/src/FreeRDP/libfreerdp/codec/zgfx.c

Source (jump to first uncovered line)
/**
 * FreeRDP: A Remote Desktop Protocol Implementation
 * ZGFX (RDP8) Bulk Data Compression
 *
 * Copyright 2014 Marc-Andre Moreau <marcandre.moreau@gmail.com>
 * Copyright 2017 Armin Novak <armin.novak@thincast.com>
 * Copyright 2017 Thincast Technologies GmbH
 *
 * 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.
 */

#include <freerdp/config.h>

#include <winpr/crt.h>
#include <winpr/print.h>
#include <winpr/bitstream.h>

#include <freerdp/log.h>
#include <freerdp/codec/zgfx.h>

#define TAG FREERDP_TAG("codec")

/**
 * RDP8 Compressor Limits:
 *
 * Maximum number of uncompressed bytes in a single segment: 65535
 * Maximum match distance / minimum history size: 2500000 bytes.
 * Maximum number of segments: 65535
 * Maximum expansion of a segment (when compressed size exceeds uncompressed): 1000 bytes
 * Minimum match length: 3 bytes
 */

typedef struct
{
  UINT32 prefixLength;
  UINT32 prefixCode;
  UINT32 valueBits;
  UINT32 tokenType;
  UINT32 valueBase;
} ZGFX_TOKEN;

struct S_ZGFX_CONTEXT
{
  BOOL Compressor;

  const BYTE* pbInputCurrent;
  const BYTE* pbInputEnd;

  UINT32 bits;
  UINT32 cBitsRemaining;
  UINT32 BitsCurrent;
  UINT32 cBitsCurrent;

  BYTE OutputBuffer[65536];
  UINT32 OutputCount;

  BYTE HistoryBuffer[2500000];
  UINT32 HistoryIndex;
  UINT32 HistoryBufferSize;
};

static const ZGFX_TOKEN ZGFX_TOKEN_TABLE[] = {
  // len code vbits type  vbase
  { 1, 0, 8, 0, 0 },           // 0
  { 5, 17, 5, 1, 0 },          // 10001
  { 5, 18, 7, 1, 32 },         // 10010
  { 5, 19, 9, 1, 160 },        // 10011
  { 5, 20, 10, 1, 672 },       // 10100
  { 5, 21, 12, 1, 1696 },      // 10101
  { 5, 24, 0, 0, 0x00 },       // 11000
  { 5, 25, 0, 0, 0x01 },       // 11001
  { 6, 44, 14, 1, 5792 },      // 101100
  { 6, 45, 15, 1, 22176 },     // 101101
  { 6, 52, 0, 0, 0x02 },       // 110100
  { 6, 53, 0, 0, 0x03 },       // 110101
  { 6, 54, 0, 0, 0xFF },       // 110110
  { 7, 92, 18, 1, 54944 },     // 1011100
  { 7, 93, 20, 1, 317088 },    // 1011101
  { 7, 110, 0, 0, 0x04 },      // 1101110
  { 7, 111, 0, 0, 0x05 },      // 1101111
  { 7, 112, 0, 0, 0x06 },      // 1110000
  { 7, 113, 0, 0, 0x07 },      // 1110001
  { 7, 114, 0, 0, 0x08 },      // 1110010
  { 7, 115, 0, 0, 0x09 },      // 1110011
  { 7, 116, 0, 0, 0x0A },      // 1110100
  { 7, 117, 0, 0, 0x0B },      // 1110101
  { 7, 118, 0, 0, 0x3A },      // 1110110
  { 7, 119, 0, 0, 0x3B },      // 1110111
  { 7, 120, 0, 0, 0x3C },      // 1111000
  { 7, 121, 0, 0, 0x3D },      // 1111001
  { 7, 122, 0, 0, 0x3E },      // 1111010
  { 7, 123, 0, 0, 0x3F },      // 1111011
  { 7, 124, 0, 0, 0x40 },      // 1111100
  { 7, 125, 0, 0, 0x80 },      // 1111101
  { 8, 188, 20, 1, 1365664 },  // 10111100
  { 8, 189, 21, 1, 2414240 },  // 10111101
  { 8, 252, 0, 0, 0x0C },      // 11111100
  { 8, 253, 0, 0, 0x38 },      // 11111101
  { 8, 254, 0, 0, 0x39 },      // 11111110
  { 8, 255, 0, 0, 0x66 },      // 11111111
  { 9, 380, 22, 1, 4511392 },  // 101111100
  { 9, 381, 23, 1, 8705696 },  // 101111101
  { 9, 382, 24, 1, 17094304 }, // 101111110
  { 0 }
};

