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

void jmpfunction(jmp_buf env_buf);

int main(int argc, char **argv)
{
   int val;
   jmp_buf env_buffer;


   int fp = 124;

   __asm__ __volatile__("fninit\n" :::);
   __asm__ __volatile__("fldcw %[a]\n" :: [a]"m"(fp) :);
   __asm__ __volatile__("fnstcw %[a]\n" : [a]"=m"(fp) ::);

   printf("Starting value %#x\n", fp);

   /* save calling environment for longjmp */
   val = setjmp( env_buffer );
   
   if( val != 0 ) 
   {
      __asm__ __volatile__("fnstcw %[a]\n" : [a]"=m"(fp) ::);

      printf("Returned from a longjmp() with value (we want the old one) = %#x\n", fp);

      exit(0);
   }
   
   printf("Jump function call\n");
   jmpfunction( env_buffer );
   
   return(0);
}

void jmpfunction(jmp_buf env_buf)
{
   int fp = 0;

   __asm__ __volatile__("fldcw %[a]\n" :: [a]"m"(fp) :);

   printf("New value (to be rollbacked) %#x\n", fp);

   longjmp(env_buf, 10);
}