/** ******************************************************************************
 * @remark Program that allows a user to set and modify short and long integers  *
 *     and then examine the results in both decimal and binary formats.          *                                                *
 *                                                                               *
 * @author Henry M. Walker                                                       *
 * @file  integer-rep.c                                                          *
 * @date  Januaary 28, 2003; revised Kamiaru 30, 2005                            *
 *                                                                               *
 *********************************************************************************/

#include <stdio.h>

void print_binary(int digits, int number);

int main (void) {
  
  short short_int = 1;
  int   inte = 1;
  int number;
  char option;

  printf ("\n");
  printf ("This program allows experimentation with different sizes of integers\n\n");
  printf ("Initial integer values:           decimal                       binary\n");
  printf ("   Short (16-bit) integer:%13hd                   ", short_int);
  print_binary (16, short_int);
  printf ("\n");
  printf (" Regular (32-bit) integer:%13d   ", inte);
  print_binary (32, inte);
  printf ("\n\n");

  while (1) 
    {
      printf ("Menu Options\n");
      printf ("  I - initialize each number to a value you have entered\n");
      printf ("  A - add 1 to each integer\n");
      printf ("  S - subtract 1 from each number\n");
      printf ("  M - multiple each number by 2\n");
      printf ("  D - divide each number by 2\n");
      printf ("  Q - Quit\n");
      printf ("Enter option:  ");
      scanf(" %c", &option);

      switch (option)
        {
        case 'i':
        case 'I':
          printf ("   Enter value that will be assigned to each integer:  ");
          scanf ("%d", &number);
          short_int = (short) number;
          inte      = number;
          break;
        case 'a':
        case 'A':
          short_int += (short) 1;
          inte      += 1;
          break;
        case 's':
        case 'S':
          short_int -= (short) 1;
          inte      -= 1;
          break;
        case 'm':
        case 'M':
          short_int *= (short) 2;
          inte      *= 2;
          break;
        case 'd':
        case 'D':
          short_int /= (short) 2;
          inte      /= 2;
          break;
        case 'q':
        case 'Q':
          printf ("Program terminated\n");
          return 0;
          break;
        default: printf ("Unrecognized option -- please try again\n");
          continue;
        }
      printf ("Resulting integer values          decimal                       binary\n");
      printf ("   Short (16-bit) integer:%13hd                   ", short_int);
      print_binary (16, short_int);
      printf ("\n");
      printf (" Regular (32-bit) integer:%13d   ", inte);
      print_binary (32, inte);
      printf ("\n\n");

    }

}

void print_binary(int digits, int number) {
  /* this function prints the bit representation of number, 
     assuming that digits gives the number of bits in the original 
     declaration of number.
  
     when called with short ints, 
          digits should be 15 (at least on Intel i7 machines)
     when called with regular ints, 
          digits should be 32
  */

  int a[digits];
  int i;
  int mask = 1;

  for (i = 0; i < digits; i++){
    a[i] = number & mask;
    number = number >> 1;
  }

  for (i = digits-1; i >= 0; i--)
    printf ("%X", a[i]);




}