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
    size_t k = 0;
    for (size_t i = pos; i < pos + len; i++) {
        if (val & (1U << k)) {
            reg |= (1U << i);
        } else {
            reg &= ~(1U << i);
        }
        k++;
    }
    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;
}