20. Clear Specific Bits in a 32-bit Register

#include <stdio.h>
#include <stdint.h>

#define CREATE_MASK(len) ((1 << len) - 1)

uint32_t clear_bits(uint32_t reg, uint8_t pos, uint8_t len) {
    reg &= ~(CREATE_MASK(len) << pos);
    return reg;
}

int main() {
    uint32_t reg;
    uint8_t pos, len;
    scanf("%u %hhu %hhu", &reg, &pos, &len);
    printf("%u", clear_bits(reg, pos, len));
    return 0;
}