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) {
    uint32_t res;
    for(uint8_t i = pos ; i<(pos+len) ;i++)
    {
        res |= 1<<i; 
    }
    return ((reg&res)>>pos);

    //uint32_t mask = (1U << len) - 1U;
    //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