static INLINE BOOL zgfx_GetBits(ZGFX_CONTEXT* zgfx, UINT32 nbits)
{
  if (!zgfx)
    return FALSE;

  while (zgfx->cBitsCurrent < nbits)
  {
    zgfx->BitsCurrent <<= 8;

    if (zgfx->pbInputCurrent < zgfx->pbInputEnd)
      zgfx->BitsCurrent += *(zgfx->pbInputCurrent)++;

    zgfx->cBitsCurrent += 8;
  }

  zgfx->cBitsRemaining -= nbits;
  zgfx->cBitsCurrent -= nbits;
  zgfx->bits = zgfx->BitsCurrent >> zgfx->cBitsCurrent;
  zgfx->BitsCurrent &= ((1 << zgfx->cBitsCurrent) - 1);
  return TRUE;
}

static void zgfx_history_buffer_ring_write(ZGFX_CONTEXT* zgfx, const BYTE* src, size_t count)
{
  UINT32 front = 0;

  if (count <= 0)
    return;

  if (count > zgfx->HistoryBufferSize)
  {
    const size_t residue = count - zgfx->HistoryBufferSize;
    count = zgfx->HistoryBufferSize;
    src += residue;
    zgfx->HistoryIndex = (zgfx->HistoryIndex + residue) % zgfx->HistoryBufferSize;
  }

  if (zgfx->HistoryIndex + count <= zgfx->HistoryBufferSize)
  {
    CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, count);

    if ((zgfx->HistoryIndex += count) == zgfx->HistoryBufferSize)
      zgfx->HistoryIndex = 0;
  }
  else
  {
    front = zgfx->HistoryBufferSize - zgfx->HistoryIndex;
    CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, front);
    CopyMemory(zgfx->HistoryBuffer, &src[front], count - front);
    zgfx->HistoryIndex = count - front;
  }
}

static void zgfx_history_buffer_ring_read(ZGFX_CONTEXT* zgfx, int offset, BYTE* dst, UINT32 count)
{
  UINT32 front = 0;
  UINT32 index = 0;
  INT32 bytes = 0;
  UINT32 valid = 0;
  INT32 bytesLeft = 0;
  BYTE* dptr = dst;
  BYTE* origDst = dst;

  if ((count <= 0) || (count > INT32_MAX))
    return;

  bytesLeft = (INT32)count;
  index = (zgfx->HistoryIndex + zgfx->HistoryBufferSize - offset) % zgfx->HistoryBufferSize;
  bytes = MIN(bytesLeft, offset);

  if ((index + bytes) <= zgfx->HistoryBufferSize)
  {
    CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), bytes);
  }
  else
  {
    front = zgfx->HistoryBufferSize - index;
    CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), front);
    CopyMemory(&dptr[front], zgfx->HistoryBuffer, bytes - front);
  }

  if ((bytesLeft -= bytes) == 0)
    return;

  dptr += bytes;
  valid = bytes;

  do
  {
    bytes = valid;

    if (bytes > bytesLeft)
      bytes = bytesLeft;

    CopyMemory(dptr, origDst, bytes);
    dptr += bytes;
    valid <<= 1;
  } while ((bytesLeft -= bytes) > 0);
}

static BOOL zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, wStream* stream, size_t segmentSize)
{
  BYTE c = 0;
  BYTE flags = 0;
  UINT32 extra = 0;
  int opIndex = 0;
  UINT32 haveBits = 0;
  UINT32 inPrefix = 0;
  UINT32 count = 0;
  UINT32 distance = 0;
  BYTE* pbSegment = NULL;
  size_t cbSegment = 0;

  WINPR_ASSERT(zgfx);
  WINPR_ASSERT(stream);

  if (segmentSize < 2)
    return FALSE;

  cbSegment = segmentSize - 1;

  if (!Stream_CheckAndLogRequiredLength(TAG, stream, segmentSize) || (segmentSize > UINT32_MAX))
    return FALSE;

  Stream_Read_UINT8(stream, flags); /* header (1 byte) */
  zgfx->OutputCount = 0;
  pbSegment = Stream_Pointer(stream);
  if (!Stream_SafeSeek(stream, cbSegment))
    return FALSE;

  if (!(flags & PACKET_COMPRESSED))
  {
    zgfx_history_buffer_ring_write(zgfx, pbSegment, cbSegment);

    if (cbSegment > sizeof(zgfx->OutputBuffer))
      return FALSE;

