经过别人在板子上几天几夜的测试，跑了6、7个任务同时开了4、5个中断，CPU满负荷。完全没问题，已经用在产品上。
主要就修改一个文件os_cpu_a.asm和任务创建时堆栈初始化代码。
花了两天时间（以前没接触过cortex-m0也没写过汇编，多年没接触过单片机了）。
以下是os_cpu_a.asm。有不少的草稿代码，应该不影响阅读的，请自行忽略。
;********************************************************************************************************
; uC/OS-II
; The Real-Time Kernel
;
; (c) Copyright 1992-2010, Micrium, Weston, FL
; All Rights Reserved
;
; ARM Cortex-M0 Port (without OS extensions)
;
; File : OS_CPU_A.ASM
; Version : V2.86
; By : Jean J. Labrosse
;
; For : ARMv6M Cortex-M0 (without OS extensions)
; Mode : Thumb2
; Toolchain : RealView Development Suite
; RealView Microcontroller Development Kit (MDK)
; ARM Developer Suite (ADS)
; Keil uVision
;********************************************************************************************************
;********************************************************************************************************
; PUBLIC FUNCTIONS
;********************************************************************************************************
EXTERN OSRunning ; External references
EXTERN OSPrioCur
EXTERN OSPrioHighRdy
EXTERN OSTCBCur
EXTERN OSTCBHighRdy
EXTERN OSIntNesting
EXTERN OSIntExit
EXTERN OSTaskSwHook
EXTERN OS_CPU_ExceptHndlr
EXTERN OS_CPU_ExceptStkBase
EXTERN OS_CPU_CtxSw
EXPORT OS_CPU_SR_Save ; Functions declared in this file
EXPORT OS_CPU_SR_Restore
EXPORT OSStartHighRdy
EXPORT OSCtxSw
EXPORT OSIntCtxSw
EXPORT OS_CPU_CM0_ExceptHndlr
;********************************************************************************************************
; EQUATES
;********************************************************************************************************
CM0_SETPEND EQU 0xE000E200
CM0_IRQ0SET EQU 0xFFFFFFFF
CM0_THUMB_CTL EQU 0x01000000
;********************************************************************************************************
; CODE GENERATION DIRECTIVES
;********************************************************************************************************
AREA |.text|, CODE, READONLY, ALIGN=2
THUMB
REQUIRE8
PRESERVE8
;*********************************************************************************************************
; CRITICAL SECTION METHOD 3 FUNCTIONS
;
; Description: Disable/Enable interrupts by preserving the state of interrupts. Generally speaking you
; would store the state of the interrupt disable flag in the local variable 'cpu_sr' and then
; disable interrupts. 'cpu_sr' is allocated in all of uC/OS-II's functions that need to
; disable interrupts. You would restore the interrupt disable state by copying back 'cpu_sr'
; into the CPU's status register.
;
; Prototypes : OS_CPU_SR OS_CPU_SR_Save(void);
; void OS_CPU_SR_Restore(OS_CPU_SR cpu_sr);
;
;
; Note(s) : 1) These functions are used in general like this:
;
; void Task (void *p_arg)
; {
; #if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
; OS_CPU_SR cpu_sr;
; #endif
;
; :
; :
; OS_ENTER_CRITICAL(); /* cpu_sr = OS_CPU_SaveSR(); */
; :
; :
; OS_EXIT_CRITICAL(); /* OS_CPU_RestoreSR(cpu_sr); */
; :
; :
; }
;*********************************************************************************************************
OS_CPU_SR_Save
MRS R0, PRIMASK ; Set prio int mask to mask all (except faults)
CPSID I
BX LR
OS_CPU_SR_Restore
MSR PRIMASK, R0
BX LR
;*********************************************************************************************************
; START MULTITASKING
; void OSStartHighRdy(void)
;
; Note(s) : 1) OSStartHighRdy() MUST:
; a) Call OSTaskSwHook() then,
; b) Set OSRunning to TRUE,
; c) Switch to the highest priority task.
;
; 2) When tested with IAR EWARM, the processor reaches the startup code in handler mode.
