Extract a Bit Field from a 32-bit Register

Code

#include <stdio.h>
#include <stdint.h>
#define SET(reg, x) reg |= (1 << x)
uint32_t extract_field(uint32_t reg, uint8_t pos, uint8_t len) {
    // Your code here
    uint32_t mask = 0;
    // Set mask
    for(int i = 0; i < len; i++){
        SET(mask, i);
    }

    return (reg >> pos) & mask;
}

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