BEGIN LICENSE BLOCK *****
Version: EPL 2.0/GPL 2.0/LGPL 2.1
The contents of this file are subject to the Eclipse Public
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.eclipse.org/legal/epl-v20.html
Software distributed under the License is distributed on an "AS
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
Copyright (C) 2002-2004 Jan Arne Petersen 
Copyright (C) 2002-2004 Anders Bengtsson 
Copyright (C) 2003-2004 Thomas E Enebo 
Copyright (C) 2004 Charles O Nutter 
Copyright (C) 2004 Stefan Matthias Aust 
Copyright (C) 2005 Derek Berner 
Copyright (C) 2006 Evan Buswell 
Copyright (C) 2007 Nick Sieger 
Copyright (C) 2009 Joseph LaFata 
Alternatively, the contents of this file may be used under the terms of
either of the GNU General Public License Version 2 or later (the "GPL"),
or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
in which case the provisions of the GPL or the LGPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
and other provisions required by the GPL or the LGPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the EPL, the GPL or the LGPL.
END LICENSE BLOCK /***** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * 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.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2002-2004 Jan Arne Petersen <jpetersen@uni-bonn.de>
 * Copyright (C) 2002-2004 Anders Bengtsson <ndrsbngtssn@yahoo.se>
 * Copyright (C) 2003-2004 Thomas E Enebo <enebo@acm.org>
 * Copyright (C) 2004 Charles O Nutter <headius@headius.com>
 * Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>
 * Copyright (C) 2005 Derek Berner <derek.berner@state.nm.us>
 * Copyright (C) 2006 Evan Buswell <ebuswell@gmail.com>
 * Copyright (C) 2007 Nick Sieger <nicksieger@gmail.com>
 * Copyright (C) 2009 Joseph LaFata <joe@quibb.org>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/

package org.jruby.util;

import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import org.jcodings.specific.ASCIIEncoding;
import org.jcodings.specific.USASCIIEncoding;
import org.jcodings.specific.UTF8Encoding;
import org.jruby.*;
import org.jruby.platform.Platform;
import org.jruby.runtime.Block;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;

import static com.headius.backport9.buffer.Buffers.markBuffer;
import static com.headius.backport9.buffer.Buffers.positionBuffer;
import static org.jruby.util.TypeConverter.toFloat;

public class Pack {
    private static final byte[] sSp10 = "          ".getBytes();
    private static final byte[] sNil10 = "\000\000\000\000\000\000\000\000\000\000".getBytes();
    private static final int IS_STAR = -1;
    private static final ASCIIEncoding ASCII = ASCIIEncoding.INSTANCE;
    private static final USASCIIEncoding USASCII = USASCIIEncoding.INSTANCE;
    private static final UTF8Encoding UTF8 = UTF8Encoding.INSTANCE;
    
Native pack type.
/** Native pack type.
     **/
    private static final String NATIVE_CODES = "sSiIlL";
    private static final String MAPPED_CODES = "sSiIqQ";
    
    private static final char BE = '>' - 1; // 61, only 1 char "free" b/w q and s
    private static final char LE = '<'; // 60
    private static final String ENDIANESS_CODES = new String(new char[] {
            's' + BE, 'S' + BE/*n*/, 'i' + BE, 'I' + BE, 'l' + BE, 'L' + BE/*N*/, 'q' + BE, 'Q' + BE,
            's' + LE, 'S' + LE/*v*/, 'i' + LE, 'I' + LE, 'l' + LE, 'L' + LE/*V*/, 'q' + LE, 'Q' + LE});
    private static final String UNPACK_IGNORE_NULL_CODES = "cC";
    private static final String PACK_IGNORE_NULL_CODES = "cCiIlLnNqQsSvV";
    private static final String PACK_IGNORE_NULL_CODES_WITH_MODIFIERS = "lLsS";
    
Unpack modes
/** Unpack modes
    **/
    private static final int UNPACK_ARRAY = 0;
    private static final int UNPACK_BLOCK = 1;
    private static final int UNPACK_1 = 2;

    private static final String sTooFew = "too few arguments";
    private static final byte[] uu_table;
    private static final byte[] b64_table;
    public static final byte[] sHexDigits;
    public static final int[] b64_xtable = new int[256];
    private static final Converter[] converters = new Converter[256];

    private static long num2quad(IRubyObject arg) {
        if (arg.isNil()) return 0L;
        if (arg instanceof RubyBignum) {
            BigInteger big = ((RubyBignum) arg).getValue();
            return big.longValue();
        }
        return RubyNumeric.num2long(arg);
    }

    private static float obj2flt(Ruby runtime, IRubyObject o) {
        return (float) toFloat(runtime, o).getDoubleValue();
    }

    private static double obj2dbl(Ruby runtime, IRubyObject o) {
        return toFloat(runtime, o).getDoubleValue();
    }

    static {
        uu_table =
            ByteList.plain("`!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_");
        b64_table =
            ByteList.plain("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");
        sHexDigits = ByteList.plain("0123456789abcdef0123456789ABCDEFx");

        // b64_xtable for decoding Base 64
        for (int i = 0; i < 256; i++) {
            b64_xtable[i] = -1;
        }
        for (int i = 0; i < 64; i++) {
            b64_xtable[(int)b64_table[i]] = i;
        }

        // single precision, little-endian
        converters['e'] = new Converter(4) {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return RubyFloat.newFloat(runtime, decodeFloatLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeFloatLittleEndian(result, obj2flt(runtime, o));
            }
        };
        // single precision, big-endian
        converters['g'] = new Converter(4) {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return RubyFloat.newFloat(runtime, decodeFloatBigEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeFloatBigEndian(result, obj2flt(runtime, o));
            }
        };
        // single precision, native
        Converter tmp = new Converter(4) {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return RubyFloat.newFloat(runtime, 
                        Platform.BYTE_ORDER == Platform.BIG_ENDIAN ? 
                        decodeFloatBigEndian(enc) : decodeFloatLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result) {
                if (Platform.BYTE_ORDER == Platform.BIG_ENDIAN) {                
                    encodeFloatBigEndian(result, obj2flt(runtime, o));
                } else {
                    encodeFloatLittleEndian(result, obj2flt(runtime, o));
                }
            }
        };
        converters['F'] = tmp; // single precision, native
        converters['f'] = tmp; // single precision, native

        // double precision, little-endian
        converters['E'] = new Converter(8) {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return RubyFloat.newFloat(runtime, decodeDoubleLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeDoubleLittleEndian(result, obj2dbl(runtime, o));
            }               
        };
        // double precision, big-endian
        converters['G'] = new Converter(8) {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return RubyFloat.newFloat(runtime, decodeDoubleBigEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeDoubleBigEndian(result, obj2dbl(runtime, o));
            }
        };
        // double precision, native
        tmp = new Converter(8) {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                if (Platform.BYTE_ORDER == Platform.BIG_ENDIAN) {
                    return RubyFloat.newFloat(runtime, decodeDoubleBigEndian(enc));
                } else {
                    return RubyFloat.newFloat(runtime, decodeDoubleLittleEndian(enc));
                }
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeDoubleLittleEndian(result, obj2dbl(runtime, o));
            }     
        };
        converters['D'] = tmp; // double precision, native
        converters['d'] = tmp; // double precision, native

        // signed short, little-endian
        tmp = new QuadConverter(2, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeShortUnsignedLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeShortLittleEndian(result, overflowQuad(num2quad(o)));
            }            
        };
        converters['v'] = tmp;
        converters['S' + LE] = tmp;
        // signed short, big-endian
        tmp = new QuadConverter(2, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeShortUnsignedBigEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result) {
                encodeShortBigEndian(result, overflowQuad(num2quad(o)));
            }
        };
        converters['n'] = tmp;
        converters['S' + BE] = tmp;
        // signed short, native
        converters['s'] = new QuadConverter(2, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(Platform.BYTE_ORDER == Platform.BIG_ENDIAN ? 
                        decodeShortBigEndian(enc) : decodeShortLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result) {
                encodeShortByByteOrder(result, overflowQuad(num2quad(o))); // XXX: 0xffff0000 on BE?
            }
        };
        // unsigned short, native
        converters['S'] = new QuadConverter(2, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(Platform.BYTE_ORDER == Platform.BIG_ENDIAN ?
                    decodeShortUnsignedBigEndian(enc) : decodeShortUnsignedLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeShortByByteOrder(result, overflowQuad(num2quad(o)));
            }
        };
        // signed short, little endian
        converters['s' + LE] = new QuadConverter(2, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeShortLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result) {
                encodeShortLittleEndian(result, overflowQuad(num2quad(o))); // XXX: 0xffff0000 on BE?
            }
        };
        // signed short, big endian
        converters['s' + BE] = new QuadConverter(2, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeShortBigEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result) {
                encodeShortBigEndian(result, overflowQuad(num2quad(o))); // XXX: 0xffff0000 on BE?
            }
        };

        // signed char
        converters['c'] = new Converter(1, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                int c = enc.get();
                return runtime.newFixnum(c > (char) 127 ? c-256 : c);
            }

            public void encode(Ruby runtime, IRubyObject o, ByteList result) {
                byte c = (byte) (num2quad(o) & 0xff);
                result.append(c);
            }
        };
        // unsigned char
        converters['C'] = new Converter(1, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(enc.get() & 0xFF);
            }

            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                byte c = o == runtime.getNil() ? 0 : (byte) (num2quad(o) & 0xff);
                result.append(c);
            }
        };

        // unsigned long, little-endian
        tmp = new Converter(4, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeIntUnsignedLittleEndian(enc));
            }
            
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeIntLittleEndian(result, (int) RubyNumeric.num2long(o));
            }
        };
        converters['V'] = tmp;
        converters['L' + LE] = tmp;
        converters['I' + LE] = tmp;
        
        // unsigned long, big-endian
        tmp = new Converter(4, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeIntUnsignedBigEndian(enc));
            }
            
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeIntBigEndian(result, (int) RubyNumeric.num2long(o));
            }
        };
        converters['N'] = tmp;
        converters['L' + BE] = tmp;
        converters['I' + BE] = tmp;

        // unsigned int, native
        tmp = new Converter(4, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                if (Platform.BYTE_ORDER == Platform.BIG_ENDIAN) {
                    return runtime.newFixnum(decodeIntUnsignedBigEndian(enc));
                } else {
                    return runtime.newFixnum(decodeIntUnsignedLittleEndian(enc));
                }
            }
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                int s = o == runtime.getNil() ? 0 : (int) RubyNumeric.num2long(o);
                packInt_i(result, s);
            }
        };
        converters['I'] = tmp; // unsigned int, native
        converters['L'] = tmp; // unsigned long, native

        // int, native
        tmp = new Converter(4, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                int value = unpackInt_i(enc);
                return runtime.newFixnum(value);
            }
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                int s = o == runtime.getNil() ? 0 : (int)RubyNumeric.num2long(o);
                packInt_i(result, s);
            }
        };
        converters['i'] = tmp; // int, native
        converters['l'] = tmp; // long, native
        
        // int, little endian
        tmp = new Converter(4, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeIntLittleEndian(enc));
            }
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                int s = o == runtime.getNil() ? 0 : (int)RubyNumeric.num2long(o);
                encodeIntLittleEndian(result, s);
            }
        };
        converters['i' + LE] = tmp; // int, native
        converters['l' + LE] = tmp; // long, native
        
