/**

 * FreeRDP: A Remote Desktop Protocol Implementation

 * MPPC Bulk Data Compression

 *

 * Copyright 2014 Marc-Andre Moreau <marcandre.moreau@gmail.com>

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <winpr/crt.h>

#include <winpr/print.h>

#include <winpr/stream.h>

#include <winpr/bitstream.h>

#include <freerdp/log.h>

#include <freerdp/codec/mppc.h>

#define TAG FREERDP_TAG("codec.mppc")

#define MPPC_MATCH_INDEX(_sym1, _sym2, _sym3) \

	((((MPPC_MATCH_TABLE[_sym3] << 16) + (MPPC_MATCH_TABLE[_sym2] << 8) + MPPC_MATCH_TABLE[_sym1]) & 0x07FFF000) >> 12)

static const UINT32 MPPC_MATCH_TABLE[256] =

{

	0x00000000, 0x009CCF93, 0x01399F26, 0x01D66EB9, 0x02733E4C, 0x03100DDF, 0x03ACDD72, 0x0449AD05,

	0x04E67C98, 0x05834C2B, 0x06201BBE, 0x06BCEB51, 0x0759BAE4, 0x07F68A77, 0x08935A0A, 0x0930299D,

	0x09CCF930, 0x0A69C8C3, 0x0B069856, 0x0BA367E9, 0x0C40377C, 0x0CDD070F, 0x0D79D6A2, 0x0E16A635,

	0x0EB375C8, 0x0F50455B, 0x0FED14EE, 0x1089E481, 0x1126B414, 0x11C383A7, 0x1260533A, 0x12FD22CD,

	0x1399F260, 0x1436C1F3, 0x14D39186, 0x15706119, 0x160D30AC, 0x16AA003F, 0x1746CFD2, 0x17E39F65,

	0x18806EF8, 0x191D3E8B, 0x19BA0E1E, 0x1A56DDB1, 0x1AF3AD44, 0x1B907CD7, 0x1C2D4C6A, 0x1CCA1BFD,

	0x1D66EB90, 0x1E03BB23, 0x1EA08AB6, 0x1F3D5A49, 0x1FDA29DC, 0x2076F96F, 0x2113C902, 0x21B09895,

	0x224D6828, 0x22EA37BB, 0x2387074E, 0x2423D6E1, 0x24C0A674, 0x255D7607, 0x25FA459A, 0x2697152D,

	0x2733E4C0, 0x27D0B453, 0x286D83E6, 0x290A5379, 0x29A7230C, 0x2A43F29F, 0x2AE0C232, 0x2B7D91C5,

	0x2C1A6158, 0x2CB730EB, 0x2D54007E, 0x2DF0D011, 0x2E8D9FA4, 0x2F2A6F37, 0x2FC73ECA, 0x30640E5D,

	0x3100DDF0, 0x319DAD83, 0x323A7D16, 0x32D74CA9, 0x33741C3C, 0x3410EBCF, 0x34ADBB62, 0x354A8AF5,

	0x35E75A88, 0x36842A1B, 0x3720F9AE, 0x37BDC941, 0x385A98D4, 0x38F76867, 0x399437FA, 0x3A31078D,

	0x3ACDD720, 0x3B6AA6B3, 0x3C077646, 0x3CA445D9, 0x3D41156C, 0x3DDDE4FF, 0x3E7AB492, 0x3F178425,

	0x3FB453B8, 0x4051234B, 0x40EDF2DE, 0x418AC271, 0x42279204, 0x42C46197, 0x4361312A, 0x43FE00BD,

	0x449AD050, 0x45379FE3, 0x45D46F76, 0x46713F09, 0x470E0E9C, 0x47AADE2F, 0x4847ADC2, 0x48E47D55,

	0x49814CE8, 0x4A1E1C7B, 0x4ABAEC0E, 0x4B57BBA1, 0x4BF48B34, 0x4C915AC7, 0x4D2E2A5A, 0x4DCAF9ED,

	0x4E67C980, 0x4F049913, 0x4FA168A6, 0x503E3839, 0x50DB07CC, 0x5177D75F, 0x5214A6F2, 0x52B17685,

