1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    unsigned char reg_return_value;
    unsigned char mask = (1 << pos);
    switch (mode) {
        case 0:
            reg_return_value = reg & ~mask;
            return reg_return_value;
        case 1:
            reg_return_value = reg | mask;
            return reg_return_value;
        default:
            return reg;
    }
}

int main() {
    unsigned char reg;
    int pos, mode;
    scanf("%hhu %d %d", &reg, &pos, &mode);
    printf("%d", modifyBit(reg, pos, mode));
    return 0;
}