/**
 * FreeRDP: A Remote Desktop Protocol Implementation
 * Implements Microsoft Point to Point Compression (MPPC) protocol
 *
 * Copyright 2011 Laxmikant Rashinkar <LK.Rashinkar@gmail.com>
 * Copyright 2012 Jiten Pathy 
 *
 * 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 <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <winpr/crt.h>

#include <freerdp/codec/mppc_dec.h>

static BYTE HuffLenLEC[] = {
0x6, 0x6, 0x6, 0x7, 0x7, 0x7, 0x7, 0x7, 0x7, 0x7, 0x7, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x9, 0x8, 0x9, 0x9, 0x9, 0x9, 0x8, 0x8, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9, 0x8, 0x9, 0x9, 0xa, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9, 0xa, 0x9, 0xa, 0xa, 0xa, 0x9, 0x9, 0xa, 0x9, 0xa, 0x9, 0xa, 0x9, 0x9, 0x9, 0xa, 0xa, 0x9, 0xa, 0x9, 0x9, 0x8, 0x9, 0x9, 0x9, 0x9, 0xa, 0xa, 0xa, 0x9, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x8, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0x7, 0x9, 0x9, 0xa, 0x9, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xd, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xb, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0xa, 0x9, 0xa, 0x8, 0x9, 0x9, 0xa, 0x9, 0xa, 0xa, 0xa, 0x9, 0xa, 0xa, 0xa, 0x9, 0x9, 0x8, 0x7, 0xd, 0xd, 0x7, 0x7, 0xa, 0x7, 0x7, 0x6, 0x6, 0x6, 0x6, 0x5, 0x6, 0x6, 0x6, 0x5, 0x6, 0x5, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x6, 0x8, 0x5, 0x6, 0x7, 0x7 }; 