        // int, big endian
        tmp = new Converter(4, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeIntBigEndian(enc));
            }
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                int s = o == runtime.getNil() ? 0 : (int)RubyNumeric.num2long(o);
                encodeIntBigEndian(result, s);
            }
        };
        converters['i' + BE] = tmp; // int, native
        converters['l' + BE] = tmp; // long, native

        // 64-bit number, native (as bignum)
        converters['Q'] = new QuadConverter(8, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                long l = Platform.BYTE_ORDER == Platform.BIG_ENDIAN ? decodeLongBigEndian(enc) : decodeLongLittleEndian(enc);

                return RubyBignum.bignorm(runtime,BigInteger.valueOf(l).and(new BigInteger("FFFFFFFFFFFFFFFF", 16)));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeLongByByteOrder(result, num2quad(o));
            }
        };
        // 64-bit number, little endian (as bignum)
        converters['Q' + LE] = new QuadConverter(8, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                long l = decodeLongLittleEndian(enc);
                return RubyBignum.bignorm(runtime,BigInteger.valueOf(l).and(new BigInteger("FFFFFFFFFFFFFFFF", 16)));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeLongLittleEndian(result, num2quad(o));
            }
        };
        // 64-bit number, big endian (as bignum)
        converters['Q' + BE] = new QuadConverter(8, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                long l = decodeLongBigEndian(enc);
                return RubyBignum.bignorm(runtime,BigInteger.valueOf(l).and(new BigInteger("FFFFFFFFFFFFFFFF", 16)));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeLongBigEndian(result, num2quad(o));
            }
        };
        // 64-bit number, native (as fixnum)
        converters['q'] = new QuadConverter(8, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(Platform.BYTE_ORDER == Platform.BIG_ENDIAN ? 
                        decodeLongBigEndian(enc) : decodeLongLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeLongByByteOrder(result, num2quad(o));
            }
        };
        // 64-bit number, little-endian (as fixnum)
        converters['q' + LE] = new QuadConverter(8, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeLongLittleEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeLongLittleEndian(result, num2quad(o));
            }
        };
        // 64-bit number, big-endian (as fixnum)
        converters['q' + BE] = new QuadConverter(8, "Integer") {
            public IRubyObject decode(Ruby runtime, ByteBuffer enc) {
                return runtime.newFixnum(decodeLongBigEndian(enc));
            }

            @Override
            public void encode(Ruby runtime, IRubyObject o, ByteList result){
                encodeLongBigEndian(result, num2quad(o));
            }
        };
    }

    public static int unpackInt_i(ByteBuffer enc) {
        int value;
        if (Platform.BYTE_ORDER == Platform.BIG_ENDIAN) {
            value = decodeIntBigEndian(enc);
        } else {
            value = decodeIntLittleEndian(enc);
        }
        return value;
    }

    public static ByteList packInt_i(ByteList result, int s) {
        if (Platform.BYTE_ORDER == Platform.BIG_ENDIAN) {
            encodeIntBigEndian(result, s);
        } else {
            encodeIntLittleEndian(result, s);
        }
        return result;
    }

    public static void encodeUM(Ruby runtime, ByteList lCurElemString, int occurrences, boolean ignoreStar, char type, ByteList result) {
        if (occurrences == 0 && type == 'm' && !ignoreStar) {
            encodes(runtime, result, lCurElemString.getUnsafeBytes(),
                    lCurElemString.getBegin(), lCurElemString.length(),
                    lCurElemString.length(), (byte) type, false);
            return;
        }

        occurrences = occurrences <= 2 ? 45 : occurrences / 3 * 3;
        if (lCurElemString.length() == 0) return;

        byte[] charsToEncode = lCurElemString.getUnsafeBytes();
        for (int i = 0; i < lCurElemString.length(); i += occurrences) {
            encodes(runtime, result, charsToEncode,
                    i + lCurElemString.getBegin(), lCurElemString.length() - i,
                    occurrences, (byte)type, true);
        }
    }

    
encodes a String in base64 or its uuencode variant.
appends the result of the encoding in a StringBuffer
Params:
io2Append – The StringBuffer which should receive the result
charsToEncode – The String to encode
startIndex – 
length – The max number of characters to encode
charCount – 
encodingType – the type of encoding required (this is the same type as used by the pack method)
tailLf – true if the traililng "\n" is needed
Returns:
the io2Append buffer/**
     * encodes a String in base64 or its uuencode variant.
     * appends the result of the encoding in a StringBuffer
     * @param io2Append The StringBuffer which should receive the result
     * @param charsToEncode The String to encode
     * @param startIndex
     * @param length The max number of characters to encode
     * @param charCount
     * @param encodingType the type of encoding required (this is the same type as used by the pack method)
     * @param tailLf true if the traililng "\n" is needed
     * @return the io2Append buffer
     **/
    private static ByteList encodes(Ruby runtime, ByteList io2Append,byte[] charsToEncode, int startIndex, int length, int charCount, byte encodingType, boolean tailLf) {
        charCount = charCount < length ? charCount : length;

        io2Append.ensure(charCount * 4 / 3 + 6);
        int i = startIndex;
        byte[] lTranslationTable = encodingType == 'u' ? uu_table : b64_table;
        byte lPadding;
        if (encodingType == 'u') {
            if (charCount >= lTranslationTable.length) {
                throw runtime.newArgumentError(charCount
                    + " is not a correct value for the number of bytes per line in a u directive.  Correct values range from 0 to "
                    + lTranslationTable.length);
            }
            io2Append.append(lTranslationTable[charCount]);
            lPadding = '`';
        } else {
            lPadding = '=';
        }
        while (charCount >= 3) {
            byte lCurChar = charsToEncode[i++];
            byte lNextChar = charsToEncode[i++];
            byte lNextNextChar = charsToEncode[i++];
            io2Append.append(lTranslationTable[077 & (lCurChar >>> 2)]);
            io2Append.append(lTranslationTable[077 & (((lCurChar << 4) & 060) | ((lNextChar >>> 4) & 017))]);
            io2Append.append(lTranslationTable[077 & (((lNextChar << 2) & 074) | ((lNextNextChar >>> 6) & 03))]);
            io2Append.append(lTranslationTable[077 & lNextNextChar]);
            charCount -= 3;
        }
        if (charCount == 2) {
            byte lCurChar = charsToEncode[i++];
            byte lNextChar = charsToEncode[i++];
            io2Append.append(lTranslationTable[077 & (lCurChar >>> 2)]);
            io2Append.append(lTranslationTable[077 & (((lCurChar << 4) & 060) | ((lNextChar >> 4) & 017))]);
            io2Append.append(lTranslationTable[077 & (((lNextChar << 2) & 074) | (('\0' >> 6) & 03))]);
            io2Append.append(lPadding);
        } else if (charCount == 1) {
            byte lCurChar = charsToEncode[i++];
            io2Append.append(lTranslationTable[077 & (lCurChar >>> 2)]);
            io2Append.append(lTranslationTable[077 & (((lCurChar << 4) & 060) | (('\0' >>> 4) & 017))]);
            io2Append.append(lPadding);
            io2Append.append(lPadding);
        }
        if (tailLf) {
            io2Append.append('\n');
        }
        return io2Append;
    }

    public static RubyArray unpack(Ruby runtime, ByteList encodedString, ByteList formatString) {
        return unpackWithBlock(runtime.getCurrentContext(), runtime, encodedString, formatString, Block.NULL_BLOCK);
    }

    
Params:
context – 
encoded – 
formatString – 
See Also:
unpackWithBlock.unpackWithBlock(ThreadContext, Ruby, ByteList, ByteList, Block)
Returns:
unpacked array/**
     * @see Pack#unpackWithBlock(ThreadContext, Ruby, ByteList, ByteList, Block)
     * @param context
     * @param encoded
     * @param formatString
     * @return unpacked array
     */
    public static RubyArray unpack(ThreadContext context, RubyString encoded, ByteList formatString) {
        return unpackWithBlock(context, encoded, formatString, Block.NULL_BLOCK);
    }

    
   Decodes str (which may contain binary data) according to the format
      string, returning an array of each value extracted.
      The format string consists of a sequence of single-character directives.

      Each directive may be followed by a number, indicating the number of times to repeat with this directive.  An asterisk (``*'') will use up all
      remaining elements.  

      Note that if passed a block, this method will return null and instead yield results to the block.
      The directives sSiIlL may each be followed by an underscore (``_'') to use the underlying platform's native size for the specified type; otherwise, it uses a platform-independent consistent size.  

      Spaces are ignored in the format string.
      

          

            


        Directives for 
                  String#unpack
                
                      


  

                    Format
                  
  

                    Function
                  
  

                    Returns
                  


  
A
  
String with trailing nulls and spaces removed.
  
String


  
a
  
String.
  
String


  
B
  
Extract bits from each character (msb first).
  
String


  
b
  
Extract bits from each character (lsb first).
  
String


  
C
  
Extract a character as an unsigned integer.
  
Fixnum


  
c
  
Extract a character as an integer.
  
Fixnum


  
d
  
Treat sizeof(double) characters as a native
          double.
  
Float


  
E
  
Treat sizeof(double) characters as a double in
          little-endian byte order.
  
Float


  
e
  
Treat sizeof(float) characters as a float in
          little-endian byte order.
  
Float


  
f
  
Treat sizeof(float) characters as a native float.
  
Float


  
G
  
Treat sizeof(double) characters as a double in
          network byte order.
  
Float


  
g
  
Treat sizeof(float) characters as a float in
          network byte order.
  
Float


  
H
  
Extract hex nibbles from each character (most
          significant first).
  
String


  
h
  
Extract hex nibbles from each character (least
          significant first).
  
String


  
I
  
Treat sizeof(int)
                    1 successive
          characters as an unsigned native integer.
  
Integer


  
i
  
Treat sizeof(int)
                    1 successive
          characters as a signed native integer.
  
Integer


  
L
  
Treat four1 successive
          characters as an unsigned native
          long integer.
  
Integer


  
l
  
Treat four1 successive
          characters as a signed native
          long integer.
  
Integer


  
M
  
Extract a quoted-printable string.
  
String


  
m
  
Extract a base64 encoded string.
  
String


  
N
  
Treat four characters as an unsigned long in network
          byte order.
  
Fixnum


  
n
  
Treat two characters as an unsigned short in network
          byte order.
  
Fixnum


  
P
  
Treat sizeof(char *) characters as a pointer, and
          return len characters from the referenced location.
  
String


  
p
  
Treat sizeof(char *) characters as a pointer to a
          null-terminated string.
  
String


  
S
  
Treat two1 successive characters as an unsigned
          short in
          native byte order.
  
Fixnum


  
s
  
Treat two1 successive
          characters as a signed short in
          native byte order.
  
Fixnum


  
U
  
Extract UTF-8 characters as unsigned integers.
  
Integer


  
u
  
Extract a UU-encoded string.
  
String


  
V
  
Treat four characters as an unsigned long in little-endian
          byte order.
  
Fixnum


  
v
  
Treat two characters as an unsigned short in little-endian
          byte order.
  
Fixnum


  
X
  
Skip backward one character.
  
---


  
x
  
Skip forward one character.
  
---


  
Z
  
String with trailing nulls removed.
  
String


  
@
  
Skip to the offset given by the length argument.
  
