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

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

void printBinary(int n) 
{
    for (int i = 31; i >= 0; i--) 
	{
        int k = n >> i;
        if (k & 1) printf("1");
        else printf("0");
        if (i % 4 == 0) printf(" ");
    }
    printf("\n");
}

uint32_t extract_field(uint32_t reg, uint8_t pos, uint8_t len) 
{
    // Your code here
    int i;
    uint32_t mask = 1;
    mask = ((1U << len) - 1); 
//    printBinary(reg);
//    printBinary(mask);
    return (reg >> pos) & mask;

}

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;
}