    CopyMemory(zgfx->OutputBuffer, pbSegment, cbSegment);
    zgfx->OutputCount = cbSegment;
    return TRUE;
  }

  zgfx->pbInputCurrent = pbSegment;
  zgfx->pbInputEnd = &pbSegment[cbSegment - 1];
  /* NumberOfBitsToDecode = ((NumberOfBytesToDecode - 1) * 8) - ValueOfLastByte */
  const UINT32 bits = 8u * (cbSegment - 1u);
  if (bits < *zgfx->pbInputEnd)
    return FALSE;

  zgfx->cBitsRemaining = bits - *zgfx->pbInputEnd;
  zgfx->cBitsCurrent = 0;
  zgfx->BitsCurrent = 0;

  while (zgfx->cBitsRemaining)
  {
    haveBits = 0;
    inPrefix = 0;

    for (opIndex = 0; ZGFX_TOKEN_TABLE[opIndex].prefixLength != 0; opIndex++)
    {
      while (haveBits < ZGFX_TOKEN_TABLE[opIndex].prefixLength)
      {
        zgfx_GetBits(zgfx, 1);
        inPrefix = (inPrefix << 1) + zgfx->bits;
        haveBits++;
      }

      if (inPrefix == ZGFX_TOKEN_TABLE[opIndex].prefixCode)
      {
        if (ZGFX_TOKEN_TABLE[opIndex].tokenType == 0)
        {
          /* Literal */
          zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
          c = (BYTE)(ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits);
          zgfx->HistoryBuffer[zgfx->HistoryIndex] = c;

          if (++zgfx->HistoryIndex == zgfx->HistoryBufferSize)
            zgfx->HistoryIndex = 0;

          if (zgfx->OutputCount >= sizeof(zgfx->OutputBuffer))
            return FALSE;

          zgfx->OutputBuffer[zgfx->OutputCount++] = c;
        }
        else
        {
          zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
          distance = ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits;

          if (distance != 0)
          {
            /* Match */
            zgfx_GetBits(zgfx, 1);

            if (zgfx->bits == 0)
            {
              count = 3;
            }
            else
            {
              count = 4;
              extra = 2;
              zgfx_GetBits(zgfx, 1);

              while (zgfx->bits == 1)
              {
                count *= 2;
                extra++;
                zgfx_GetBits(zgfx, 1);
              }

              zgfx_GetBits(zgfx, extra);
              count += zgfx->bits;
            }

            if (count > sizeof(zgfx->OutputBuffer) - zgfx->OutputCount)
              return FALSE;

            zgfx_history_buffer_ring_read(
                zgfx, distance, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
            zgfx_history_buffer_ring_write(
                zgfx, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
            zgfx->OutputCount += count;
          }
          else
          {
            /* Unencoded */
            zgfx_GetBits(zgfx, 15);
            count = zgfx->bits;
            zgfx->cBitsRemaining -= zgfx->cBitsCurrent;
            zgfx->cBitsCurrent = 0;
            zgfx->BitsCurrent = 0;

            if (count > sizeof(zgfx->OutputBuffer) - zgfx->OutputCount)
              return FALSE;
            else if (count > zgfx->cBitsRemaining / 8)
              return FALSE;
            else if (zgfx->pbInputCurrent + count > zgfx->pbInputEnd)
              return FALSE;

            CopyMemory(&(zgfx->OutputBuffer[zgfx->OutputCount]), zgfx->pbInputCurrent,
                       count);
            zgfx_history_buffer_ring_write(zgfx, zgfx->pbInputCurrent, count);
            zgfx->pbInputCurrent += count;
            zgfx->cBitsRemaining -= (8 * count);
            zgfx->OutputCount += count;
          }
        }

        break;
      }
    }
  }

  return TRUE;
}

/* Allocate the buffers a bit larger.
 *
 * Due to optimizations some h264 decoders will read data beyond
 * the actual available data, so ensure that it will never be a
 * out of bounds read.
 */
static BYTE* aligned_zgfx_malloc(size_t size)
{
  return malloc(size + 64);
}

static BOOL zgfx_append(ZGFX_CONTEXT* zgfx, BYTE** ppConcatenated, size_t uncompressedSize,
                        size_t* pUsed)
{
  WINPR_ASSERT(zgfx);
  WINPR_ASSERT(ppConcatenated);
  WINPR_ASSERT(pUsed);

  const size_t used = *pUsed;
  if (zgfx->OutputCount > UINT32_MAX - used)
    return FALSE;

  if (used + zgfx->OutputCount > uncompressedSize)
    return FALSE;