---


                  

                
              

        1 May be modified by appending ``_'' to the directive.

      
          
        
See Also:
RubyArray.pack/**
     *    Decodes <i>str</i> (which may contain binary data) according to the format
     *       string, returning an array of each value extracted.
     *       The format string consists of a sequence of single-character directives.<br/>
     *       Each directive may be followed by a number, indicating the number of times to repeat with this directive.  An asterisk (``<code>*</code>'') will use up all
     *       remaining elements.  <br/>
     *       Note that if passed a block, this method will return null and instead yield results to the block.
     *       The directives <code>sSiIlL</code> may each be followed by an underscore (``<code>_</code>'') to use the underlying platform's native size for the specified type; otherwise, it uses a platform-independent consistent size.  <br/>
     *       Spaces are ignored in the format string.
     * 
     *       <table border="2" width="500" bgcolor="#ffe0e0">
     *           <tr>
     *             <td>
     * <P></P>
     *         <b>Directives for <a href="ref_c_string.html#String.unpack">
     *                   <code>String#unpack</code>
     *                 </a>
     *               </b>        <table class="codebox" cellspacing="0" border="0" cellpadding="3">
     * <tr bgcolor="#ff9999">
     *   <td valign="top">
     *                     <b>Format</b>
     *                   </td>
     *   <td valign="top">
     *                     <b>Function</b>
     *                   </td>
     *   <td valign="top">
     *                     <b>Returns</b>
     *                   </td>
     * </tr>
     * <tr>
     *   <td valign="top">A</td>
     *   <td valign="top">String with trailing nulls and spaces removed.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">a</td>
     *   <td valign="top">String.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">B</td>
     *   <td valign="top">Extract bits from each character (msb first).</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">b</td>
     *   <td valign="top">Extract bits from each character (lsb first).</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">C</td>
     *   <td valign="top">Extract a character as an unsigned integer.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">c</td>
     *   <td valign="top">Extract a character as an integer.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">d</td>
     *   <td valign="top">Treat <em>sizeof(double)</em> characters as a native
     *           double.</td>
     *   <td valign="top">Float</td>
     * </tr>
     * <tr>
     *   <td valign="top">E</td>
     *   <td valign="top">Treat <em>sizeof(double)</em> characters as a double in
     *           little-endian byte order.</td>
     *   <td valign="top">Float</td>
     * </tr>
     * <tr>
     *   <td valign="top">e</td>
     *   <td valign="top">Treat <em>sizeof(float)</em> characters as a float in
     *           little-endian byte order.</td>
     *   <td valign="top">Float</td>
     * </tr>
     * <tr>
     *   <td valign="top">f</td>
     *   <td valign="top">Treat <em>sizeof(float)</em> characters as a native float.</td>
     *   <td valign="top">Float</td>
     * </tr>
     * <tr>
     *   <td valign="top">G</td>
     *   <td valign="top">Treat <em>sizeof(double)</em> characters as a double in
     *           network byte order.</td>
     *   <td valign="top">Float</td>
     * </tr>
     * <tr>
     *   <td valign="top">g</td>
     *   <td valign="top">Treat <em>sizeof(float)</em> characters as a float in
     *           network byte order.</td>
     *   <td valign="top">Float</td>
     * </tr>
     * <tr>
     *   <td valign="top">H</td>
     *   <td valign="top">Extract hex nibbles from each character (most
     *           significant first).</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">h</td>
     *   <td valign="top">Extract hex nibbles from each character (least
     *           significant first).</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">I</td>
     *   <td valign="top">Treat <em>sizeof(int)</em>
     *                     <sup>1</sup> successive
     *           characters as an unsigned native integer.</td>
     *   <td valign="top">Integer</td>
     * </tr>
     * <tr>
     *   <td valign="top">i</td>
     *   <td valign="top">Treat <em>sizeof(int)</em>
     *                     <sup>1</sup> successive
     *           characters as a signed native integer.</td>
     *   <td valign="top">Integer</td>
     * </tr>
     * <tr>
     *   <td valign="top">L</td>
     *   <td valign="top">Treat four<sup>1</sup> successive
     *           characters as an unsigned native
     *           long integer.</td>
     *   <td valign="top">Integer</td>
     * </tr>
     * <tr>
     *   <td valign="top">l</td>
     *   <td valign="top">Treat four<sup>1</sup> successive
     *           characters as a signed native
     *           long integer.</td>
     *   <td valign="top">Integer</td>
     * </tr>
     * <tr>
     *   <td valign="top">M</td>
     *   <td valign="top">Extract a quoted-printable string.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">m</td>
     *   <td valign="top">Extract a base64 encoded string.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">N</td>
     *   <td valign="top">Treat four characters as an unsigned long in network
     *           byte order.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">n</td>
     *   <td valign="top">Treat two characters as an unsigned short in network
     *           byte order.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">P</td>
     *   <td valign="top">Treat <em>sizeof(char *)</em> characters as a pointer, and
     *           return <em>len</em> characters from the referenced location.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">p</td>
     *   <td valign="top">Treat <em>sizeof(char *)</em> characters as a pointer to a
     *           null-terminated string.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">S</td>
     *   <td valign="top">Treat two<sup>1</sup> successive characters as an unsigned
     *           short in
     *           native byte order.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">s</td>
     *   <td valign="top">Treat two<sup>1</sup> successive
     *           characters as a signed short in
     *           native byte order.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">U</td>
     *   <td valign="top">Extract UTF-8 characters as unsigned integers.</td>
     *   <td valign="top">Integer</td>
     * </tr>
     * <tr>
     *   <td valign="top">u</td>
     *   <td valign="top">Extract a UU-encoded string.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">V</td>
     *   <td valign="top">Treat four characters as an unsigned long in little-endian
     *           byte order.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">v</td>
     *   <td valign="top">Treat two characters as an unsigned short in little-endian
     *           byte order.</td>
     *   <td valign="top">Fixnum</td>
     * </tr>
     * <tr>
     *   <td valign="top">X</td>
     *   <td valign="top">Skip backward one character.</td>
     *   <td valign="top">---</td>
     * </tr>
     * <tr>
     *   <td valign="top">x</td>
     *   <td valign="top">Skip forward one character.</td>
     *   <td valign="top">---</td>
     * </tr>
     * <tr>
     *   <td valign="top">Z</td>
     *   <td valign="top">String with trailing nulls removed.</td>
     *   <td valign="top">String</td>
     * </tr>
     * <tr>
     *   <td valign="top">@</td>
     *   <td valign="top">Skip to the offset given by the length argument.</td>
     *   <td valign="top">---</td>
     * </tr>
     * <tr>
     *                   <td colspan="9" bgcolor="#ff9999" height="2"><img src="dot.gif" width="1" height="1"></td>
     *                 </tr>
     *               </table>
     * <P></P>
     *         <sup>1</sup>&nbsp;May be modified by appending ``_'' to the directive.
     * <P></P>
     *       </td>
     *           </tr>
     *         </table>
     *
     * @see RubyArray#pack
     **/
    public static RubyArray unpackWithBlock(ThreadContext context, RubyString encoded, ByteList formatString, Block block) {
        return (RubyArray) unpackInternal(context, encoded, formatString, block.isGiven() ? UNPACK_BLOCK : UNPACK_ARRAY, block);
    }

    private static RubyString unpackBase46Strict(Ruby runtime, ByteList input) {
        int index = 0; // current index of out
        int s = -1;
        int a = -1;
        int b = -1;
        int c = 0;

        byte[] buf = input.unsafeBytes();
        int begin = input.begin();
        int length = input.realSize();
        int end = begin + length;

        if (length % 4 != 0) throw runtime.newArgumentError("invalid base64");

        int p = begin;
        byte[] out = new byte[3 * ((length + 3) / 4)];

        while (p < end && s != '=') {
            // obtain a
            s = buf[p++];
            a = b64_xtable[s];
            if (a == -1) throw runtime.newArgumentError("invalid base64");

            // obtain b
            s = buf[p++];
            b = b64_xtable[s];
            if (b == -1) throw runtime.newArgumentError("invalid base64");

            // obtain c
            s = buf[p++];
            c = b64_xtable[s];
            if (s == '=') {
                if (buf[p++] != '=') throw runtime.newArgumentError("invalid base64");
                break;
            }
            if (c == -1) throw runtime.newArgumentError("invalid base64");

            // obtain d
            s = buf[p++];
            int d = b64_xtable[s];
            if (s == '=') break;
            if (d == -1) throw runtime.newArgumentError("invalid base64");

            // calculate based on a, b, c and d
            out[index++] = (byte) (a << 2 | b >> 4);
            out[index++] = (byte) (b << 4 | c >> 2);
            out[index++] = (byte) (c << 6 | d);
        }

        if (p < end) throw runtime.newArgumentError("invalid base64");

        if (a != -1 && b != -1) {
            if (c == -1 && s == '=') {
                if ((b & 15) > 0) throw runtime.newArgumentError("invalid base64");
                out[index++] = (byte)((a << 2 | b >> 4) & 255);
            } else if(c != -1 && s == '=') {
                if ((c & 3) > 0) throw runtime.newArgumentError("invalid base64");
                out[index++] = (byte)((a << 2 | b >> 4) & 255);
                out[index++] = (byte)((b << 4 | c >> 2) & 255);
            }
        }
        return runtime.newString(new ByteList(out, 0, index));
    }

    public static IRubyObject unpack1WithBlock(ThreadContext context, RubyString encoded, ByteList formatString, Block block) {
        int formatLength = formatString.realSize();

        // Strict m0 is commmonly used in cookie handling so it has a fast path.
        if (formatLength >= 1) {
            byte first = (byte) (formatString.get(0) & 0xff);

            if (first == 'm') {
                if (formatLength == 2) {
                    byte second = (byte) (formatString.get(1) & 0xff);

                    if (second == '0') return unpackBase46Strict(context.runtime, encoded.getByteList());
                }
            }
        }

        return unpackInternal(context, encoded, formatString, UNPACK_1, block);
    }

    private static IRubyObject unpackInternal(ThreadContext context, RubyString encoded, ByteList formatString, int mode, Block block) {
        final Ruby runtime = context.runtime;
        final RubyArray result = (mode == UNPACK_BLOCK) || (mode == UNPACK_1) ? null : runtime.newArray();
        final ByteList encodedString = encoded.getByteList();
        final boolean tainted = encoded.isTaint();
        // FIXME: potentially could just use ByteList here?
        ByteBuffer format = ByteBuffer.wrap(formatString.getUnsafeBytes(), formatString.begin(), formatString.length());
        ByteBuffer encode = ByteBuffer.wrap(encodedString.getUnsafeBytes(), encodedString.begin(), encodedString.length());
        int next = safeGet(format);
        IRubyObject value = null; // UNPACK_1

        mainLoop: while (next != 0) {
            int type = next;
            next = safeGet(format);
            if (UNPACK_IGNORE_NULL_CODES.indexOf(type) != -1 && next == 0) {
                next = safeGetIgnoreNull(format);
            }
            
            if (type == '#') {
                while (type != '\n') {
                    if (next == 0) break mainLoop;
                    type = next;
                    next = safeGet(format);
                }
            }