static UINT16 HuffIndexLEC[512] = { 
0x007b, 0xff1f, 0xff0d, 0xfe27, 0xfe00, 0xff05, 0xff17, 0xfe68, 0x00c5, 0xfe07, 0xff13, 0xfec0, 0xff08, 0xfe18, 0xff1b, 0xfeb3, 0xfe03, 0x00a2, 0xfe42, 0xff10, 0xfe0b, 0xfe02, 0xfe91, 0xff19, 0xfe80, 0x00e9, 0xfe3a, 0xff15, 0xfe12, 0x0057, 0xfed7, 0xff1d, 0xff0e, 0xfe35, 0xfe69, 0xff22, 0xff18, 0xfe7a, 0xfe01, 0xff23, 0xff14, 0xfef4, 0xfeb4, 0xfe09, 0xff1c, 0xfec4, 0xff09, 0xfe60, 0xfe70, 0xff12, 0xfe05, 0xfe92, 0xfea1, 0xff1a, 0xfe0f, 0xff07, 0xfe56, 0xff16, 0xff02, 0xfed8, 0xfee8, 0xff1e, 0xfe1d, 0x003b, 0xffff, 0xff06, 0xffff, 0xfe71, 0xfe89, 0xffff, 0xffff, 0xfe2c, 0xfe2b, 0xfe20, 0xffff, 0xfebb, 0xfecf, 0xfe08, 0xffff, 0xfee0, 0xfe0d, 0xffff, 0xfe99, 0xffff, 0xfe04, 0xfeaa, 0xfe49, 0xffff, 0xfe17, 0xfe61, 0xfedf, 0xffff, 0xfeff, 0xfef6, 0xfe4c, 0xffff, 0xffff, 0xfe87, 0xffff, 0xff24, 0xffff, 0xfe3c, 0xfe72, 0xffff, 0xffff, 0xfece, 0xffff, 0xfefe, 0xffff, 0xfe23, 0xfebc, 0xfe0a, 0xfea9, 0xffff, 0xfe11, 0xffff, 0xfe82, 0xffff, 0xfe06, 0xfe9a, 0xfef5, 0xffff, 0xfe22, 0xfe4d, 0xfe5f, 0xffff, 0xff03, 0xfee1, 0xffff, 0xfeca, 0xfecc, 0xffff, 0xfe19, 0xffff, 0xfeb7, 0xffff, 0xffff, 0xfe83, 0xfe29, 0xffff, 0xffff, 0xffff, 0xfe6c, 0xffff, 0xfeed, 0xffff, 0xffff, 0xfe46, 0xfe5c, 0xfe15, 0xffff, 0xfedb, 0xfea6, 0xffff, 0xffff, 0xfe44, 0xffff, 0xfe0c, 0xffff, 0xfe95, 0xfefc, 0xffff, 0xffff, 0xfeb8, 0x16c9, 0xffff, 0xfef0, 0xffff, 0xfe38, 0xffff, 0xffff, 0xfe6d, 0xfe7e, 0xffff, 0xffff, 0xffff, 0xffff, 0xfe5b, 0xfedc, 0xffff, 0xffff, 0xfeec, 0xfe47, 0xfe1f, 0xffff, 0xfe7f, 0xfe96, 0xffff, 0xffff, 0xfea5, 0xffff, 0xfe10, 0xfe40, 0xfe32, 0xfebf, 0xffff, 0xffff, 0xfed4, 0xfef1, 0xffff, 0xffff, 0xffff, 0xfe75, 0xffff, 0xffff, 0xfe8d, 0xfe31, 0xffff, 0xfe65, 0xfe1b, 0xffff, 0xfee4, 0xfefb, 0xffff, 0xffff, 0xfe52, 0xffff, 0xfe0e, 0xffff, 0xfe9d, 0xfeaf, 0xffff, 0xffff, 0xfe51, 0xfed3, 0xffff, 0xff20, 0xffff, 0xfe2f, 0xffff, 0xffff, 0xfec1, 0xfe8c, 0xffff, 0xffff, 0xffff, 0xfe3f, 0xffff, 0xffff, 0xfe76, 0xffff, 0xfefa, 0xfe53, 0xfe25, 0xffff, 0xfe64, 0xfee5, 0xffff, 0xffff, 0xfeae, 0xffff, 0xfe13, 0xffff, 0xfe88, 0xfe9e, 0xffff, 0xfe43, 0xffff, 0xffff, 0xfea4, 0xfe93, 0xffff, 0xffff, 0xffff, 0xfe3d, 0xffff, 0xffff, 0xfeeb, 0xfed9, 0xffff, 0xfe14, 0xfe5a, 0xffff, 0xfe28, 0xfe7d, 0xffff, 0xffff, 0xfe6a, 0xffff, 0xffff, 0xff01, 0xfec6, 0xfec8, 0xffff, 0xffff, 0xfeb5, 0xffff, 0xffff, 0xffff, 0xfe94, 0xfe78, 0xffff, 0xffff, 0xffff, 0xfea3, 0xffff, 0xffff, 0xfeda, 0xfe58, 0xffff, 0xfe1e, 0xfe45, 0xfeea, 0xffff, 0xfe6b, 0xffff, 0xffff, 0xfe37, 0xffff, 0xffff, 0xffff, 0xfe7c, 0xfeb6, 0xffff, 0xffff, 0xfef8, 0xffff, 0xffff, 0xffff, 0xfec7, 0xfe9b, 0xffff, 0xffff, 0xffff, 0xfe50, 0xffff, 0xffff, 0xfead, 0xfee2, 0xffff, 0xfe1a, 0xfe63, 0xfe4e, 0xffff, 0xffff, 0xfef9, 0xffff, 0xfe73, 0xffff, 0xffff, 0xffff, 0xfe30, 0xfe8b, 0xffff, 0xffff, 0xfebd, 0xfe2e, 0x0100, 0xffff, 0xfeee, 0xfed2, 0xffff, 0xffff, 0xffff, 0xfeac, 0xffff, 0xffff, 0xfe9c, 0xfe84, 0xffff, 0xfe24, 0xfe4f, 0xfef7, 0xffff, 0xffff, 0xfee3, 0xfe62, 0xffff, 0xffff, 0xffff, 0xffff, 0xfe8a, 0xfe74, 0xffff, 0xffff, 0xfe3e, 0xffff, 0xffff, 0xffff, 0xfed1, 0xfebe, 0xffff, 0xffff, 0xfe2d, 0xffff, 0xfe4a, 0xfef3, 0xffff, 0xffff, 0xfedd, 0xfe5e, 0xfe16, 0xffff, 0xfe48, 0xfea8, 0xffff, 0xfeab, 0xfe97, 0xffff, 0xffff, 0xfed0, 0xffff, 0xffff, 0xfecd, 0xfeb9, 0xffff, 0xffff, 0xffff, 0xfe2a, 0xffff, 0xffff, 0xfe86, 0xfe6e, 0xffff, 0xffff, 0xffff, 0xfede, 0xffff, 0xffff, 0xfe5d, 0xfe4b, 0xfe21, 0xffff, 0xfeef, 0xfe98, 0xffff, 0xffff, 0xfe81, 0xffff, 0xffff, 0xffff, 0xfea7, 0xffff, 0xfeba, 0xfefd, 0xffff, 0xffff, 0xffff, 0xfecb, 0xffff, 0xffff, 0xfe6f, 0xfe39, 0xffff, 0xffff, 0xffff, 0xfe85, 0xffff, 0x010c, 0xfee6, 0xfe67, 0xfe1c, 0xffff, 0xfe54, 0xfeb2, 0xffff, 0xffff, 0xfe9f, 0xffff, 0xffff, 0xffff, 0xfe59, 0xfeb1, 0xffff, 0xfec2, 0xffff, 0xffff, 0xfe36, 0xfef2, 0xffff, 0xffff, 0xfed6, 0xfe77, 0xffff, 0xffff, 0xffff, 0xfe33, 0xffff, 0xffff, 0xfe8f, 0xfe55, 0xfe26, 0x010a, 0xff04, 0xfee7, 0xffff, 0x0121, 0xfe66, 0xffff, 0xffff, 0xffff, 0xfeb0, 0xfea0, 0xffff, 0x010f, 0xfe90, 0xffff, 0xffff, 0xfed5, 0xffff, 0xffff, 0xfec3, 0xfe34, 0xffff, 0xffff, 0xffff, 0xfe8e, 0xffff, 0x0111, 0xfe79, 0xfe41, 0x010b };

