/*
 * Copyright (c) 2026 Roger Seguin <rgrsgn@gmail.com>
 *				(https://frogzie.duckdns.org)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

// $Id: bitfield.c,v 1.2 2026/02/14 20:48:25 RogerSeguin Exp $

/* Display order of a 32-bitfield structure */

/* gcc -o bitfield bitfield.c */

#include <stdio.h>
#include <stdint.h>

typedef struct BitField {
    uint32_t b31: 1;
    uint32_t b30: 1;
    uint32_t b29: 1;
    uint32_t b28: 1;
    uint32_t b27: 1;
    uint32_t b26: 1;
    uint32_t b25: 1;
    uint32_t b24: 1;
    uint32_t b23: 1;
    uint32_t b22: 1;
    uint32_t b21: 1;
    uint32_t b20: 1;
    uint32_t b19: 1;
    uint32_t b18: 1;
    uint32_t b17: 1;
    uint32_t b16: 1;
    uint32_t b15: 1;
    uint32_t b14: 1;
    uint32_t b13: 1;
    uint32_t b12: 1;
    uint32_t b11: 1;
    uint32_t b10: 1;
    uint32_t b9: 1;
    uint32_t b8: 1;
    uint32_t b7: 1;
    uint32_t b6: 1;
    uint32_t b5: 1;
    uint32_t b4: 1;
    uint32_t b3: 1;
    uint32_t b2: 1;
    uint32_t b1: 1;
    uint32_t b0: 1;
} BitField;

typedef union Number32 {
    BitField bit;
    uint32_t val;
} Number32;

void writeln(uint32_t num, uint32_t bit)
{
    printf ("b%u: %10u\n", bit, num);
}

#define BITVAL(n,x) {	\
	n.val = 0;	\
	n.bit.b ## x = 1;	\
	writeln (n.val, x);	\
}

int main()
{
    printf ("sizeof(BitField): %lu bytes\n", sizeof(BitField));
    printf ("sizeof(Number32): %lu bytes\n", sizeof(Number32));

    Number32 n;

    BITVAL(n, 0);
    BITVAL(n, 1);
    BITVAL(n, 2);
    BITVAL(n, 3);
    BITVAL(n, 4);
    BITVAL(n, 5);
    BITVAL(n, 6);
    BITVAL(n, 7);
    BITVAL(n, 8);
    BITVAL(n, 9);
    BITVAL(n, 10);
    BITVAL(n, 11);
    BITVAL(n, 12);
    BITVAL(n, 13);
    BITVAL(n, 14);
    BITVAL(n, 15);
    BITVAL(n, 16);
    BITVAL(n, 17);
    BITVAL(n, 18);
    BITVAL(n, 19);
    BITVAL(n, 20);
    BITVAL(n, 21);
    BITVAL(n, 22);
    BITVAL(n, 23);
    BITVAL(n, 24);
    BITVAL(n, 25);
    BITVAL(n, 26);
    BITVAL(n, 27);
    BITVAL(n, 28);
    BITVAL(n, 29);
    BITVAL(n, 30);
    BITVAL(n, 31);

    for (int i = 0; i < 32; i++)
        printf ("1 << %2d = %10u\n", i, (1 << i));
    return 0;
}