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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

typedef  unsigned char  uchar;

uchar get_bit(uchar byte, int bit_idx) {
    uchar bit = byte << bit_idx;
    return bit >> 7;
}

uchar set_bit(uchar byte, int bit_idx, uchar new_bit) {
    if(new_bit == 1) {
        return byte | 1 << (7 - bit_idx);
    }
    else {
        return byte & ~(1 << (7 - bit_idx));
    }
}

uchar set_bit(uchar byte, int bit_idx, uchar new_bit) {
    assert(new_bit == 0 || new_bit == 1);
    return (new_bit == 1 ? byte | 1 << (7 - bit_idx) : byte & ~(1 << (7 - bit_idx)));
}

int main(int argc, char* argv[]) {
    uchar byte = 0x2f;  // 00101111
                        //     △
                        // idx=4
    int idx = 4;
    //int bit = (byte << idx) >> 7;
    // internally
    uchar bit = (byte << idx);  // 00000…01011100000
    bit = bit >> 7;
    printf("bit == %d\n", bit);

    printf("set_bit(0x00101111, 3, 1) == 0x%02x\n", set_bit(0x2f, 3, 1));
    assert(set_bit(0x2f, 3, 1) == 0x3f);

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

© Copyright 2024 Alexander J. Quinn         This content is protected and may not be shared, uploaded, or distributed.