; Consequently, to re-enable interrupts, it is necessary to return from OSStartHighRdy()
; as if returning from an exception. The commented code at the end of this function
; performs the 'normal' function return and MIGHT need to be substituted for the last three
; lines of code in this function, which load the link register with the exception return
; value and then return.
;*********************************************************************************************************
NVIC_INT_CTRL EQU 0xE000ED04 ; interrupt control state register
NVIC_SHPR3 EQU 0xE000ED20 ; system priority register (2)
NVIC_PENDSV_PRI EQU 0x00FF0000 ; PendSV priority value (lowest)
NVIC_PENDSVSET EQU 0x10000000 ; value to trigger PendSV exception
PendSV_Handler PROC
EXPORT PendSV_Handler
OS_CPU_PendSVHandler
CPSID I ; Prevent interruption during context switch
MRS R0, PSP ; PSP is process stack pointer
CMP R0, #0X00
BEQ OS_CPU_PendSVHandler_nosave
; 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}
MRS R1, MSP
MSR MSP, R0
MSR PSP, R1
MOV R0, R8
MOV R1, R9
MOV R0, R8
MOV R1, R9
PUSH {R0-R7}
MRS R0,MSP
MRS R2, MSP ; PSP is process stack pointer
MRS R3, PSP ; PSP is process stack pointer
MSR MSP, R3
MSR PSP, R2
; PUSH {R0-R7}
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 {R0}
; MSR LR, R0
MOV LR, 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, {R0-R7} ; Restore r4-11 from new process stack
; ADDS R0, R0, #0x20
; MSR PSP, R0 ; Load PSP with new process SP
LDR R0, [R2] ; R0 is new process SP; SP = OSTCBHighRdy->OSTCBStkPtr;
;LDM R0, {R0-R7} ; Restore r4-11 from new process stack
ADDS R0, R0, #0x20
MSR PSP, R0 ; Load PSP with new process SP
SUBS R0, R0, #0X20
LDM R0, {R0-R7}
MOV R8, R0
MOV R9, R1
MOV R10, R2
MOV R11, R3
MOVS R2, #0x04
MOV R0, LR
ORRS R0, R2
MOV LR, R0
; ORR LR, LR, #0x04 ; Ensure exception return uses process stack
CPSIE I
BX LR ; Exception return will restore remaining context
ENDP
OSStartHighRdy
; set the PendSV exception priority
LDR r0, =NVIC_SHPR3
LDR r1, =NVIC_PENDSV_PRI
LDR r2, [r0,#0x00] ; read
ORRS r1,r1,r2 ; modify
STR r1, [r0] ; write-back
MOVS R0, #0 ; Set the PSP to 0 for initial context switch call
MSR PSP, R0
LDR R0, =OS_CPU_ExceptStkBase ; Initialize the MSP to the OS_CPU_ExceptStkBase
LDR R1, [R0]
MSR MSP, 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
B OSStartHang ; Should never get here
; set the PendSV exception priority
LDR r0, =NVIC_SHPR3
LDR r1, =NVIC_PENDSV_PRI
LDR r2, [r0,#0x00] ; read
ORRS r1,r1,r2 ; modify
STR r1, [r0] ; write-back
; trigger the PendSV exception (causes context switch)
LDR r0, =NVIC_INT_CTRL
LDR r1, =NVIC_PENDSVSET
STR r1, [r0]
B .
LDR R0, __OS_TaskSwHook ; OSTaskSwHook();
BLX R0
LDR R0, __OS_Running ; OSRunning = TRUE;
MOVS R1, #1
STRB R1, [R0]
; SWITCH TO HIGHEST PRIORITY TASK:
LDR R0, __OS_TCBHighRdy ; Get highest priority task TCB address,
LDR R1, [R0] ; Get stack pointer,
LDR R2, [R1]
MSR MSP, R2 ; Switch to the new stack,
POP {R0-R7} ; Pop new task's R8-R11 (into R0-R3), R4-R7
MOV R8, R0
MOV R9, R1
MOV R10, R2
MOV R11, R3
; NORMAL FUNCTION RETURN (see Note #2)
ADD SP, #0x10
POP {R0-R3} ; Pop new task's R12, PC, LR, PSR into (R0, R1, R2, R3, respectively)
MOV R12, R0
MOV LR, R1
MSR PSR, R3
PUSH {R2} ; Save PC
SUB SP, #0x1C
POP {R0-R3} ; Pop new task's R0-R3
ADD SP, #0x0C
CPSIE I ; Enable interrupts
POP {PC} ; Pop new task's PC
; EXCEPTION FUNCTION RETURN (see Note #2)
; LDR R0, =CM1_EXCEPTRTN ; Load LR (R14) with exception return value.