	0x534E4618, 0x53EB15AB, 0x5487E53E, 0x5524B4D1, 0x55C18464, 0x565E53F7, 0x56FB238A, 0x5797F31D,

	0x5834C2B0, 0x58D19243, 0x596E61D6, 0x5A0B3169, 0x5AA800FC, 0x5B44D08F, 0x5BE1A022, 0x5C7E6FB5,

	0x5D1B3F48, 0x5DB80EDB, 0x5E54DE6E, 0x5EF1AE01, 0x5F8E7D94, 0x602B4D27, 0x60C81CBA, 0x6164EC4D,

	0x6201BBE0, 0x629E8B73, 0x633B5B06, 0x63D82A99, 0x6474FA2C, 0x6511C9BF, 0x65AE9952, 0x664B68E5,

	0x66E83878, 0x6785080B, 0x6821D79E, 0x68BEA731, 0x695B76C4, 0x69F84657, 0x6A9515EA, 0x6B31E57D,

	0x6BCEB510, 0x6C6B84A3, 0x6D085436, 0x6DA523C9, 0x6E41F35C, 0x6EDEC2EF, 0x6F7B9282, 0x70186215,

	0x70B531A8, 0x7152013B, 0x71EED0CE, 0x728BA061, 0x73286FF4, 0x73C53F87, 0x74620F1A, 0x74FEDEAD,

	0x759BAE40, 0x76387DD3, 0x76D54D66, 0x77721CF9, 0x780EEC8C, 0x78ABBC1F, 0x79488BB2, 0x79E55B45,

	0x7A822AD8, 0x7B1EFA6B, 0x7BBBC9FE, 0x7C589991, 0x7CF56924, 0x7D9238B7, 0x7E2F084A, 0x7ECBD7DD,

	0x7F68A770, 0x80057703, 0x80A24696, 0x813F1629, 0x81DBE5BC, 0x8278B54F, 0x831584E2, 0x83B25475,

	0x844F2408, 0x84EBF39B, 0x8588C32E, 0x862592C1, 0x86C26254, 0x875F31E7, 0x87FC017A, 0x8898D10D,

	0x8935A0A0, 0x89D27033, 0x8A6F3FC6, 0x8B0C0F59, 0x8BA8DEEC, 0x8C45AE7F, 0x8CE27E12, 0x8D7F4DA5,

	0x8E1C1D38, 0x8EB8ECCB, 0x8F55BC5E, 0x8FF28BF1, 0x908F5B84, 0x912C2B17, 0x91C8FAAA, 0x9265CA3D,

	0x930299D0, 0x939F6963, 0x943C38F6, 0x94D90889, 0x9575D81C, 0x9612A7AF, 0x96AF7742, 0x974C46D5,

	0x97E91668, 0x9885E5FB, 0x9922B58E, 0x99BF8521, 0x9A5C54B4, 0x9AF92447, 0x9B95F3DA, 0x9C32C36D

};

//#define DEBUG_MPPC	1

int mppc_decompress(MPPC_CONTEXT* mppc, BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData,

                    UINT32* pDstSize, UINT32 flags)

{

	BYTE Literal;

	BYTE* SrcPtr;

	UINT32 CopyOffset;

	UINT32 LengthOfMatch;

	UINT32 accumulator;

	BYTE* HistoryPtr;

	BYTE* HistoryBuffer;

	BYTE* HistoryBufferEnd;

	UINT32 HistoryBufferSize;

	UINT32 CompressionLevel;

	wBitStream* bs = mppc->bs;

	HistoryBuffer = mppc->HistoryBuffer;

	HistoryBufferSize = mppc->HistoryBufferSize;

	HistoryBufferEnd = &HistoryBuffer[HistoryBufferSize - 1];

	CompressionLevel = mppc->CompressionLevel;

	BitStream_Attach(bs, pSrcData, SrcSize);

	BitStream_Fetch(bs);

	if (flags & PACKET_AT_FRONT)

	{

		mppc->HistoryOffset = 0;

		mppc->HistoryPtr = HistoryBuffer;

	}

	if (flags & PACKET_FLUSHED)

	{

		mppc->HistoryOffset = 0;

		mppc->HistoryPtr = HistoryBuffer;

