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) {
   uint32_t len_mask = 0;
   for( uint8_t bpos = 0; bpos < len; bpos++)
   {
        len_mask |= (1 << bpos);
   }

   return (((reg >> pos) & len_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;
}