📄 os_cpu_a.s
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;**********************************************************************
;****************************************************
; $Workfile: os_cpu_a.S for SkyEye simulator $
; $Revision: 1.1.1.1 $
; $Author: skyeye $
; $Email: lmcs00;mails.tsinghua.edu.cn $
; $Date: 2003/02/19 02:42:22 $
;****************************************************
;****************************************************
; $Workfile: os_cpu_a.S for SkyEye simulator $
; $Revision: 1.1.1.1 $
; $Author: skyeye $
; $Email: chenyu;hpclab.cs.tsinghua.edu.cn $
; $Email: lmcs00;mails.tsinghua.edu.cn $
; $Date: 2003/02/19 02:42:22 $
;****************************************************
;****************************************************
; $Workfile: os_cpu_a.S for SkyEye simulator $
; $Revision: 1.1.1.1 $
; $Author: skyeye $
; $Email: chenyu;hpclab.cs.tsinghua.edu.cn $
; $Email: lmcs00;mails.tsinghua.edu.cn $
; $Date: 2003/02/19 02:42:22 $
;****************************************************
; BASED ON
;***************************************************
; $Workfile: Os_cpu_a.s $
; $Revision: 1.1.1.1 $
; $Author: skyeye $
; $Date: 2003/02/19 02:42:22 $
; **************************************************
;********************************************************************/
AREA |subr|, CODE, READONLY
;/***********************************************************************
;
; Function: OSStartHighRdy
;
; Purpose:
; To start the task with the highest priority during OS startup
;
; Processing:
; See uC/OS-II Task Level Context Switch flow chart
;
; Parameters: void
;
; Outputs: None
;
; Returns: void
;
; Notes:
; Called once during OSStart()
;
;*********************************************************************/
EXPORT OSStartHighRdy
IMPORT OSTaskSwHook
IMPORT OSTCBHighRdy
IMPORT OSRunning
OSStartHighRdy
BL OSTaskSwHook ; Call user-defined hook function
LDR r4,=OSRunning ; Indicate that multitasking has started
MOV r5, #1
STRB r5, [r4] ; OSRunning = true
LDR r4, =OSTCBHighRdy ; Get highest priority task TCB address
LDR r4, [r4] ; get stack pointer
LDR sp, [r4] ; switch to the new stack
; next two lines removed by YJ
; LDMFD sp!, {r4} ; pop new task s spsr_cxsf
; 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
;/***********************************************************************
;
; Function: OS_TASK_SW
;
; Purpose:
; To perform a context switch from the Task Level.
;
; Processing:
; See uC/OS-II Task Level Context Switch flow chart
;
; Parameters: void
;
; Outputs: None
;
; Returns: void
;
; Notes:
; The whole function is executed in CRITICAL state. See OSSched().
;
; On entry, OSTCBCur and OSPrioCur hold the current TCB and priority
; and OSTCBHighRdy and OSPrioHighRdy contain the same for the task
; to be switched to.
;
; The following code assumes that the virtual memory is directly
; mapped into physical memory. If this is not true, the cache must
; be flushed at context switch to avoid address aliasing.
;
;*********************************************************************/
EXPORT OSCtxSw
IMPORT OSPrioCur
IMPORT OSPrioHighRdy
IMPORT OSTCBCur
IMPORT OSTaskSwHook
IMPORT OSTCBHighRdy
OSCtxSw
STMFD sp!, {lr} ; push pc (lr is actually be pushed in place of PC)
STMFD sp!, {r0-r12,lr} ; push lr & register file
MRS r4, cpsr
STMFD sp!, {r4} ; push current psr
; next two lines removed by YJ
; MRS r4, spsr
; STMFD sp!, {r4} ; push current spsr_cxsf
LDR r4, =OSTCBCur ; Get current task TCB address
LDR r5, [r4]
STR sp, [r5] ; store sp in preempted tasks s TCB
; OSIntCtxSw does the remainder work, so
; following removed by YJ-------------------------------------------<<
;_OSCtxSw
; BL OSTaskSwHook ; call Task Switch Hook
; LDR r5, =OSTCBHighRdy ; Get highest priority task TCB address
; LDR r5, [r5]
; STR r5, [r4] ; OSTCBCur = OSTCBHighRdy
; LDR r6, =OSPrioHighRdy
; LDRB r6, [r6]
; LDR r4, =OSPrioCur
; STRB r6, [r4] ; OSPrioCur = OSPrioHighRdy
; LDR sp, [r5] ; get new task s stack pointer
;; next two lines removed by YJ
;; LDMFD sp!, {r4} ; pop new task spsr_cxsf
;; MSR spsr_cxsf, r4
; LDMFD sp!, {r4} ; pop new task cpsr
; MSR cpsr_cxsf, r4
; LDMFD sp!, {r0-r12,lr,pc} ; pop new task r0-r12,lr & pc
;***********************************************************************
;
; Function: OSIntCtxSw
;
; Purpose:
; To perform a context switch from the interrupt level.
