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83 lines
1.8 KiB
C
83 lines
1.8 KiB
C
/**
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* @file semaphore.h
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* @author fslngjin (lonjin@RinGoTek.cn)
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* @brief 信号量
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* @version 0.1
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* @date 2022-04-12
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*
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* @copyright Copyright (c) 2022
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*
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*/
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#pragma once
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#include <process/atomic.h>
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#include <process/process.h>
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#include <sched/sched.h>
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#include "wait_queue.h"
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/**
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* @brief 信号量的结构体
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*
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*/
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typedef struct
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{
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atomic_t counter;
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wait_queue_node_t wait_queue;
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} semaphore_t;
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/**
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* @brief 初始化信号量
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*
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* @param sema 信号量对象
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* @param count 信号量的初始值
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*/
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void semaphore_init(semaphore_t *sema, ul count)
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{
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atomic_set(&sema->counter, count);
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wait_queue_init(&sema->wait_queue, NULL);
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}
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/**
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* @brief 信号量down
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*
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* @param sema
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*/
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void semaphore_down(semaphore_t *sema)
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{
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if (atomic_read(&sema->counter) > 0) // 信号量大于0，资源充足
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atomic_dec(&sema->counter);
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else // 资源不足，进程休眠
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{
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// 将当前进程加入信号量的等待队列
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wait_queue_node_t wait;
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wait_queue_init(&wait, current_pcb);
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current_pcb->state = PROC_UNINTERRUPTIBLE;
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list_append(&sema->wait_queue.wait_list, &wait.wait_list);
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// 执行调度
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sched_cfs();
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}
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}
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void semaphore_up(semaphore_t *sema)
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{
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if (list_empty(&sema->wait_queue.wait_list)) // 没有进程在等待资源
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{
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atomic_inc(&sema->counter);
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}
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else // 有进程在等待资源，唤醒进程
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{
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wait_queue_node_t *wq = container_of(list_next(&sema->wait_queue.wait_list), wait_queue_node_t, wait_list);
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list_del(&wq->wait_list);
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wq->pcb->state = PROC_RUNNING;
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sched_cfs_enqueue(wq->pcb);
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// 当前进程缺少需要的资源，立即标为需要被调度
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current_pcb->flags |= PF_NEED_SCHED;
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}
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} |