static UINT16 LECHTab[] = {511, 0, 508, 448, 494, 347, 486, 482};

static BYTE HuffLenLOM[] = {
0x4, 0x2, 0x3, 0x4, 0x3, 0x4, 0x4, 0x5, 0x4, 0x5, 0x5, 0x6, 0x6, 0x7, 0x7, 0x8, 0x7, 0x8, 0x8, 0x9, 0x9, 0x8, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9, 0x9 };

static UINT16 HuffIndexLOM[] = {
0xfe1, 0xfe0, 0xfe2, 0xfe8, 0xe, 0xfe5, 0xfe4, 0xfea, 0xff1, 0xfe3, 0x15, 0xfe7, 0xfef, 0x46, 0xff0, 0xfed, 0xfff, 0xff7, 0xffb, 0x19, 0xffd, 0xff4, 0x12c, 0xfeb, 0xffe, 0xff6, 0xffa, 0x89, 0xffc, 0xff3, 0xff8, 0xff2 };

static BYTE LOMHTab[] = {0, 4, 10, 19};

static BYTE CopyOffsetBitsLUT[] = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15 };

static UINT32 CopyOffsetBaseLUT[] = {
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577, 32769, 49153, 65537 };

static BYTE LOMBitsLUT[] = {
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 6, 6, 8, 8, 14, 14 };

static UINT16 LOMBaseLUT[] = {
2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 22, 26, 30, 34, 42, 50, 58, 66, 82, 98, 114, 130, 194, 258, 514, 2, 2 };

UINT16 LEChash(UINT16 key)
{
	return ((key & 0x1ff) ^ (key  >> 9) ^ (key >> 4) ^ (key >> 7));
}

UINT16 LOMhash(UINT16 key)
{
	return ((key & 0x1f) ^ (key  >> 5) ^ (key >> 9));
}
			
UINT16 miniLEChash(UINT16 key)
{
	UINT16 h;
	h = ((((key >> 8) ^ (key & 0xff)) >> 2) & 0xf);
	if(key >> 9)
		h = ~h;
	return (h % 12);
}

BYTE miniLOMhash(UINT16 key)
{
	BYTE h;
	h = (key >> 4) & 0xf;
	return ((h ^ (h >> 2) ^ (h >> 3)) & 0x3);
}

UINT16 getLECindex(UINT16 huff)
{
	UINT16 h = HuffIndexLEC[LEChash(huff)];
	if((h ^ huff) >> 9)
		return h & 0x1ff;
	else
		return HuffIndexLEC[LECHTab[miniLEChash(huff)]];
}