  BYTE* tmp = realloc(*ppConcatenated, used + zgfx->OutputCount + 64ull);
  if (!tmp)
    return FALSE;
  *ppConcatenated = tmp;
  CopyMemory(&tmp[used], zgfx->OutputBuffer, zgfx->OutputCount);
  *pUsed = used + zgfx->OutputCount;
  return TRUE;
}

int zgfx_decompress(ZGFX_CONTEXT* zgfx, const BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData,
                    UINT32* pDstSize, UINT32 flags)
{
  int status = -1;
  BYTE descriptor = 0;
  wStream sbuffer = { 0 };
  size_t used = 0;
  BYTE* pConcatenated = NULL;
  wStream* stream = Stream_StaticConstInit(&sbuffer, pSrcData, SrcSize);

  WINPR_ASSERT(zgfx);
  WINPR_ASSERT(stream);
  WINPR_ASSERT(ppDstData);
  WINPR_ASSERT(pDstSize);

  *ppDstData = NULL;
  *pDstSize = 0;

  if (!Stream_CheckAndLogRequiredLength(TAG, stream, 1))
    goto fail;

  Stream_Read_UINT8(stream, descriptor); /* descriptor (1 byte) */

  if (descriptor == ZGFX_SEGMENTED_SINGLE)
  {
    if (!zgfx_decompress_segment(zgfx, stream, Stream_GetRemainingLength(stream)))
      goto fail;

    if (zgfx->OutputCount > 0)
    {
      if (!zgfx_append(zgfx, &pConcatenated, zgfx->OutputCount, &used))
        goto fail;
      if (used != zgfx->OutputCount)
        goto fail;
      *ppDstData = pConcatenated;
      *pDstSize = zgfx->OutputCount;
    }
  }
  else if (descriptor == ZGFX_SEGMENTED_MULTIPART)
  {
    UINT32 segmentSize = 0;
    UINT16 segmentNumber = 0;
    UINT16 segmentCount = 0;
    UINT32 uncompressedSize = 0;

    if (!Stream_CheckAndLogRequiredLength(TAG, stream, 6))
      goto fail;

    Stream_Read_UINT16(stream, segmentCount);     /* segmentCount (2 bytes) */
    Stream_Read_UINT32(stream, uncompressedSize); /* uncompressedSize (4 bytes) */

    for (segmentNumber = 0; segmentNumber < segmentCount; segmentNumber++)
    {
      if (!Stream_CheckAndLogRequiredLength(TAG, stream, sizeof(UINT32)))
        goto fail;

      Stream_Read_UINT32(stream, segmentSize); /* segmentSize (4 bytes) */

      if (!zgfx_decompress_segment(zgfx, stream, segmentSize))
        goto fail;

      if (!zgfx_append(zgfx, &pConcatenated, uncompressedSize, &used))
        goto fail;
    }

    if (used != uncompressedSize)
      goto fail;

    *ppDstData = pConcatenated;
    *pDstSize = uncompressedSize;
  }
  else
  {
    goto fail;
  }

  status = 1;
fail:
  if (status < 0)
    free(pConcatenated);
  return status;
}

static BOOL zgfx_compress_segment(ZGFX_CONTEXT* zgfx, wStream* s, const BYTE* pSrcData,
                                  UINT32 SrcSize, UINT32* pFlags)
{
  /* FIXME: Currently compression not implemented. Just copy the raw source */
  if (!Stream_EnsureRemainingCapacity(s, SrcSize + 1))
  {
    WLog_ERR(TAG, "Stream_EnsureRemainingCapacity failed!");
    return FALSE;
  }

  (*pFlags) |= ZGFX_PACKET_COMPR_TYPE_RDP8; /* RDP 8.0 compression format */
  Stream_Write_UINT8(s, (*pFlags));         /* header (1 byte) */
  Stream_Write(s, pSrcData, SrcSize);
  return TRUE;
}

int zgfx_compress_to_stream(ZGFX_CONTEXT* zgfx, wStream* sDst, const BYTE* pUncompressed,
                            UINT32 uncompressedSize, UINT32* pFlags)
{
  int fragment = 0;
  UINT16 maxLength = 0;
  UINT32 totalLength = 0;
  size_t posSegmentCount = 0;
  const BYTE* pSrcData = NULL;
  int status = 0;
  maxLength = ZGFX_SEGMENTED_MAXSIZE;
  totalLength = uncompressedSize;
  pSrcData = pUncompressed;

  for (; (totalLength > 0) || (fragment == 0); fragment++)
  {
    UINT32 SrcSize = 0;
    size_t posDstSize = 0;
    size_t posDataStart = 0;
    UINT32 DstSize = 0;
    SrcSize = (totalLength > maxLength) ? maxLength : totalLength;
    posDstSize = 0;
    totalLength -= SrcSize;

