Replace Bit Field in a 32-bit Register

Code

#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
    // step  1: Mask:
    uint32_t mask = ((1u << len) - 1u) << pos;

    // Limit the value to fit into the bit field
    val &= (1u << len) - 1u;

    // step 2: clear targetted bits in the original:
    return (reg & ~mask) | (val << pos);

}

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;
}

Solving Approach