/*********************************************************
 * From C PROGRAMMING: A MODERN APPROACH, Second Edition *
 * By K. N. King                                         *
 * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
 * All rights reserved.                                  *
 * This program may be freely distributed for class use, *
 * provided that this copyright notice is retained.      *
 *********************************************************/

/* viewmemory.c (Chapter 20, page 521) */
/* Allows the user to view regions of computer memory */

#include <ctype.h>
#include <stdio.h>

typedef unsigned char BYTE;

int main(void)
{
  unsigned int addr;
  int i, n;
  BYTE *ptr;

  printf("Address of main function: %x\n", (unsigned int) main);
  printf("Address of addr variable: %x\n", (unsigned int) &addr);

  printf("\nEnter a (hex) address: ");
  scanf("%x", &addr);
  printf("Enter number of bytes to view: ");
  scanf("%d", &n);

  printf("\n");
  printf(" Address              Bytes              Characters\n");
  printf(" -------  -----------------------------  ----------\n");

  ptr = (BYTE *) addr;
  for (; n > 0; n -= 10) {
    printf("%8X  ", (unsigned int) ptr);
    for (i = 0; i < 10 && i < n; i++)
      printf("%.2X ", *(ptr + i));
    for (; i < 10; i++)
      printf("   ");
    printf(" ");
    for (i = 0;  i < 10 && i < n; i++) {
      BYTE ch = *(ptr + i);
      if (!isprint(ch))
        ch = '.';
      printf("%c", ch);
    }
    printf("\n");
    ptr += 10;
  }

  return 0;
}