From ae0e966564311410675456bcb472e0d3ac243b47 Mon Sep 17 00:00:00 2001 From: morkt Date: Mon, 27 Nov 2017 12:47:15 +0400 Subject: [PATCH] implemented CPZ7 archives. --- ArcFormats/ArcFormats.csproj | 2 + ArcFormats/Cmvs/ArcCPZ.cs | 151 +++++++++----------------- ArcFormats/Cmvs/CmvsMD5.cs | 22 +++- ArcFormats/Cmvs/CpzHeader.cs | 175 ++++++++++++++++++++++++++++++ ArcFormats/Cmvs/HuffmanDecoder.cs | 108 ++++++++++++++++++ 5 files changed, 356 insertions(+), 102 deletions(-) create mode 100644 ArcFormats/Cmvs/CpzHeader.cs create mode 100644 ArcFormats/Cmvs/HuffmanDecoder.cs diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj index 918d02c1..b1d078fa 100644 --- a/ArcFormats/ArcFormats.csproj +++ b/ArcFormats/ArcFormats.csproj @@ -104,6 +104,8 @@ + + diff --git a/ArcFormats/Cmvs/ArcCPZ.cs b/ArcFormats/Cmvs/ArcCPZ.cs index 4f5f2c87..080a46b7 100644 --- a/ArcFormats/Cmvs/ArcCPZ.cs +++ b/ArcFormats/Cmvs/ArcCPZ.cs @@ -2,7 +2,7 @@ //! \date Tue Nov 24 11:27:23 2015 //! \brief Purple Software resource archive. // -// Copyright (C) 2015-2016 by morkt +// Copyright (C) 2015-2017 by morkt // // Permission is hereby granted, free of charge, to any person obtaining a copy // of this software and associated documentation files (the "Software"), to @@ -29,7 +29,6 @@ using System.ComponentModel.Composition; using System.IO; using System.Linq; using GameRes.Utility; -using System.Security.Cryptography; namespace GameRes.Formats.Purple { @@ -41,6 +40,7 @@ namespace GameRes.Formats.Purple public Cmvs.Md5Variant Md5Variant; public uint DecoderFactor; public uint EntryInitKey; + public uint EntrySubKey = 0x5C29E87B; public byte EntryTailKey; public byte EntryKeyPos = 9; public uint IndexSeed = 0x2A65CB4E; @@ -57,17 +57,6 @@ namespace GameRes.Formats.Purple public uint Key; } - internal class CpzHeader - { - public int DirCount; - public int DirEntriesSize; - public int FileEntriesSize; - public uint[] CmvsMd5 = new uint[4]; - public uint MasterKey; - public bool IsEncrypted; - public uint EntryKey; - } - internal class CpzArchive : ArcFile { public CpzHeader Header; @@ -98,7 +87,7 @@ namespace GameRes.Formats.Purple public CpzOpener () { - Signatures = new uint[] { 0x355A5043, 0x365A5043 }; + Signatures = new uint[] { 0x355A5043, 0x365A5043, 0x375A5043 }; } public static Dictionary KnownSchemes = new Dictionary(); @@ -113,75 +102,40 @@ namespace GameRes.Formats.Purple { if (null == KnownSchemes) throw new OperationCanceledException ("Outdated encryption schemes database"); - var header = file.View.ReadBytes (0, 0x3C); - var checksum = file.View.ReadUInt32 (0x3C); - if (checksum != CheckSum (header, 0, 0x3C, 0x923A564Cu)) - return null; - int version = header[3] - '0'; - CpzHeader cpz = 5 == version ? ReadHeaderV5 (header) : ReadHeaderV6 (header); - int index_size = cpz.DirEntriesSize + cpz.FileEntriesSize; - var index = file.View.ReadBytes (0x40, (uint)index_size); - if (index.Length != index_size) + + var cpz = CpzHeader.Parse (file); + if (null == cpz) return null; - using (var md5 = MD5.Create()) + var index = file.View.ReadBytes (cpz.IndexOffset, cpz.IndexSize); + if (!cpz.VerifyIndex (index)) + return null; + + int file_table_size = cpz.DirEntriesSize + cpz.FileEntriesSize; + if (cpz.IndexKeySize > 24) { - var hash = md5.ComputeHash (index); - if (!header.Skip (0x10).Take (0x10).SequenceEqual (hash)) - return null; + var index_key = UnpackIndexKey (index, file_table_size, cpz.IndexKeySize); + for (int i = 0; i < file_table_size; ++i) + { + index[i] ^= index_key[(i + 3) % 0x3FF]; + } } + + var index_copy = new CowArray (index, 0, file_table_size).ToArray(); var cmvs_md5 = cpz.CmvsMd5.Clone() as uint[]; - foreach (var scheme in KnownSchemes.Values.Where (s => s.Version == version)) + foreach (var scheme in KnownSchemes.Values.Where (s => s.Version == cpz.Version)) { var arc = ReadIndex (file, scheme, cpz, index); if (null != arc) return arc; // both CmvsMd5 and index was altered by ReadIndex in decryption attempt Array.Copy (cmvs_md5, cpz.CmvsMd5, 4); - file.View.Read (0x40, index, 0, (uint)index_size); + Array.Copy (index, index_copy, file_table_size); } throw new UnknownEncryptionScheme(); } - CpzHeader ReadHeaderV5 (byte[] header) - { - uint entry_key = 0x37ACF831 ^ LittleEndian.ToUInt32 (header, 0x38); - var cpz = new CpzHeader - { - DirCount = -0x1C5AC27 ^ LittleEndian.ToInt32 (header, 4), - DirEntriesSize = 0x37F298E7 ^ LittleEndian.ToInt32 (header, 8), - FileEntriesSize = 0x7A6F3A2C ^ LittleEndian.ToInt32 (header, 0x0C), - MasterKey = 0xAE7D39BF ^ LittleEndian.ToUInt32 (header, 0x30), - IsEncrypted = 0 != (0xFB73A955 ^ LittleEndian.ToUInt32 (header, 0x34)), - EntryKey = 0, - }; - cpz.CmvsMd5[0] = 0x43DE7C19 ^ LittleEndian.ToUInt32 (header, 0x20); - cpz.CmvsMd5[1] = 0xCC65F415 ^ LittleEndian.ToUInt32 (header, 0x24); - cpz.CmvsMd5[2] = 0xD016A93C ^ LittleEndian.ToUInt32 (header, 0x28); - cpz.CmvsMd5[3] = 0x97A3BA9A ^ LittleEndian.ToUInt32 (header, 0x2C); - return cpz; - } - - CpzHeader ReadHeaderV6 (byte[] header) - { - uint entry_key = 0x37ACF832 ^ LittleEndian.ToUInt32 (header, 0x38); - var cpz = new CpzHeader - { - DirCount = -0x1C5AC26 ^ LittleEndian.ToInt32 (header, 4), - DirEntriesSize = 0x37F298E8 ^ LittleEndian.ToInt32 (header, 8), - FileEntriesSize = 0x7A6F3A2D ^ LittleEndian.ToInt32 (header, 0x0C), - MasterKey = 0xAE7D39B7 ^ LittleEndian.ToUInt32 (header, 0x30), - IsEncrypted = 0 != (0xFB73A956 ^ LittleEndian.ToUInt32 (header, 0x34)), - EntryKey = 0x7DA8F173 * Binary.RotR (entry_key, 5) + 0x13712765, - }; - cpz.CmvsMd5[0] = 0x43DE7C1A ^ LittleEndian.ToUInt32 (header, 0x20); - cpz.CmvsMd5[1] = 0xCC65F416 ^ LittleEndian.ToUInt32 (header, 0x24); - cpz.CmvsMd5[2] = 0xD016A93D ^ LittleEndian.ToUInt32 (header, 0x28); - cpz.CmvsMd5[3] = 0x97A3BA9B ^ LittleEndian.ToUInt32 (header, 0x2C); - return cpz; - } - - ArcFile ReadIndex (ArcView file, CmvsScheme scheme, CpzHeader cpz, byte[] index) + internal ArcFile ReadIndex (ArcView file, CmvsScheme scheme, CpzHeader cpz, byte[] index) { var cmvs_md5 = Cmvs.MD5.Create (scheme.Md5Variant); cmvs_md5.Compute (cpz.CmvsMd5); @@ -200,7 +154,7 @@ namespace GameRes.Formats.Purple DecryptIndexDirectory (index, cpz.DirEntriesSize, key); decoder.Init (cpz.MasterKey, cpz.CmvsMd5[2]); - int base_offset = 0x40 + index.Length; + uint base_offset = cpz.IndexOffset + cpz.IndexSize; int dir_offset = 0; var dir = new List(); for (int i = 0; i < cpz.DirCount; ++i) @@ -239,16 +193,20 @@ namespace GameRes.Formats.Purple for (int j = 0; j < file_count; ++j) { int entry_size = LittleEndian.ToInt32 (index, cur_offset); - if (entry_size > index.Length || entry_size <= 0x18) + if (entry_size > index.Length || entry_size <= cpz.EntryNameOffset) return null; - var name = Binary.GetCString (index, cur_offset+0x18, cur_entries_end-(cur_offset+0x18)); + int name_offset = cur_offset + cpz.EntryNameOffset; + var name = Binary.GetCString (index, name_offset, cur_entries_end - name_offset); if (!is_root_dir) name = Path.Combine (dir_name, name); var entry = FormatCatalog.Instance.Create (name); entry.Offset = LittleEndian.ToInt64 (index, cur_offset+4) + base_offset; entry.Size = LittleEndian.ToUInt32 (index, cur_offset+0xC); - entry.CheckSum = LittleEndian.ToUInt32 (index, cur_offset+0x10); - entry.Key = LittleEndian.ToUInt32 (index, cur_offset+0x14) + dir_key; + int key_offset = cur_offset + 0x10; + if (cpz.IsLongSize) + key_offset += 4; + entry.CheckSum = LittleEndian.ToUInt32 (index, key_offset); + entry.Key = LittleEndian.ToUInt32 (index, key_offset+4) + dir_key; if (!entry.CheckPlacement (file.MaxOffset)) return null; dir.Add (entry); @@ -271,7 +229,8 @@ namespace GameRes.Formats.Purple var data = carc.File.View.ReadBytes (entry.Offset, entry.Size); if (carc.Header.IsEncrypted) { - uint key = (carc.Header.MasterKey ^ cent.Key) + (uint)carc.Header.DirCount - 0x5C29E87B; + uint key = (carc.Header.MasterKey ^ cent.Key) + (uint)carc.Header.DirCount; + key -= carc.Decoder.Scheme.EntrySubKey; key ^= carc.Header.EntryKey; carc.Decoder.DecryptEntry (data, carc.Header.CmvsMd5, key); } @@ -282,6 +241,21 @@ namespace GameRes.Formats.Purple return new BinMemoryStream (data, entry.Name); } + internal byte[] UnpackIndexKey (byte[] data, int offset, int length) + { + int key_offset = offset + 20; + int packed_offset = offset + 24; + int packed_length = length - 24; + for (int i = 0; i < packed_length; ++i) + { + data[packed_offset + i] ^= data[key_offset + (i & 3)]; + } + int unpacked_length = data.ToInt32 (offset + 16); + var output = new byte[unpacked_length]; + var decoder = new HuffmanDecoder (data, packed_offset, packed_length, output); + return decoder.Unpack(); + } + void DecryptIndexStage1 (byte[] data, uint key, CmvsScheme scheme) { var secret = scheme.Cpz5Secret; @@ -367,33 +341,6 @@ namespace GameRes.Formats.Purple } } - public static uint CheckSum (byte[] data, int index, int length, uint crc) - { - if (null == data) - throw new ArgumentNullException ("data"); - if (index < 0 || index > data.Length) - throw new ArgumentOutOfRangeException ("index"); - if (length < 0 || length > data.Length || length > data.Length-index) - throw new ArgumentException ("length"); - int dwords = length / 4; - if (dwords > 0) - { - unsafe - { - fixed (byte* raw = &data[index]) - { - uint* raw32 = (uint*)raw; - for (int i = 0; i < dwords; ++i) - crc += raw32[i]; - } - } - index += length & -4; - } - for (int i = 0; i < (length & 3); ++i) - crc += data[index+i]; - return crc; - } - byte[] UnpackPs2 (byte[] data) { DecryptPs2 (data); @@ -471,6 +418,8 @@ namespace GameRes.Formats.Purple protected byte[] m_decode_table = new byte[0x100]; protected CmvsScheme m_scheme; + public CmvsScheme Scheme { get { return m_scheme; } } + public Cpz5Decoder (CmvsScheme scheme, uint key, uint summand) { m_scheme = scheme; diff --git a/ArcFormats/Cmvs/CmvsMD5.cs b/ArcFormats/Cmvs/CmvsMD5.cs index 7042ec40..e68e7fea 100644 --- a/ArcFormats/Cmvs/CmvsMD5.cs +++ b/ArcFormats/Cmvs/CmvsMD5.cs @@ -27,7 +27,7 @@ using GameRes.Utility; namespace GameRes.Formats.Cmvs { - public enum Md5Variant { A, B, Chrono, Memoria, Natsu } + public enum Md5Variant { A, B, Chrono, Memoria, Natsu, Aoi } public abstract class MD5 : Cryptography.MD5Base { @@ -45,6 +45,7 @@ namespace GameRes.Formats.Cmvs case Md5Variant.Chrono: return new Md5Chrono(); case Md5Variant.Memoria: return new Md5Memoria(); case Md5Variant.Natsu: return new Md5Natsu(); + case Md5Variant.Aoi: return new Md5Aoi(); default: throw new System.ArgumentException ("Unknown MD5 variant", "variant"); } } @@ -151,4 +152,23 @@ namespace GameRes.Formats.Cmvs data[3] = m_state[0] ^ 0xE3F9A742; } } + + public class Md5Aoi : MD5 + { + protected override void InitState () + { + m_state[0] = 0xC74A2B02; + m_state[1] = 0xE7C8AB8F; + m_state[2] = 0x38BEBC4E; + m_state[3] = 0x7531A4C3; + } + + protected override void SetResult (uint[] data) + { + data[0] = m_state[2] ^ 0x53A76D2E; + data[1] = m_state[1] + 0x5BB17FDA; + data[2] = m_state[0] + 0x6853E14D; + data[3] = m_state[3] ^ 0xF5C6A9A3; + } + } } diff --git a/ArcFormats/Cmvs/CpzHeader.cs b/ArcFormats/Cmvs/CpzHeader.cs new file mode 100644 index 00000000..630718a1 --- /dev/null +++ b/ArcFormats/Cmvs/CpzHeader.cs @@ -0,0 +1,175 @@ +//! \file CpzHeader.cs +//! \date 2017 Nov 27 +//! \brief CPZ archives header class. +// +// Copyright (C) 2017 by morkt +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to +// deal in the Software without restriction, including without limitation the +// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or +// sell copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS +// IN THE SOFTWARE. +// + +using System; +using System.Collections.Generic; +using System.Linq; +using System.Security.Cryptography; +using GameRes.Utility; + +namespace GameRes.Formats.Purple +{ + internal class CpzHeader + { + public int Version; + public int DirCount; + public int DirEntriesSize; + public int FileEntriesSize; + public uint[] CmvsMd5 = new uint[4]; + public uint MasterKey; + public bool IsEncrypted; + public uint EntryKey; + public int IndexKeySize; + public uint Checksum; + + public uint InitChecksum = 