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) {
    //int extract;
    //uint32_t mask = (1U << len) - 1;  
    //extract = (reg >> pos) & mask;
    //extract = val;      
    //return reg;
    uint32_t mask = (1U << len) - 1;  // Create mask for length
    reg = (reg & ~(mask << pos)) | ((val & mask) << pos);
    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;
}

Solving Approach