有关STARTUP.A51的问题

2005-11-21 12:07:19 773 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

51平台下初始化文件的引入导致全局变量无法初始化的问题写在前面－－－－－－－－－－－－－－－－－在前段时间的工作中，就遇见过全局变量无法初始化的问题，不过之前是在一些C文件中定义的变量能初始化，而其他C文件中不能初始化，当时将这个问题绕过去了，并没有去深究...而这一周又出现了这个问题。于是就有了这篇文章这里不去讨论其他情况下全局变量无法初始化的问题，只是针对我所遇见的问题讨论....原因：由于引入库文件INIT.A51和STA 阅读详情

请问有谁知道在startup.a51 文件里的EXTRN CODE (?C_START) 和LJMP ?C_START 中的C_START在哪儿定义的吗？还是在keil c中它就默认为是main()函数呢？如果这样，可每次编译时总是出现C_START没有定义或是无法辨认的符号的警告。当程序运行时也确实没有跳到main()地方开始执行，甚至在调试状态下连断点都无法设！为什么啊？请哪位老兄搭把手，先谢啦！！！

...全文

2023年全国职业院校技能大赛高职组“区块链技术应用”赛项赛卷（3卷）解析我们先绘制题组中所有设计图我这边作图用的国内的在线作图工具。阅读详情

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muzikuhai 2005-11-22

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muzikuhai 2005-11-21

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to： goodluckyxl(被人遗忘的狗<写驱动不是我强项,但我可以做好>)，你说的“使用默认的main函数入口”是怎么用啊？

muzikuhai 2005-11-21

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我用的就是keil c里自带的startup.a51啊。如下：
$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 0H ; the absolute start-address of XDATA memory
XDATALEN EQU 0H ; the length of XDATA memory in bytes.
;
PDATASTART EQU 0H ; the absolute start-address of PDATA memory
PDATALEN EQU 0H ; 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 0 ; set to 1 if pdata object are used.
PPAGE EQU 0 ; define PPAGE number.
;
;------------------------------------------------------------------------------

; 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 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
; 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

flowercity 2005-11-21

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goodluckyxl 2005-11-21

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使用默认的main函数入口

LanceJin 2005-11-21

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启动文件自动生成，不需要用户再定义，当然你可以根据需要修改启动代码。你在startup.a51文件中应当能找到以上语句，如果你不打算用Keil自动生成的启动文件的话，你也可以参照它的启动文件来写。你的启动文件没贴上来，也没描述清楚，不好说是什么原因

有关STARTUP.A51的问题

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