os_cpu_a.asm

ucosz在2407上的移植代码

;                                           SI
;                                           BP
;                                           SP
;                                           BX
;                                           DX
;                                           CX
;                                           AX
;                                           OFFSET  of task code address
;                                           SEGMENT of task code address
;                                           Flags to load in PSW                       (High memory)
;
;          3) The stack frame of the task to resume looks as follows:
; 
;             OSTCBHighRdy->OSTCBStkPtr --> DS                               (Low memory)
;                                           ES
;                                           DI
;                                           SI
;                                           BP
;                                           SP
;                                           BX
;                                           DX
;                                           CX
;                                           AX
;                                           OFFSET  of task code address
;                                           SEGMENT of task code address
;                                           Flags to load in PSW             (High memory)
;*********************************************************************************************************
funcstack .set 3
	;必须检查OSIntExit()被编译器汇编的
	;程序,计算其使用的堆栈个数,因为
	;OSIntCtxSw()并没有用到堆栈,所以不必
	;理睬。OSIntExit用到的堆栈为
	;1	返回地址
	;2	AR0
	;3	临时变量
	;每次编译后都应检查OSIntExit的汇编程序
	;的头部是不是如下
	;_OSIntExit:
	;	POPD	*+
	;	SAR	AR0,*+
	;	SAR	AR1,*
	;	LARK	AR0,1
	;	LAR	AR0,*0+
	;并且还要检查后面到CALL	_OSIntCtxSw前
	;的程序是否改变了SP(AR1)
	;在CPU本身的堆栈顶是OSIntCtxSw的返回地址,
	;因为不需要返回,所以丢弃,当然也可以用
	;popd *指令将其丢弃,本程序未如此。
_OSIntCtxSw:; PROC   FAR
;;                                                  ;  Ignore calls to OSIntExit and OSIntCtxSw
;;	ADD SP,8                            ; (Uncomment if OS_CRITICAL_METHOD is 1, see OS_CPU.H)
;	ADD SP,10                           ; (Uncomment if OS_CRITICAL_METHOD is 2, see OS_CPU.H)
;;
;	MOV AX, SEG _OSTCBCur               ; Reload DS in case it was altered
;	MOV DS, AX                          ; 
;;
;	LES BX, DWORD PTR DS:_OSTCBCur      ; OSTCBCur->OSTCBStkPtr = SS:SP
;	MOV ES:[BX+2], SS                   ; 
;	MOV ES:[BX+0], SP                   ; 
;;
;	CALL FAR PTR _OSTaskSwHook           ; Call user defined task switch hook
;;
;	MOV AX, WORD PTR DS:_OSTCBHighRdy+2 ; OSTCBCur = OSTCBHighRdy
;	MOV DX, WORD PTR DS:_OSTCBHighRdy   ; 
;	MOV WORD PTR DS:_OSTCBCur+2, AX     ; 
;	MOV WORD PTR DS:_OSTCBCur, DX       ; 
;;
;	MOV AL, BYTE PTR DS:_OSPrioHighRdy  ; OSPrioCur = OSPrioHighRdy
;	MOV BYTE PTR DS:_OSPrioCur, AL        
;;
;	LES BX, DWORD PTR DS:_OSTCBHighRdy  ; SS:SP = OSTCBHighRdy->OSTCBStkPtr
;	MOV SS, ES:[BX+2]                   ; 
;	MOV SP, ES:[BX]                     ; 
;;
;	POP DS                              ; Load new task's context
;	POP ES                              ; 
;	POPA                                   ; 
;;
;	IRET                                   ; Return to new task
;;
	sbrk funcstack