    /* Ensure we have enough space for headers */
    if (!Stream_EnsureRemainingCapacity(sDst, 12))
    {
      WLog_ERR(TAG, "Stream_EnsureRemainingCapacity failed!");
      return -1;
    }

    if (fragment == 0)
    {
      /* First fragment */
      /* descriptor (1 byte) */
      Stream_Write_UINT8(sDst, (totalLength == 0) ? ZGFX_SEGMENTED_SINGLE
                                                  : ZGFX_SEGMENTED_MULTIPART);

      if (totalLength > 0)
      {
        posSegmentCount = Stream_GetPosition(sDst); /* segmentCount (2 bytes) */
        Stream_Seek(sDst, 2);
        Stream_Write_UINT32(sDst, uncompressedSize); /* uncompressedSize (4 bytes) */
      }
    }

    if (fragment > 0 || totalLength > 0)
    {
      /* Multipart */
      posDstSize = Stream_GetPosition(sDst); /* size (4 bytes) */
      Stream_Seek(sDst, 4);
    }

    posDataStart = Stream_GetPosition(sDst);

    if (!zgfx_compress_segment(zgfx, sDst, pSrcData, SrcSize, pFlags))
      return -1;

    if (posDstSize)
    {
      /* Fill segment data size */
      DstSize = Stream_GetPosition(sDst) - posDataStart;
      Stream_SetPosition(sDst, posDstSize);
      Stream_Write_UINT32(sDst, DstSize);
      Stream_SetPosition(sDst, posDataStart + DstSize);
    }

    pSrcData += SrcSize;
  }

  Stream_SealLength(sDst);

  /* fill back segmentCount */
  if (posSegmentCount)
  {
    Stream_SetPosition(sDst, posSegmentCount);
    Stream_Write_UINT16(sDst, fragment);
    Stream_SetPosition(sDst, Stream_Length(sDst));
  }

  return status;
}

int zgfx_compress(ZGFX_CONTEXT* zgfx, const BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData,
                  UINT32* pDstSize, UINT32* pFlags)
{
  int status = 0;
  wStream* s = Stream_New(NULL, SrcSize);
  status = zgfx_compress_to_stream(zgfx, s, pSrcData, SrcSize, pFlags);
  (*ppDstData) = Stream_Buffer(s);
  (*pDstSize) = Stream_GetPosition(s);
  Stream_Free(s, FALSE);
  return status;
}

void zgfx_context_reset(ZGFX_CONTEXT* zgfx, BOOL flush)
{
  zgfx->HistoryIndex = 0;
}

ZGFX_CONTEXT* zgfx_context_new(BOOL Compressor)
{
  ZGFX_CONTEXT* zgfx = NULL;
  zgfx = (ZGFX_CONTEXT*)calloc(1, sizeof(ZGFX_CONTEXT));

  if (zgfx)
  {
    zgfx->Compressor = Compressor;
    zgfx->HistoryBufferSize = sizeof(zgfx->HistoryBuffer);
    zgfx_context_reset(zgfx, FALSE);
  }

