FreeRTOS实时操作系统临界段保护场合示例 FreeRTOS实时操作系统临界段保护

临界段保护场合

非中断场合
中断场合

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