; MOV LR, R0
;
; BX LR ; Return, as if from exception.
;*********************************************************************************************************
; PERFORM A CONTEXT SWITCH (From task level)
; OSCtxSw()
;
; Note(s) : 1) OSCtxSw() is called when OS wants to do a task context switch.
;
; 2) This function triggers an IRQ #0, which will perform the context switch. The variable
; OS_CPU_CtxSw is set to '1' to indicate that a context switch should be performed.
;*********************************************************************************************************
OSCtxSw
LDR R0, =NVIC_INT_CTRL ; Trigger the PendSV exception (causes context switch)
LDR R1, =NVIC_PENDSVSET
STR R1, [R0]
BX LR
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = TRUE
; MOVS R1, #1
; STRB R1, [R0]
; LDR R0, =CM0_SETPEND ; Trigger interrupt
; LDR R1, =CM0_IRQ0SET
; STR R1, [R0]
CPSID I
SUB SP,#0x10
PUSH {R0-R3}
ADD SP,#0x20
MRS R3, xPSR
LDR R2, =CM0_THUMB_CTL
ORRS R3, R2
MOVS R2, #0x01
;MOV R2, LR
MOV R1, LR
ORRS R2, R1
MOV R1, R2
MOV R0, R12
PUSH {R0-R3}
SUB SP, #0x10
MOV R0, R8
MOV R1, R9
MOV R2, R10
MOV R3, R11
PUSH {R0-R7}
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = TRUE
; MOVS R1, #1
; STRB R1, [R0]
MRS R0, MSP
LDR R1, __OS_TCBCur ; OSTCBCur->OSTCBStkPtr = SP;
LDR R1, [R1]
STR R0, [R1]
LDR R0, __OS_TaskSwHook ; OSTaskSwHook();
BLX R0
; POP {R0}
; MOV LR, R0
LDR R0, __OS_PrioCur ; OSPrioCur = OSPrioHighRdy;
LDR R1, __OS_PrioHighRdy
LDRB R2, [R1]
STRB R2, [R0]
LDR R0, __OS_TCBCur ; OSTCBCur = OSTCBHighRdy;
LDR R1, __OS_TCBHighRdy
LDR R2, [R1]
STR R2, [R0]
LDR R0, [R2] ; SP = OSTCBHighRdy->OSTCBStkPtr;
MSR MSP, R0
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = 0;
; MOVS R1, #0
; STRB R1, [R0]
; RESTORE TASK's CONTEXT
POP {R0-R7} ; Pop new task's R8-R11 (into R0-R3), R4-R7
MOV R8, R0
MOV R9, R1
MOV R10, R2
MOV R11, R3
ADD SP, #0x10
POP {R0-R3} ; Pop new task's R12, PC, LR, PSR into (R0, R1, R2, R3, respectively)
MOV R12, R0
MOV LR, R1
MSR PSR, R3
PUSH {R2} ; Save PC
SUB SP, #0x1C
POP {R0-R3} ; Pop new task's R0-R3
ADD SP, #0x0C
CPSIE I ; Enable interrupts
;CPSID I
; BX LR
POP {PC}
NOP
;*********************************************************************************************************
; PERFORM A CONTEXT SWITCH (From interrupt level)
; OSIntCtxSw()
;
; Notes: 1) OSIntCtxSw() is called by OSIntExit() when it determines a context switch is needed as
; the result of an interrupt.
;
; 2) This function triggers an IRQ #0, which will perform the context switch. The variable
; OS_CPU_CtxSw is set to '1' to indicate that a context switch should be performed.
