On debug method(How to implement the "TRACE" macro?)

MFC implement it for us while Keil C don't

I'll get back to you when I'm done with my port of MFC to the 8051. I still have some issues with the DirectX 9 support for multiprocessor support.

In the meantime, it's a pretty easy macro to write:

#if DEBUG
#define TRACE(args) printf(args)
#else
#define TRACE(args)
#endif

Define DEBUG, and you get your debug code. Don't define it, and the statements all vanish.

If I've got a fancy CLI to play with, I like to add a "debug level" to the macro to control verbosity of the output. I assign the debug output to "high", "medium", "low" levels of detail (1, 2, 3). Then, I can use an 'if' statement to compare to a dynamically controlled debug level variable so that I'm not always buried in the maximum spew from the debug code, but can turn it on when I want. A little more macro sleight-of-hand lets you selectively compile out debug levels you don't want in the code.

Different preprocessors seem to handle the problem of variable arguments differently. That is, if you have

printf ("%d %d %d\n", d1, d2, d2);

you may or may not be able to call

TRACE ("%d %d %d\n", d1, d2, d2);

since there are four actual arguments to TRACE but only one formal argument declared. Some preprocessors simply make the last argument match all arguments to the macro. If I recall correctly, C99 actually adds support for variadic macro declarations. But I also can sometimes get away with an extra level of parens:

TRACE (("%d %d %d\n", d1, d2, d2));

which is a little ugly, but groups all the arguments into one single one for the macro expansion.

MFC implement it for us while Keil C don't

I'll get back to you when I'm done with my port of MFC to the 8051. I still have some issues with the DirectX 9 support for multiprocessor support.

In the meantime, it's a pretty easy macro to write:

#if DEBUG
#define TRACE(args) printf(args)
#else
#define TRACE(args)
#endif

Define DEBUG, and you get your debug code. Don't define it, and the statements all vanish.

If I've got a fancy CLI to play with, I like to add a "debug level" to the macro to control verbosity of the output. I assign the debug output to "high", "medium", "low" levels of detail (1, 2, 3). Then, I can use an 'if' statement to compare to a dynamically controlled debug level variable so that I'm not always buried in the maximum spew from the debug code, but can turn it on when I want. A little more macro sleight-of-hand lets you selectively compile out debug levels you don't want in the code.

Different preprocessors seem to handle the problem of variable arguments differently. That is, if you have

printf ("%d %d %d\n", d1, d2, d2);

you may or may not be able to call

TRACE ("%d %d %d\n", d1, d2, d2);

since there are four actual arguments to TRACE but only one formal argument declared. Some preprocessors simply make the last argument match all arguments to the macro. If I recall correctly, C99 actually adds support for variadic macro declarations. But I also can sometimes get away with an extra level of parens:

TRACE (("%d %d %d\n", d1, d2, d2));

which is a little ugly, but groups all the arguments into one single one for the macro expansion.

The extra level of parenthesis works fine with C51.

Many thanks,Davis.You give a very smart way.But the following statements

typedef unsigned long ULONG;
ULONG xdata * data pMem = 0;
TRACE (("Read Value:%lXH\n", *pMem));

//debug.h
#ifndef __DEBUG_H__
#define __DEBUG_H__

#ifdef _RELEASE
//release mode
#define TRACE(const char * format, ...)//cause error
#else
//debug mode
#include <stdio.h>
void TRACE (const char * format, ...);
#endif //_RELEASE

#endif //__DEBUG_H__

//debug.c
#include <stdio.h>
#include <stdarg.h>

void TRACE (const char * format, ...)
{
	va_list ap;
	va_start (ap, format);
	printf (format, ap)
	va_end (ap);
}

That error C214 you got almost certainly has nothing to do with the TRACE macro as such, but with the argument list you passed it.

#defining DEBUG or RELEASE is supposed to be done by the project / makefile, so you can decide at compile time, outside the code, which modules to compile with the debug printouts active.

Seriously, though: if you need to look into Microsoft SDKs to rip off a HIBYTE() macro instead of rolling your own, that's a strong sign you're in well over your head already. You'll have to brush up your knowledge of the C programming language considerably before you go on working on embedded software, I think.

What's wrong with my arg list?

"macros such as HIBYTE,LOBYTE etc,we must define it ourselves.A direct way is to steal the codes from the windows SDK or MFC"

Be very careful!

Not only are you dealing with a different Compiler, but also a completely different target.

You can't just steal them - you will need to read them carefully & fully understand them to be able to decide if they will give the right resuls with Keil C51, or what modifications are required!

You need something like this:

ifdef DEBUG
//Debug mode - TRACE causes printf output
#include <stdio.h>
#define TRACE(params) printf params;
#else
//Release mode - TRACE expands to nothing!
#define TRACE(params)
#endif // DEBUG

void some_func( char x )
{
   TRACE( ("Entered some_func( %bX )", x) )
   :
   :
}