  return zgfx;
}

void zgfx_context_free(ZGFX_CONTEXT* zgfx)
{
  free(zgfx);
}

Coverage Report

Created: 2024-05-20 06:11

Line	Count	Source (jump to first uncovered line)
1		/**
2		* FreeRDP: A Remote Desktop Protocol Implementation
3		* ZGFX (RDP8) Bulk Data Compression
4		*
5		* Copyright 2014 Marc-Andre Moreau <marcandre.moreau@gmail.com>
6		* Copyright 2017 Armin Novak <armin.novak@thincast.com>
7		* Copyright 2017 Thincast Technologies GmbH
8		*
9		* Licensed under the Apache License, Version 2.0 (the "License");
10		* you may not use this file except in compliance with the License.
11		* You may obtain a copy of the License at
12		*
13		* http://www.apache.org/licenses/LICENSE-2.0
14		*
15		* Unless required by applicable law or agreed to in writing, software
16		* distributed under the License is distributed on an "AS IS" BASIS,
17		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18		* See the License for the specific language governing permissions and
19		* limitations under the License.
20		*/
21
22		#include <freerdp/config.h>
23
24		#include <winpr/crt.h>
25		#include <winpr/print.h>
26		#include <winpr/bitstream.h>
27
28		#include <freerdp/log.h>
29		#include <freerdp/codec/zgfx.h>
30
31		#define TAG FREERDP_TAG("codec")
32
33		/**
34		* RDP8 Compressor Limits:
35		*
36		* Maximum number of uncompressed bytes in a single segment: 65535
37		* Maximum match distance / minimum history size: 2500000 bytes.
38		* Maximum number of segments: 65535
39		* Maximum expansion of a segment (when compressed size exceeds uncompressed): 1000 bytes
40		* Minimum match length: 3 bytes
41		*/
42
43		typedef struct
44		{
45		UINT32 prefixLength;
46		UINT32 prefixCode;
47		UINT32 valueBits;
48		UINT32 tokenType;
49		UINT32 valueBase;
50		} ZGFX_TOKEN;
51
52		struct S_ZGFX_CONTEXT
53		{
54		BOOL Compressor;
55
56		const BYTE* pbInputCurrent;
57		const BYTE* pbInputEnd;
58
59		UINT32 bits;
60		UINT32 cBitsRemaining;
61		UINT32 BitsCurrent;
62		UINT32 cBitsCurrent;
63
64		BYTE OutputBuffer[65536];
65		UINT32 OutputCount;
66
67		BYTE HistoryBuffer[2500000];
68		UINT32 HistoryIndex;
69		UINT32 HistoryBufferSize;
70		};
71
72		static const ZGFX_TOKEN ZGFX_TOKEN_TABLE[] = {
73		// len code vbits type vbase
74		{ 1, 0, 8, 0, 0 }, // 0
75		{ 5, 17, 5, 1, 0 }, // 10001
76		{ 5, 18, 7, 1, 32 }, // 10010
77		{ 5, 19, 9, 1, 160 }, // 10011
78		{ 5, 20, 10, 1, 672 }, // 10100
79		{ 5, 21, 12, 1, 1696 }, // 10101
80		{ 5, 24, 0, 0, 0x00 }, // 11000
81		{ 5, 25, 0, 0, 0x01 }, // 11001
82		{ 6, 44, 14, 1, 5792 }, // 101100
83		{ 6, 45, 15, 1, 22176 }, // 101101
84		{ 6, 52, 0, 0, 0x02 }, // 110100
85		{ 6, 53, 0, 0, 0x03 }, // 110101
86		{ 6, 54, 0, 0, 0xFF }, // 110110
87		{ 7, 92, 18, 1, 54944 }, // 1011100
88		{ 7, 93, 20, 1, 317088 }, // 1011101
89		{ 7, 110, 0, 0, 0x04 }, // 1101110
90		{ 7, 111, 0, 0, 0x05 }, // 1101111
91		{ 7, 112, 0, 0, 0x06 }, // 1110000
92		{ 7, 113, 0, 0, 0x07 }, // 1110001
93		{ 7, 114, 0, 0, 0x08 }, // 1110010
94		{ 7, 115, 0, 0, 0x09 }, // 1110011
95		{ 7, 116, 0, 0, 0x0A }, // 1110100
96		{ 7, 117, 0, 0, 0x0B }, // 1110101
97		{ 7, 118, 0, 0, 0x3A }, // 1110110
98		{ 7, 119, 0, 0, 0x3B }, // 1110111
99		{ 7, 120, 0, 0, 0x3C }, // 1111000
100		{ 7, 121, 0, 0, 0x3D }, // 1111001
101		{ 7, 122, 0, 0, 0x3E }, // 1111010
102		{ 7, 123, 0, 0, 0x3F }, // 1111011
103		{ 7, 124, 0, 0, 0x40 }, // 1111100
104		{ 7, 125, 0, 0, 0x80 }, // 1111101
105		{ 8, 188, 20, 1, 1365664 }, // 10111100
106		{ 8, 189, 21, 1, 2414240 }, // 10111101
