os_cpu_a.asm

dsp常用例程UCOS程序源代码 基于TIDSP

_EVIFRB  .set 7430h
         
    .global	I$$SAVE						
    .global	I$$REST
	.global	_OSIntEnter
	.global	_OSIntExit
    .global	_OSTimeTick				
	.global	_OSTCBCur
	.global	_OSTCBHighRdy
	.global	_OSStartHighRdy
    .global	_OSCtxSw
    .global	_OSIntCtxSw
    .global _OSTaskSwHook
    .global _OSRunning
    .global _OSPrioCur
    .global _OSPrioHighRdy
	.global _OSIntNesting
	.global	_OSTickISR
	
	.text
    

_OSStartHighRdy:
    call _OSTaskSwHook,ar1		    ; call _OSTaskSwHook
    ldpk _OSRunning                 ;set OSRunning true
    splk #1,_OSRunning
    ldpk _OSTCBHighRdy
    lar	 AR1,_OSTCBHighRdy     ; point to the pointer to the highest priority task.
    ;lar AR1,#_OSTCBHighRdy
    ;lar  AR1,*                  ; point to the highest priority task.
    nop
    nop
    lar  AR1,*	                ; get OSTCBCur->OSTCBStkPtr.
    nop
    nop
    b	I$$REST			        ; go let TI do the hard work.

    
_OSCtxSw:
	
    call	I$$SAVE		; save this task's context.
   
    
_OSCtxSw_0:
    call _OSTaskSwHook
    ldpk    _OSPrioCur
    bldd   #_OSPrioHighRdy,_OSPrioCur
    lar   AR2,#_OSTCBCur	                     ; point AR2 at the OSTCBCur pointer.
    mar   *,AR2		                     ; make AR2 the currently used address register.
    lar	  AR0,*,AR0			     ; point AR0 at current TCB, and switch to using AR0.
    sar	  AR1,*	          		     ; save the current task's current stack ptr in the current TCB.
     
    lar	  AR0,#_OSTCBHighRdy		     ; point to OSTCBHighRdy pointer.
    lar	  AR0,* 			     ; point to the highest priority task that is ready.
    lar	  AR1,*,AR2       		     ; get the new task's stack ptr, switch
    					     ; to using AR2 which points to OSTCBCur pointer.
    sar	  AR0,*,AR1              	     ; move _OSTCBHighRdy to _OSTCBCur,
    					     ; and switch to using the new current stack pointer.
    b    I$$REST			     ; let TI do the hard work of restoring this task's context.
    

_OSIntCtxSw:
	
    POP 			    ; pop-off the return address
    sbrk   3			; clean-up the sw stack's pushed frame pointer and return address from the call to "OSIntExit."
                        ;before v2.15 these instructions are needed
    b	_OSCtxSw_0		

_OSTickISR:                             
	call I$$SAVE			; save the interrupted task's context.
    
    ldpk _OSIntNesting
    lacc _OSIntNesting
    add #1
    sacl _OSIntNesting
    
    ldp #232
    splk #0001h,_EVIFRB
    clrc INTM               ;enable interrupt
    call _OSTimeTick		; increment the uC/OS timer tick.
    call   _OSIntExit		; inform uC/OS we're leaving the ISR; we may exit through that path if there is a context switch.
    b	I$$REST			

     .end