public static String u4(int v) {
    char[] result = new char[8];
    for (int i = 0; i < 8; i++) {
      result[7 - i] = Character.forDigit(v & 0x0f, 16);
      v >>= 4;
    }

    return new String(result);
  }
Formats an {@code int} as a 4-byte unsigned hex value.

@param v value to format
@return {@code non-null;} formatted form
android/android_framework/dex-maker/src/main/java/com/android/dx/util/Hex.java