gcc/testsuite/gcc.target/x86_64/abi/test_varargs.c

/* Test variable number of arguments passed to functions. For now this is
   just a simple test to see if it's working.  */

#include <stdarg.h>
#include "defines.h"


#define ARG_INT     1
#define ARG_DOUBLE  2
#define ARG_POINTER 3

union types
{
  int ivalue;
  double dvalue;
  void *pvalue;
};

struct arg
{
  int type;
  union types value;
};

struct arg *arglist;

/* This tests the argumentlist to see if it matches the format string which
   is printf-like. Nothing will be printed of course. It can handle ints,
   doubles and void pointers. The given value will be tested against the
   values given in arglist.  
   This test only assures that the variable argument passing is working.
   No attempt is made to see if argument passing is done the right way.
   Since the ABI doesn't say how it's done, checking this is not really
   relevant.  */
void
my_noprintf (char *format, ...)
{
  va_list va_arglist;
  char *c;

  int ivalue;
  double dvalue;
  void *pvalue;
  struct arg *argp = arglist;

  va_start (va_arglist, format);
  for (c = format; *c; c++)
    if (*c == '%')
      {
	switch (*++c)
	  {
	  case 'd':
	    assert (argp->type == ARG_INT);
	    ivalue = va_arg (va_arglist, int);
	    assert (argp->value.ivalue == ivalue);
	    break;
	  case 'f':
	    assert (argp->type == ARG_DOUBLE);
	    dvalue = va_arg (va_arglist, double);
	    assert (argp->value.dvalue == dvalue);
	    break;
	  case 'p':
	    assert (argp->type == ARG_POINTER);
	    pvalue = va_arg (va_arglist, void *);
	    assert (argp->value.pvalue == pvalue);
	    break;
	  default:
	    abort ();
	  }

	argp++;
      }
}

int
main (void)
{
#ifdef CHECK_VARARGS
  struct arg al[5];

  al[0].type = ARG_INT;
  al[0].value.ivalue = 256;
  al[1].type = ARG_DOUBLE;
  al[1].value.dvalue = 257.0;
  al[2].type = ARG_POINTER;
  al[2].value.pvalue = al;
  al[3].type = ARG_DOUBLE;
  al[3].value.dvalue = 258.0;
  al[4].type = ARG_INT;
  al[4].value.ivalue = 259;

  arglist = al;
  my_noprintf("%d%f%p%f%d", 256, 257.0, al, 258.0, 259);
#endif

  return 0;
}