mirror of
https://github.com/openmv/openmv.git
synced 2025-11-04 14:49:50 +08:00
53 lines
964 B
C
53 lines
964 B
C
/*
|
|
* This file is part of the OpenMV project.
|
|
* Copyright (c) 2013/2014 Ibrahim Abdelkader <i.abdalkader@gmail.com>
|
|
* This work is licensed under the MIT license, see the file LICENSE for details.
|
|
*
|
|
* Mutex.
|
|
*
|
|
*/
|
|
#include <stm32f4xx.h>
|
|
#include <core_cm4.h>
|
|
#include <core_cmInstr.h>
|
|
#include "mutex.h"
|
|
|
|
void mutex_init(mutex_t *mutex)
|
|
{
|
|
mutex_unlock(mutex);
|
|
}
|
|
|
|
void mutex_lock(mutex_t *mutex)
|
|
{
|
|
volatile int locked = 0;
|
|
// Wait for mutex to be unlocked
|
|
do {
|
|
// Attempt exclusive read
|
|
while (__LDREXW(mutex) != 0);
|
|
|
|
// Attempt to lock mutex
|
|
locked = __STREXW(1, mutex);
|
|
} while (locked != 0);
|
|
__DMB();
|
|
}
|
|
|
|
int mutex_try_lock(mutex_t *mutex)
|
|
{
|
|
volatile int locked = 1;
|
|
|
|
if (__LDREXW(mutex) != 0) {
|
|
return 0;
|
|
}
|
|
|
|
// Attempt to lock mutex
|
|
locked = __STREXW(1, mutex);
|
|
__DMB();
|
|
|
|
return (locked == 0);
|
|
}
|
|
|
|
void mutex_unlock(mutex_t *mutex)
|
|
{
|
|
__DMB();
|
|
*mutex = 0;
|
|
}
|