;
; Processing:
; See uC/OS-II Interrupt Level Context Switch flow chart
;
; Parameters: void
;
; Outputs: None
;
; Returns: void
;
; Notes:
; Sets up the stacks and registers to call the task level
; context switch
;
;*********************************************************************/
EXPORT OSIntCtxSw
;----------------------------------------------------------------
; modefied by YJ
;----------------------------------------------------------------
; added starts --------------<<
IMPORT OSTaskSwHook
OSIntCtxSw
BL OSTaskSwHook
LDR r4, =OSTCBHighRdy
LDR r4, [r4]
LDR r5, =OSTCBCur
STR r4, [r5] ; OSTCBCur = OSTCBHighRdy
LDR r6, =OSPrioHighRdy
LDRB r6, [r6]
LDR r5, =OSPrioCur
STRB r6, [r5] ; OSPrioCur = OSPrioHighRdy
LDR sp, [r4]
LDMFD sp!, {r4} ; pop new task cpsr
MSR cpsr_cxsf, r4
LDMFD sp!, {r0-r12,lr,pc} ; pop new task r0-r12,lr & pc
; >>---------------- added ends
; removed starts ------------<<
; IMPORT OSIntCtxSwFlag
;OSIntCtxSw
; LDR r0, =OSIntCtxSwFlag ; OSIntCtxSwFlag = true
; MOV r1, #1
; STR r1, [r0]
;
; MOV pc, lr ; return
; >>-------------- removed ends
;----------------------------------------------------------------
; end of modification
;----------------------------------------------------------------
;/***********************************************************************
;
;yangye 2003-2-14
;changed this function name from OSTickISR to OSISR(it is not a TICK isr)
; Function: OSISR
;
; Purpose:
; The IRQ interrupt handler
;
; Processing:
; Saves context
; Calls the IRQ dispatcher
; Checks if context switch necessary
; If not, restores context and returns from interrupt
; If switch required, branches without link to IRQContextSwap
; which performs context switch if interrupts not nested
; and returns from interrupt to new context
;
; Parameters: void
;
; Outputs: None
;
; Returns: void
;
; Notes:
; (1) here we use OSIntCtxSwFlag to indicate a request for int-level
; context switch
; (2) _IntCtxSw is used to perform a real switch operation
;
;*********************************************************************/
;----------------------------------------------------------------------
; modified by YJ
;----------------------------------------------------------------------
; added starts <<------------------------------------------------------
EXPORT OSTickISR
IMPORT OSIntEnter
IMPORT OSTimeTick
IMPORT tick_hook
IMPORT OSIntExit
LINK_SAVE DCD 0
PSR_SAVE DCD 0
OSTickISR
STMFD sp!, {r4}
LDR r4, =LINK_SAVE
STR lr, [r4] ; LINK_SAVE = lr_irq
MRS lr, spsr
STR lr, [r4, #4] ; PSR_SAVE = spsr_irq
LDMFD sp!, {r4}
ORR lr, lr, #0x80 ; Mask irq for context switching before
MSR cpsr_cxsf, lr ; returning back from irq mode.
SUB sp, sp, #4 ; Space for PC
STMFD sp!, {r0-r12, lr}
LDR r4, =LINK_SAVE
LDR lr, [r4, #0]
SUB lr, lr, #4 ; lr = LINK_SAVE - 4,
STR lr, [sp, #(14*4)] ; the return address for pc.
LDR r4, [r4, #4] ; r4 = PSR_SAVE,
STMFD sp!, {r4} ; CPSR of the task
LDR r4, =OSTCBCur
LDR r4, [r4]
STR sp, [r4] ; OSTCBCur -> stkptr = sp
; BL DmpStk
BL OSIntEnter
BL OSTimeTick
BL tick_hook ; here do_IRQ is used to clear some virtual-hardware flags
BL OSIntExit
; BL DmpStk
; LDR r4, =OSTCBHighRdy
LDMFD sp!, {r4} ; pop new task cpsr
MSR cpsr_cxsf, r4
LDMFD sp!, {r0-r12,lr,pc} ; pop new task r0-r12,lr & pc
; --------------------------------------------------------->> added ends
; removed starts <<-----------------------------------------------------
;SAVED_LR_SVC DCD 0x00000000 ; some variables for temparal use
;SAVED_LR_IRQ DCD 0x00000000
;SAVED_SPSR DCD 0x00000000
;INTPND DCD 0x03ff4004 ;IRQ controller
; EXPORT OSTickISR
; IMPORT OSIntEnter
; IMPORT OSTimeTick
; IMPORT timer_irq
; IMPORT OSIntExit
; IMPORT OSIntCtxSwFlag
;OSTickISR
; SUB lr, lr, #4
; STMFD sp!, {r0-r12, lr} ; push r0-r12 register file and lr( pc return address )
; MRS r4, spsr
; STMFD sp!, {r4} ; push current spsr_cxsf_irq ( =cpsr_svc )
; ; -- identify source of interrupt .........................
