www.pudn.com > ucosins3c2410.zip > Os_cpu_a.s
;********************************************************************************************************
; uC/OS-II
; The Real-Time Kernel
;
; (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
; All Rights Reserved
;
; File : OS_CPU_A.ASM
; By : Jean J. Labrosse
;********************************************************************************************************
;********************************************************************************************************
; ARM Port
;
; Target : ARM (Includes ARM7, ARM9)
; Ported by : Michael Anburaj
; URL : http://geocities.com/michaelanburaj/ Email : michaelanburaj@hotmail.com
;
;********************************************************************************************************
AREA UCOS_ARM, CODE, READONLY
;*********************************************************************************************************
; START MULTITASKING
; void OSStartHighRdy(void)
;
; Note : OSStartHighRdy() MUST:
; a) Call OSTaskSwHook() then,
; b) Set OSRunning to TRUE,
; c) Switch to the highest priority task.
;*********************************************************************************************************
IMPORT OSTaskSwHook
IMPORT OSRunning
IMPORT OSTCBHighRdy
EXPORT OSStartHighRdy
OSStartHighRdy
bl OSTaskSwHook ; Call user defined task switch hook
ldr r4,=OSRunning ; Indicate that multitasking has started
mov r5,#1
strb r5,[r4]
ldr r4,=OSTCBHighRdy ; Get highest priority task TCB address
ldr r4,[r4] ; get stack pointer
ldr sp,[r4] ; switch to the new stack
ldmfd sp!,{r4} ; pop new task's spsr
msr SPSR_cxsf,r4
ldmfd sp!,{r4} ; pop new task's psr
msr CPSR_cxsf,r4
ldmfd sp!,{r0-r12,lr,pc} ; pop new task's r0-r12,lr & pc
;*********************************************************************************************************
; PERFORM A CONTEXT SWITCH (From task level)
; void OSCtxSw(void)
;
; Note(s): Upon entry,
; OSTCBCur points to the OS_TCB of the task to suspend
; OSTCBHighRdy points to the OS_TCB of the task to resume
;
;*********************************************************************************************************
IMPORT OSTCBCur
IMPORT OSTaskSwHook
IMPORT OSTCBHighRdy
IMPORT OSPrioCur
IMPORT OSPrioHighRdy
EXPORT OSCtxSw
OSCtxSw
; Special optimised code below:
stmfd sp!,{lr} ; push pc (lr should be pushed in place of PC)
stmfd sp!,{r0-r12,lr} ; push lr & register file
mrs r4,cpsr
stmfd sp!,{r4} ; push current psr
mrs r4,spsr
stmfd sp!,{r4} ; push current spsr
; OSPrioCur = OSPrioHighRdy
ldr r4,=OSPrioCur
ldr r5,=OSPrioHighRdy
ldrb r6,[r5]
strb r6,[r4]
; Get current task TCB address
ldr r4,=OSTCBCur
ldr r5,[r4]
str sp,[r5] ; store sp in preempted tasks's TCB
bl OSTaskSwHook ; call Task Switch Hook
; Get highest priority task TCB address
ldr r6,=OSTCBHighRdy
ldr r6,[r6]
ldr sp,[r6] ; get new task's stack pointer
; OSTCBCur = OSTCBHighRdy
str r6,[r4] ; set new current task TCB address
ldmfd sp!,{r4} ; pop new task's spsr
msr SPSR_cxsf,r4
ldmfd sp!,{r4} ; pop new task's psr
msr CPSR_cxsf,r4
ldmfd sp!,{r0-r12,lr,pc} ; pop new task's r0-r12,lr & pc