		ZeroMemory(HistoryBuffer, mppc->HistoryBufferSize);

	}

	HistoryPtr = mppc->HistoryPtr;

	if (!(flags & PACKET_COMPRESSED))

	{

		*pDstSize = SrcSize;

		*ppDstData = pSrcData;

		return 1;

	}

	while ((bs->length - bs->position) >= 8)

	{

		accumulator = bs->accumulator;

		/**

		 * Literal Encoding

		 */

		if (HistoryPtr > HistoryBufferEnd)

		{

			WLog_ERR(TAG,  "history buffer index out of range");

			return -1004;

		}

		if ((accumulator & 0x80000000) == 0x00000000)

		{

			/**

			 * Literal, less than 0x80

			 * bit 0 followed by the lower 7 bits of the literal

			 */

			Literal = ((accumulator & 0x7F000000) >> 24);

			*(HistoryPtr) = Literal;

			HistoryPtr++;

			BitStream_Shift(bs, 8);

			continue;

		}

		else if ((accumulator & 0xC0000000) == 0x80000000)

		{

			/**

			 * Literal, greater than 0x7F

			 * bits 10 followed by the lower 7 bits of the literal

			 */

			Literal = ((accumulator & 0x3F800000) >> 23) + 0x80;

			*(HistoryPtr) = Literal;

			HistoryPtr++;

			BitStream_Shift(bs, 9);

			continue;

		}

		/**

		 * CopyOffset Encoding

		 */

		if (CompressionLevel) /* RDP5 */

		{

			if ((accumulator & 0xF8000000) == 0xF8000000)

			{

				/**

				 * CopyOffset, range [0, 63]

				 * bits 11111 + lower 6 bits of CopyOffset

				 */

				CopyOffset = ((accumulator >> 21) & 0x3F);

				BitStream_Shift(bs, 11);

			}

			else if ((accumulator & 0xF8000000) == 0xF0000000)

			{

				/**

				 * CopyOffset, range [64, 319]

				 * bits 11110 + lower 8 bits of (CopyOffset - 64)

				 */

				CopyOffset = ((accumulator >> 19) & 0xFF) + 64;

				BitStream_Shift(bs, 13);

			}

			else if ((accumulator & 0xF0000000) == 0xE0000000)

			{

				/**

				 * CopyOffset, range [320, 2367]

				 * bits 1110 + lower 11 bits of (CopyOffset - 320)

				 */

				CopyOffset = ((accumulator >> 17) & 0x7FF) + 320;

				BitStream_Shift(bs, 15);

			}

			else if ((accumulator & 0xE0000000) == 0xC0000000)

			{

				/**

				 * CopyOffset, range [2368, ]

				 * bits 110 + lower 16 bits of (CopyOffset - 2368)

				 */

				CopyOffset = ((accumulator >> 13) & 0xFFFF) + 2368;

				BitStream_Shift(bs, 19);

			}

			else

			{

				/* Invalid CopyOffset Encoding */

				return -1001;

			}

		}

		else /* RDP4 */

		{

			if ((accumulator & 0xF0000000) == 0xF0000000)

			{

				/**

				 * CopyOffset, range [0, 63]

				 * bits 1111 + lower 6 bits of CopyOffset

				 */

				CopyOffset = ((accumulator >> 22) & 0x3F);

				BitStream_Shift(bs, 10);

			}

			else if ((accumulator & 0xF0000000) == 0xE0000000)

			{

				/**

				 * CopyOffset, range [64, 319]

				 * bits 1110 + lower 8 bits of (CopyOffset - 64)

				 */

				CopyOffset = ((accumulator >> 20) & 0xFF) + 64;

				BitStream_Shift(bs, 12);

			}

			else if ((accumulator & 0xE0000000) == 0xC0000000)

			{

				/**

				 * CopyOffset, range [320, 8191]

				 * bits 110 + lower 13 bits of (CopyOffset - 320)

				 */

				CopyOffset = ((accumulator >> 16) & 0x1FFF) + 320;

				BitStream_Shift(bs, 16);

			}

			else

			{

				/* Invalid CopyOffset Encoding */

				return -1002;

