TO 12楼：我按照上面10楼的提士做了修改，更改后的代码如下，可能和你的有些不一样，请给予指导：
OSStartHighRdy
LDR R0, =NVIC_SYSPRI2 ; Set the PendSV exception priority
LDR R1, =NVIC_PENDSV_PRI
STRB R1, [R0]
MRS R0, MSP
MSR PSP, R0
MRS R0, CONTROL
ORR R0, R0, #0x02
MSR CONTROL, R0
LDR R1, =OSTCBCur
MRS R0, PSP
SUBS R0, R0, #0x24
STR R0, [R1]
LDR R0, =OSRunning ; OSRunning = TRUE
MOVS R1, #1
STRB R1, [R0]
LDR R0, =NVIC_INT_CTRL ; Trigger the PendSV exception (causes context switch)
LDR R1, =NVIC_PENDSVSET
STR R1, [R0]
CPSIE I ; Enable interrupts at processor level
OSStartHang
NOP
B OSStartHang ; Should never get here
OSCtxSw
LDR R0, =NVIC_INT_CTRL ; Trigger the PendSV exception (causes context switch)
LDR R1, =NVIC_PENDSVSET
STR R1, [R0]
BX LR
OSIntCtxSw
LDR R0, =NVIC_INT_CTRL ; Trigger the PendSV exception (causes context switch)
LDR R1, =NVIC_PENDSVSET
STR R1, [R0]
BX LR
OS_CPU_PendSVHandler
;CPSID I ; Prevent interruption during context switch
MRS R0, PSP ; PSP is process stack pointer
;CBZ R0, OS_CPU_PendSVHandler_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
OS_CPU_PendSVHandler_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
END |
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