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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include <stdint.h>
#include <stdbool.h>
#include "print_bits.h"

bool get_bit(uint8_t byte, int bit_idx) {
    uint8_t mask = 0x01 << bit_idx; // single bit 1 set
                                    // bit_idx 0s to the right
    uint8_t set_bit = byte & mask; // 0 if bit unset
                                   // mask if bit is set
    return set_bit == mask;
}

uint8_t set_bit(uint8_t byte, int bit_idx, bool new_value) {
    uint8_t mask = 0x01 << bit_idx; // 1 in exactly 1 bit
    // if the bit is at the proper value, no change needed
    // if the bit is the wrong value, XOR will toggle it
    if (get_bit(byte, bit_idx) != new_value) {
        byte ^= mask;
    }

    return byte;
}
uint8_t get_bits(uint8_t byte, int start_bit, int end_bit) {
    uint8_t mask = 0xff;
    // make the proper number of 1s is set
    int num_bits_needed = end_bit - start_bit + 1;
    int total_bits = sizeof(byte) * 8;
    // has proper number of 1s, but wrong position
    mask = mask >> (total_bits - num_bits_needed);
    // get ones into proper position
    mask = mask << start_bit;

    uint8_t gotten_bits = byte & mask;
    gotten_bits >>= start_bit;
    // gotten_bits = gotten_bits >> start_bit
    return gotten_bits;
}
uint8_t set_bits(uint8_t byte, int bit_idx,
                 uint8_t new_bits, int num_bits) {
    return byte;
}

#define log_bool(b) printf("(%s) == %s\n", (#b), b ? "true" : "false")

int main(int argc, char* argv[]) {
    uint8_t bits = 0x5f; // 0b01011111
    print_bits_plain(bits);

    log_bool(get_bit(bits, 0));
    log_bool(get_bit(bits, 1));
    log_bool(get_bit(bits, 2));
    log_bool(get_bit(bits, 3));
    log_bool(get_bit(bits, 4));
    log_bool(get_bit(bits, 5));
    log_bool(get_bit(bits, 6));
    log_bool(get_bit(bits, 7));

    print_bits_plain(bits);
    uint8_t updated_bits = set_bit(bits, 5, true);
    print_bits_plain(updated_bits);

    print_bits_plain(bits);
    updated_bits = set_bit(bits, 2, false);
    print_bits_plain(updated_bits);


    print_bits_plain(bits);
    print_bits_plain(get_bits(bits, 2, 7));


    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */

© Copyright 2022 Alexander J. Quinn         This content is protected and may not be shared, uploaded, or distributed.