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// copied from https://github.com/killme2008/xmemcached/tree/90dd456f29/src/main/java/net/rubyeye/xmemcached/transcoders
// Copyright (c) 2006  Dustin Sallings 
package org.eclipse.jetty.redis.session.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';
    }

}