Dump itself

own_dump.c

#include <stdio.h>

extern char __executable_start;
extern char __etext;

static void dump(const void* data, size_t size)
{
  char ascii[17];
  size_t i, j;

  ascii[16] = '\0';
  for (i = 0; i < size; ++i) {
    if (i % 16 == 0)
      printf("%p: ", (unsigned char*)data+i);
    printf("%02X ", ((unsigned char*)data)[i]);
    if (((unsigned char*)data)[i] >= ' ' && ((unsigned char*)data)[i] <= '~') {
      ascii[i % 16] = ((unsigned char*)data)[i];
    } else {
      ascii[i % 16] = '.';
    }
    if ((i+1) % 8 == 0 || i+1 == size) {
      printf(" ");
      if ((i+1) % 16 == 0) {
        printf("|  %s \n", ascii);
      } else if (i+1 == size) {
        ascii[(i+1) % 16] = '\0';
        if ((i+1) % 16 <= 8) {
          printf(" ");
        }
        for (j = (i+1) % 16; j < 16; ++j) {
          printf("   ");
        }
        printf("|  %s \n", ascii);
      }
    }
  }
}

void main(void)
{
  void *start = &__executable_start;
  void *end = &__etext;
  dump(start, end - start);
}