session-android/libsession/src/main/java/org/session/libsession/utilities/Conversions.java

/**
 * Copyright (C) 2014 Open Whisper Systems
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.session.libsession.utilities;

public class Conversions {

  public static byte intsToByteHighAndLow(int highValue, int lowValue) {
    return (byte)((highValue << 4 | lowValue) & 0xFF);
  }

  public static int highBitsToInt(byte value) {
    return (value & 0xFF) >> 4;
  }

  public static int lowBitsToInt(byte value) {
    return (value & 0xF);
  }

  public static int highBitsToMedium(int value) {
    return (value >> 12);
  }

  public static int lowBitsToMedium(int value) {
    return (value & 0xFFF);
  }

  public static byte[] shortToByteArray(int value) {
    byte[] bytes = new byte[2];
    shortToByteArray(bytes, 0, value);
    return bytes;
  }

  public static int shortToByteArray(byte[] bytes, int offset, int value) {
    bytes[offset+1] = (byte)value;
    bytes[offset]   = (byte)(value >> 8);
    return 2;
  }

  public static int shortToLittleEndianByteArray(byte[] bytes, int offset, int value) {
    bytes[offset]   = (byte)value;
    bytes[offset+1] = (byte)(value >> 8);
    return 2;
  }

  public static byte[] mediumToByteArray(int value) {
    byte[] bytes = new byte[3];
    mediumToByteArray(bytes, 0, value);
    return bytes;
  }

  public static int mediumToByteArray(byte[] bytes, int offset, int value) {
    bytes[offset + 2] = (byte)value;
    bytes[offset + 1] = (byte)(value >> 8);
    bytes[offset]     = (byte)(value >> 16);
    return 3;
  }

  public static byte[] intToByteArray(int value) {
    byte[] bytes = new byte[4];
    intToByteArray(bytes, 0, value);
    return bytes;
  }

  public static int intToByteArray(byte[] bytes, int offset, int value) {
    bytes[offset + 3] = (byte)value;
    bytes[offset + 2] = (byte)(value >> 8);
    bytes[offset + 1] = (byte)(value >> 16);
    bytes[offset]     = (byte)(value >> 24);
    return 4;
  }

  public static int intToLittleEndianByteArray(byte[] bytes, int offset, int value) {
    bytes[offset]   = (byte)value;
    bytes[offset+1] = (byte)(value >> 8);
    bytes[offset+2] = (byte)(value >> 16);
    bytes[offset+3] = (byte)(value >> 24);
    return 4;
  }

  public static byte[] longToByteArray(long l) {
    byte[] bytes = new byte[8];
    longToByteArray(bytes, 0, l);
    return bytes;
  }

  public static int longToByteArray(byte[] bytes, int offset, long value) {
    bytes[offset + 7] = (byte)value;
    bytes[offset + 6] = (byte)(value >> 8);
    bytes[offset + 5] = (byte)(value >> 16);
    bytes[offset + 4] = (byte)(value >> 24);
    bytes[offset + 3] = (byte)(value >> 32);
    bytes[offset + 2] = (byte)(value >> 40);
    bytes[offset + 1] = (byte)(value >> 48);
    bytes[offset]     = (byte)(value >> 56);
    return 8;
  }

  public static int longTo4ByteArray(byte[] bytes, int offset, long value) {
    bytes[offset + 3] = (byte)value;
    bytes[offset + 2] = (byte)(value >> 8);
    bytes[offset + 1] = (byte)(value >> 16);
    bytes[offset + 0] = (byte)(value >> 24);
    return 4;
  }

  public static int byteArrayToShort(byte[] bytes) {
    return byteArrayToShort(bytes, 0);
  }

  public static int byteArrayToShort(byte[] bytes, int offset) {
    return
      (bytes[offset] & 0xff) << 8 | (bytes[offset + 1] & 0xff);
  }

  // The SSL patented 3-byte Value.
  public static int byteArrayToMedium(byte[] bytes, int offset) {
    return
      (bytes[offset]     & 0xff) << 16 |
      (bytes[offset + 1] & 0xff) << 8  |
      (bytes[offset + 2] & 0xff);
  }

  public static int byteArrayToInt(byte[] bytes) {
    return byteArrayToInt(bytes, 0);
  }

  public static int byteArrayToInt(byte[] bytes, int offset)  {
    return
      (bytes[offset]     & 0xff) << 24 |
      (bytes[offset + 1] & 0xff) << 16 |
      (bytes[offset + 2] & 0xff) << 8  |
      (bytes[offset + 3] & 0xff);
  }

  public static int byteArrayToIntLittleEndian(byte[] bytes, int offset) {
    return
      (bytes[offset + 3] & 0xff) << 24 |
      (bytes[offset + 2] & 0xff) << 16 |
      (bytes[offset + 1] & 0xff) << 8  |
      (bytes[offset]     & 0xff);
  }

  public static long byteArrayToLong(byte[] bytes) {
    return byteArrayToLong(bytes, 0);
  }

  public static long byteArray4ToLong(byte[] bytes, int offset) {
    return
        ((bytes[offset + 0] & 0xffL) << 24) |
        ((bytes[offset + 1] & 0xffL) << 16) |
        ((bytes[offset + 2] & 0xffL) << 8)  |
        ((bytes[offset + 3] & 0xffL));
  }

  public static long byteArrayToLong(byte[] bytes, int offset) {
    return
      ((bytes[offset]     & 0xffL) << 56) |
      ((bytes[offset + 1] & 0xffL) << 48) |
      ((bytes[offset + 2] & 0xffL) << 40) |
      ((bytes[offset + 3] & 0xffL) << 32) |
      ((bytes[offset + 4] & 0xffL) << 24) |
      ((bytes[offset + 5] & 0xffL) << 16) |
      ((bytes[offset + 6] & 0xffL) << 8)  |
      ((bytes[offset + 7] & 0xffL));
  }
}