1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

#define SET_MODE 1
#define CLEAR_MODE 0

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    switch(mode)
    {
        case SET_MODE:
            reg |= (1U << pos);
            break;
        case CLEAR_MODE:
            reg &= ~(1U << pos);
            break;
        default:
            printf("Invalid mode given");
            break;
    }

    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;
}