19. 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
    if (pos + len >= 32) {
        return reg >> pos;
    };
    uint32_t bitmask = (1 << len) - 1;
    bitmask = bitmask << pos;
    return (reg & bitmask) >> pos;
}

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;
}

First check if bits will overflow the 32-bit reg, if so return whatever is from the position, Otherwise, set the bitmask accordingly and do bit shifting to get the exact bits in the window.