	ldpk _OSTCBCur
	lar ar3,_OSTCBCur
	mar *,ar3
	sar ar1,*,ar1

	call _OSTaskSwHook

	ldpk _OSTCBHighRdy
	lar ar1,_OSTCBHighRdy
	;ldpk _OSTCBCur
	sar ar1,_OSTCBCur
	
	lacl _OSPrioHighRdy
	sacl _OSPrioCur
	
	lar ar1,*
	b I$$REST,ar1




;_OSIntCtxSw ENDP
;
;	PAGE	; /*$PAGE*/
;*********************************************************************************************************
;                                            HANDLE TICK ISR
;
; Description: This function is called 199.99 times per second or, 11 times faster than the normal DOS
;              tick rate of 18.20648 Hz.  Thus every 11th time, the normal DOS tick handler is called.
;              This is called chaining.  10 times out of 11, however, the interrupt controller on the PC
;              must be cleared to allow for the next interrupt.
;
; Arguments  : none
;
; Returns    : none
;
; Note(s)    : The following C-like pseudo-code describe the operation being performed in the code below.
;
;              Save all registers on the current task's stack;
;              OSIntNesting++;
;              OSTickDOSCtr--;
;              if (OSTickDOSCtr == 0) {
;                  INT 81H;               Chain into DOS every 54.925 mS 
;                                         (Interrupt will be cleared by DOS)
;              } else {
;                  Send EOI to PIC;       Clear tick interrupt by sending an End-Of-Interrupt to the 8259
;                                         PIC (Priority Interrupt Controller)
;              }
;              OSTimeTick();              Notify uC/OS-II that a tick has occured       
;              OSIntExit();               Notify uC/OS-II about end of ISR
;              Restore all registers that were save on the current task's stack;
;              Return from Interrupt;
;*********************************************************************************************************
;
	.ref _timesforlight
	.ref _timesfortx
	.ref _pivr
	.ref _gptcona
	.ref _evaifrb
	.ref _evaifra
_OSTickISR:;  PROC   FAR
;;
;	PUSHA                                ; Save interrupted task's context
;	PUSH   ES
;	PUSH   DS
;;
;	MOV    AX, SEG _OSTickDOSCtr         ; Reload DS 
;	MOV    DS, AX
;;
;	INC    BYTE PTR _OSIntNesting        ; Notify uC/OS-II of ISR
;;
;	DEC    BYTE PTR DS:_OSTickDOSCtr
;	CMP    BYTE PTR DS:_OSTickDOSCtr, 0
;	JNE    SHORT _OSTickISR1             ; Every 11 ticks (~199.99 Hz), chain into DOS
;;
;	MOV    BYTE PTR DS:_OSTickDOSCtr, 11
;	INT    081H                          ; Chain into DOS's tick ISR
;	JMP    SHORT _OSTickISR2
;
;_OSTickISR1:
;	MOV    AL, 20H                       ; Move EOI code into AL.
;	MOV    DX, 20H                       ; Address of 8259 PIC in DX.
;	OUT    DX, AL                        ; Send EOI to PIC if not processing DOS timer.
;;
;_OSTickISR2:
;	CALL   FAR PTR _OSTimeTick           ; Process system tick
;;
;	CALL   FAR PTR _OSIntExit            ; Notify uC/OS-II of end of ISR
;;
;	POP    DS                            ; Restore interrupted task's context
;	POP    ES
;	POPA
;;
;	IRET                                 ; Return to interrupted task
;;
	call I$$SAVE
	ldp #_pivr;/128
	lacc _pivr
	
	ldp #_gptcona;/128
	lacc #80h
	sacl _evaifra
	
	ldpk _OSIntNesting
	lacc _OSIntNesting
	addk 1
	sacl _OSIntNesting
;the next program can be cut if no other function
;need to be execute	
;	.if TICKISRFOROTHERFUNC
;	lacc _OSTickDOSCtr
;	subk 1
;	bnz _OSTickISR1
;	call _OSTickISRForOther
;	lacl #_TickTimesForOther
;_OSTickISR1:
;	sacl _OSTickDOSCtr
;	.endif
	;user code
	ldpk _timesfortx
	lacl _timesfortx
	addk 1
	sacl _timesfortx
	ldpk _timesforlight
	lacl _timesforlight
	addk 1
	sacl _timesforlight
	;user code
;
	call _OSTimeTick
	
	call _OSIntExit
	b I$$REST
	
	
;_OSTickISR  ENDP
;
            .end