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 mask = ((1U << len) - 1) << pos;

        // Step 2: Clear those bits in reg
            reg &= ~mask;

                // Step 3: Keep only 'len' bits from val
                    val = val & ((1U << len) - 1);

                        // Step 4: Shift val to correct position
                            val = val << pos;

                                // Step 5: Insert into reg
                                    reg |= val;

                                        
    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;
}