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how to use a bit variable defined in another module?

Gentlemen:
I wanna use a bit variable in file:assem.asm.And the bit variable is defined in another file:main.c;Just as follows:

in main.c
unsigned char bdata flags;
sbit red_flag = flags^1;

in assem.asm

what should I do to let the keil know I want invoke the red_flag bit variable which is defined in main.c;how to declare it? The MCU I use is atmel at89s52.Thanks.
---going to mad.

Parents

0 Jim King over 21 years ago in reply to Angus John

Sorry,John.Now I have compiled it successfully.It will be right,I think.

//my.h
#ifndef __MY_H__
#define __MY_H__

//Declaration
#ifdef __A51__
    EXTRN DATA (flags)
    EXTRN BIT  (red_flag)
#else
    extern unsigned char bdata flags;
    extern bit red_flag;
#endif

#ifdef __C51__
//C function prototype
void TextOut (BYTE byChar);
#endif //__C51__

#endif //__MY_H__

Then put the two lines into your C file.

//my.c
unsigned char bdata flags;
sbit red_flag = flags^1;

Then #include the .h file in your asm files.It will be OK.

Reply

0 Jim King over 21 years ago in reply to Angus John

Sorry,John.Now I have compiled it successfully.It will be right,I think.

//my.h
#ifndef __MY_H__
#define __MY_H__

//Declaration
#ifdef __A51__
    EXTRN DATA (flags)
    EXTRN BIT  (red_flag)
#else
    extern unsigned char bdata flags;
    extern bit red_flag;
#endif

#ifdef __C51__
//C function prototype
void TextOut (BYTE byChar);
#endif //__C51__

#endif //__MY_H__

Then put the two lines into your C file.

//my.c
unsigned char bdata flags;
sbit red_flag = flags^1;

Then #include the .h file in your asm files.It will be OK.

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