27. Extract Bit Field from 16-bit Register

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

uint16_t clear_range(uint16_t reg, uint8_t start, uint8_t end) {
    uint16_t mask = 0x0000;
    for (uint8_t i = start; i <= end; i++) {
        mask |= (1U << i);
    }
    reg &= ~mask;
    return reg;
}

uint16_t extract_field(uint16_t reg) {
    reg = clear_range(reg >>= 4, 5, 31);
    return reg;
}

int main() {
    uint16_t reg;
    scanf("%hx", &reg);
    printf("%u", extract_field(reg));
    return 0;
}