关于OSIntCtxSw的问题

靠谱的鱼干

我看资料上说这个函数是完成任务切换的，即保存当前SP PC等寄存器  然后把最高级TCB的PC SP等寄存器推出

我看起资料倒是看得懂，但是我看不懂原子哥的代码是怎么实现这个功能的，求指点代码如下：

OSIntCtxSw
  USH    {R4, R5}
        LDR     R4, =NVIC_INT_CTRL      ;causes context switch
        LDR     R5, =NVIC_PENDSVSET
        STR     R5, [R4]
  OP     {R4, R5}
        BX      LR
        NOP

正点原子

正真的保存是在这里执行的:

[mw_shl_code=c,true]PendSV_Handler CPSID I ; Prevent interruption during context switch MRS R0, PSP ; PSP is process stack pointer 如果在用PSP堆栈,则可以忽略保存寄存器,参考CM3权威中的双堆栈-白菜注 CBZ R0, PendSV_Handler_Nosave ; Skip register save the first time SUBS R0, R0, #0x20 ; Save remaining regs r4-11 on process stack STM R0, {R4-R11} LDR R1, =OSTCBCur ; OSTCBCur->OSTCBStkPtr = SP; LDR R1, [R1] STR R0, [R1] ; R0 is SP of process being switched out ; At this point, entire context of process has been saved PendSV_Handler_Nosave PUSH {R14} ; Save LR exc_return value LDR R0, =OSTaskSwHook ; OSTaskSwHook(); BLX R0 POP {R14} LDR R0, =OSPrioCur ; OSPrioCur = OSPrioHighRdy; LDR R1, =OSPrioHighRdy LDRB R2, [R1] STRB R2, [R0] LDR R0, =OSTCBCur ; OSTCBCur = OSTCBHighRdy; LDR R1, =OSTCBHighRdy LDR R2, [R1] STR R2, [R0] LDR R0, [R2] ; R0 is new process SP; SP = OSTCBHighRdy->OSTCBStkPtr; LDM R0, {R4-R11} ; Restore r4-11 from new process stack ADDS R0, R0, #0x20 MSR PSP, R0 ; Load PSP with new process SP ORR LR, LR, #0x04 ; Ensure exception return uses process stack CPSIE I BX LR ; Exception return will restore remaining context [/mw_shl_code]

靠谱的鱼干

这段代码在哪里找得到啊？

靠谱的鱼干

回复【2楼】正点原子:
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这段代码在哪里找得到啊？

靠谱的鱼干

回复【2楼】正点原子:
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找到了