test-example-projects/c_projects/30wklite/sources/kernel/mutex.c

/******************************************************************************
* Copyright (c) 2015-2024 jiangxiaogang<kerndev@foxmail.com>
*
* This file is part of KLite distribution.
*
* KLite is free software, you can redistribute it and/or modify it under
* the MIT Licence.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
******************************************************************************/
#include "internal.h"
#include "kernel.h"

struct mutex
{
	struct tcb_list list;
	struct tcb *owner;
	uint32_t lock;
};

mutex_t mutex_create(void)
{
	struct mutex *mutex;
	mutex = heap_alloc(NULL, sizeof(struct mutex));
	if(mutex != NULL)
	{
		memset(mutex, 0, sizeof(struct mutex));
	}
	return (mutex_t)mutex;
}

void mutex_delete(mutex_t mutex)
{
	heap_free(NULL, mutex);
}

bool mutex_try_lock(mutex_t mutex)
{
	cpu_enter_critical();
	if(mutex->owner == NULL)
	{
		mutex->lock++;
		mutex->owner = sched_tcb_now;
		cpu_leave_critical();
		return true;
	}
	if(mutex->owner == sched_tcb_now)
	{
		mutex->lock++;
		cpu_leave_critical();
		return true;
	}
	cpu_leave_critical();
	return false;
}

void mutex_lock(mutex_t mutex)
{
	cpu_enter_critical();
	if(mutex->owner == NULL)
	{
		mutex->lock++;
		mutex->owner = sched_tcb_now;
		cpu_leave_critical();
		return;
	}
	if(mutex->owner == sched_tcb_now)
	{
		mutex->lock++;
		cpu_leave_critical();
		return;
	}
	sched_tcb_wait(sched_tcb_now, &mutex->list);
	sched_switch();
	cpu_leave_critical();
	return;
}

void mutex_unlock(mutex_t mutex)
{
	cpu_enter_critical();
	mutex->lock--;
	if(mutex->lock == 0)
	{
		mutex->owner = sched_tcb_wake_from(&mutex->list);
		if(mutex->owner != NULL)
		{
			mutex->lock++;
			sched_preempt(false);
		}
	}
	cpu_leave_critical();
}