            // Next indicates to decode using native encoding format
            if (next == '_' || next == '!') {
                int index = NATIVE_CODES.indexOf(type);
                if (index == -1) {
                    throw runtime.newArgumentError("'" + next + "' allowed only after types " + NATIVE_CODES);
                }
                type = MAPPED_CODES.charAt(index);
                
                next = safeGet(format);
            }
            
            if (next == '>' || next == '<') {
                next = next == '>' ? BE : LE;
                int index = ENDIANESS_CODES.indexOf(type + next);
                if (index == -1) {
                    throw runtime.newArgumentError("'" + (char)next + "' allowed only after types sSiIlLqQ");
                }
                type = ENDIANESS_CODES.charAt(index);
                next = safeGet(format);
                
                if (next == '_' || next == '!') next = safeGet(format);
            }

            // How many occurrences of 'type' we want
            int occurrences;
            if (next == 0) {
                occurrences = 1;
            } else {
                if (next == '*') {
                    occurrences = IS_STAR;
                    next = safeGet(format);
                } else if (ASCII.isDigit(next)) {
                    occurrences = 0;
                    do {
                        occurrences = occurrences * 10 + Character.digit((char)(next & 0xFF), 10);
                        next = safeGet(format);
                    } while (next != 0 && ASCII.isDigit(next));
                } else {
                    occurrences = type == '@' ? 0 : 1;
                }
            }

            // See if we have a converter for the job...
            Converter converter = converters[type];
            if (converter != null) {
                value = decode(context, runtime, encode, occurrences, result, block, converter, mode);
                if (mode == UNPACK_1 && value != null) {
                    return value;
                } else {
                    continue;
                }
            }

            // Otherwise the unpack should be here...
            switch (type) {
                case '@':
                    unpack_at(runtime, encodedString, encode, occurrences);
                    break;
                case '%':
                    throw runtime.newArgumentError("% is not supported");
                case 'A':
                    value = unpack_A(context, block, result, tainted, encode, occurrences, mode);
                    break;
                case 'Z':
                    value = unpack_Z(context, block, result, tainted, encode, occurrences, mode);
                    break;
                case 'a':
                    value = unpack_a(context, block, result, tainted, encode, occurrences, mode);
                    break;
                case 'b':
                    value = unpack_b(context, block, result, tainted, encode, occurrences, mode);
                    break;
                case 'B':
                    value = unpack_B(context, block, result, tainted, encode, occurrences, mode);
                    break;
                case 'h':
                    value = unpack_h(context, block, result, tainted, encode, occurrences, mode);
                    break;
                case 'H':
                    value = unpack_H(context, block, result, tainted, encode, occurrences, mode);
                    break;
                case 'u':
                    value = unpack_u(context, block, result, tainted, encode, mode);
                    break;
                case 'm':
                    value = unpack_m(context, block, runtime, result, tainted, encode, occurrences, mode);
                    break;
                case 'M':
                    value = unpack_M(context, block, result, tainted, encode, mode);
                    break;
                case 'U':
                    value = unpack_U(context, block, runtime, result, encode, occurrences, mode);
                    break;
                case 'X':
                    unpack_X(runtime, encode, occurrences);
                    break;
                case 'x':
                    unpack_x(runtime, encode, occurrences);
                    break;
                case 'w':
                    value = unpack_w(context, block, runtime, result, encode, occurrences, mode);
                    break;
            }
            if (mode == UNPACK_1 && value != null) {
                return value;
            }
        }
        return result;
    }

    private static IRubyObject unpack_w(ThreadContext context, Block block, Ruby runtime, RubyArray result, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining()) {
            occurrences = encode.remaining();
        }

        long ul = 0;
        long ulmask = (0xfeL << 56) & 0xffffffff;
        RubyBignum big128 = RubyBignum.newBignum(runtime, 128);
        int pos = encode.position();

        while (occurrences > 0 && pos < encode.limit()) {
            ul <<= 7;
            ul |= encode.get(pos) & 0x7f;
            if((encode.get(pos++) & 0x80) == 0) {
                IRubyObject value = RubyFixnum.newFixnum(runtime, ul);
                if (mode == UNPACK_1) {
                    return value;
                }
                appendOrYield(context, block, result, value, mode);
                occurrences--;
                ul = 0;
            } else if((ul & ulmask) == 0) {
                RubyBignum big = RubyBignum.newBignum(runtime, ul);
                while(occurrences > 0 && pos < encode.limit()) {
                    IRubyObject mulResult = big.op_mul(runtime.getCurrentContext(), big128);
                    IRubyObject v = mulResult.callMethod(runtime.getCurrentContext(), "+",
                            RubyBignum.newBignum(runtime, encode.get(pos) & 0x7f));
                    if(v instanceof RubyFixnum) {
                        big = RubyBignum.newBignum(runtime, RubyNumeric.fix2long(v));
                    } else if (v instanceof RubyBignum) {
                        big = (RubyBignum)v;
                    }
                    if((encode.get(pos++) & 0x80) == 0) {
                        IRubyObject value = RubyBignum.bignorm(runtime, big.getValue());
                        if (mode == UNPACK_1) {
                            return value;
                        }
                        appendOrYield(context, block, result, value, mode);
                        occurrences--;
                        ul = 0;
                        break;
                    }
                }
            }
        }
        try {
            positionBuffer(encode, pos);
        } catch (IllegalArgumentException e) {
            throw runtime.newArgumentError("in `unpack': poorly encoded input");
        }
        return context.nil;
    }

    private static void unpack_x(Ruby runtime, ByteBuffer encode, int occurrences) {
        if (occurrences == IS_STAR) {
             occurrences = encode.remaining();
        }

        try {
            positionBuffer(encode, encode.position() + occurrences);
        } catch (IllegalArgumentException e) {
            throw runtime.newArgumentError("in `unpack': x outside of string");
        }
    }

    private static void unpack_X(Ruby runtime, ByteBuffer encode, int occurrences) {
        if (occurrences == IS_STAR) {
            // MRI behavior: Contrary to what seems to be logical,
            // when '*' is given, MRI calculates the distance
            // to the end, in order to go backwards.
            occurrences = /*encode.limit() - */encode.remaining();
        }

        try {
            positionBuffer(encode, encode.position() - occurrences);
        } catch (IllegalArgumentException e) {
            throw runtime.newArgumentError("in `unpack': X outside of string");
        }
    }

    private static IRubyObject unpack_U(ThreadContext context, Block block, Ruby runtime, RubyArray result, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining()) {
            occurrences = encode.remaining();
        }

        while (occurrences-- > 0 && encode.remaining() > 0) {
            try {
                // TODO: for now, we use a faithful
                // reimplementation of MRI's algorithm,
                // but should use UTF8Encoding facilities
                // from Joni, once it starts prefroming
                // UTF-8 content validation.
                RubyFixnum item = runtime.newFixnum(utf8Decode(encode));
                if (mode == UNPACK_1) {
                    return item;
                }
                appendOrYield(context, block, result, item, mode);
            } catch (IllegalArgumentException e) {
                throw runtime.newArgumentError(e.getMessage());
            }
        }
        return context.nil;
    }

    private static IRubyObject unpack_M(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int mode) {
        byte[] lElem = new byte[Math.max(encode.remaining(),0)];
        int index = 0;
        for(;;) {
            if (!encode.hasRemaining()) break;
            int c = safeGet(encode);
            if (c != '=') {
                lElem[index++] = (byte)c;
            } else {
                if (!encode.hasRemaining()) break;
                markBuffer(encode);
                int c1 = safeGet(encode);
                if (c1 == '\n' || (c1 == '\r' && (c1 = safeGet(encode)) == '\n')) continue;
                int d1 = Character.digit(c1, 16);
                if (d1 == -1) {
                    encode.reset();
                    break;
                }
                markBuffer(encode);
                if (!encode.hasRemaining()) break;
                int c2 = safeGet(encode);
                int d2 = Character.digit(c2, 16);
                if (d2 == -1) {
                    encode.reset();
                    break;
                }
                byte value = (byte)(d1 << 4 | d2);
                lElem[index++] = value;
            }
        }
        return appendOrYield(context, block, result, new ByteList(lElem, 0, index, ASCII, false), mode, tainted);
    }

    private static IRubyObject unpack_m(ThreadContext context, Block block, Ruby runtime, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        int length = encode.remaining()*3/4;
        byte[] lElem = new byte[length];
        int a = -1, b = -1, c = 0, d;
        int index = 0;
        int s = -1;

        if (occurrences == 0){
            index = unpack_m_zeroOccurrences(runtime, encode, lElem, a, b, c, index, s);
        } else {
            index = unpack_m_nonzeroOccurrences(encode, lElem, a, b, c, index);
        }
        return appendOrYield(context, block, result, new ByteList(lElem, 0, index, ASCII, false), mode, tainted);
    }

    private static int unpack_m_nonzeroOccurrences(ByteBuffer encode, byte[] lElem, int a, int b, int c, int index) {
        int d;
        int s;
        while (encode.hasRemaining()) {
            a = b = c = d = -1;

            // obtain a
            s = safeGet(encode);
            while (((a = b64_xtable[s]) == -1) && encode.hasRemaining()) {
                s = safeGet(encode);
            }
            if (a == -1) break;

            // obtain b
            s = safeGet(encode);
            while (((b = b64_xtable[s]) == -1) && encode.hasRemaining()) {
                s = safeGet(encode);
            }
            if (b == -1) break;

            // obtain c
            s = safeGet(encode);
            while (((c = b64_xtable[s]) == -1) && encode.hasRemaining()) {
                if (s == '=') break;
                s = safeGet(encode);
            }
            if ((s == '=') || c == -1) {
                if (s == '=') {
                    positionBuffer(encode, encode.position() - 1);
                }
                break;
            }

            // obtain d
            s = safeGet(encode);
            while (((d = b64_xtable[s]) == -1) && encode.hasRemaining()) {
                if (s == '=') break;
                s = safeGet(encode);
            }
            if ((s == '=') || d == -1) {
                if (s == '=') {
                    positionBuffer(encode, encode.position() - 1);
                }
                break;
            }

            // calculate based on a, b, c and d
            lElem[index++] = (byte)((a << 2 | b >> 4) & 255);
            lElem[index++] = (byte)((b << 4 | c >> 2) & 255);
            lElem[index++] = (byte)((c << 6 | d) & 255);
            a = -1;
        }

        if (a != -1 && b != -1) {
            if (c == -1) {
                lElem[index++] = (byte)((a << 2 | b >> 4) & 255);
            } else {
                lElem[index++] = (byte)((a << 2 | b >> 4) & 255);
                lElem[index++] = (byte)((b << 4 | c >> 2) & 255);
            }
        }
        return index;
    }

    private static int unpack_m_zeroOccurrences(Ruby runtime, ByteBuffer encode, byte[] lElem, int a, int b, int c, int index, int s) {
        int d;
        if (encode.remaining()%4 != 0) {
            throw runtime.newArgumentError("invalid base64");
        }
        while (encode.hasRemaining() && s != '=') {
            a = b = c = -1;
            d = -2;

            // obtain a
            s = safeGet(encode);
            a = b64_xtable[s];
            if (a == -1) throw runtime.newArgumentError("invalid base64");

            // obtain b
            s = safeGet(encode);
            b = b64_xtable[s];
            if (b == -1) throw runtime.newArgumentError("invalid base64");

