context.asm

强实时嵌入式系统开发 Rev1.00 网上下载所得

;*
;==============================================================================
; COPYRIGHT (C) 2004-2006 Haishen Ruan, All rights reserved.
; SUMMARY: 
;   Timer service.
;
;
; LICENSE INFORMATION
;   RS-RTOS is free software; you can redistribute it and/or modify it under
;   terms of the GNU General Public License as published by the
;   Free Software Foundation; either version 2, or (at your option) any
;   later version.
;
;   RS-RTOS is distributed in the hope that it will be useful,
;   but WITHOUT ANY WARRANTY; without even the implied warranty of
;   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;   General Public License for more details.
;
;   You should have received a copy of the GNU General Public License
;   along with RS-RTOS; see file COPYING. If not, write to the Free Software
;   Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
;
;   As a special exception, including RS-RTOS header files in a file,
;   instantiating RS-RTOS generics or templates, or linking other files
;   with RS-RTOS objects to produce an executable application, does not
;   by itself cause the resulting executable application to be covered
;   by the GNU General Public License. This exception does not
;   however invalidate any other reasons why the executable file might be
;   covered by the GNU Public License.
;
;
; DESCRIPTION:
;   See http://www.RS-RTOS.org for documentation, latest information, license
;   and contact details.
;   email:[e-mail]
;============================================================================*/
;*===========================================================================*/
#include "example/KeilC51/config.h"
#include "arch/C51/inc/mem_model.h"

;Priority of idle task
#define RSI_IDLE_PRIO           (CFG_MAX_TASKS - 1)

        public  __task_fore
        extrn   code(__do_tick)
        extrn   code(__schedule)

#if RSI_MEM_MODEL == SMALL

        extrn   data(_sched_lock)

#elif RSI_MEM_MODEL == COMPACT

        extrn   xdata(_sched_lock)

#else

        extrn   xdata(_sched_lock)

#endif

        
        COUNTER         EQU       20000
        T0H_COUNTER     EQU       (65536 - COUNTER) / 256
        T0L_COUNTER     EQU       (65536 - COUNTER) - T0H_COUNTER * 256


CSEG    AT      000BH
        CLR     EA
        MOV     TH0, #T0H_COUNTER
        MOV     TL0, #T0L_COUNTER
        JMP     __timer_handle


CSEG    AT      0100H

;*===========================================================================*/
;void __task_fore(void)
;{
__task_fore:

        ; Get argument from stack
        MOV     A, SP
        MOV     R0, A
        INC     R0
        INC     R0
        INC     R0

        ; Save argument to R6 & R7
        MOV     A, @R0
        MOV     R6, A
        INC     R0
        MOV     A, @R0
        MOV     R7, A

        ; Enable interrupt
        SETB    EA
        
        RET
;}

;*===========================================================================*/
;void __timer_handle(void)
;{
__timer_handle:
        PUSH    ACC
        PUSH    B
        PUSH    PSW
        PUSH    DPH
        PUSH    DPL
        PUSH    00H
        PUSH    01H
        PUSH    02H
        PUSH    03H
        PUSH    04H
        PUSH    05H
        PUSH    06H
        PUSH    07H

;   _sched_lock++
#if RSI_MEM_MODEL == SMALL

        INC     _sched_lock

#elif RSI_MEM_MODEL == COMPACT

        MOV     R0, #LOW _sched_lock
        MOVX    A, @R0
        INC     A
        MOVX    @R0, A

#else

        MOV     DPTR, #_sched_lock
        MOVX    A, @DPTR
        INC     A
        MOVX    @DPTR, A

#endif

        SETB    EA

;================================================
        LCALL   __do_tick
        MOV     A, #LOW  timer_exit
        PUSH    ACC
        MOV     A, #HIGH timer_exit
        PUSH    ACC
        RETI

;================================================
timer_exit:

#if RSI_MEM_MODEL == SMALL

        DEC     _sched_lock
        MOV     A, _sched_lock
        
#elif RSI_MEM_MODEL == COMPACT

        MOV     R0, #LOW _sched_lock
        MOVX    A, @R0
        DEC     A
        MOVX    @R0, A

#else

        MOV     DPTR, #_sched_lock
        MOVX    A, @DPTR
        DEC     A
        MOVX    @DPTR, A

#endif

        JNZ     timer_return

        LCALL   __schedule

timer_return:

        POP     07H
        POP     06H
        POP     05H
        POP     04H
        POP     03H
        POP     02H
        POP     01H
        POP     00H
        POP     DPL
        POP     DPH
        POP     PSW
        POP     B
        POP     ACC
        RET
;}
;*===========================================================================*/
        END