; LDR r0, INTPND
; LDR r0, [r0]
; TST r0, #0x0400
; BNE handler_event_timer
; LDMFD sp!, {r4} ; get cpsr_svc from stack
; MSR spsr_cxsf, r4 ; prepare spsr_cxsf to return svc mode
; LDMFD sp!, {r0-r12, pc}^ ; recover r0-r12 and pc from stack, cpsr also
;handler_event_timer
; BL OSIntEnter
; BL OSTimeTick
; BL timer_irq ; here do_IRQ is used to clear some virtual-hardware flags
; BL OSIntExit
; LDR r0, =OSIntCtxSwFlag ; check if OSIntCtxFlag is marked as true
; LDR r1, [r0]
; CMP r1, #1
; BEQ _IntCtxSw ; if OSIntCtxFlag = true, then jump to _IntCtxSw
;_IntCtxSw
; MOV r1, #0 ; clear OSIntCtxSwFlag = flase
; STR r1, [r0]
; LDMFD sp!, {r4} ; restore spsr_cxsf_irq
; MSR spsr_cxsf, r4
; str r4, SAVED_SPSR
; LDMFD sp!, {r0-r12, lr} ; recover the irq stack pointer
; STR lr, SAVED_LR_IRQ ; save lr_irq to SAVED_LR_IRQ
; MOV lr, #0x000000d3 ; change forcely cpsr to svc mode
; MSR cpsr_cxsf, lr
; STR lr, SAVED_LR_SVC ; save lr_svc to SAVED_LR_SVC
; LDR lr, SAVED_LR_IRQ ; get lr_irq value saved in SAVED_LR_IRQ
; STMFD sp!, {lr} ; push future task pc (lr_irq should be pushed in place of PC)
; LDR lr, SAVED_LR_SVC ; get lr_svc value saved in SAVED_LR_SVC
; STMFD sp!, {r0-r12,lr} ; push lr & r0-r12 register file
; ldr r4, SAVED_SPSR
; ; MRS r4, spsr
; STMFD sp!, {r4} ; push current psr
; ; MRS r4, spsr
; STMFD sp!, {r4} ; push spsr_cxsf
; B _OSCtxSw ; jump to _OSCtxSw
; --------------------------------------------------------->> removed ends
;/***********************************************************************
;
; Functions: ARMDisableInt
; ARMEnableInt
;
; Purpose:
; Disable and enable IRQ and FIQ preserving current CPU mode.
;
; Processing:
; Push the cpsr onto the stack
; Disable IRQ and FIQ interrupts
; Return
;
; Parameters: void
;
; Outputs: None
;
; Returns: void
;
; Notes:
; (1) Can be called from SVC mode to protect Critical Sections.
; (2) Do not use these calls at interrupt level.
; (3) Used in pairs within the same function level;
; (4) Will restore interrupt state when called; i.e., if interrupts
; are disabled when DisableInt is called, interrupts will still
; still be disabled when the matching EnableInt is called.
; (5) Uses the method described by Labrosse as "Method 2".
;
;*********************************************************************/
EXPORT ARMDisableInt
ARMDisableInt
MRS r0, cpsr
STMFD sp!, {r0} ; push current PSR
ORR r0, r0, #0xC0
MSR cpsr_c, r0 ; disable IRQ Int s
MOV pc, lr
EXPORT ARMEnableInt
ARMEnableInt
LDMFD sp!, {r0} ; pop current PSR
MSR cpsr_c, r0 ; restore original cpsr
MOV pc, lr
;---------------------------------------------------------------------
; function : dump stack
; Added by YJ for debug
;---------------------------------------------------------------------
EXPORT DmpStk
DmpStk
LDR r0, =Dump_Pool
MOV r1, sp
MOV r2, sp
ADD r2, r2, #64
DmpLoop
LDR r3, [r1]
STR r3, [r0]
ADD r0, r0, #4
ADD r1, r1, #4
CMP r1, r2
BNE DmpLoop
MOV pc, lr
ALIGN
Dump_Pool DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
DCD 0
END
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