            // obtain c
            s = safeGet(encode);
            c = b64_xtable[s];
            if (s == '=') {
                if (safeGet(encode) != '=') throw runtime.newArgumentError("invalid base64");
                break;
            }
            if (c == -1) throw runtime.newArgumentError("invalid base64");

            // obtain d
            s = safeGet(encode);
            d = b64_xtable[s];
            if (s == '=') break;
            if (d == -1) throw runtime.newArgumentError("invalid base64");

            // calculate based on a, b, c and d
            lElem[index++] = (byte)((a << 2 | b >> 4) & 255);
            lElem[index++] = (byte)((b << 4 | c >> 2) & 255);
            lElem[index++] = (byte)((c << 6 | d) & 255);
        }

        if (encode.hasRemaining()) throw runtime.newArgumentError("invalid base64");

        if (a != -1 && b != -1) {
            if (c == -1 && s == '=') {
                if ((b & 15) > 0) throw runtime.newArgumentError("invalid base64");
                lElem[index++] = (byte)((a << 2 | b >> 4) & 255);
            } else if(c != -1 && s == '=') {
                if ((c & 3) > 0) throw runtime.newArgumentError("invalid base64");
                lElem[index++] = (byte)((a << 2 | b >> 4) & 255);
                lElem[index++] = (byte)((b << 4 | c >> 2) & 255);
            }
        }
        return index;
    }

    private static IRubyObject unpack_u(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int mode) {
        int length = encode.remaining() * 3 / 4;
        byte[] lElem = new byte[length];
        int index = 0;
        int s = 0;
        int total = 0;
        if (length > 0) s = encode.get();
        while (encode.hasRemaining() && s > ' ' && s < 'a') {
            int a, b, c, d;
            byte[] hunk = new byte[3];

            int len = (s - ' ') & 077;
            s = safeGet(encode);
            total += len;
            if (total > length) {
                len -= total - length;
                total = length;
            }

            while (len > 0) {
                int mlen = len > 3 ? 3 : len;

                if (encode.hasRemaining() && s >= ' ') {
                    a = (s - ' ') & 077;
                    s = safeGet(encode);
                } else
                    a = 0;
                if (encode.hasRemaining() && s >= ' ') {
                    b = (s - ' ') & 077;
                    s = safeGet(encode);
                } else
                    b = 0;
                if (encode.hasRemaining() && s >= ' ') {
                    c = (s - ' ') & 077;
                    s = safeGet(encode);
                } else
                    c = 0;
                if (encode.hasRemaining() && s >= ' ') {
                    d = (s - ' ') & 077;
                    s = safeGet(encode);
                } else
                    d = 0;
                hunk[0] = (byte)((a << 2 | b >> 4) & 255);
                hunk[1] = (byte)((b << 4 | c >> 2) & 255);
                hunk[2] = (byte)((c << 6 | d) & 255);

                for (int i = 0; i < mlen; i++) lElem[index++] = hunk[i];
                len -= mlen;
            }
            if (s == '\r') {
                s = safeGet(encode);
            }
            if (s == '\n') {
                s = safeGet(encode);
            }
            else if (encode.hasRemaining()) {
                if (safeGet(encode) == '\n') {
                    safeGet(encode); // Possible Checksum Byte
                } else if (encode.hasRemaining()) {
                    positionBuffer(encode, encode.position() - 1);
                }
            }
        }
        return appendOrYield(context, block, result, new ByteList(lElem, 0, index, ASCII, false), mode, tainted);
    }

    private static IRubyObject unpack_H(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining() * 2) {
            occurrences = encode.remaining() * 2;
        }
        int bits = 0;
        byte[] lElem = new byte[occurrences];
        for (int lCurByte = 0; lCurByte < occurrences; lCurByte++) {
            if ((lCurByte & 1) != 0) {
                bits <<= 4;
            } else {
                bits = encode.get();
            }
            lElem[lCurByte] = sHexDigits[(bits >>> 4) & 15];
        }
        return appendOrYield(context, block, result, new ByteList(lElem, USASCII, false), mode, tainted);
    }

    private static IRubyObject unpack_h(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining() * 2) {
            occurrences = encode.remaining() * 2;
        }
        int bits = 0;
        byte[] lElem = new byte[occurrences];
        for (int lCurByte = 0; lCurByte < occurrences; lCurByte++) {
            if ((lCurByte & 1) != 0) {
                bits >>>= 4;
            } else {
                bits = encode.get();
            }
            lElem[lCurByte] = sHexDigits[bits & 15];
        }
        return appendOrYield(context, block, result, new ByteList(lElem, USASCII, false), mode, tainted);
    }

    private static IRubyObject unpack_B(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining() * 8) {
            occurrences = encode.remaining() * 8;
        }
        int bits = 0;
        byte[] lElem = new byte[occurrences];
        for (int lCurByte = 0; lCurByte < occurrences; lCurByte++) {
            if ((lCurByte & 7) != 0) {
                bits <<= 1;
            } else {
                bits = encode.get();
            }
            lElem[lCurByte] = (bits & 128) != 0 ? (byte)'1' : (byte)'0';
        }

        return appendOrYield(context, block, result, new ByteList(lElem, ASCII, false), mode, tainted);
    }

    private static IRubyObject unpack_b(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining() * 8) {
            occurrences = encode.remaining() * 8;
        }
        int bits = 0;
        byte[] lElem = new byte[occurrences];
        for (int lCurByte = 0; lCurByte < occurrences; lCurByte++) {
            if ((lCurByte & 7) != 0) {
                bits >>>= 1;
            } else {
                bits = encode.get();
            }
            lElem[lCurByte] = (bits & 1) != 0 ? (byte)'1' : (byte)'0';
        }
        return appendOrYield(context, block, result, new ByteList(lElem, USASCII, false), mode, tainted);
    }

    private static IRubyObject unpack_a(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining()) {
            occurrences = encode.remaining();
        }
        byte[] potential = new byte[occurrences];
        encode.get(potential);
        return appendOrYield(context, block, result, new ByteList(potential, ASCII, false), mode,tainted);
    }

    private static IRubyObject unpack_Z(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        boolean isStar = (occurrences == IS_STAR);

        if (occurrences == IS_STAR || occurrences > encode.remaining()) {
            occurrences = encode.remaining();
        }

        byte[] potential = new byte[occurrences];
        int t = 0;

        while (t < occurrences) {
            byte b = encode.get();
            if (b == 0) {
                break;
            }
            potential[t] = b;
            t++;
        }

        IRubyObject value = appendOrYield(context, block, result, new ByteList(potential, 0, t, ASCII, false), mode, tainted);
        if (mode == UNPACK_1) {
             return value;
        }

        // When the number of occurrences is
        // explicitly specified, we have to read up
        // the remaining garbage after the '\0' to
        // satisfy the requested pattern.
        if (!isStar) {
            if (t < occurrences) {
                // We encountered '\0' when
                // reading the buffer above,
                // increment the number of read bytes.
                t++;
            }

            while (t < occurrences) {
                encode.get();
                t++;
            }
        }
        return context.nil;
    }

    private static IRubyObject unpack_A(ThreadContext context, Block block, RubyArray result, boolean tainted, ByteBuffer encode, int occurrences, int mode) {
        if (occurrences == IS_STAR || occurrences > encode.remaining()) {
            occurrences = encode.remaining();
        }

        byte[] potential = new byte[occurrences];
        encode.get(potential);

        for (int t = occurrences - 1; occurrences > 0; occurrences--, t--) {
            byte c = potential[t];
            if (c != '\0' && c != ' ') {
               break;
            }
        }

        return appendOrYield(context, block, result, new ByteList(potential, 0, occurrences, ASCII, false), mode, tainted);
    }

    private static void unpack_at(Ruby runtime, ByteList encodedString, ByteBuffer encode, int occurrences) {
        try {
            int limit;
            if (occurrences == IS_STAR) {
                limit = checkLimit(runtime, encode, encodedString.begin() + encode.remaining());
            } else {
                limit = checkLimit(runtime, encode, encodedString.begin() + occurrences);
            }
            positionBuffer(encode, limit);
        } catch (IllegalArgumentException iae) {
            throw runtime.newArgumentError("@ outside of string");
        }
    }

    private static int checkLimit(Ruby runtime, ByteBuffer encode, int limit) {
        if (limit >= encode.capacity() || limit < 0) {
            throw runtime.newRangeError("pack length too big");
        }
        return limit;
    }

    @Deprecated
    public static RubyArray unpackWithBlock(ThreadContext context, Ruby runtime, ByteList encodedString, ByteList formatString, Block block) {
        return unpackWithBlock(context, RubyString.newStringLight(runtime, encodedString), formatString, block);
    }

    private static void appendOrYield(ThreadContext context, Block block, RubyArray result, IRubyObject item, int mode) {
        if (mode == UNPACK_BLOCK) {
            block.yield(context, item);
        } else if (mode == UNPACK_ARRAY) {
            result.append(item);
        }
    }

    private static IRubyObject appendOrYield(ThreadContext context, Block block, RubyArray result, ByteList item, int mode, boolean taint) {
        RubyString itemStr = RubyString.newString(context.runtime, item);
        if (taint) itemStr.setTaint(true);
        if (mode == UNPACK_1) {
            return itemStr;
        } else {
            appendOrYield(context, block, result, itemStr, mode);
            return context.nil;
        }
    }

    
rb_uv_to_utf8
/** rb_uv_to_utf8
     *
     */
    public static int utf8Decode(Ruby runtime, byte[]to, int p, int code) {
        if (code <= 0x7f) {
            to[p] = (byte)code;
            return 1;
        }
        if (code <= 0x7ff) {
            to[p + 0] = (byte)(((code >>> 6) & 0xff) | 0xc0);
            to[p + 1] = (byte)((code & 0x3f) | 0x80);
            return 2;
        }
        if (code <= 0xffff) {
            to[p + 0] = (byte)(((code >>> 12) & 0xff) | 0xe0);
            to[p + 1] = (byte)(((code >>> 6) & 0x3f) | 0x80);
            to[p + 2] = (byte)((code & 0x3f) | 0x80);
            return 3;
        }
        if (code <= 0x1fffff) {
            to[p + 0] = (byte)(((code >>> 18) & 0xff) | 0xf0);
            to[p + 1] = (byte)(((code >>> 12) & 0x3f) | 0x80);
            to[p + 2] = (byte)(((code >>> 6) & 0x3f) | 0x80);
            to[p + 3] = (byte)((code & 0x3f) | 0x80);
            return 4;
        }
        if (code <= 0x3ffffff) {
            to[p + 0] = (byte)(((code >>> 24) & 0xff) | 0xf8);
            to[p + 1] = (byte)(((code >>> 18) & 0x3f) | 0x80);
            to[p + 2] = (byte)(((code >>> 12) & 0x3f) | 0x80);
            to[p + 3] = (byte)(((code >>> 6) & 0x3f) | 0x80);
            to[p + 4] = (byte)((code & 0x3f) | 0x80);
            return 5;
        }
        if (code <= 0x7fffffff) {
            to[p + 0] = (byte)(((code >>> 30) & 0xff) | 0xfc);
            to[p + 1] = (byte)(((code >>> 24) & 0x3f) | 0x80);
            to[p + 2] = (byte)(((code >>> 18) & 0x3f) | 0x80);
            to[p + 3] = (byte)(((code >>> 12) & 0x3f) | 0x80);
            to[p + 4] = (byte)(((code >>> 6) & 0x3f) | 0x80);
            to[p + 5] = (byte)((code & 0x3f) | 0x80);
            return 6;
        }
        throw runtime.newRangeError("pack(U): value out of range");
    }

