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

typedef unsigned char uchar;

uchar get_bit(uchar ch, int bit_idx) {
    return ch >> (7 - bit_idx) & 1;
}

uchar set_bit(uchar ch, int bit_idx, uchar new_value) {
    if(new_value) {                         //                                   bit_idx==2
        // Set bit (to 1)                   //                                      ↓
        return ch | (1 << (7 - bit_idx));   // bitwise-or with a byte like this:  00100000
    }
    else {
        // Unset bit (to 0)                   //                                    bit_idx==2
        assert(new_value == 0);               //                                       ↓
        return ch & (~ (1 << (7 - bit_idx))); // bitwise-and with a byte like this:  11011111
    }
}

int main(int argc, char* argv[]) {
    assert( get_bit(0xcb, 1) == 1 );
    assert( set_bit(0x00, 0, 1) == 0x80 ); // 10000000₂
    assert( set_bit(0xcb, 2, 1) == 0xeb ); // 0xcb == 11001011₂, 0xeb == 11101011₂
    assert( set_bit(0xeb, 2, 0) == 0xcb ); // 0xcb == 11001011₂, 0xeb == 11101011₂
    return EXIT_SUCCESS;
}
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