107		{ 8, 252, 0, 0, 0x0C }, // 11111100
108		{ 8, 253, 0, 0, 0x38 }, // 11111101
109		{ 8, 254, 0, 0, 0x39 }, // 11111110
110		{ 8, 255, 0, 0, 0x66 }, // 11111111
111		{ 9, 380, 22, 1, 4511392 }, // 101111100
112		{ 9, 381, 23, 1, 8705696 }, // 101111101
113		{ 9, 382, 24, 1, 17094304 }, // 101111110
114		{ 0 }
115		};
116
117		static INLINE BOOL zgfx_GetBits(ZGFX_CONTEXT* zgfx, UINT32 nbits)
118	49.6M	{
119	49.6M	if (!zgfx)
120	0	return FALSE;
121
122	75.4M	while (zgfx->cBitsCurrent < nbits)
123	25.8M	{
124	25.8M	zgfx->BitsCurrent <<= 8;
125
126	25.8M	if (zgfx->pbInputCurrent < zgfx->pbInputEnd)
127	1.69M	zgfx->BitsCurrent += *(zgfx->pbInputCurrent)++;
128
129	25.8M	zgfx->cBitsCurrent += 8;
130	25.8M	}
131
132	49.6M	zgfx->cBitsRemaining -= nbits;
133	49.6M	zgfx->cBitsCurrent -= nbits;
134	49.6M	zgfx->bits = zgfx->BitsCurrent >> zgfx->cBitsCurrent;
135	49.6M	zgfx->BitsCurrent &= ((1 << zgfx->cBitsCurrent) - 1);
136	49.6M	return TRUE;
137	49.6M	}
138
139		static void zgfx_history_buffer_ring_write(ZGFX_CONTEXT* zgfx, const BYTE* src, size_t count)
140	44.4k	{
141	44.4k	UINT32 front = 0;
142
143	44.4k	if (count <= 0)
144	789	return;
145
146	43.6k	if (count > zgfx->HistoryBufferSize)
147	0	{
148	0	const size_t residue = count - zgfx->HistoryBufferSize;
149	0	count = zgfx->HistoryBufferSize;
150	0	src += residue;
151	0	zgfx->HistoryIndex = (zgfx->HistoryIndex + residue) % zgfx->HistoryBufferSize;
152	0	}
153
154	43.6k	if (zgfx->HistoryIndex + count <= zgfx->HistoryBufferSize)
155	43.6k	{
156	43.6k	CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, count);
157
158	43.6k	if ((zgfx->HistoryIndex += count) == zgfx->HistoryBufferSize)
159	0	zgfx->HistoryIndex = 0;
160	43.6k	}
161	0	else
162	0	{
163	0	front = zgfx->HistoryBufferSize - zgfx->HistoryIndex;
164	0	CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, front);
165	0	CopyMemory(zgfx->HistoryBuffer, &src[front], count - front);
166	0	zgfx->HistoryIndex = count - front;
167	0	}
168	43.6k	}
169
170		static void zgfx_history_buffer_ring_read(ZGFX_CONTEXT* zgfx, int offset, BYTE* dst, UINT32 count)
171	43.1k	{
172	43.1k	UINT32 front = 0;
173	43.1k	UINT32 index = 0;
174	43.1k	INT32 bytes = 0;
175	43.1k	UINT32 valid = 0;
176	43.1k	INT32 bytesLeft = 0;
177	43.1k	BYTE* dptr = dst;
178	43.1k	BYTE* origDst = dst;
179
180	43.1k	if ((count <= 0) \|\| (count > INT32_MAX))
181	267	return;
182
183	42.9k	bytesLeft = (INT32)count;
184	42.9k	index = (zgfx->HistoryIndex + zgfx->HistoryBufferSize - offset) % zgfx->HistoryBufferSize;
185	42.9k	bytes = MIN(bytesLeft, offset);
186
187	42.9k	if ((index + bytes) <= zgfx->HistoryBufferSize)
188	42.7k	{
189	42.7k	CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), bytes);
190	42.7k	}
191	110	else
192	110	{
193	110	front = zgfx->HistoryBufferSize - index;
194	110	CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), front);
195	110	CopyMemory(&dptr[front], zgfx->HistoryBuffer, bytes - front);
196	110	}
197
198	42.9k	if ((bytesLeft -= bytes) == 0)
199	41.6k	return;
200
201	1.21k	dptr += bytes;
202	1.21k	valid = bytes;
203
204	1.21k	do
205	2.35k	{
206	2.35k	bytes = valid;
207
208	2.35k	if (bytes > bytesLeft)
209	1.19k	bytes = bytesLeft;
210
211	2.35k	CopyMemory(dptr, origDst, bytes);
212	2.35k	dptr += bytes;
213	2.35k	valid <<= 1;
214	2.35k	} while ((bytesLeft -= bytes) > 0);
215	1.21k	}
216
217		static BOOL zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, wStream* stream, size_t segmentSize)
218	2.72k	{
219	2.72k	BYTE c = 0;
220	2.72k	BYTE flags = 0;
