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