print_bits.c

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "stdint.h"


void print_bits(uintmax_t number)
{
    unsigned char* output = calloc (8*sizeof (uintmax_t), 1);
    unsigned char* mov    = output;

    // Test bits found in "number" from LSB to MSB.
    for (uintmax_t nbit = 8 * sizeof (uintmax_t); nbit-- != 0; ++mov) {
        if ((number & ((uintmax_t)1 << nbit)) != 0)
            *mov = '1';
        else
            *mov = '0';
    }
    // print in binary.
    mov = output;
    while (printf ("%c", *mov++), *mov) {
        if ((mov - output) % 32 == 0)
            printf (" | ");
        else if ((mov - output) % 8 == 0) {
            printf (" ");
        }
    }
    printf ("\n");
    // print in hex.
    mov = ((unsigned char*)&number + sizeof(number) - 1);
    do {
        printf ("%4s0x%02x ","", (unsigned int)*mov);
        if ((mov - (unsigned char*)&number) == sizeof(number)/2)
            printf ("| ");
    } while ((mov-- - (unsigned char*)&number) != 0);

    printf("\n");
    free (output);
}