* semaphore.c
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*
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* Created on: Oct 25, 2015
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* Author: tkl
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*/
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#include <stdbool.h>
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#include <stddef.h>
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#include "irq.h"
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#include "queue.h"
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#include "semaphore.h"
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#include "stack.h"
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#include "thread.h"
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#include "schedule.h"
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extern volatile struct thread_context *current_thread;
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int semaphore_init(struct semaphore *sem, int value)
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{
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if(NULL == sem)
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return -1;
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sem->cnt = value;
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queue_init(&sem->queue);
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return 0;
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}
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int semaphore_wait(struct semaphore *sem)
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{
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unsigned int irq_state;
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if(NULL == sem)
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return -1;
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irq_state = disable_irq();
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if(sem->cnt > 0) {
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sem->cnt--;
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restore_irq(irq_state);
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}
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else {
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current_thread->sem_queue_node.data = (unsigned int) current_thread;
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queue_push(&sem->queue, (struct queue_node *)¤t_thread->sem_queue_node);
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current_thread->status = THREAD_STATUS_WAITING;
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restore_irq(irq_state);
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schedule();
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}
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return 0;
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}
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int semaphore_post(struct semaphore *sem)
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{
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unsigned int irq_state;
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if(NULL == sem)
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return -1;
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irq_state = disable_irq();
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if(queue_is_empty(&sem->queue))
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sem->cnt++;
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else {
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struct queue_node next;
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queue_pop(&sem->queue, &next);
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struct thread_context *ctx = (struct thread_context *) next.data;
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ctx->status = THREAD_STATUS_EXECUTING;
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restore_irq(irq_state);
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schedule();
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}
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restore_irq(irq_state);
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return 0;
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}
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