Extract a Bit Field from a 32-bit Register

Code

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

uint32_t extract_field(uint32_t reg, uint8_t pos, uint8_t len) {
    // We want to create a mask of ones with length len and shifted pos positions to the left
    // 1. Mask of ones
    // Select the next bit for the length and substract one, this way a mask of ones is created
    // mask = ((1<<len) - 1)
    // Shift position
    // reg & mask
    // Compact in a one liner below
    if (len == 0)
    {
        return reg;
    }

    uint32_t result = ((reg & (((1<<len) - 1) << pos)) >> pos);
    return result;
}

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;
}

Solving Approach