			}

		}

		/**

		 * LengthOfMatch Encoding

		 */

		accumulator = bs->accumulator;

		if ((accumulator & 0x80000000) == 0x00000000)

		{

			/**

			 * LengthOfMatch [3]

			 * bit 0 + 0 lower bits of LengthOfMatch

			 */

			LengthOfMatch = 3;

			BitStream_Shift(bs, 1);

		}

		else if ((accumulator & 0xC0000000) == 0x80000000)

		{

			/**

			 * LengthOfMatch [4, 7]

			 * bits 10 + 2 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 28) & 0x0003) + 0x0004;

			BitStream_Shift(bs, 4);

		}

		else if ((accumulator & 0xE0000000) == 0xC0000000)

		{

			/**

			 * LengthOfMatch [8, 15]

			 * bits 110 + 3 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 26) & 0x0007) + 0x0008;

			BitStream_Shift(bs, 6);

		}

		else if ((accumulator & 0xF0000000) == 0xE0000000)

		{

			/**

			 * LengthOfMatch [16, 31]

			 * bits 1110 + 4 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 24) & 0x000F) + 0x0010;

			BitStream_Shift(bs, 8);

		}

		else if ((accumulator & 0xF8000000) == 0xF0000000)

		{

			/**

			 * LengthOfMatch [32, 63]

			 * bits 11110 + 5 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 22) & 0x001F) + 0x0020;

			BitStream_Shift(bs, 10);

		}

		else if ((accumulator & 0xFC000000) == 0xF8000000)

		{

			/**

			 * LengthOfMatch [64, 127]

			 * bits 111110 + 6 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 20) & 0x003F) + 0x0040;

			BitStream_Shift(bs, 12);

		}

		else if ((accumulator & 0xFE000000) == 0xFC000000)

		{

			/**

			 * LengthOfMatch [128, 255]

			 * bits 1111110 + 7 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 18) & 0x007F) + 0x0080;

			BitStream_Shift(bs, 14);

		}

		else if ((accumulator & 0xFF000000) == 0xFE000000)

		{

			/**

			 * LengthOfMatch [256, 511]

			 * bits 11111110 + 8 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 16) & 0x00FF) + 0x0100;

			BitStream_Shift(bs, 16);

		}

		else if ((accumulator & 0xFF800000) == 0xFF000000)

		{

			/**

			 * LengthOfMatch [512, 1023]

			 * bits 111111110 + 9 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 14) & 0x01FF) + 0x0200;

			BitStream_Shift(bs, 18);

		}

		else if ((accumulator & 0xFFC00000) == 0xFF800000)

		{

			/**

			 * LengthOfMatch [1024, 2047]

			 * bits 1111111110 + 10 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 12) & 0x03FF) + 0x0400;

			BitStream_Shift(bs, 20);

		}

		else if ((accumulator & 0xFFE00000) == 0xFFC00000)

		{

			/**

			 * LengthOfMatch [2048, 4095]

			 * bits 11111111110 + 11 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 10) & 0x07FF) + 0x0800;

			BitStream_Shift(bs, 22);

		}

		else if ((accumulator & 0xFFF00000) == 0xFFE00000)

		{

			/**

			 * LengthOfMatch [4096, 8191]

			 * bits 111111111110 + 12 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 8) & 0x0FFF) + 0x1000;

			BitStream_Shift(bs, 24);

		}

		else if (((accumulator & 0xFFF80000) == 0xFFF00000) && CompressionLevel) /* RDP5 */

		{

			/**

			 * LengthOfMatch [8192, 16383]

			 * bits 1111111111110 + 13 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 6) & 0x1FFF) + 0x2000;

			BitStream_Shift(bs, 26);

		}

		else if (((accumulator & 0xFFFC0000) == 0xFFF80000) && CompressionLevel) /* RDP5 */

		{

			/**

			 * LengthOfMatch [16384, 32767]

			 * bits 11111111111110 + 14 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 4) & 0x3FFF) + 0x4000;

			BitStream_Shift(bs, 28);

		}

		else if (((accumulator & 0xFFFE0000) == 0xFFFC0000) && CompressionLevel) /* RDP5 */