UINT16 getLOMindex(UINT16 huff)
{
	UINT16 h = HuffIndexLOM[LOMhash(huff)];
	if((h ^ huff) >> 5)
	{	
		return h & 0x1f;
	}	
	else
		return HuffIndexLOM[LOMHTab[miniLOMhash(huff)]];
}

UINT32 transposebits(UINT32 x)
{
	x = ((x & 0x55555555) << 1) | ((x >> 1) & 0x55555555);
	x = ((x & 0x33333333) << 2) | ((x >> 2) & 0x33333333);
	x = ((x & 0x0f0f0f0f) << 4) | ((x >> 4) & 0x0f0f0f0f);
	if((x >> 8) == 0) 
		return x;
	x = ((x & 0x00ff00ff) << 8) | ((x >> 8) & 0x00ff00ff);
	if((x >> 16) == 0) 
		return x;
	x = ((x & 0x0000ffff) << 16) | ((x >> 16) & 0x0000ffff);
	return x;
}

#define cache_add(_s, _x) do { \
		*((UINT32*)((_s)+2)) <<= 16; \
		*((UINT32*)((_s)+2)) |= (*((UINT32*)(_s)) >> 16); \
		*((UINT32*)(_s)) = (*((UINT32*)(_s)) << 16) | (_x); } while(0)

#define cache_swap(_s, _i) do { \
		UINT16 t = *(_s); \
		*(_s) = *((_s) + (_i)); \
		*((_s) + (_i)) = t; } while(0)

/**
 * decompress RDP 6 data
 *
 * @param rdp     per session information
 * @param cbuf    compressed data
 * @param len     length of compressed data
 * @param ctype   compression flags
 * @param roff    starting offset of uncompressed data
 * @param rlen    length of uncompressed data
 *
 * @return        True on success, False on failure
 */

int decompress_rdp_6(struct rdp_mppc_dec* dec, BYTE* cbuf, int len, int ctype, UINT32* roff, UINT32* rlen)
{
	BYTE*    history_buf;    /* uncompressed data goes here */
	UINT16*   offset_cache;	  /* Copy Offset cache */
	BYTE*    history_ptr;    /* points to next free slot in bistory_buf */
	UINT32    d32;            /* we process 4 compressed bytes at a time */
	UINT16    copy_offset;    /* location to copy data from */
	UINT16    lom;            /* length of match */
	UINT16    LUTIndex;       /* LookUp table Index */
	BYTE*    src_ptr;        /* used while copying compressed data */
	BYTE*    cptr;           /* points to next byte in cbuf */
	BYTE     cur_byte;       /* last byte fetched from cbuf */
	int       bits_left;      /* bits left in d32 for processing */
	int       cur_bits_left;  /* bits left in cur_byte for processing */
	int       tmp, i;
	UINT32    i32;

	if ((dec == NULL) || (dec->history_buf == NULL))
	{
		fprintf(stderr, "decompress_rdp_6: null\n");
		return FALSE;
	}

	src_ptr = 0;
	cptr = cbuf;
	copy_offset = 0;
	lom = 0;
	bits_left = 0;
	cur_bits_left = 0;
	d32 = 0;
	cur_byte = 0;
	*rlen = 0;

	/* get start of history buffer */
	history_buf = dec->history_buf;

	/* get start of offset_cache */
	offset_cache = dec->offset_cache;

	/* get next free slot in history buffer */
	history_ptr = dec->history_ptr;
	*roff = history_ptr - history_buf;

	if (ctype & PACKET_AT_FRONT)
	{
		/* slid history_buf and reset history_buf to middle */
		memmove(history_buf, (history_buf + (history_ptr - history_buf - 32768)), 32768);
		history_ptr = history_buf + 32768;
		dec->history_ptr = history_ptr;
		*roff = 32768;
	}
	
	if (ctype & PACKET_FLUSHED)
	{
		/* re-init history buffer */
		history_ptr = dec->history_buf;
		memset(history_buf, 0, RDP6_HISTORY_BUF_SIZE);
		memset(offset_cache, 0, RDP6_OFFSET_CACHE_SIZE);
		*roff = 0;
	}

	if ((ctype & PACKET_COMPRESSED) != PACKET_COMPRESSED)
	{
		/* data in cbuf is not compressed - copy to history buf as is */
		memcpy(history_ptr, cbuf, len);
		history_ptr += len;
		*rlen = history_ptr - dec->history_ptr;
		dec->history_ptr = history_ptr;
		return TRUE;
	}

