startup.a51

MP3播放器详细设计方案

;------------------------------------------------------------------------------
;  This file is part of the C51 Compiler package
;  Copyright (c) 1988-1999 Keil Elektronik GmbH and Keil Software, Inc.
;------------------------------------------------------------------------------
;  STARTUP.A51:  This code is executed after processor reset.
;
;  To translate this file use A51 with the following invocation:
;
;     A51 STARTUP.A51
;
;  To link the modified STARTUP.OBJ file to your application use the following
;  BL51 invocation:
;
;     BL51 <your object file list>, STARTUP.OBJ <controls>
;
;------------------------------------------------------------------------------
;
;  User-defined Power-On Initialization of Memory
;
;  With the following EQU statements the initialization of memory
;  at processor reset can be defined:
;
;       ; the absolute start-address of IDATA memory is always 0
IDATALEN    EQU 100H    ; the length of IDATA memory in bytes.
;
XDATASTART  EQU 0H      ; the absolute start-address of XDATA memory
XDATALEN    EQU 800H    ; the length of XDATA memory in bytes.
;
PDATASTART  EQU 0H      ; the absolute start-address of PDATA memory
PDATALEN    EQU 200H    ; the length of PDATA memory in bytes.
;
;  Notes:  The IDATA space overlaps physically the DATA and BIT areas of the
;          8051 CPU. At minimum the memory space occupied from the C51 
;          run-time routines must be set to zero.
;------------------------------------------------------------------------------
;
;  Reentrant Stack Initilization
;
;  The following EQU statements define the stack pointer for reentrant
;  functions and initialized it:
;
;  Stack Space for reentrant functions in the SMALL model.
IBPSTACK    EQU 0       ; set to 1 if small reentrant is used.
IBPSTACKTOP EQU 0FFH+1  ; set top of stack to highest location+1.
;
;  Stack Space for reentrant functions in the LARGE model.	
XBPSTACK    EQU 0       ; set to 1 if large reentrant is used.
XBPSTACKTOP EQU 0FFFFH+1; set top of stack to highest location+1.
;
;  Stack Space for reentrant functions in the COMPACT model.	
PBPSTACK    EQU 0       ; set to 1 if compact reentrant is used.
PBPSTACKTOP EQU 0FFFFH+1; set top of stack to highest location+1.
;
;------------------------------------------------------------------------------
;
;  Page Definition for Using the Compact Model with 64 KByte xdata RAM
;
;  The following EQU statements define the xdata page used for pdata
;  variables. The EQU PPAGE must conform with the PPAGE control used
;  in the linker invocation.
;
PPAGEENABLE EQU 1   ; set to 1 if pdata object are used.
PPAGE       EQU 0   ; define PPAGE number.
;
;------------------------------------------------------------------------------

        NAME    ?C_STARTUP


?C_C51STARTUP   SEGMENT   CODE
?STACK          SEGMENT   IDATA

        RSEG    ?STACK
        DS      1

        EXTRN CODE (?C_START)
        PUBLIC  ?C_STARTUP

        CSEG    AT  0
?C_STARTUP:
        LJMP    STARTUP1

        RSEG    ?C_C51STARTUP

STARTUP1:

IF IDATALEN <> 0
        MOV     R0,#IDATALEN - 1
        CLR     A
  IDATALOOP:
        MOV     @R0,A
        DJNZ    R0,IDATALOOP
ENDIF

IF XDATALEN <> 0
        MOV     DPTR,#XDATASTART
        MOV     R7,#LOW (XDATALEN)
  IF (LOW (XDATALEN)) <> 0
        MOV     R6,#(HIGH XDATALEN) +1
  ELSE
        MOV     R6,#HIGH (XDATALEN)
  ENDIF
        CLR     A
  XDATALOOP:
        MOVX    @DPTR,A
        INC     DPTR
        DJNZ    R7,XDATALOOP
        DJNZ    R6,XDATALOOP
ENDIF

IF PPAGEENABLE <> 0
;        MOV     P2,#PPAGE
ENDIF

IF PDATALEN <> 0
        MOV     R0,#PDATASTART
        MOV     R7,#LOW (PDATALEN)
        CLR     A
PDATALOOP:
        MOVX    @R0,A
        INC     R0
        DJNZ    R7,PDATALOOP
ENDIF

IF IBPSTACK <> 0
EXTRN DATA (?C_IBP)

        MOV     ?C_IBP,#LOW IBPSTACKTOP
ENDIF

IF XBPSTACK <> 0
EXTRN DATA (?C_XBP)

        MOV     ?C_XBP,#HIGH XBPSTACKTOP
        MOV     ?C_XBP+1,#LOW XBPSTACKTOP
ENDIF

IF PBPSTACK <> 0
EXTRN DATA (?C_PBP)
        MOV     ?C_PBP,#LOW PBPSTACKTOP
ENDIF

        MOV     SP,#?STACK-1
        LJMP    ?C_START

        END