;*********************************************************************************************************
SysTick_Handler_bak PROC
EXPORT SysTick_Handler_bak
;IMPORT SysTick_Handler_Aux
;IMPORT OSIntExit2
MOV R0, LR
PUSH {R0}
;LDR R0, =SysTick_Handler_Aux
BLX R0
CPSID I
;LDR R0, =OSIntExit2
BLX R0
CMP R0, #0X00
BEQ HandlerReturn
; B OSIntCtxSw
ADD SP,#0x1C
POP {R0}
MOVS R2, #0x01
ORRS R0, R2
PUSH {R0}
SUB SP,#0x1C
POP {R0}
MOV LR, R0
;; SUB SP,#0x10
;; PUSH {R0-R3}
;; ADD SP,#0x20
;; MRS R3, PSR
;; MOV R2, LR
;; MOV R1, LR
;; MOV R0, R12
;; PUSH {R0-R3}
;; SUB SP, #0x10
MOV R0, R8
MOV R1, R9
MOV R2, R10
MOV R3, R11
PUSH {R0-R7}
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = TRUE
; MOVS R1, #1
; STRB R1, [R0]
MRS R0, MSP
LDR R1, __OS_TCBCur ; OSTCBCur->OSTCBStkPtr = SP;
LDR R1, [R1]
STR R0, [R1]
MOV R0, LR
PUSH {R0}
LDR R0, __OS_TaskSwHook ; OSTaskSwHook();
BLX R0
POP {R0}
MOV LR, R0
LDR R0, __OS_PrioCur ; OSPrioCur = OSPrioHighRdy;
LDR R1, __OS_PrioHighRdy
LDRB R2, [R1]
STRB R2, [R0]
LDR R0, __OS_TCBCur ; OSTCBCur = OSTCBHighRdy;
LDR R1, __OS_TCBHighRdy
LDR R2, [R1]
STR R2, [R0]
LDR R0, [R2] ; SP = OSTCBHighRdy->OSTCBStkPtr;
MSR MSP, R0
POP {R0-R7}
MOV R8,R0
MOV R9,R1
MOV R10,R2
MOV R11,R3
CPSIE I
BX LR
HandlerReturn
POP {R0}
MOV LR, R0
CPSIE I
BX LR
ENDP
OSIntCtxSw
LDR R0, =NVIC_INT_CTRL ; Trigger the PendSV exception (causes context switch)
LDR R1, =NVIC_PENDSVSET
STR R1, [R0]
BX LR
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = TRUE
; MOVS R1, #1
; STRB R1, [R0]
; LDR R0, =CM0_SETPEND ; Trigger interrupt
; LDR R1, =CM0_IRQ0SET
; STR R1, [R0]
; BX LR
CPSID I
SUB SP,#0x10
PUSH {R0-R3}
ADD SP,#0x20
MRS R3, xPSR
MOV R2, LR
MOV R1, LR
MOV R0, R12
PUSH {R0-R3}
SUB SP, #0x10
MOV R0, R8
MOV R1, R9
MOV R2, R10
MOV R3, R11
PUSH {R0-R7}
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = TRUE
; MOVS R1, #1
; STRB R1, [R0]
MRS R0, MSP
LDR R1, __OS_TCBCur ; OSTCBCur->OSTCBStkPtr = SP;
LDR R1, [R1]
STR R0, [R1]
LDR R0, __OS_TaskSwHook ; OSTaskSwHook();
BLX R0
; POP {R0}
; MOV LR, R0
LDR R0, __OS_PrioCur ; OSPrioCur = OSPrioHighRdy;
LDR R1, __OS_PrioHighRdy
LDRB R2, [R1]
STRB R2, [R0]
LDR R0, __OS_TCBCur ; OSTCBCur = OSTCBHighRdy;
LDR R1, __OS_TCBHighRdy
LDR R2, [R1]
STR R2, [R0]
LDR R0, [R2] ; SP = OSTCBHighRdy->OSTCBStkPtr;
MSR MSP, R0
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = 0;
; MOVS R1, #0
; STRB R1, [R0]
; RESTORE TASK's CONTEXT
POP {R0-R7} ; Pop new task's R8-R11 (into R0-R3), R4-R7
MOV R8, R0
MOV R9, R1
MOV R10, R2
MOV R11, R3
ADD SP, #0x10
POP {R0-R3} ; Pop new task's R12, PC, LR, PSR into (R0, R1, R2, R3, respectively)
MOV R12, R0
MOV LR, R1
MSR PSR, R3
PUSH {R2} ; Save PC
SUB SP, #0x1C
POP {R0-R3} ; Pop new task's R0-R3
ADD SP, #0x0C
CPSIE I ; Enable interrupts
; BX LR
POP {PC}
NOP
;*********************************************************************************************************
; HANDLE EXTERNAL IRQ #0
; OS_CPU_CM1_ExceptHndlr()
;
; Note(s) : 1) This function handles external IRQ #0. This port requires that this be the ONLY
; external IRQ (though multiple interrupt sources may be multiplexed onto the single vector
; via an external controller).
