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$NOMOD51 ;------------------------------------------------------------------------------ ; This file is part of the C51 Compiler package ; Copyright (c) 1988-2002 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 80H ; the length of IDATA memory in bytes. ; XDATASTART EQU 100H ; the absolute start-address of XDATA memory XDATALEN EQU 7F00H ; the length of XDATA memory in bytes. ; PDATASTART EQU 0H ; the absolute start-address of PDATA memory PDATALEN EQU 100H ; 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 1 ; set to 1 if large reentrant is used. XBPSTACKTOP EQU 3FFFH+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 0 ; set to 1 if pdata object are used. ; PPAGE EQU 0 ; define PPAGE number. ; PPAGE_SFR DATA 0A0H ; SFR that supplies uppermost address byte ; (most 8051 variants use P2 as uppermost address byte) ; ;------------------------------------------------------------------------------ ; Standard SFR Symbols ACC DATA 0E0H B DATA 0F0H SP DATA 81H DPL DATA 82H DPH DATA 83H 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 PPAGE_SFR,#PPAGE ENDIF IF PDATALEN <> 0 MOV R0,#LOW (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 ; This code is required if you use L51_BANK.A51 with Banking Mode 4 ; EXTRN CODE (?B_SWITCH0) ; CALL ?B_SWITCH0 ; init bank mechanism to code bank 0 LJMP ?C_START END
I am using above startup.a51 in my project. I want to use one global variable as a flag, so that its value should be retained after resetting device. I set one global variable at memory location 8000 and I changed in startup.a51 initialization from XDATALEN EQU 7F00H to XDATALEN EQU 7EFFH But still it is intializing this variable to 0 after resetting. Please give me the solution for this problem.