using macros to share code between two projects

[jsnes]

I need merge two nearly identical .c files so that the new file remains 100% compatible with the first project (changing the actual code as little as possible), but will accomodate useage from the second project where the function calls are similar, but (for instance) have more parameters. I need to use macros in the .h as much as possible.

How do I make (.c file)

void foo (int x){...

merge with this

void foo (int x, int x){...

what's the best way to do this with a macro in the header?

 

[DaveSinkula]

Maybe something like this.

/* mycode.h */
#if   defined(PROJECTA)
void foo (int x);
#elif defined(PROJECTB)
void foo (int x, int y);
#else
#error Please #define either PROJECTA or PROJECTB.
#endif

/* mycode.c */
#include "mycode.h"

#if   defined(PROJECTA)
void foo (int x)
{
   /* ... */
}
#elif defined(PROJECTB)
void foo (int x, int y)
{
   /* ... */
}
#endif

/* main.c */
#include "mycode.h"

void bar(void)
{
#if   defined(PROJECTA)
   foo(1);
#elif defined(PROJECTB)
   foo(1,2);
#endif
}

Or maybe this.

/* mycode.h */
#if   defined(PROJECTA)
void foo (int x);
#define FOO(x,y) foo(x)
#elif defined(PROJECTB)
void foo (int x, int y);
#define FOO(x,y) foo(x,y)
#else
#error Please #define either PROJECTA or PROJECTB.
#endif

/* main.c */
#include "mycode.h"

void bar(void)
{
   FOO(1,2);
}