Extract a Bit Field from a 32-bit Register

Code

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

uint32_t extract_field(uint32_t reg, uint8_t pos, uint8_t len) {
    // Your code here
    uint32_t temp,mask;
??Method 1 --> return (reg >>pos) & ((1<<len)-1);
    mask = pow(2, len) - 1;
    temp = ((reg>>pos)&mask);
    return temp;
}

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