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) {
    uint32_t mask = val << pos; // Left Shift the val till the pos
    //Towards right of the given val but make all bits as 1
    for(int  i = 31; i >= pos+len; i--){
        mask |= (1 << i);
    }
    //Towards left of the given val but make all bits as 1
    for(int i = 0; i < pos; i++){
        mask |= (1 << i);
    }
    //And operate the reg and mask
    return reg & mask;

}

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