临界段保护场合
FreeRTOS中临界段保护有2种场合，中断和非中断，通过关中断（或者关部分中断）来实现临界保护。
非中断场合
task.h 中
#define taskENTER_CRITICAL()portENTER_CRITICAL()
#define taskEXIT_CRITICAL()portEXIT_CRITICAL()portmacro.h中
#define portENTER_CRITICAL()vPortEnterCritical()
#define portEXIT_CRITICAL()vPortExitCritical()port.c中
//这个值用来记录中断嵌套次数，在调度器启动时会被重新初始化为0//vTaskStartScheduler()->xPortStartScheduler()->uxCriticalNesting = 0。static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;void vPortEnterCritical( void ){portDISABLE_INTERRUPTS();//关中断uxCriticalNesting++;__dsb( portSY_FULL_READ_WRITE );__isb( portSY_FULL_READ_WRITE );if( uxCriticalNesting == 1 ){configASSERT( ( portNVIC_INT_CTRL_REG & portVECTACTIVE_MASK ) == 0 );}}void vPortExitCritical( void ){configASSERT( uxCriticalNesting );uxCriticalNesting--;if( uxCriticalNesting == 0 ) //没有嵌套的话就可以开中断了{portENABLE_INTERRUPTS();}}//这个值用来记录中断嵌套次数，在调度器启动时会被重新初始化为0
//vTaskStartScheduler()->xPortStartScheduler()->uxCriticalNesting = 0。
static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;
void vPortEnterCritical( void )
{
portDISABLE_INTERRUPTS();//关中断
uxCriticalNesting++;
__dsb( portSY_FULL_READ_WRITE );
__isb( portSY_FULL_READ_WRITE );
if( uxCriticalNesting == 1 )
{
configASSERT( ( portNVIC_INT_CTRL_REG & portVECTACTIVE_MASK ) == 0 );
}
}
void vPortExitCritical( void )
{
configASSERT( uxCriticalNesting );
uxCriticalNesting--;
if( uxCriticalNesting == 0 ) //没有嵌套的话就可以开中断了
{
portENABLE_INTERRUPTS();
}
}
portmacro.h中
#define portDISABLE_INTERRUPTS()ulPortSetInterruptMask()
#define portENABLE_INTERRUPTS()vPortClearInterruptMask( 0 )port.c中
__asm uint32_t ulPortSetInterruptMask( void )
{
PRESERVE8
mrs r0, basepri //r0作为函数返回值
mov r1, #configMAX_SYSCALL_INTERRUPT_PRIORITY
msr basepri, r1
bx r14
}
__asm void vPortClearInterruptMask( uint32_t ulNewMask )
{
PRESERVE8
msr basepri, r0
bx r14
}
中断场合
task.h
#define taskENTER_CRITICAL_FROM_ISR() portSET_INTERRUPT_MASK_FROM_ISR()
#define taskEXIT_CRITICAL_FROM_ISR( x ) portCLEAR_INTERRUPT_MASK_FROM_ISR( x )portmacro.h中
下面这2个函数在前面的port.c中已经实现，只是这里形参是x而不是0
#define portSET_INTERRUPT_MASK_FROM_ISR()ulPortSetInterruptMask()
#define portCLEAR_INTERRUPT_MASK_FROM_ISR(x)vPortClearInterruptMask(x)使用例子
以上就是FreeRTOS实时操作系统临界段保护场合示例的详细内容，更多关于FreeRTOS实时操作系统临界段保护的资料请关注编程网其它相关文章！
