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) {
    // Your code here
    if(len==0||(pos+len)>32) return 0;
    unsigned int mask = ((1u<<len)-1);
    reg= (reg>>pos)&mask;
    return reg;
    //Input: reg = 0b1011 0110 0111 0000 0000 0000 0000 0000, pos = 28, len = 4 
    //Output: 0b1011
}

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