Set Specific Bits in a 32-bit Register

Code

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

uint32_t set_bits(uint32_t reg, uint8_t pos, uint8_t len) {
  uint32_t mask = ((1U << len) - 1);
  mask <<= 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;
}

Solving Approach