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 a=0;
    int b=0;
    
    for(int i=pos;i<pos+len;i++){ 
        uint32_t bit = (reg >> i) & 1;   // extract 1 bit
        a |= (bit << b);                 // store it in position b
        b++;
    }
    return a; 
    }

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