    
utf8_to_uv
/** utf8_to_uv
     */
    private static int utf8Decode(ByteBuffer buffer) {
        int c = buffer.get() & 0xFF;
        int uv = c;
        int n;

        if ((c & 0x80) == 0) {
            return c;
        }

        if ((c & 0x40) == 0) {
            throw new IllegalArgumentException("malformed UTF-8 character");
        }
        
      if      ((uv & 0x20) == 0) { n = 2; uv &= 0x1f; }
      else if ((uv & 0x10) == 0) { n = 3; uv &= 0x0f; }
      else if ((uv & 0x08) == 0) { n = 4; uv &= 0x07; }
      else if ((uv & 0x04) == 0) { n = 5; uv &= 0x03; }
      else if ((uv & 0x02) == 0) { n = 6; uv &= 0x01; }
      else {
          throw new IllegalArgumentException("malformed UTF-8 character");
      }
      if (n > buffer.remaining() + 1) {
          throw new IllegalArgumentException(
                  "malformed UTF-8 character (expected " + n + " bytes, "
                  + "given " + (buffer.remaining() + 1)  + " bytes)");
      }

      int limit = n - 1;

      n--;

      if (n != 0) {
          while (n-- != 0) {
              c = buffer.get() & 0xff;
              if ((c & 0xc0) != 0x80) {
                  throw new IllegalArgumentException("malformed UTF-8 character");
              }
              else {
                  c &= 0x3f;
                  uv = uv << 6 | c;
              }
          }
      }

      if (uv < utf8_limits[limit]) {
          throw new IllegalArgumentException("redundant UTF-8 sequence");
      }

      return uv;
    }

    private static final long utf8_limits[] = {
        0x0,                        /* 1 */
        0x80,                       /* 2 */
        0x800,                      /* 3 */
        0x10000,                    /* 4 */
        0x200000,                   /* 5 */
        0x4000000,                  /* 6 */
        0x80000000,                 /* 7 */
    };

    public static int safeGet(ByteBuffer encode) {
        while (encode.hasRemaining()) {
            int got = encode.get() & 0xff;
            
            if (got != 0) return got;
        }
        
        return 0;
    }

    private static int safeGetIgnoreNull(ByteBuffer encode) {
        int next = 0;
        while (encode.hasRemaining() && next == 0) {
            next = safeGet(encode);
        }
        return next;
    }

    public static IRubyObject decode(ThreadContext context, Ruby runtime, ByteBuffer encode, int occurrences,
            RubyArray result, Block block, Converter converter, int mode) {
        int lPadLength = 0;

        if (occurrences == IS_STAR) {
            occurrences = encode.remaining() / converter.size;
        } else if (occurrences > encode.remaining() / converter.size) {
            lPadLength = occurrences - encode.remaining() / converter.size;
            occurrences = encode.remaining() / converter.size;
        }
        for (; occurrences-- > 0;) {
            IRubyObject value = converter.decode(runtime, encode);
            if (mode == UNPACK_1) {
                return value;
            }
            appendOrYield(context, block, result, value, mode);
        }

        for (; lPadLength-- > 0;) {
            if (mode == UNPACK_1) {
                return context.nil;
            }
            appendOrYield(context, block, result, context.nil, mode);
        }
        return context.nil;
    }

    public static int encode(Ruby runtime, int occurrences, ByteList result,
            RubyArray list, int index, ConverterExecutor converter) {
        int listSize = list.size();

        while (occurrences-- > 0) {
            if (listSize-- <= 0 || index >= list.size()) {
                throw runtime.newArgumentError(sTooFew);
            }

            IRubyObject from = list.eltInternal(index++);

            converter.encode(runtime, from, result);
        }

        return index;
    }

    private abstract static class ConverterExecutor {
        protected Converter converter;
        public void setConverter(Converter converter) {
            this.converter = converter;
        }

        public abstract IRubyObject decode(Ruby runtime, ByteBuffer format);
        public abstract void encode(Ruby runtime, IRubyObject from, ByteList result);
    }

    private static ConverterExecutor executor() {
        return new ConverterExecutor() {
            @Override
            public IRubyObject decode(Ruby runtime, ByteBuffer format) {
                return converter.decode(runtime, format);
            }

            @Override
            public void encode(Ruby runtime, IRubyObject from, ByteList result) {
                if (from == runtime.getNil() && converter.getType() != null) throw runtime.newTypeError(from, converter.getType());                
                converter.encode(runtime, from, result);
            }
        };
    }

    public abstract static class Converter {
        public int size;
        public String type;

        public Converter(int size) {
            this(size, null);
        }
        
        public Converter(int size, String type) {
            this.size = size;
            this.type = type;
        }
        
        public String getType() {
            return type;
        }

        public abstract IRubyObject decode(Ruby runtime, ByteBuffer format);
        public abstract void encode(Ruby runtime, IRubyObject from, ByteList result);
    }

    private abstract static class QuadConverter extends Converter{
        public QuadConverter(int size, String type) {
            super(size, type);
        }
        
        public QuadConverter(int size) {
            super(size);
        }

        protected int overflowQuad(long quad) {
            return (int) (quad & 0xffff);
        }

        protected void encodeShortByByteOrder(ByteList result, int s) {
            if (Platform.BYTE_ORDER == Platform.BIG_ENDIAN) {
                encodeShortBigEndian(result, s);
            } else {
                encodeShortLittleEndian(result, s);
            }
        }

        protected void encodeLongByByteOrder(ByteList result, long l) {
            if (Platform.BYTE_ORDER == Platform.BIG_ENDIAN) {
                encodeLongBigEndian(result, l);
            } else {
                encodeLongLittleEndian(result, l);
            }
        }
    }

    
shrinks a stringbuffer.
shrinks a stringbuffer by a number of characters.
Params:
i2Shrink – the stringbuffer
iLength – how much to shrink
Returns:
the stringbuffer/**
     * shrinks a stringbuffer.
     * shrinks a stringbuffer by a number of characters.
     * @param i2Shrink the stringbuffer
     * @param iLength how much to shrink
     * @return the stringbuffer
     **/
    private static final ByteList shrink(ByteList i2Shrink, int iLength) {
        iLength = i2Shrink.length() - iLength;

        if (iLength < 0) {
            throw new IllegalArgumentException();
        }
        i2Shrink.length(iLength);
        return i2Shrink;
    }

    
grows a stringbuffer.
uses the Strings to pad the buffer for a certain length
Params:
i2Grow – the buffer to grow
iPads – the string used as padding
iLength – how much padding is needed
Returns:
the padded buffer/**
     * grows a stringbuffer.
     * uses the Strings to pad the buffer for a certain length
     * @param i2Grow the buffer to grow
     * @param iPads the string used as padding
     * @param iLength how much padding is needed
     * @return the padded buffer
     **/
    private static final ByteList grow(ByteList i2Grow, byte[]iPads, int iLength) {
        int lPadLength = iPads.length;
        while (iLength >= lPadLength) {
            i2Grow.append(iPads);
            iLength -= lPadLength;
        }
        i2Grow.append(iPads, 0, iLength);
        return i2Grow;
    }

    
Same as pack but defaults tainting of output to false.
/**
     * Same as pack but defaults tainting of output to false.
     */
    public static RubyString pack(Ruby runtime, RubyArray list, ByteList formatString) {
        RubyString buffer = runtime.newString();
        return packCommon(runtime.getCurrentContext(), list, formatString, false, executor(), buffer);
    }

    @Deprecated
    public static RubyString pack(ThreadContext context, Ruby runtime, RubyArray list, RubyString formatString) {
        RubyString buffer = runtime.newString();
        return pack(context, list, formatString, buffer);
    }

    @Deprecated
    public static void decode(ThreadContext context, Ruby runtime, ByteBuffer encode, int occurrences,
          RubyArray result, Block block, Converter converter) {
        decode(context, runtime, encode, occurrences,
            result, block, converter, block.isGiven() ? UNPACK_BLOCK : UNPACK_ARRAY);
    }

    public static RubyString pack(ThreadContext context, RubyArray list, RubyString formatString, RubyString buffer) {
        RubyString pack = packCommon(context, list, formatString.getByteList(), formatString.isTaint(), executor(), buffer);
        return (RubyString) pack.infectBy(formatString);
    }

    
Introduced to allow outlining cases in #packCommon that update both of these values.
/**
     * Introduced to allow outlining cases in #packCommon that update both of these values.
     */
    private static class PackInts {
        PackInts(int listSize, int idx) {
            this.listSize = listSize;
            this.idx = idx;
        }
        int listSize;
        int idx;
    }

    private static RubyString packCommon(ThreadContext context, RubyArray list, ByteList formatString, boolean tainted, ConverterExecutor executor, RubyString buffer) {
        ByteBuffer format = ByteBuffer.wrap(formatString.getUnsafeBytes(), formatString.begin(), formatString.length());

        buffer.modify();
        ByteList result = buffer.getByteList();
        boolean taintOutput = tainted;
        PackInts packInts = new PackInts(list.size(), 0);
        int type;
        int next = safeGet(format);

        int enc_info = 1;

        mainLoop: while (next != 0) {
            type = next;
            next = safeGet(format);
            if (PACK_IGNORE_NULL_CODES.indexOf(type) != -1 && next == 0) {
                next = safeGetIgnoreNull(format);
            }

            // Skip all whitespace in pack format string
            while (ASCII.isSpace(type)) {
                if (next == 0) break mainLoop;
                type = next;
                next = safeGet(format);
            }

            // Skip embedded comments in pack format string
            if (type == '#') {
                while (type != '\n') {
                    if (next == 0) break mainLoop;
                    type = next;
                    next = safeGet(format);
                }
            }

            if (next == '!' || next == '_') {
                int index = NATIVE_CODES.indexOf(type);
                if (index == -1) {
                    throw context.runtime.newArgumentError("'" + next + "' allowed only after types " + NATIVE_CODES);
                }
                int typeBeforeMap = type;
                type = MAPPED_CODES.charAt(index);

                next = safeGet(format);
                if (PACK_IGNORE_NULL_CODES_WITH_MODIFIERS.indexOf(typeBeforeMap) != -1 && next == 0) {
                    next = safeGetIgnoreNull(format);
                }
            }
            
            if (next == '>' || next == '<') {
                next = next == '>' ? BE : LE;
                int index = ENDIANESS_CODES.indexOf(type + next);
                if (index == -1) {
                    throw context.runtime.newArgumentError("'" + (char) next + "' allowed only after types sSiIlLqQ");
                }
                type = ENDIANESS_CODES.charAt(index);
                next = safeGet(format);
            }

            // Determine how many of type are needed (default: 1)
            int occurrences = 1;
            boolean isStar = false;
            boolean ignoreStar = false;
            if (next != 0) {
                if (next == '*') {
                    if ("@XxumM".indexOf(type) != -1) {
                        occurrences = 0;
                        ignoreStar = true;
                    } else {
                        occurrences = list.size() - packInts.idx;
                        isStar = true;
                    }
                    next = safeGet(format);
                } else if (ASCII.isDigit(next)) {
                    occurrences = 0;
                    do {
                        occurrences = occurrences * 10 + Character.digit((char)(next & 0xFF), 10);
                        next = safeGet(format);
                    } while (next != 0 && ASCII.isDigit(next));
                }
            }

            enc_info = adjustEncInfo(type, enc_info);

