19. Extract a Bit Field from a 32-bit Register

#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
    int mask=1;
    for(int i =1;i<=len;i++) {
        mask*=2;
    }
reg = (reg>>pos) & (mask-1); //better one --> return (reg>>pos) & ((1U<<len)-1);
    return reg;
}

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;
}