21. Replace Bit Field in a 32-bit Register

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

uint32_t replace_field(uint32_t reg, uint32_t val, uint8_t pos, uint8_t len) {
    // Your code here
    uint32_t reg2 = 0, reg3 = 0, reg4 = 0;
    if((pos >= 0 && pos <= 31) && (len >= 0 && len <= 31)){
        for(uint8_t i = 0; i < len; i++){
            reg2 |= (1 <<i);
        }
        reg2 <<= pos;
        reg &= ~(reg2);
       reg3 =(val << pos);
       reg |= reg3;
    }
    return reg;
}

int main() {
    uint32_t reg, val;
    uint8_t pos, len;
    scanf("%u %u %hhu %hhu", &reg, &val, &pos, &len);
    printf("%u", replace_field(reg, val, pos, len));
    return 0;
}