            Converter converter = converters[type];

            if (converter != null) {
                executor.setConverter(converter);
                packInts.idx = encode(context.runtime, occurrences, result, list, packInts.idx, executor);
                continue;
            }

            switch (type) {
                case '%':
                    throw context.runtime.newArgumentError("% is not supported");
                case 'A':
                case 'a':
                case 'Z':
                case 'B':
                case 'b':
                case 'H':
                case 'h':
                    taintOutput = pack_h(context, list, result, taintOutput, packInts, type, occurrences, isStar);
                    break;
                case 'x':
                    grow(result, sNil10, occurrences);
                    break;
                case 'X':
                    pack_X(context, result, occurrences);
                    break;
                case '@':
                    pack_at(result, occurrences);
                    break;
                case 'u':
                case 'm':
                    taintOutput = pack_m(context, list, result, taintOutput, packInts, (char) type, occurrences, ignoreStar);
                    break;
                case 'M':
                    taintOutput = pack_M(context, list, result, taintOutput, packInts, occurrences);
                    break;
                case 'U':
                    pack_U(context, list, result, packInts, occurrences);
                    break;
                case 'w':
                    pack_w(context, list, result, packInts, occurrences);
                    break;
            }
        }

        if (taintOutput) buffer.setTaint(true);

        switch (enc_info) {
            case 1:
                buffer.setEncodingAndCodeRange(USASCII, StringSupport.CR_7BIT);
                break;
            case 2:
                buffer.associateEncoding(UTF8);
                break;
            default:
                /* do nothing, keep ASCII-8BIT */
        }

        return buffer;
    }

    private static void pack_w(ThreadContext context, RubyArray list, ByteList result, PackInts packInts, int occurrences) {
        while (occurrences-- > 0) {
            if (packInts.listSize-- <= 0) throw context.runtime.newArgumentError(sTooFew);

            IRubyObject from = list.eltInternal(packInts.idx++);
            if (from == context.nil) throw context.runtime.newTypeError("pack('w') does not take nil");

            final ByteList buf = new ByteList();

            if (from instanceof RubyBignum) {
                RubyBignum big128 = RubyBignum.newBignum(context.runtime, 128);
                while (from instanceof RubyBignum) {
                    RubyArray ary = (RubyArray) ((RubyBignum) from).divmod(context, big128);
                    buf.append((byte) (RubyNumeric.fix2int(ary.eltInternal(1)) | 0x80) & 0xff);
                    from = ary.eltInternal(0);
                }
            }

            long l = RubyNumeric.num2long(from);

            // we don't deal with negatives.
            if (l >= 0) {

                while(l != 0) {
                    buf.append((byte)(((l & 0x7f) | 0x80) & 0xff));
                    l >>= 7;
                }

                int left = 0;
                int right = buf.getRealSize() - 1;

                if (right >= 0) {
                    buf.getUnsafeBytes()[0] &= 0x7F;
                } else {
                    buf.append(0);
                }

                while (left < right) {
                    byte tmp = buf.getUnsafeBytes()[left];
                    buf.getUnsafeBytes()[left] = buf.getUnsafeBytes()[right];
                    buf.getUnsafeBytes()[right] = tmp;

                    left++;
                    right--;
                }

                result.append(buf);
            } else {
                throw context.runtime.newArgumentError("can't compress negative numbers");
            }
        }
    }

    private static void pack_U(ThreadContext context, RubyArray list, ByteList result, PackInts packInts, int occurrences) {
        while (occurrences-- > 0) {
            if (packInts.listSize-- <= 0) throw context.runtime.newArgumentError(sTooFew);

            IRubyObject from = list.eltInternal(packInts.idx++);
            int code = from == context.nil ? 0 : RubyNumeric.num2int(from);

            if (code < 0) throw context.runtime.newRangeError("pack(U): value out of range");

            int len = result.getRealSize();
            result.ensure(len + 6);
            result.setRealSize(len + utf8Decode(context.runtime, result.getUnsafeBytes(), result.getBegin() + len, code));
        }
    }

    private static boolean pack_M(ThreadContext context, RubyArray list, ByteList result, boolean taintOutput, PackInts packInts, int occurrences) {
        ByteList lCurElemString;
        if (packInts.listSize-- <= 0) throw context.runtime.newArgumentError(sTooFew);

        IRubyObject from = list.eltInternal(packInts.idx++);
        if (from.isTaint()) taintOutput = true;
        lCurElemString = from == context.nil ? ByteList.EMPTY_BYTELIST : from.asString().getByteList();

        if (occurrences <= 1) {
            occurrences = 72;
        }

        PackUtils.qpencode(result, lCurElemString, occurrences);
        return taintOutput;
    }

    private static boolean pack_h(ThreadContext context, RubyArray list, ByteList result, boolean taintOutput, PackInts packInts, int type, int occurrences, boolean isStar) {
        ByteList lCurElemString;
        if (packInts.listSize-- <= 0) {
            throw context.runtime.newArgumentError(sTooFew);
        }

        IRubyObject from = list.eltInternal(packInts.idx++);
        lCurElemString = from == context.nil ? ByteList.EMPTY_BYTELIST : from.convertToString().getByteList();
        if (from.isTaint()) taintOutput = true;

        if (isStar) {
            occurrences = lCurElemString.length();
            // 'Z' adds extra null pad (versus 'a')
            if (type == 'Z') occurrences++;
        }

        pack_h_inner(result, type, lCurElemString, occurrences);
        return taintOutput;
    }

    private static boolean pack_m(ThreadContext context, RubyArray list, ByteList result, boolean taintOutput, PackInts packInts, char type, int occurrences, boolean ignoreStar) {
        ByteList lCurElemString;
        if (packInts.listSize-- <= 0) throw context.runtime.newArgumentError(sTooFew);

        IRubyObject from = list.eltInternal(packInts.idx++);
        if (from == context.nil) throw context.runtime.newTypeError(from, "Integer");
        lCurElemString = from.convertToString().getByteList();
        if (from.isTaint()) taintOutput = true;
        encodeUM(context.runtime, lCurElemString, occurrences, ignoreStar, type, result);
        return taintOutput;
    }

    private static void pack_at(ByteList result, int occurrences) {
        occurrences -= result.length();
        if (occurrences > 0) {
            grow(result, sNil10, occurrences);
        }
        occurrences = -occurrences;
        if (occurrences > 0) {
            shrink(result, occurrences);
        }
    }

    private static void pack_X(ThreadContext context, ByteList result, int occurrences) {
        try {
            shrink(result, occurrences);
        } catch (IllegalArgumentException e) {
            throw context.runtime.newArgumentError("in `pack': X outside of string");
        }
    }

    private static void pack_h_inner(ByteList result, int type, ByteList lCurElemString, int occurrences) {
        switch (type) {
            case 'a' :
            case 'A' :
            case 'Z' :
                pack_h_aAZ(result, type, lCurElemString, occurrences);
                break;
            case 'b' :
                    pack_h_b(result, lCurElemString, occurrences);
            break;
            case 'B' :
                    pack_h_B(result, lCurElemString, occurrences);
            break;
            case 'h' :
                    pack_h_h(result, lCurElemString, occurrences);
            break;
            case 'H' :
                    pack_h_H(result, lCurElemString, occurrences);
            break;
        }
    }

    private static void pack_h_H(ByteList result, ByteList lCurElemString, int occurrences) {
        int currentByte = 0;
        int padLength = 0;

        if (occurrences > lCurElemString.length()) {
            padLength = occurrences - lCurElemString.length() + 1;
            occurrences = lCurElemString.length();
        }

        for (int i = 0; i < occurrences;) {
            byte currentChar = (byte)lCurElemString.charAt(i++);

            if (Character.isJavaIdentifierStart(currentChar)) {
                //this test may be too lax but it is the same as in MRI
                currentByte |= ((currentChar & 15) + 9) & 15;
            } else {
                currentByte |= currentChar & 15;
            }

            if ((i & 1) != 0) {
                currentByte <<= 4;
            } else {
                result.append((byte) (currentByte & 0xff));
                currentByte = 0;
            }
        }

        if ((occurrences & 1) != 0) {
            result.append((byte) (currentByte & 0xff));
            if (padLength > 0) padLength--;
        }

        result.length(result.length() + padLength / 2);
    }

    private static void pack_h_h(ByteList result, ByteList lCurElemString, int occurrences) {
        int currentByte = 0;
        int padLength = 0;

        if (occurrences > lCurElemString.length()) {
            padLength = occurrences - lCurElemString.length() + 1;
            occurrences = lCurElemString.length();
        }

        for (int i = 0; i < occurrences;) {
            byte currentChar = (byte)lCurElemString.charAt(i++);

            if (Character.isJavaIdentifierStart(currentChar)) {
                //this test may be too lax but it is the same as in MRI
                currentByte |= (((currentChar & 15) + 9) & 15) << 4;
            } else {
                currentByte |= (currentChar & 15) << 4;
            }

            if ((i & 1) != 0) {
                currentByte >>= 4;
            } else {
                result.append((byte) (currentByte & 0xff));
                currentByte = 0;
            }
        }

        if ((occurrences & 1) != 0) {
            result.append((byte) (currentByte & 0xff));
            if (padLength > 0) padLength--;
        }

        result.length(result.length() + padLength / 2);
    }

    private static void pack_h_B(ByteList result, ByteList lCurElemString, int occurrences) {
        int currentByte = 0;
        int padLength = 0;

        if (occurrences > lCurElemString.length()) {
            padLength = (occurrences - lCurElemString.length()) / 2 + (occurrences + lCurElemString.length()) % 2;
            occurrences = lCurElemString.length();
        }

        for (int i = 0; i < occurrences;) {
            currentByte |= lCurElemString.charAt(i++) & 1;

            // we filled up current byte; append it and create next one
            if ((i & 7) == 0) {
                result.append((byte) (currentByte & 0xff));
                currentByte = 0;
                continue;
            }

            //if the index is not a multiple of 8, we are not on a byte boundary
            currentByte <<= 1;
        }

        if ((occurrences & 7) != 0) { //if the length is not a multiple of 8
            currentByte <<= 7 - (occurrences & 7); //we need to pad the last byte
            result.append((byte) (currentByte & 0xff));
        }

        result.length(result.length() + padLength);
    }

    private static void pack_h_b(ByteList result, ByteList lCurElemString, int occurrences) {
        int currentByte = 0;
        int padLength = 0;

        if (occurrences > lCurElemString.length()) {
            padLength = (occurrences - lCurElemString.length()) / 2 + (occurrences + lCurElemString.length()) % 2;
            occurrences = lCurElemString.length();
        }

        for (int i = 0; i < occurrences;) {
            if ((lCurElemString.charAt(i++) & 1) != 0) {//if the low bit is set
                currentByte |= 128; //set the high bit of the result
            }

            if ((i & 7) == 0) {
                result.append((byte) (currentByte & 0xff));
                currentByte = 0;
                continue;
            }

