protected static short codeUnit(int low, int high) {
    if ((low & 0xff) != low) {
      throw new IllegalArgumentException("low out of range 0..255");
    }

    if ((high & 0xff) != high) {
      throw new IllegalArgumentException("high out of range 0..255");
    }

    return (short) (low | (high << 8));
  }
Helper method to combine two bytes into a code unit.

@param low {@code 0..255;} low byte
@param high {@code 0..255;} high byte
@return combined value
android/android_framework/dex-maker/src/main/java/com/android/dx/dex/code/InsnFormat.java