;
; 2) A context switch is accomplished by triggering an IRQ from OSCtxSw(). If the exception
; is going to be used for this purpose, the variable OS_CPU_CtxSw will have been assigned
; the value '1' in OSCtxSw().
;*********************************************************************************************************
OS_CPU_CM0_ExceptHndlr
B .
CPSID I
; SAVE CONTEXT ONTO TASK STACK:
MOV R0, R8
MOV R1, R9
MOV R2, R10
MOV R3, R11
PUSH {R0-R7} ; Push task's R8-R11, R4-R7.
; LDR R0, __OS_CPU_CtxSw ; if (OS_CPU_CtxSw == TRUE)
LDRB R1, [R0]
CMP R1, #1
BEQ OS_CPU_CM0_ExceptHndlr_CtxSw
;*********************************************************************************************************
; HANDLE EXTERNAL IRQ #0
; OS_CPU_CM0_ExceptHndlr_Except()
;
; Note(s) : 1) This function handles external IRQ #0. This port requires that this be the ONLY
; external IRQ (though multiple interrupt sources may be multiplexed onto the single vector
; via an external controller).
;
; 2) The pseudo-code for OS_CPU_CM1_ExceptHndlr_Except() is:
; a) Save registers r4-r11 on task stack (which is the current stack);
; b) OSTCBCur->OSTCBStkPtr = SP;
; c) OSIntNesting++;
; d) SP = OS_CPU_ExceptStkBase;
; e) OS_CPU_ExceptHndlr();
; f) OSIntExit();
; g) SP = OSTCBCur->OSTCBStkPtr;
; h) Restore new task's R4-R11 from new task's stack;
; i) Perform exception return which will restore R0-R3, R12, LR, PC, PSR.
;
; 3) On entry into this function:
; a) OS_CPU_CtxSw == 0
; b) The following have been saved on the task stack (by processor):
; xPSR, PC, LR, R12, R0-R3
; c) The following have been saved on the task stack (by OS_CPU_CM1_ExceptHndlr):
; R8-R11, R4-R7
; d) OSTCBCur points to the OS_TCB of the current task
;*********************************************************************************************************
OS_CPU_CM0_ExceptHndlr_Except
LDR R0, __OS_TCBCur ; OSTCBCur->OSTCBStkPtr = SP;
LDR R1, [R0]
MRS R2, MSP
STR R2, [R1]
; HANDLE NESTING COUNTER:
LDR R0, __OS_IntNesting ; OSIntNesting++;
LDRB R1, [R0]
ADDS R1, #1
STRB R1, [R0]
LDR R0, __OS_CPU_ExceptStkBase ; SP = OS_CPU_ExceptStkBase;
LDR R1, [R0]
MSR MSP, R1
PUSH {LR} ; Push exception return.
; EXECUTE EXCEPTION HANDLER:
LDR R0, __OS_CPU_ExceptHndlr ; OS_CPU_ExceptHndlr()
BLX R0
LDR R0, __OS_IntExit ; OSIntExit()
BLX R0
POP {R0} ; Pop exception return.