		{

			/**

			 * LengthOfMatch [32768, 65535]

			 * bits 111111111111110 + 15 lower bits of LengthOfMatch

			 */

			LengthOfMatch = ((accumulator >> 2) & 0x7FFF) + 0x8000;

			BitStream_Shift(bs, 30);

		}

		else

		{

			/* Invalid LengthOfMatch Encoding */

			return -1003;

		}

#ifdef DEBUG_MPPC

		WLog_DBG(TAG, "<%"PRIu32",%"PRIu32">", CopyOffset, LengthOfMatch);

#endif

		if ((HistoryPtr + LengthOfMatch - 1) > HistoryBufferEnd)

		{

			WLog_ERR(TAG,  "history buffer overflow");

			return -1005;

		}

		SrcPtr = &HistoryBuffer[(HistoryPtr - HistoryBuffer - CopyOffset) & (CompressionLevel ? 0xFFFF :

		                        0x1FFF)];

		do

		{

			*HistoryPtr++ = *SrcPtr++;

		}

		while (--LengthOfMatch);

	}

	*pDstSize = (UINT32)(HistoryPtr - mppc->HistoryPtr);

	*ppDstData = mppc->HistoryPtr;

	mppc->HistoryPtr = HistoryPtr;

	return 1;

}

int mppc_compress(MPPC_CONTEXT* mppc, BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData,

                  UINT32* pDstSize, UINT32* pFlags)

{

	BYTE* pSrcPtr;

	BYTE* pSrcEnd;

	BYTE* MatchPtr;

	UINT32 DstSize;

	BYTE* pDstData;

	UINT32 MatchIndex;

	UINT32 accumulator;

	BOOL PacketFlushed;

	BOOL PacketAtFront;

	DWORD CopyOffset;

	DWORD LengthOfMatch;

	BYTE* HistoryBuffer;

	BYTE* HistoryPtr;

	UINT32 HistoryOffset;

	UINT32 HistoryBufferSize;

	BYTE Sym1, Sym2, Sym3;

	UINT32 CompressionLevel;

	wBitStream* bs = mppc->bs;

	HistoryBuffer = mppc->HistoryBuffer;

	HistoryBufferSize = mppc->HistoryBufferSize;

	CompressionLevel = mppc->CompressionLevel;

	HistoryOffset = mppc->HistoryOffset;

	*pFlags = 0;

	PacketFlushed = FALSE;

	if (((HistoryOffset + SrcSize) < (HistoryBufferSize - 3)) && HistoryOffset)

	{

		PacketAtFront = FALSE;

	}

	else

	{

		if (HistoryOffset == (HistoryBufferSize + 1))

			PacketFlushed = TRUE;

		HistoryOffset = 0;

		PacketAtFront = TRUE;

	}

	HistoryPtr = &(HistoryBuffer[HistoryOffset]);

	pDstData = *ppDstData;

	if (!pDstData)

		return -1;

	if (*pDstSize > SrcSize)

		DstSize = SrcSize;

	else

		DstSize = *pDstSize;

	BitStream_Attach(bs, pDstData, DstSize);

	pSrcPtr = pSrcData;

	pSrcEnd = &(pSrcData[SrcSize - 1]);

	while (pSrcPtr < (pSrcEnd - 2))

	{

		Sym1 = pSrcPtr[0];

		Sym2 = pSrcPtr[1];

		Sym3 = pSrcPtr[2];

		*HistoryPtr++ = *pSrcPtr++;

		MatchIndex = MPPC_MATCH_INDEX(Sym1, Sym2, Sym3);

		MatchPtr = &(HistoryBuffer[mppc->MatchBuffer[MatchIndex]]);

		if (MatchPtr != (HistoryPtr - 1))

			mppc->MatchBuffer[MatchIndex] = (UINT16)(HistoryPtr - HistoryBuffer);

		if (mppc->HistoryPtr < HistoryPtr)

			mppc->HistoryPtr = HistoryPtr;

		if ((Sym1 != *(MatchPtr - 1)) || (Sym2 != MatchPtr[0]) || (Sym3 != MatchPtr[1]) ||

