Set Specific Bits in a 32-bit Register

#include <stdio.h>
#include <stdint.h>

uint32_t set_bits(uint32_t reg, uint8_t pos, uint8_t len) {
    // Your code here
    if(len == 0 || pos >= 32){
        return reg;
    }
    
    if ((uint16_t)pos + (uint16_t)len > 32) {

        len = 32 - pos;
    }

    
uint32_t mask;
    if (len == 32) {
        mask = 0xFFFFFFFFu;               // (theoretically unreachable after capping)
    } else {
        mask = ((1u << len) - 1u) << pos; // safe because len ∈ [1, 32 - pos]
    }

    return reg | mask;
}

int main() {
    uint32_t reg;
    uint8_t pos, len;
    scanf("%u %hhu %hhu", &reg, &pos, &len);
    printf("%u", set_bits(reg, pos, len));
    return 0;
}