os_cpu_a.asm

ucosz在2407上的移植代码

;********************************************************************************************************
;                                               uC/OS-II
;                                         The Real-Time Kernel
;
;                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL
;                                          All Rights Reserved
;
;
;                                       80x86/80x88 Specific code
;                                          LARGE MEMORY MODEL
;
;                                        IBM/PC Compatible Target
;
; File : OS_CPU_A.ASM
; By   : Jean J. Labrosse
;********************************************************************************************************
TICKISRFOROTHERFUNC	.SET 0
	.mmregs
	.def _OSTickISR
	.def _OSStartHighRdy
	.def _OSCtxSw
	.def _OSIntCtxSw

	.ref _OSIntExit;	:FAR
	.ref _OSTimeTick;	:FAR
	.ref _OSTaskSwHook;	:FAR

	.ref _OSIntNesting;	:BYTE
	.ref _OSTickDOSCtr;	:BYTE
	.ref _OSPrioHighRdy;	:BYTE
	.ref _OSPrioCur;	:BYTE
	.ref _OSRunning;	:BYTE
	.ref _OSTCBCur;		:DWORD
	.ref _OSTCBHighRdy;	:DWORD

	.if TICKISRFOROTHERFUNC
	.ref _OSTickISRForOther
	.ref _TickTimesForOther
	.endif

	.ref I$$SAVE
	.ref I$$REST
;.MODEL      LARGE
;.CODE
;.186
;            PAGE                                  ; /*$PAGE*/
;*********************************************************************************************************
;                                          START MULTITASKING
;                                       void OSStartHighRdy(void)
;
; The stack frame is assumed to look 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             
;                               OFFSET  of task code address
;                               SEGMENT of task code address
;                               OFFSET  of 'pdata'
;                               SEGMENT of 'pdata'               (High memory)
;
; Note : OSStartHighRdy() MUST:
;           a) Call OSTaskSwHook() then,
;           b) Set OSRunning to TRUE,
;           c) Switch to the highest priority task.
;*********************************************************************************************************
	.ref _OSTaskSwHook

_OSStartHighRdy:;  PROC FAR

;	MOV AX,SEG _OSTCBHighRdy; Reload DS
;	MOV DS,AX; 
;;
;	CALL FAR PTR _OSTaskSwHook; Call user defined task switch hook
;;
;	INC BYTE PTR DS:_OSRunning; Indicate that multitasking has started
;;
;	LES BX,DWORD PTR DS:_OSTCBHighRdy ; SS:SP = OSTCBHighRdy->OSTCBStkPtr
;	MOV SS,ES:[BX+2]                  ; 
;	MOV SP,ES:[BX+0]                  ; 
;;
;	POP DS; Load task's context
;	POP ES; 
;	POPA; 
;;
;	IRET ; Run task
	;ldpk _OSTCBHighRdy
	
	call _OSTaskSwHook,ar1

	ldpk _OSRunning
	lac _OSRunning
	addk 1
	sacl _OSRunning

	ldpk _OSTCBHighRdy
	lar ar1,_OSTCBHighRdy
	lar ar1,*
	;mar *,ar1
	b I$$REST


;_OSStartHighRdy  ENDP
;
;            PAGE                                  ; /*$PAGE*/

;*********************************************************************************************************
;                                PERFORM A CONTEXT SWITCH (From task level)
;                                           void OSCtxSw(void)
;
; Note(s): 1) Upon entry, 
;             OSTCBCur     points to the OS_TCB of the task to suspend
;             OSTCBHighRdy points to the OS_TCB of the task to resume
;
;          2) The stack frame of the task to suspend looks as follows:
;
;                 SP -> OFFSET  of task to suspend    (Low memory)
;                       SEGMENT of task to suspend      
;                       PSW     of task to suspend    (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)
;*********************************************************************************************************

_OSCtxSw:;    PROC   FAR
;;
;	PUSHA                                  ; Save current task's context
;	PUSH ES                              ; 
;	PUSH DS                              ; 
;;
;	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
;
	call I$$SAVE

	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


;_OSCtxSw	ENDP
;
;	PAGE			; /*$PAGE*/
;*********************************************************************************************************
;                                PERFORM A CONTEXT SWITCH (From an ISR)
;                                        void OSIntCtxSw(void)
;
; Note(s): 1) Upon entry, 
;             OSTCBCur     points to the OS_TCB of the task to suspend
;             OSTCBHighRdy points to the OS_TCB of the task to resume
;
;          2) The stack frame of the task to suspend looks as follows:
;
;                                  SP+0 --> OFFSET  of return address of OSIntCtxSw()  (Low memory)
;                                    +2     SEGMENT of return address of OSIntCtxSw()
;                                    +4     PSW saved by OS_ENTER_CRITICAL() in OSIntExit()
;                                    +6     OFFSET  of return address of OSIntExit()
;                                    +8     SEGMENT of return address of OSIntExit()
;                                    +10    DS                               
;                                           ES
;                                           DI