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Bushido service library
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/**
 * Copyright 2011 bccapi.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.bccapi.bitlib.util;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Utilities for converting between byte arrays and unsigned integer values.
 */
public class BitUtils {

   public static long uint16ToLong(byte[] buf, int offset) {
      return ((buf[offset++] & 0xFFL) << 0) | ((buf[offset++] & 0xFFL) << 8);
   }

   public static long uint32ToLong(byte[] buf, int offset) {
      return ((buf[offset++] & 0xFFL) << 0) | ((buf[offset++] & 0xFFL) << 8) | ((buf[offset++] & 0xFFL) << 16)
            | ((buf[offset] & 0xFFL) << 24);
   }

   public static long uint64ToLong(byte[] buf, int offset) {
      return ((buf[offset++] & 0xFFL) << 0) | ((buf[offset++] & 0xFFL) << 8) | ((buf[offset++] & 0xFFL) << 16)
            | ((buf[offset++] & 0xFFL) << 24) | ((buf[offset++] & 0xFFL) << 32) | ((buf[offset++] & 0xFFL) << 40)
            | ((buf[offset++] & 0xFFL) << 48) | ((buf[offset++] & 0xFFL) << 56);
   }

   public static int uint16FromStream(DataInputStream stream) throws IOException {
      return (int) (((stream.read() & 0xFFL) << 0) | ((stream.read() & 0xFFL) << 8));
   }

   public static int uint16FromStreamBE(DataInputStream stream) throws IOException {
      return (int) (((stream.read() & 0xFFL) << 8) | ((stream.read() & 0xFFL) << 0));
   }

   public static int uint32FromStream(DataInputStream stream) throws IOException {
      return (int) (((stream.read() & 0xFFL) << 0) | ((stream.read() & 0xFFL) << 8) | ((stream.read() & 0xFFL) << 16) | ((stream
            .read() & 0xFFL) << 24));
   }

   public static long uint64FromStream(DataInputStream stream) throws IOException {
      return ((stream.read() & 0xFFL) << 0) | ((stream.read() & 0xFFL) << 8) | ((stream.read() & 0xFFL) << 16)
            | ((stream.read() & 0xFFL) << 24) | ((stream.read() & 0xFFL) << 32) | ((stream.read() & 0xFFL) << 40)
            | ((stream.read() & 0xFFL) << 48) | ((stream.read() & 0xFFL) << 56);
   }

   public static void uint32ToStream(long value, OutputStream stream) throws IOException {
      stream.write((byte) (0xFFL & (value >> 0)));
      stream.write((byte) (0xFFL & (value >> 8)));
      stream.write((byte) (0xFFL & (value >> 16)));
      stream.write((byte) (0xFFL & (value >> 24)));
   }

   public static void uint64ToStream(long value, OutputStream stream) throws IOException {
      stream.write((byte) (0xFFL & (value >> 0)));
      stream.write((byte) (0xFFL & (value >> 8)));
      stream.write((byte) (0xFFL & (value >> 16)));
      stream.write((byte) (0xFFL & (value >> 24)));
      stream.write((byte) (0xFFL & (value >> 32)));
      stream.write((byte) (0xFFL & (value >> 40)));
      stream.write((byte) (0xFFL & (value >> 48)));
      stream.write((byte) (0xFFL & (value >> 56)));
   }

   public static void uint32ToByteArrayLE(long value, byte[] output, int offset) {
      output[offset + 0] = (byte) (0xFFL & (value >> 0));
      output[offset + 1] = (byte) (0xFFL & (value >> 8));
      output[offset + 2] = (byte) (0xFFL & (value >> 16));
      output[offset + 3] = (byte) (0xFFL & (value >> 24));
   }

   public static void uint64ToByteArrayLE(long value, byte[] output, int offset) {
      output[offset + 0] = (byte) (0xFFL & (value >> 0));
      output[offset + 1] = (byte) (0xFFL & (value >> 8));
      output[offset + 2] = (byte) (0xFFL & (value >> 16));
      output[offset + 3] = (byte) (0xFFL & (value >> 24));
      output[offset + 4] = (byte) (0xFFL & (value >> 32));
      output[offset + 5] = (byte) (0xFFL & (value >> 40));
      output[offset + 6] = (byte) (0xFFL & (value >> 48));
      output[offset + 7] = (byte) (0xFFL & (value >> 56));
   }

   public static boolean areEqual(byte[] a, byte[] b) {
      if (a == null && b == null) {
         return true;
      }
      if (a == null || b == null) {
         return false;
      }
      if (a.length != b.length) {
         return false;
      }
      for (int i = 0; i < a.length; i++) {
         if (a[i] != b[i]) {
            return false;
         }
      }
      return true;
   }

   public static byte[] copyByteArray(byte[] source) {
      byte[] buf = new byte[source.length];
      System.arraycopy(source, 0, buf, 0, buf.length);
      return buf;
   }

   /**
    * Returns a copy of the given byte array in reverse order.
    *
    * @param bytes input bytes
    * @return reversed bytes
    */
   public static byte[] reverseBytes(byte[] bytes) {
      byte[] buf = new byte[bytes.length];
      for (int i = 0; i < bytes.length; i++)
         buf[i] = bytes[bytes.length - 1 - i];
      return buf;
   }

   /**
    * Read a number of bytes or throw.
    * 
    * @param size The number of bytes read
    * @return The array of bytes read.
    * @throws java.io.IOException if first byte cannot be read for some reason
    */
   public static byte[] readBytes(DataInputStream stream, int size) throws IOException {
      byte[] buf = new byte[size];
      int toRead = size;
      int done = 0;
      while (toRead > 0) {
         int read = stream.read(buf, done, toRead);
         if (read == -1) {
            throw new IOException();
         }
         done += read;
         toRead -= read;
      }
      return buf;
   }

}