		    (&MatchPtr[1] > mppc->HistoryPtr) || (MatchPtr == HistoryBuffer) ||

		    (MatchPtr == (HistoryPtr - 1)) || (MatchPtr == HistoryPtr))

		{

			if (((bs->position / 8) + 2) > (DstSize - 1))

			{

				mppc_context_reset(mppc, TRUE);

				*pFlags |= PACKET_FLUSHED;

				*pFlags |= CompressionLevel;

				*ppDstData = pSrcData;

				*pDstSize = SrcSize;

				return 1;

			}

			accumulator = Sym1;

#ifdef DEBUG_MPPC

			WLog_DBG(TAG, "%"PRIu32"", accumulator);

#endif

			if (accumulator < 0x80)

			{

				/* 8 bits of literal are encoded as-is */

				BitStream_Write_Bits(bs, accumulator, 8);

			}

			else

			{

				/* bits 10 followed by lower 7 bits of literal */

				accumulator = 0x100 | (accumulator & 0x7F);

				BitStream_Write_Bits(bs, accumulator, 9);

			}

		}

		else

		{

			CopyOffset = (HistoryBufferSize - 1) & (HistoryPtr - MatchPtr);

			*HistoryPtr++ = Sym2;

			*HistoryPtr++ = Sym3;

			pSrcPtr += 2;

			LengthOfMatch = 3;

			MatchPtr += 2;

			while ((*pSrcPtr == *MatchPtr) && (pSrcPtr < pSrcEnd) && (MatchPtr <= mppc->HistoryPtr))

			{

				MatchPtr++;

				*HistoryPtr++ = *pSrcPtr++;

				LengthOfMatch++;

			}

#ifdef DEBUG_MPPC

			WLog_DBG(TAG, "<%"PRIu32",%"PRIu32">", CopyOffset, LengthOfMatch);

#endif

			/* Encode CopyOffset */

			if (((bs->position / 8) + 7) > (DstSize - 1))

			{

				mppc_context_reset(mppc, TRUE);

				*pFlags |= PACKET_FLUSHED;

				*pFlags |= CompressionLevel;

				*ppDstData = pSrcData;

				*pDstSize = SrcSize;

				return 1;

			}

			if (CompressionLevel) /* RDP5 */

			{

				if (CopyOffset < 64)

				{

					/* bits 11111 + lower 6 bits of CopyOffset */

					accumulator = 0x07C0 | (CopyOffset & 0x003F);

					BitStream_Write_Bits(bs, accumulator, 11);

				}

				else if ((CopyOffset >= 64) && (CopyOffset < 320))

				{

					/* bits 11110 + lower 8 bits of (CopyOffset - 64) */

					accumulator = 0x1E00 | ((CopyOffset - 64) & 0x00FF);

					BitStream_Write_Bits(bs, accumulator, 13);

				}

				else if ((CopyOffset >= 320) && (CopyOffset < 2368))

				{

					/* bits 1110 + lower 11 bits of (CopyOffset - 320) */

					accumulator = 0x7000 | ((CopyOffset - 320) & 0x07FF);

					BitStream_Write_Bits(bs, accumulator, 15);

				}

				else

				{

					/* bits 110 + lower 16 bits of (CopyOffset - 2368) */

					accumulator = 0x060000 | ((CopyOffset - 2368) & 0xFFFF);

					BitStream_Write_Bits(bs, accumulator, 19);

				}

			}

			else /* RDP4 */

			{

				if (CopyOffset < 64)

				{

					/* bits 1111 + lower 6 bits of CopyOffset */

					accumulator = 0x03C0 | (CopyOffset & 0x003F);

					BitStream_Write_Bits(bs, accumulator, 10);

				}

				else if ((CopyOffset >= 64) && (CopyOffset < 320))

				{

					/* bits 1110 + lower 8 bits of (CopyOffset - 64) */

					accumulator = 0x0E00 | ((CopyOffset - 64) & 0x00FF);

					BitStream_Write_Bits(bs, accumulator, 12);

				}

				else if ((CopyOffset >= 320) && (CopyOffset < 8192))

				{

					/* bits 110 + lower 13 bits of (CopyOffset - 320) */

					accumulator = 0xC000 | ((CopyOffset - 320) & 0x1FFF);

