/*      Title:  Test setjmp/longjmp rounding mode save/restsore
         File:  testsetjmp.c
       Author:  David N. Williams
      License:  Public Domain
      Version:  May 27, 2005

   This code is intended to test whether setjmp() and longjmp()
   in a C99 system save and restore the IEEE 754 floating-point
   rounding control mode.  The Single UNIX 3 Specification is
   silent on the issue, and there are indeed systems that
   implement either alternative.

   On our Mac OS X system we build the code this way:

     gcc -o testsetjmp testsetjmp.c

   With Linux we build it this way:

     gcc -lm -o testsetjmp testsetjmp.c 

   Other systems may require linking with different libraries.
*/

#include <stdio.h>
#include <setjmp.h>
#include <fenv.h>

jmp_buf mybuf;

void
change_round ( int round )
{
  fesetround ( round );
  printf ("\nrounding direction changed to %i", fegetround() );
  longjmp ( mybuf, 15 );  /* 15 just to see what happens */
}

int
main (void)
{
  int status;
  
  printf ("\nrounding direction before setjmp is %i", fegetround() );  
  
  status = setjmp (mybuf);

  if ( status !=0 )
  {
    printf ("\nstatus = %i", status);
    printf ( "\nrounding direction after longjmp is %i\n", fegetround() );
    return 1;
  }

  change_round (FE_DOWNWARD);
  return 0;
}