	/* load initial data */
	tmp = 0;
	while (cptr < cbuf + len)
	{
		i32 = *cptr++;
		d32  |= i32 << tmp;
		bits_left += 8;
		tmp += 8;
		if (tmp >= 32)
		{
			break;
		}
	}

	d32 = transposebits(d32);

	if (cptr < cbuf + len)
	{
		cur_byte = transposebits(*cptr++);
		cur_bits_left = 8;
	}
	else
	{
		cur_bits_left = 0;
	}

	/*
	** start uncompressing data in cbuf
	*/

	while (bits_left >= 8)
	{
		/* Decode Huffman Code for Literal/EOS/CopyOffset */
		copy_offset = 0;
		for(i = 0x5; i <= 0xd; i++)
		{
			if(i == 0xc)
				continue;
			i32 = transposebits((d32 & (0xffffffff << (32 - i))));
			i32 = getLECindex(i32);
			if(i == HuffLenLEC[i32])
				break;
		}
		d32 <<= i;
		bits_left -= i;
		if(i32 < 256)
			*history_ptr++ = (BYTE)i32;
		else if(i32 > 256 && i32 < 289)
		{
			LUTIndex = i32 - 257;
			tmp = CopyOffsetBitsLUT[LUTIndex];
			copy_offset = CopyOffsetBaseLUT[LUTIndex] - 0x1;
			if(tmp != 0)
				copy_offset += transposebits(d32 & (0xffffffff << (32 - tmp)));
			cache_add(offset_cache, copy_offset);
			d32 <<= tmp;
			bits_left -= tmp;
		}
		else if( i32 > 288 && i32 < 293)
		{
			LUTIndex = i32 - 289;
			copy_offset = *(offset_cache + LUTIndex);
			if(LUTIndex != 0)
				cache_swap(offset_cache, LUTIndex);
		}
		else if(i32 == 256)
			break;


		/*
		** get more bits before we process length of match
		*/

		/* how may bits do we need to get? */
		tmp = 32 - bits_left;
		while (tmp)
		{
			if (cur_bits_left < tmp)
			{	
				/* we have less bits than we need */
				i32 = cur_byte >> (8 - cur_bits_left);
				d32 |= i32 << ((32 - bits_left) - cur_bits_left);
				bits_left += cur_bits_left;
				tmp -= cur_bits_left;
				if (cptr < cbuf + len)
				{
					/* more compressed data available */
					cur_byte = transposebits(*cptr++);
					cur_bits_left = 8;
				}
				else
				{
					/* no more compressed data available */
					tmp = 0;
					cur_bits_left = 0;
				}
			}
			else if (cur_bits_left > tmp)
			{	
				/* we have more bits than we need */
				d32 |= cur_byte >> (8 - tmp);
				cur_byte <<= tmp;
				cur_bits_left -= tmp;
				bits_left = 32;
				break;
			}
			else
			{
				/* we have just the right amount of bits */
				d32 |= cur_byte >> (8 - tmp);
				bits_left = 32;
				if (cptr < cbuf + len)
				{
					cur_byte = transposebits(*cptr++);
					cur_bits_left = 8;
				}
				else
					cur_bits_left = 0;
				break;
			}
		}

		if (!copy_offset)
			continue;

		for(i = 0x2; i <= 0x9; i++)
		{
			i32 = transposebits((d32 & (0xffffffff << (32 - i))));
			i32 = getLOMindex(i32);
			if(i == HuffLenLOM[i32])
				break;
		}
		d32 <<= i;
		bits_left -= i;
		tmp = LOMBitsLUT[i32];
		lom = LOMBaseLUT[i32];
		if(tmp != 0)
			lom += transposebits(d32 & (0xffffffff << (32 - tmp)));
		d32 <<= tmp;
		bits_left -= tmp;