					BitStream_Write_Bits(bs, accumulator, 16);

				}

			}

			/* Encode LengthOfMatch */

			if (LengthOfMatch == 3)

			{

				/* 0 + 0 lower bits of LengthOfMatch */

				BitStream_Write_Bits(bs, 0, 1);

			}

			else if ((LengthOfMatch >= 4) && (LengthOfMatch < 8))

			{

				/* 10 + 2 lower bits of LengthOfMatch */

				accumulator = 0x0008 | (LengthOfMatch & 0x0003);

				BitStream_Write_Bits(bs, accumulator, 4);

			}

			else if ((LengthOfMatch >= 8) && (LengthOfMatch < 16))

			{

				/* 110 + 3 lower bits of LengthOfMatch */

				accumulator = 0x0030 | (LengthOfMatch & 0x0007);

				BitStream_Write_Bits(bs, accumulator, 6);

			}

			else if ((LengthOfMatch >= 16) && (LengthOfMatch < 32))

			{

				/* 1110 + 4 lower bits of LengthOfMatch */

				accumulator = 0x00E0 | (LengthOfMatch & 0x000F);

				BitStream_Write_Bits(bs, accumulator, 8);

			}

			else if ((LengthOfMatch >= 32) && (LengthOfMatch < 64))

			{

				/* 11110 + 5 lower bits of LengthOfMatch */

				accumulator = 0x03C0 | (LengthOfMatch & 0x001F);

				BitStream_Write_Bits(bs, accumulator, 10);

			}

			else if ((LengthOfMatch >= 64) && (LengthOfMatch < 128))

			{

				/* 111110 + 6 lower bits of LengthOfMatch */

				accumulator = 0x0F80 | (LengthOfMatch & 0x003F);

				BitStream_Write_Bits(bs, accumulator, 12);

			}

			else if ((LengthOfMatch >= 128) && (LengthOfMatch < 256))

			{

				/* 1111110 + 7 lower bits of LengthOfMatch */

				accumulator = 0x3F00 | (LengthOfMatch & 0x007F);

				BitStream_Write_Bits(bs, accumulator, 14);

			}

			else if ((LengthOfMatch >= 256) && (LengthOfMatch < 512))

			{

				/* 11111110 + 8 lower bits of LengthOfMatch */

				accumulator = 0xFE00 | (LengthOfMatch & 0x00FF);

				BitStream_Write_Bits(bs, accumulator, 16);

			}

			else if ((LengthOfMatch >= 512) && (LengthOfMatch < 1024))

			{

				/* 111111110 + 9 lower bits of LengthOfMatch */

				accumulator = 0x3FC00 | (LengthOfMatch & 0x01FF);

				BitStream_Write_Bits(bs, accumulator, 18);

			}

			else if ((LengthOfMatch >= 1024) && (LengthOfMatch < 2048))

			{

				/* 1111111110 + 10 lower bits of LengthOfMatch */

				accumulator = 0xFF800 | (LengthOfMatch & 0x03FF);

				BitStream_Write_Bits(bs, accumulator, 20);

			}

			else if ((LengthOfMatch >= 2048) && (LengthOfMatch < 4096))

			{

				/* 11111111110 + 11 lower bits of LengthOfMatch */

				accumulator = 0x3FF000 | (LengthOfMatch & 0x07FF);

				BitStream_Write_Bits(bs, accumulator, 22);

			}

			else if ((LengthOfMatch >= 4096) && (LengthOfMatch < 8192))

			{

				/* 111111111110 + 12 lower bits of LengthOfMatch */

				accumulator = 0xFFE000 | (LengthOfMatch & 0x0FFF);

				BitStream_Write_Bits(bs, accumulator, 24);

			}

			else if (((LengthOfMatch >= 8192) && (LengthOfMatch < 16384)) && CompressionLevel) /* RDP5 */

			{

				/* 1111111111110 + 13 lower bits of LengthOfMatch */

				accumulator = 0x3FFC000 | (LengthOfMatch & 0x1FFF);

				BitStream_Write_Bits(bs, accumulator, 26);

