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

/*
 *  Display a byte in binary format (called by debug macro below)
 */
void debug_out(const char* name, uint8_t value)
{
    char out[CHAR_BIT + 1];
    int i = CHAR_BIT;

    out[i--] = '\0';
    for (; i >= 0; --i) {
        int bitnum = CHAR_BIT - i - 1;
        out[i] = (value & (1 << bitnum)) ? '1' : '0';
    }

    printf("%-10s: 0b%s\n", name, out);
}
/*----------------------------------------------------*/

/*
 *  Debug MACRO
 */
#if !defined(NDEBUG)
#define DEBUG_BITS(a) do { debug_out(#a, a); } while(0)
#else
#define DEBUG_BITS(a) do { /**/ } while(0)
#endif
/*----------------------------------------------------*/

/*
 *  flip bit at location BITNUM using bitwise OR, AND
 *  operation
 */
uint8_t flip1(uint8_t bits, int bitnum)
{
    assert(0 <= bitnum && bitnum <= 7);

    uint8_t flipped = bits;
    uint8_t single_bit = (uint8_t)(1 << bitnum);

    DEBUG_BITS(bits);

    if ((flipped & single_bit) != 0) {
        flipped &= ~single_bit;
    }
    else {
        flipped |= single_bit;
    }

    DEBUG_BITS(flipped);
    return flipped;
}
/*----------------------------------------------------*/

/*
 *  flip bit at location BITNUM using bitwise XOR operation
 */
uint8_t flip2(uint8_t bits, int bitnum)
{
    assert(0 <= bitnum && bitnum <= 7);

    uint8_t flipped = bits;
    uint8_t single_bit = (uint8_t)(1 << bitnum);

    DEBUG_BITS(bits);

    /* XOR bitwise operation */
    flipped ^= single_bit;

    DEBUG_BITS(flipped);
    return flipped;
}
/*----------------------------------------------------*/

int main()
{
    for (int value = 0; value <= 255; ++value) {
        for (int bitnum = 0; bitnum < 8; ++bitnum) {
            uint8_t f1, f2;

            printf("value = %d, bitnum = %d\n", value, bitnum);
            printf("=======================\n");
            f1 = flip1((uint8_t) value, bitnum);
            printf("\n");
            f2 = flip2((uint8_t) value, bitnum);
            assert(f1 == f2);
            printf("\n\n");
        }
    }
}
/*----------------------------------------------------*/