MOV LR, R0
LDR R0, __OS_TCBCur ; SP = OSTCBCur->OSTCBStkPtr;
LDR R1, [R0]
LDR R2, [R1]
MSR MSP, R2
; RESTORE TASK's CONTEXT
POP {R0-R7} ; Pop new task's R8-R11 (into R0-R3), R4-R7
MOV R8, R0
MOV R9, R1
MOV R10, R2
MOV R11, R3
CPSIE I
BX LR ; Exception return restores R0-R3, R12, LR, PC, PSR
;*********************************************************************************************************
; EXECUTE CONTEXT SWTICH
; OS_CPU_CM0_ExceptHndlr_CtxSw()
;
; Note(s) : 1) OS_CPU_CM1_ExceptHndlr_CtxSw(), called from OS_CPU_CM1_ExceptHndlr(), is used to cause a
; context switch, similar to the use of OSPendSV on a Cortex-M3. Using the exception this way
; means that context saving and restoring is identical whether it is initiated from a thread
; or occurs due to an interrupt or exception.
;
; 2) The pseudo-code for OS_CPU_CM1_ExceptHndlr_CtxSw() is:
; b) OSTCBCur->OSTCBStkPtr = SP;
; c) OSTaskSwHook();
; d) OSPrioCur = OSPrioHighRdy;
; e) OSTCBCur = OSTCBHighRdy;
; f) SP = OSTCBHighRdy->OSTCBStkPtr;
; g) Restore new task's R4-R11 from new task's stack;
; h) OS_CPU_CtxSw = 0;
; i) Perform exception return which will restore R0-R3, R12, LR, PC, PSR.
;
; 3) On entry into this function:
; a) OS_CPU_CtxSw == 1
; b) The following have been saved on the task stack (by processor):
; xPSR, PC, LR, R12, R0-R3
; c) The following have been saved on the task stack (by OS_CPU_CM1_ExceptHndlr):
; R8-R11, R4-R7
; d) OSTCBCur points to the OS_TCB of the task to suspend
; OSTCBHighRdy points to the OS_TCB of the task to resume
;*********************************************************************************************************
OS_CPU_CM0_ExceptHndlr_CtxSw
PUSH {LR}
LDR R0, __OS_TaskSwHook ; OSTaskSwHook();
BLX R0
POP {R0}
MOV LR, R0
MRS R0, MSP
LDR R1, __OS_TCBCur ; OSTCBCur->OSTCBStkPtr = SP;
LDR R1, [R1]
STR R0, [R1]
LDR R0, __OS_PrioCur ; OSPrioCur = OSPrioHighRdy;
LDR R1, __OS_PrioHighRdy
LDRB R2, [R1]
STRB R2, [R0]
LDR R0, __OS_TCBCur ; OSTCBCur = OSTCBHighRdy;
LDR R1, __OS_TCBHighRdy
LDR R2, [R1]
STR R2, [R0]
LDR R0, [R2] ; SP = OSTCBHighRdy->OSTCBStkPtr;
MSR MSP, R0
; RESTORE NEW TASK's CONTEXT
POP {R0-R7} ; Pop new task's R8-R11 (into R0-R3), R4-R7
MOV R8, R0
MOV R9, R1
MOV R10, R2
MOV R11, R3
; LDR R0, __OS_CPU_CtxSw ; OS_CPU_CtxSw = 0;
; MOVS R1, #0
; STRB R1, [R0]
CPSIE I
BX LR ; Exception return restores R0-R3, R12, LR, PC, PSR
NOP
;*********************************************************************************************************
; POINTERS TO VARIABLES
;*********************************************************************************************************
__OS_CPU_CtxSw
DCD OS_CPU_CtxSw
__OS_CPU_ExceptStkBase
DCD OS_CPU_ExceptStkBase
__OS_CPU_ExceptHndlr
DCD OS_CPU_ExceptHndlr
__OS_TaskSwHook
DCD OSTaskSwHook
__OS_IntExit
DCD OSIntExit
__OS_IntNesting
DCD OSIntNesting
__OS_PrioCur
DCD OSPrioCur
__OS_PrioHighRdy
DCD OSPrioHighRdy
__OS_Running
DCD OSRunning
__OS_TCBCur
DCD OSTCBCur
__OS_TCBHighRdy
DCD OSTCBHighRdy
END