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
    // uint32_t mask = ((1<<(pos+len))-1)^((1<<pos)-1);
    // if((pos+len)==32)
    // {
    //     mask = (0xFFFFFFFF)^((1<<pos)-1);
    // }
    // reg = (reg&mask)>>pos;
    uint32_t mask = (1U << len) - 1;   // Create a mask with 'length' ones
    return (reg >> pos) & mask;          // Shift down and mask
    // 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;
}