		/* now that we have copy_offset and LoM, process them */

		src_ptr = history_ptr - copy_offset;
		tmp = (lom > copy_offset) ? copy_offset : lom;
		i32 = 0;
		if (src_ptr >= dec->history_buf)
		{
			while(tmp > 0)
			{
				*history_ptr++ = *src_ptr++;
				tmp--;
			}
			while (lom > copy_offset)
			{	
				i32 = ((i32 >= copy_offset)) ? 0 : i32;
				*history_ptr++ = *(src_ptr + i32++);
				lom--;
			}
		}
		else
		{
			src_ptr = dec->history_buf_end - (copy_offset - (history_ptr - dec->history_buf));
			src_ptr++;
			while (tmp && (src_ptr <= dec->history_buf_end))
			{
				*history_ptr++ = *src_ptr++;
				tmp--;
			}
			src_ptr = dec->history_buf;
			while (tmp > 0)
			{
				*history_ptr++ = *src_ptr++;
				tmp--;
			}
			while (lom > copy_offset)
			{
				i32 = ((i32 > copy_offset)) ? 0 : i32;
				*history_ptr++ = *(src_ptr + i32++);
				lom--;
			}
		}

		/*
		** get more bits before we restart the loop
		*/

		/* how may bits do we need to get? */
		assert(bits_left <= 32);
		assert(cur_bits_left <= bits_left);
		tmp = 32 - bits_left;

		while (tmp)
		{
			if (cur_bits_left < tmp)
			{
				/* we have less bits than we need */
				i32 = cur_byte >> (8 - cur_bits_left);
				d32 |= (i32 << ((32 - bits_left) - cur_bits_left)) & 0xFFFFFFFF;
				bits_left += cur_bits_left;
				tmp -= cur_bits_left;
				if (cptr < cbuf + len)
				{
					/* more compressed data available */
					cur_byte = transposebits(*cptr++);
					cur_bits_left = 8;
				}
				else
				{
					/* no more compressed data available */
					tmp = 0;
					cur_bits_left = 0;
				}
			}
			else if (cur_bits_left > tmp)
			{
				/* we have more bits than we need */
				d32 |= cur_byte >> (8 - tmp);
				cur_byte <<= tmp;
				cur_bits_left -= tmp;
				bits_left = 32;
				break;
			}
			else
			{
				/* we have just the right amount of bits */
				d32 |= cur_byte >> (8 - tmp);
				bits_left = 32;
				if (cptr < cbuf + len)
				{
					cur_byte = transposebits(*cptr++);
					cur_bits_left = 8;
				}
				else
				{
					cur_bits_left = 0;
				}
				break;
			}
		}

	}/* end while (bits_left >= 8) */

	if(ctype & PACKET_FLUSHED)
		*rlen = history_ptr - history_buf;
	else
		*rlen = history_ptr - dec->history_ptr;

	dec->history_ptr = history_ptr;

	return TRUE;
}

/**
 * allocate space to store history buffer
 *
 * @param rdp rdp struct that contains rdp_mppc struct
 * @return pointer to new struct, or NULL on failure
 */

struct rdp_mppc_dec* mppc_dec_new(void)
{
	struct rdp_mppc_dec* ptr;

	ptr = (struct rdp_mppc_dec*) malloc(sizeof(struct rdp_mppc_dec));
	if (!ptr)
	{
		fprintf(stderr, "mppc_new(): system out of memory\n");
		return NULL;
	}

	ptr->history_buf = (BYTE*) malloc(RDP6_HISTORY_BUF_SIZE);
	ZeroMemory(ptr->history_buf, RDP6_HISTORY_BUF_SIZE);

	ptr->offset_cache = (UINT16*) malloc(RDP6_OFFSET_CACHE_SIZE);
	ZeroMemory(ptr->offset_cache, RDP6_OFFSET_CACHE_SIZE);

	if (!ptr->history_buf)
	{
		fprintf(stderr, "mppc_new(): system out of memory\n");
		free(ptr);
		return NULL;
	}

	ptr->history_ptr = ptr->history_buf;
	ptr->history_buf_end = ptr->history_buf + RDP6_HISTORY_BUF_SIZE - 1;
	return ptr;
}

/**
 * free history buffer
 *
 * @param rdp rdp struct that contains rdp_mppc struct
 */

void mppc_dec_free(struct rdp_mppc_dec* dec)
{
	if (!dec)
	{
		return;
	}

	if (dec->history_buf)
	{
		free(dec->history_buf);
		dec->history_buf = NULL;
		dec->history_ptr = NULL;
	}
	if (dec->offset_cache)
	{
		free(dec->offset_cache);
		dec->offset_cache = NULL;
	}
	free(dec);
}