有关STARTUP.A51的问题

[muzikuhai]

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！！！

[LanceJin]

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

[goodluckyxl]

使用默认的main函数入口

[flowercity]

up

[muzikuhai]

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

[muzikuhai]

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]

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