0x923A564Cu; + public uint IndexOffset; + public uint IndexSize; + public IEnumerable IndexMd5; + public int EntryNameOffset; + + public bool IsLongSize { get { return Version > 6; } } + + public static CpzHeader Parse (ArcView file) + { + var cpz = new CpzHeader { Version = file.View.ReadByte (3) - '0' }; + int checksum_length; + byte[] header; + if (cpz.Version < 7) + { + header = file.View.ReadBytes (0, 0x40); + if (cpz.Version < 6) + cpz.ParseV5 (header); + else + cpz.ParseV6 (header); + cpz.IndexOffset = 0x40; + cpz.IndexSize = (uint)(cpz.DirEntriesSize + cpz.FileEntriesSize); + cpz.Checksum = header.ToUInt32 (0x3C); + checksum_length = 0x3C; + } + else + { + header = file.View.ReadBytes (0, 0x48); + cpz.ParseV7 (header); + cpz.IndexOffset = 0x48; + cpz.IndexSize = (uint)(cpz.DirEntriesSize + cpz.FileEntriesSize + cpz.IndexKeySize); + cpz.Checksum = header.ToUInt32 (0x44); + checksum_length = 0x40; + } + if (cpz.Checksum != CheckSum (header, 0, checksum_length, cpz.InitChecksum)) + return null; + + cpz.IndexMd5 = header.Skip (0x10).Take (0x10).ToArray(); + return cpz; + } + + private void ParseV5 (byte[] header) + { + DirCount = -0x1C5AC27 ^ LittleEndian.ToInt32 (header, 4); + DirEntriesSize = 0x37F298E7 ^ LittleEndian.ToInt32 (header, 8); + FileEntriesSize = 0x7A6F3A2C ^ LittleEndian.ToInt32 (header, 0x0C); + MasterKey = 0xAE7D39BF ^ LittleEndian.ToUInt32 (header, 0x30); + IsEncrypted = 0 != (0xFB73A955 ^ LittleEndian.ToUInt32 (header, 0x34)); + EntryKey = 0; + EntryNameOffset = 0x18; + CmvsMd5[0] = 0x43DE7C19 ^ LittleEndian.ToUInt32 (header, 0x20); + CmvsMd5[1] = 0xCC65F415 ^ LittleEndian.ToUInt32 (header, 0x24); + CmvsMd5[2] = 0xD016A93C ^ LittleEndian.ToUInt32 (header, 0x28); + CmvsMd5[3] = 0x97A3BA9A ^ LittleEndian.ToUInt32 (header, 0x2C); + } + + private void ParseV6 (byte[] header) + { + uint entry_key = 0x37ACF832 ^ LittleEndian.ToUInt32 (header, 0x38); + DirCount = -0x1C5AC26 ^ LittleEndian.ToInt32 (header, 4); + DirEntriesSize = 0x37F298E8 ^ LittleEndian.ToInt32 (header, 8); + FileEntriesSize = 0x7A6F3A2D ^ LittleEndian.ToInt32 (header, 0x0C); + MasterKey = 0xAE7D39B7 ^ LittleEndian.ToUInt32 (header, 0x30); + IsEncrypted = 0 != (0xFB73A956 ^ LittleEndian.ToUInt32 (header, 0x34)); + EntryKey = 0x7DA8F173 * Binary.RotR (entry_key, 5) + 0x13712765; + EntryNameOffset = 0x18; + CmvsMd5[0] = 0x43DE7C1A ^ LittleEndian.ToUInt32 (header, 0x20); + CmvsMd5[1] = 0xCC65F416 ^ LittleEndian.ToUInt32 (header, 0x24); + CmvsMd5[2] = 0xD016A93D ^ LittleEndian.ToUInt32 (header, 0x28); + CmvsMd5[3] = 0x97A3BA9B ^ LittleEndian.ToUInt32 (header, 0x2C); + } + + private void ParseV7 (byte[] header) + { + ParseV6 (header); + var index_key_size = LittleEndian.ToInt32 (header, 0x40); + IndexKeySize = 0x65EF99F3 ^ index_key_size; + InitChecksum = (uint)index_key_size - 0x6DC5A9B4u; + EntryNameOffset = 0x1C; + } + + public bool VerifyIndex (byte[] index) + { + if (index.Length != (int)IndexSize) + return false; + using (var md5 = MD5.Create()) + { + var hash = md5.ComputeHash (index); + if (!hash.SequenceEqual (IndexMd5)) + return false; + if (Version > 6 && IndexKeySize > 0x10) + { + int index_size = DirEntriesSize + FileEntriesSize; + hash = md5.ComputeHash (index, index_size+0x10, IndexKeySize-0x10); + if (!hash.SequenceEqual (index.Skip (index_size).Take (0x10))) + return false; + } + return true; + } + } + + public static uint CheckSum (byte[] data, int index, int length, uint crc) + { + if (null == data) + throw new ArgumentNullException ("data"); + if (index < 0 || index > data.Length) + throw new ArgumentOutOfRangeException ("index"); + if (length < 0 || length > data.Length || length > data.Length-index) + throw new ArgumentException ("length"); + int dwords = length / 4; + if (dwords > 0) + { + unsafe + { + fixed (byte* raw = &data[index]) + { + uint* raw32 = (uint*)raw; + for (int i = 0; i < dwords; ++i) + crc += raw32[i]; + } + } + index += length & -4; + } + for (int i = 0; i < (length & 3); ++i) + crc += data[index+i]; + return crc; + } + } +} diff --git a/ArcFormats/Cmvs/HuffmanDecoder.cs b/ArcFormats/Cmvs/HuffmanDecoder.cs new file mode 100644 index 00000000..9e5842bb --- /dev/null +++ b/ArcFormats/Cmvs/HuffmanDecoder.cs @@ -0,0 +1,108 @@ +//! \file HuffmanDecoder.cs +//! \date 2017 Nov 27 +//! \brief Custom Huffman decoder for CPZ archives. +// +// Copyright (C) 2017 by morkt +// +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to +// deal in the Software without restriction, including without limitation the +// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or +// sell copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in +// all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS +// IN THE SOFTWARE. +// + +using System.IO; +using GameRes.Utility; + +namespace GameRes.Formats.Purple +{ + internal sealed class HuffmanDecoder + { + byte[] m_input; + byte[] m_output; + + int m_src; + int m_bits; + int m_bit_count; + + ushort[] lhs = new ushort[512]; + ushort[] rhs = new ushort[512]; + ushort token = 256; + + public HuffmanDecoder (byte[] src, int index, int length, byte[] dst) + { + m_input = src; + m_output = dst; + + m_src = index; + m_bit_count = 0; + } + + public byte[] Unpack () + { + int dst = 0; + token = 256; + ushort root = CreateTree(); + while (dst < m_output.Length) + { + ushort symbol = root; + while (symbol >= 0x100) + { + if (0 != GetBits (1)) + symbol = rhs[symbol]; + else + symbol = lhs[symbol]; + } + m_output[dst++] = (byte)symbol; + } + return m_output; + } + + ushort CreateTree() + { + if (0 != GetBits (1)) + { + ushort v = token++; + if (v >= 511) + throw new InvalidDataException ("Invalid compressed data"); + lhs[v] = CreateTree(); + rhs[v] = CreateTree(); + return v; + } + else + { + return (ushort)GetBits (8); + } + } + + int GetBits (int count) + { + int bits = 0; + while (count --> 0) + { + if (0 == m_bit_count) + { + m_bits = LittleEndian.ToInt32 (m_input, m_src); + m_src += 4; + m_bit_count = 32; + } + bits = bits << 1 | (m_bits & 1); + m_bits >>= 1; + --m_bit_count; + } + return bits; + } + } +}