               //if the index is not a multiple of 8, we are not on a byte boundary
               currentByte >>= 1; //shift the byte
        }

        if ((occurrences & 7) != 0) { //if the length is not a multiple of 8
            currentByte >>= 7 - (occurrences & 7); //we need to pad the last byte
            result.append((byte) (currentByte & 0xff));
        }

        //do some padding, I don't understand the padding strategy
        result.length(result.length() + padLength);
    }

    private static void pack_h_aAZ(ByteList result, int type, ByteList lCurElemString, int occurrences) {
        if (lCurElemString.length() >= occurrences) {
            result.append(lCurElemString.getUnsafeBytes(), lCurElemString.getBegin(), occurrences);
        } else {//need padding
            //I'm fairly sure there is a library call to create a
            //string filled with a given char with a given length but I couldn't find it
            result.append(lCurElemString);
            occurrences -= lCurElemString.length();

            switch (type) {
              case 'a':
              case 'Z':
                  grow(result, sNil10, occurrences);
                  break;
              default:
                  grow(result, sSp10, occurrences);
                  break;
            }
        }
    }

    private static int adjustEncInfo(int type, int enc_info) {
        switch (type) {
            case 'U':
                if (enc_info == 1) enc_info = 2;
                break;
            case 'm':
            case 'M':
            case 'u':
                break;
            default:
                enc_info = 0;
                break;
        }
        return enc_info;
    }

    
Retrieve an encoded int in little endian starting at index in the
string value.
Params:
encode – string to get int from
Returns:
the decoded integer/**
     * Retrieve an encoded int in little endian starting at index in the
     * string value.
     *
     * @param encode string to get int from
     * @return the decoded integer
     */
    private static int decodeIntLittleEndian(ByteBuffer encode) {
        encode.order(ByteOrder.LITTLE_ENDIAN);
        int value = encode.getInt();
        encode.order(ByteOrder.BIG_ENDIAN);
        return value;
    }

    
Retrieve an encoded int in little endian starting at index in the
string value.
Params:
encode – string to get int from
Returns:
the decoded integer/**
     * Retrieve an encoded int in little endian starting at index in the
     * string value.
     *
     * @param encode string to get int from
     * @return the decoded integer
     */
    private static int decodeIntBigEndian(ByteBuffer encode) {
        return encode.getInt();
    }

    
Retrieve an encoded int in big endian starting at index in the string
value.
Params:
encode – string to get int from
Returns:
the decoded integer/**
     * Retrieve an encoded int in big endian starting at index in the string
     * value.
     *
     * @param encode string to get int from
     * @return the decoded integer
     */
    private static long decodeIntUnsignedBigEndian(ByteBuffer encode) {
        return (long)encode.getInt() & 0xFFFFFFFFL;
    }

    
Retrieve an encoded int in little endian starting at index in the
string value.
Params:
encode – the encoded string
Returns:
the decoded integer/**
     * Retrieve an encoded int in little endian starting at index in the
     * string value.
     *
     * @param encode the encoded string
     * @return the decoded integer
     */
    private static long decodeIntUnsignedLittleEndian(ByteBuffer encode) {
        encode.order(ByteOrder.LITTLE_ENDIAN);
        long value = encode.getInt() & 0xFFFFFFFFL;
        encode.order(ByteOrder.BIG_ENDIAN);
        return value;
    }

    
Encode an int in little endian format into a packed representation.
Params:
result – to be appended to
s – the integer to encode/**
     * Encode an int in little endian format into a packed representation.
     *
     * @param result to be appended to
     * @param s the integer to encode
     */
    private static void encodeIntLittleEndian(ByteList result, int s) {
        result.append((byte) (s & 0xff)).append((byte) ((s >> 8) & 0xff));
        result.append((byte) ((s>>16) & 0xff)).append((byte) ((s >> 24) & 0xff));
    }

    
Encode an int in big-endian format into a packed representation.
Params:
result – to be appended to
s – the integer to encode/**
     * Encode an int in big-endian format into a packed representation.
     *
     * @param result to be appended to
     * @param s the integer to encode
     */
    private static void encodeIntBigEndian(ByteList result, int s) {
        result.append((byte) ((s>>24) &0xff)).append((byte) ((s>>16) &0xff));
        result.append((byte) ((s >> 8) & 0xff)).append((byte) (s & 0xff));
    }

    
Decode a long in big-endian format from a packed value
Params:
encode – string to get int from
Returns:
the long value/**
     * Decode a long in big-endian format from a packed value
     *
     * @param encode string to get int from
     * @return the long value
     */
    private static long decodeLongBigEndian(ByteBuffer encode) {
        int c1 = decodeIntBigEndian(encode);
        int c2 = decodeIntBigEndian(encode);

        return ((long) c1 << 32) + (c2 & 0xffffffffL);
    }

    
Decode a long in little-endian format from a packed value
Params:
encode – string to get int from
Returns:
the long value/**
     * Decode a long in little-endian format from a packed value
     *
     * @param encode string to get int from
     * @return the long value
     */
    private static long decodeLongLittleEndian(ByteBuffer encode) {
        int c1 = decodeIntLittleEndian(encode);
        int c2 = decodeIntLittleEndian(encode);

        return ((long) c2 << 32) + (c1 & 0xffffffffL);
    }

    
Encode a long in little-endian format into a packed value
Params:
result – to pack long into
l – is the long to encode/**
     * Encode a long in little-endian format into a packed value
     *
     * @param result to pack long into
     * @param l is the long to encode
     */
    private static void encodeLongLittleEndian(ByteList result, long l) {
        encodeIntLittleEndian(result, (int) (l & 0xffffffff));
        encodeIntLittleEndian(result, (int) (l >>> 32));
    }

    
Encode a long in big-endian format into a packed value
Params:
result – to pack long into
l – is the long to encode/**
     * Encode a long in big-endian format into a packed value
     *
     * @param result to pack long into
     * @param l is the long to encode
     */
    private static void encodeLongBigEndian(ByteList result, long l) {
        encodeIntBigEndian(result, (int) (l >>> 32));
        encodeIntBigEndian(result, (int) (l & 0xffffffff));
    }

    
Decode a double from a packed value
Params:
encode – string to get int from
Returns:
the double value/**
     * Decode a double from a packed value
     *
     * @param encode string to get int from
     * @return the double value
     */
    private static double decodeDoubleLittleEndian(ByteBuffer encode) {
        return Double.longBitsToDouble(decodeLongLittleEndian(encode));
    }

    
Decode a double in big-endian from a packed value
Params:
encode – string to get int from
Returns:
the double value/**
     * Decode a double in big-endian from a packed value
     *
     * @param encode string to get int from
     * @return the double value
     */
    private static double decodeDoubleBigEndian(ByteBuffer encode) {
        return Double.longBitsToDouble(decodeLongBigEndian(encode));
    }

    
Encode a double in little endian format into a packed value
Params:
result – to pack double into
d – is the double to encode/**
     * Encode a double in little endian format into a packed value
     *
     * @param result to pack double into
     * @param d is the double to encode
     */
    private static void encodeDoubleLittleEndian(ByteList result, double d) {
        encodeLongLittleEndian(result, Double.doubleToRawLongBits(d));
    }

    
Encode a double in big-endian format into a packed value
Params:
result – to pack double into
d – is the double to encode/**
     * Encode a double in big-endian format into a packed value
     *
     * @param result to pack double into
     * @param d is the double to encode
     */
    private static void encodeDoubleBigEndian(ByteList result, double d) {
        encodeLongBigEndian(result, Double.doubleToRawLongBits(d));
    }

    
Decode a float in big-endian from a packed value
Params:
encode – string to get int from
Returns:
the double value/**
     * Decode a float in big-endian from a packed value
     *
     * @param encode string to get int from
     * @return the double value
     */
    private static float decodeFloatBigEndian(ByteBuffer encode) {
        return Float.intBitsToFloat(decodeIntBigEndian(encode));
    }

    
Decode a float in little-endian from a packed value
Params:
encode – string to get int from
Returns:
the double value/**
     * Decode a float in little-endian from a packed value
     *
     * @param encode string to get int from
     * @return the double value
     */
    private static float decodeFloatLittleEndian(ByteBuffer encode) {
        return Float.intBitsToFloat(decodeIntLittleEndian(encode));
    }

    
Encode a float in little endian format into a packed value
Params:
result – to pack float into
f – is the float to encode/**
     * Encode a float in little endian format into a packed value
     * @param result to pack float into
     * @param f is the float to encode
     */
    private static void encodeFloatLittleEndian(ByteList result, float f) {
        encodeIntLittleEndian(result, Float.floatToRawIntBits(f));
    }

    
Encode a float in big-endian format into a packed value
Params:
result – to pack float into
f – is the float to encode/**
     * Encode a float in big-endian format into a packed value
     * @param result to pack float into
     * @param f is the float to encode
     */
    private static void encodeFloatBigEndian(ByteList result, float f) {
        encodeIntBigEndian(result, Float.floatToRawIntBits(f));
    }

    
Decode a short in little-endian from a packed value
Params:
encode – string to get int from
Returns:
the short value/**
     * Decode a short in little-endian from a packed value
     *
     * @param encode string to get int from
     * @return the short value
     */
    private static int decodeShortUnsignedLittleEndian(ByteBuffer encode) {
        encode.order(ByteOrder.LITTLE_ENDIAN);
        int value = encode.getShort() & 0xFFFF;
        encode.order(ByteOrder.BIG_ENDIAN);
        return value;
    }

    
Decode a short in big-endian from a packed value
Params:
encode – string to get int from
Returns:
the short value/**
     * Decode a short in big-endian from a packed value
     *
     * @param encode string to get int from
     * @return the short value
     */
    private static int decodeShortUnsignedBigEndian(ByteBuffer encode) {
        int value = encode.getShort() & 0xFFFF;
        return value;
    }

    
Decode a short in little-endian from a packed value
Params:
encode – string to get int from
Returns:
the short value/**
     * Decode a short in little-endian from a packed value
     *
     * @param encode string to get int from
     * @return the short value
     */
    private static int decodeShortLittleEndian(ByteBuffer encode) {
        encode.order(ByteOrder.LITTLE_ENDIAN);
        int value = encode.getShort();
        encode.order(ByteOrder.BIG_ENDIAN);
        return value;
    }

    
Decode a short in big-endian from a packed value
Params:
encode – string to get int from
Returns:
the short value/**
     * Decode a short in big-endian from a packed value
     *
     * @param encode string to get int from
     * @return the short value
     */
    private static short decodeShortBigEndian(ByteBuffer encode) {
        return encode.getShort();
    }

    
Encode an short in little endian format into a packed representation.
Params:
result – to be appended to
s – the short to encode/**
     * Encode an short in little endian format into a packed representation.
     *
     * @param result to be appended to
     * @param s the short to encode
     */
    private static void encodeShortLittleEndian(ByteList result, int s) {
        result.append((byte) (s & 0xff)).append((byte) ((s & 0xff00) >> 8));
    }

    
Encode an shortin big-endian format into a packed representation.
Params:
result – to be appended to
s – the short to encode/**
     * Encode an shortin big-endian format into a packed representation.
     *
     * @param result to be appended to
     * @param s the short to encode
     */
    private static void encodeShortBigEndian(ByteList result, int s) {
        result.append((byte) ((s & 0xff00) >> 8)).append((byte) (s & 0xff));
    }

}