;*********************************************************************************************************
; PERFORM A CONTEXT SWITCH (From an ISR)
; void OSIntCtxSw(void)
;
; Note(s): This function only flags a context switch to the ISR Handler
;
;*********************************************************************************************************
IMPORT OSIntCtxSwFlag
EXPORT OSIntCtxSw
OSIntCtxSw
;OSIntCtxSwFlag = True
ldr r0,=OSIntCtxSwFlag
mov r1,#1
str r1,[r0]
mov pc,lr
;*********************************************************************************************************
; IRQ HANDLER
;
; This handles all the IRQs
; Note: FIQ Handler should be written similar to this
;
;*********************************************************************************************************
IMPORT C_IRQHandler
IMPORT OSIntEnter
IMPORT OSIntExit
IMPORT OSIntCtxSwFlag
IMPORT OSTCBCur
IMPORT OSTaskSwHook
IMPORT OSTCBHighRdy
IMPORT OSPrioCur
IMPORT OSPrioHighRdy
NOINT EQU 0xc0
EXPORT UCOS_IRQHandler
UCOS_IRQHandler
stmfd sp!,{r0-r3,r12,lr}
bl OSIntEnter
bl C_IRQHandler
bl OSIntExit
ldr r0,=OSIntCtxSwFlag
ldr r1,[r0]
cmp r1,#1
beq _IntCtxSw
ldmfd sp!,{r0-r3,r12,lr}
subs pc,lr,#4
_IntCtxSw
mov r1,#0
str r1,[r0]
ldmfd sp!,{r0-r3,r12,lr}
stmfd sp!,{r0-r3}
mov r1,sp
add sp,sp,#16
sub r2,lr,#4
mrs r3,spsr
orr r0,r3,#NOINT
msr spsr_c,r0
ldr r0,=.+8
movs pc,r0
stmfd sp!,{r2} ; push old task's pc
stmfd sp!,{r4-r12,lr} ; push old task's lr,r12-r4
mov r4,r1 ; Special optimised code below
mov r5,r3
ldmfd r4!,{r0-r3}
stmfd sp!,{r0-r3} ; push old task's r3-r0
stmfd sp!,{r5} ; push old task's psr
mrs r4,spsr
stmfd sp!,{r4} ; push old task's spsr
; OSPrioCur = OSPrioHighRdy
ldr r4,=OSPrioCur
ldr r5,=OSPrioHighRdy
ldrb r5,[r5]
strb r5,[r4]
; Get current task TCB address
ldr r4,=OSTCBCur
ldr r5,[r4]
str sp,[r5] ; store sp in preempted tasks's TCB
bl OSTaskSwHook ; call Task Switch Hook
; Get highest priority task TCB address
ldr r6,=OSTCBHighRdy
ldr r6,[r6]
ldr sp,[r6] ; get new task's stack pointer
; OSTCBCur = OSTCBHighRdy
str r6,[r4] ; set new current task TCB address
ldmfd sp!,{r4} ; pop new task's spsr
msr SPSR_cxsf,r4
ldmfd sp!,{r4} ; pop new task's psr
msr CPSR_cxsf,r4
ldmfd sp!,{r0-r12,lr,pc} ; pop new task's r0-r12,lr & pc
;*********************************************************************************************************
; 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.
;
; OS_CPU_SR OSCPUSaveSR()
; Arguments : none
;
; Returns : OS_CPU_SR
;
; OSCPURestoreSR(OS_CPU_SR cpu_sr)
; Arguments : OS_CPU_SR
;
; Returns : none
;
; Note(s) : These functions are used in general like this,
;
; void Task (void *data)
; {
; #if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
; OS_CPU_SR cpu_sr;
; #endif
; :
; :
; OS_ENTER_CRITICAL(); /* cpu_sr = OSCPUSaveSR(); */
; :
; :
; OS_EXIT_CRITICAL(); /* OSCPURestoreSR(cpu_sr); */
; :
; :
; }
;*********************************************************************************************************
EXPORT OSCPUSaveSR
OSCPUSaveSR
mrs r0,CPSR
orr r1,r0,#NOINT
msr CPSR_c,r1
mov pc,lr
EXPORT OSCPURestoreSR
OSCPURestoreSR
msr CPSR_c,r0
mov pc,lr
END