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

static void hexdump(const void * memory, size_t bytes);

int main(void) {
    unsigned char ascii[256];
    int i;

    for (i = 0; i < sizeof ascii; ++i)
      ascii[i] = i;
    hexdump(ascii, sizeof ascii);
    return 0;
  }

static void hexdump(const void * memory, size_t bytes) {
    const unsigned char * p, * q;
    int i;

    p = memory;
    while (bytes) {
        q = p;
        printf("%p: ", (void *) p);
        for (i = 0; i < 16 && bytes; ++i) {
            printf("%02X ", *p);
            ++p;
            --bytes;
          }
        bytes += i;
        while (i < 16) {
            printf("XX ");
            ++i;
          }
        printf("| ");
        p = q;
        for (i = 0; i < 16 && bytes; ++i) {
            printf("%c", isprint(*p) && !isspace(*p) ? *p : ' ');
            ++p;
            --bytes;
          }
        while (i < 16) {
            printf(" ");
            ++i;
          }
        printf(" |\n");
      }
    return;
  }