C macros with new lines in generated code

Question

I need macro which expands into multiple lines of code. For example:

#define foo(...)
foo(something, something_else, ...)
...

Should be converted into:

something
something_else
...

And not into:

something something_else ...

Also if you wonder why I need such thing. I need to generate such code, new line is part of inline assembly syntax.

_asm
{
    mov eax, 3
    div 5
}

I'm interested in any form of achieving this, so all suggestions are welcome.

Just an idea after reading this answer. Would it be possible to have a macro for new line and call foo(something, NL, something_else, NL, ...)?

I'm also more interested into variadic version but knowing simpler version may also help.

You cannot. This doesn't even make sense, as there are no longer any lines after preprocessing. There is only an unbroken stream of tokens. — n. m. could be an AI, Jul 27 '15 at 08:36
You *can* nest _asm statements and/or give each instruction its own _asm prefix. You don't need newlines in this case. — n. m. could be an AI, Jul 27 '15 at 08:47
Depending how your code generation works exactly, you could also get away with just `#include`ing different snippets of code which make use of variables you define prior to `#include`ing. — Frerich Raabe, Jul 27 '15 at 08:49
@n.m. Have been thinking about that. However instruction may have or may not have comma, so that annoys me. — ST3, Jul 27 '15 at 08:49
I have to ask why? What does it achieve to put your assembly language instructions in a macro? — JeremyP, Jul 27 '15 at 08:58
The compiler used here might be relevant. With `gcc`, inline assembly in a single line wouldn't be an issue... — , Jul 27 '15 at 09:03
@ST3 how does writing `foo( .... )` save time over writing `_asm { ... }`? The answer is important because, depending on what it is, I might have a solution for you that isn't what you asked for exactly but will do the job. — JeremyP, Jul 27 '15 at 09:07
@ST3 look here: https://msdn.microsoft.com/en-us/library/352sth8z.aspx -- the syntax looks a bit silly, but from how I read it, you get your `__asm` block all in one line by prefixing each single instruction with `__asm` — , Jul 27 '15 at 09:08
You may be able to use this http://coliru.stacked-crooked.com/a/27875b7bbe4cc6aa — n. m. could be an AI, Jul 27 '15 at 09:11
@n.m. Good suggestion, it is slightly more typing but works. Thanks! You can add this as an answer. — ST3, Jul 27 '15 at 10:58

score 1 · Answer 1 · answered Aug 05 '15 at 09:20

This may provide a little bit of help , to just give you an idea

    #include "stdio.h"
    #define EXPAND_MULTIPLE_LINES(X, Y, Z) /*
    */ X /*
    */ Y /*
    */ Z

    int main()
    {
        int X, Y, Z;
        EXPAND_MULTIPLE_LINES(X, Y, Z);
        return 0;
    }

use gcc -E -CC testMacro.c

Output like

     # 844 "/usr/include/stdio.h" 3 4

     # 2 "testMacro.c" 2
     # 12 "testMacro.c"
     int main()

     {

          int X, Y, Z;
          /*

          */ X /*
          */ Y /*
          */ Z;
          # 18 "testMacro.c"
          return 0;
     }

C macros with new lines in generated code

1 Answers1