11. Extract a Bit Field from a 32-bit Register

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

uint32_t extract_field(uint32_t reg, uint8_t pos, uint8_t len) {
    // Move the desired bits to the rightmost side
    // Then apply a mask to get only those bits
    return (reg >> pos) & ((1U << len) - 1);
}

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

We shift the register so the target bits are at the rightmost position,
Then, a mask is applied to extract just those bits.