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// Copyright (c) 2006 Dustin Sallings 

package net.rubyeye.xmemcached.transcoders;

/**
 * Utility class for transcoding Java types.
 */
public final class TranscoderUtils {

  private boolean packZeros;

  /**
   * Get an instance of TranscoderUtils.
   * 
   * @param pack if true, remove all zero bytes from the MSB of the packed num
   */
  public TranscoderUtils(boolean pack) {
    super();
    this.packZeros = pack;
  }

  public final boolean isPackZeros() {
    return this.packZeros;
  }

  public final void setPackZeros(boolean packZeros) {
    this.packZeros = packZeros;
  }

  public final byte[] encodeNum(long l, int maxBytes) {
    byte[] rv = new byte[maxBytes];
    for (int i = 0; i < rv.length; i++) {
      int pos = rv.length - i - 1;
      rv[pos] = (byte) ((l >> (8 * i)) & 0xff);
    }
    if (this.packZeros) {
      int firstNon0 = 0;
      for (; firstNon0 < rv.length && rv[firstNon0] == 0; firstNon0++) {
        // Just looking for what we can reduce
      }
      if (firstNon0 > 0) {
        byte[] tmp = new byte[rv.length - firstNon0];
        System.arraycopy(rv, firstNon0, tmp, 0, rv.length - firstNon0);
        rv = tmp;
      }
    }
    return rv;
  }

  public final byte[] encodeLong(long l) {
    return encodeNum(l, 8);
  }

  public final long decodeLong(byte[] b) {
    assert b.length <= 8 : "Too long to be an long (" + b.length + ") bytes";
    long rv = 0;
    for (byte i : b) {
      rv = (rv << 8) | (i < 0 ? 256 + i : i);
    }
    return rv;
  }

  public final byte[] encodeInt(int in) {
    return encodeNum(in, 4);
  }

  public final int decodeInt(byte[] in) {
    assert in.length <= 4 : "Too long to be an int (" + in.length + ") bytes";
    return (int) decodeLong(in);
  }

  public final byte[] encodeByte(byte in) {
    return new byte[] {in};
  }

  public final byte decodeByte(byte[] in) {
    assert in.length <= 1 : "Too long for a byte";
    byte rv = 0;
    if (in.length == 1) {
      rv = in[0];
    }
    return rv;
  }

  public final byte[] encodeBoolean(boolean b) {
    byte[] rv = new byte[1];
    rv[0] = (byte) (b ? '1' : '0');
    return rv;
  }

  public final boolean decodeBoolean(byte[] in) {
    assert in.length == 1 : "Wrong length for a boolean";
    return in[0] == '1';
  }

}