/* longjmp example */
#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>
#include <time.h>

#define RETURN_NOTHING return;
#define ABS_ZERO (1-1)
#define BOOLEAN int

#define MAX_LOOPS 15000

struct salesinfo {
       int count;
       int values[MAX_LOOPS+1];
};

int subtotal;

void addvaluetosubtotal(int in_value) {
     subtotal += in_value;
}

/* this subroutine is called thousands of times.
use longjmp instead of loops to increase speed.
Daren 12/03/05 */

void
calculate(struct salesinfo*sales){
        jmp_buf buffer;
        int i=setjmp(buffer);

        if (!(i<sales->count))
                RETURN_NOTHING;

        addvaluetosubtotal(sales->values[i]);

        if (i<sales->count){
                longjmp(buffer,i+1);
        }
}

main()
{
  
  int t, m;
  struct salesinfo s; 
  jmp_buf my_buffer, my_buffer2;

  time_t timer;

  t = setjmp(my_buffer2);
      
  if (t < MAX_LOOPS) {
    s.values[t] = t;
    s.count = t+1;
        
    longjmp(my_buffer2,t+1);        
  }    

  timer=time(NULL);
  printf("Start:%s\n",asctime(localtime(&timer)));  
  
  m = setjmp(my_buffer);
  
  if (m < 5000) {  /* function comment says calculate is called
                      "thousands of times" 5000 should be enough! */
      
      subtotal = 0;
      calculate(&s);
        
      longjmp(my_buffer,m+1);    
        
  }
  
  timer=time(NULL);  
  printf("  End:%s\n\n",asctime(localtime(&timer)));
  
  printf("Press Enter to Continue");
  getch();
  
  return 0;
}