Extract a Bit Field from a 32-bit Register

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

uint32_t extract_field(uint32_t reg, uint8_t pos, uint8_t len) {
    // Your code here
    //len = 4 1111 -> 100 -> 2 ^ 4 = 16 -1  3 2 ^ 3 =1000 -> -111

    uint32_t val = ((((1<<len) - 1 )) & (reg>> pos)) ; //1 0000 - 1 =0xf // 1000 111 << 2
    return val;
    
}

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;
}