			}

			else if (((LengthOfMatch >= 16384) && (LengthOfMatch < 32768)) && CompressionLevel) /* RDP5 */

			{

				/* 11111111111110 + 14 lower bits of LengthOfMatch */

				accumulator = 0xFFF8000 | (LengthOfMatch & 0x3FFF);

				BitStream_Write_Bits(bs, accumulator, 28);

			}

			else if (((LengthOfMatch >= 32768) && (LengthOfMatch < 65536)) && CompressionLevel) /* RDP5 */

			{

				/* 111111111111110 + 15 lower bits of LengthOfMatch */

				accumulator = 0x3FFF0000 | (LengthOfMatch & 0x7FFF);

				BitStream_Write_Bits(bs, accumulator, 30);

			}

		}

	}

	/* Encode trailing symbols as literals */

	while (pSrcPtr <= pSrcEnd)

	{

		if (((bs->position / 8) + 2) > (DstSize - 1))

		{

			mppc_context_reset(mppc, TRUE);

			*pFlags |= PACKET_FLUSHED;

			*pFlags |= CompressionLevel;

			*ppDstData = pSrcData;

			*pDstSize = SrcSize;

			return 1;

		}

		accumulator = *pSrcPtr;

#ifdef DEBUG_MPPC

		WLog_DBG(TAG, "%"PRIu32"", accumulator);

#endif

		if (accumulator < 0x80)

		{

			/* 8 bits of literal are encoded as-is */

			BitStream_Write_Bits(bs, accumulator, 8);

		}

		else

		{

			/* bits 10 followed by lower 7 bits of literal */

			accumulator = 0x100 | (accumulator & 0x7F);

			BitStream_Write_Bits(bs, accumulator, 9);

		}

		*HistoryPtr++ = *pSrcPtr++;

	}

	BitStream_Flush(bs);

	*pFlags |= PACKET_COMPRESSED;

	*pFlags |= CompressionLevel;

	if (PacketAtFront)

		*pFlags |= PACKET_AT_FRONT;

	if (PacketFlushed)

		*pFlags |= PACKET_FLUSHED;

	*pDstSize = ((bs->position + 7) / 8);

	mppc->HistoryPtr = HistoryPtr;

	mppc->HistoryOffset = HistoryPtr - HistoryBuffer;

	return 1;

}

void mppc_set_compression_level(MPPC_CONTEXT* mppc, DWORD CompressionLevel)

{

	if (CompressionLevel < 1)

	{

		mppc->CompressionLevel = 0;

		mppc->HistoryBufferSize = 8192;

	}

	else

	{

		mppc->CompressionLevel = 1;

		mppc->HistoryBufferSize = 65536;

	}

}

void mppc_context_reset(MPPC_CONTEXT* mppc, BOOL flush)

{

	ZeroMemory(&(mppc->HistoryBuffer), sizeof(mppc->HistoryBuffer));

	ZeroMemory(&(mppc->MatchBuffer), sizeof(mppc->MatchBuffer));

	if (flush)

		mppc->HistoryOffset = mppc->HistoryBufferSize + 1;

	else

		mppc->HistoryOffset = 0;

	mppc->HistoryPtr = &(mppc->HistoryBuffer[mppc->HistoryOffset]);

}

MPPC_CONTEXT* mppc_context_new(DWORD CompressionLevel, BOOL Compressor)

{

	MPPC_CONTEXT* mppc;

	mppc = calloc(1, sizeof(MPPC_CONTEXT));

	if (mppc)

	{

		mppc->Compressor = Compressor;

		if (CompressionLevel < 1)

		{

			mppc->CompressionLevel = 0;

			mppc->HistoryBufferSize = 8192;

		}

		else

		{

			mppc->CompressionLevel = 1;

			mppc->HistoryBufferSize = 65536;

		}

		mppc->bs = BitStream_New();

		if (!mppc->bs)

		{

			free(mppc);

			return NULL;

		}

		mppc_context_reset(mppc, FALSE);

	}

	return mppc;

}

void mppc_context_free(MPPC_CONTEXT* mppc)

{

	if (mppc)

	{

		BitStream_Free(mppc->bs);

		free(mppc);

	}

}