221	2.72k	UINT32 extra = 0;
222	2.72k	int opIndex = 0;
223	2.72k	UINT32 haveBits = 0;
224	2.72k	UINT32 inPrefix = 0;
225	2.72k	UINT32 count = 0;
226	2.72k	UINT32 distance = 0;
227	2.72k	BYTE* pbSegment = NULL;
228	2.72k	size_t cbSegment = 0;
229
230	2.72k	WINPR_ASSERT(zgfx);
231	2.72k	WINPR_ASSERT(stream);
232
233	2.72k	if (segmentSize < 2)
234	29	return FALSE;
235
236	2.69k	cbSegment = segmentSize - 1;
237
238	2.69k	if (!Stream_CheckAndLogRequiredLength(TAG, stream, segmentSize) \|\| (segmentSize > UINT32_MAX))
239	126	return FALSE;
240
241	2.56k	Stream_Read_UINT8(stream, flags); /* header (1 byte) */
242	2.56k	zgfx->OutputCount = 0;
243	2.56k	pbSegment = Stream_Pointer(stream);
244	2.56k	if (!Stream_SafeSeek(stream, cbSegment))
245	0	return FALSE;
246
247	2.56k	if (!(flags & PACKET_COMPRESSED))
248	228	{
249	228	zgfx_history_buffer_ring_write(zgfx, pbSegment, cbSegment);
250
251	228	if (cbSegment > sizeof(zgfx->OutputBuffer))
252	17	return FALSE;
253
254	211	CopyMemory(zgfx->OutputBuffer, pbSegment, cbSegment);
255	211	zgfx->OutputCount = cbSegment;
256	211	return TRUE;
257	228	}
258
259	2.33k	zgfx->pbInputCurrent = pbSegment;
260	2.33k	zgfx->pbInputEnd = &pbSegment[cbSegment - 1];
261		/* NumberOfBitsToDecode = ((NumberOfBytesToDecode - 1) * 8) - ValueOfLastByte */
262	2.33k	const UINT32 bits = 8u * (cbSegment - 1u);
263	2.33k	if (bits < *zgfx->pbInputEnd)
264	33	return FALSE;
265
266	2.30k	zgfx->cBitsRemaining = bits - *zgfx->pbInputEnd;
267	2.30k	zgfx->cBitsCurrent = 0;
268	2.30k	zgfx->BitsCurrent = 0;
269
270	23.0M	while (zgfx->cBitsRemaining)
271	23.0M	{
272	23.0M	haveBits = 0;
273	23.0M	inPrefix = 0;
274
275	37.4M	for (opIndex = 0; ZGFX_TOKEN_TABLE[opIndex].prefixLength != 0; opIndex++)
276	37.4M	{
277	63.8M	while (haveBits < ZGFX_TOKEN_TABLE[opIndex].prefixLength)
278	26.4M	{
279	26.4M	zgfx_GetBits(zgfx, 1);
280	26.4M	inPrefix = (inPrefix << 1) + zgfx->bits;
281	26.4M	haveBits++;
282	26.4M	}
283
284	37.4M	if (inPrefix == ZGFX_TOKEN_TABLE[opIndex].prefixCode)
285	23.0M	{
286	23.0M	if (ZGFX_TOKEN_TABLE[opIndex].tokenType == 0)
287	23.0M	{
288		/* Literal */
289	23.0M	zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
290	23.0M	c = (BYTE)(ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits);
291	23.0M	zgfx->HistoryBuffer[zgfx->HistoryIndex] = c;
292
293	23.0M	if (++zgfx->HistoryIndex == zgfx->HistoryBufferSize)
294	0	zgfx->HistoryIndex = 0;
295
296	23.0M	if (zgfx->OutputCount >= sizeof(zgfx->OutputBuffer))
297	401	return FALSE;
298
299	23.0M	zgfx->OutputBuffer[zgfx->OutputCount++] = c;
300	23.0M	}
301	44.2k	else
302	44.2k	{
303	44.2k	zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
304	44.2k	distance = ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits;
305
306	44.2k	if (distance != 0)
307	43.2k	{
308		/* Match */
309	43.2k	zgfx_GetBits(zgfx, 1);
310
311	43.2k	if (zgfx->bits == 0)
312	26.7k	{
313	26.7k	count = 3;
314	26.7k	}
315	16.5k	else
316	16.5k	{
317	16.5k	count = 4;
318	16.5k	extra = 2;
319	16.5k	zgfx_GetBits(zgfx, 1);
320
321	68.8k	while (zgfx->bits == 1)
322	52.2k	{
323	52.2k	count *= 2;
324	52.2k	extra++;
325	52.2k	zgfx_GetBits(zgfx, 1);
326	52.2k	}
327
328	16.5k	zgfx_GetBits(zgfx, extra);
329	16.5k	count += zgfx->bits;
330	16.5k	}
331
332	43.2k	if (count > sizeof(zgfx->OutputBuffer) - zgfx->OutputCount)
333	49	return FALSE;
334
335	43.1k	zgfx_history_buffer_ring_read(
336	43.1k	zgfx, distance, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
337	43.1k	zgfx_history_buffer_ring_write(
338	43.1k	zgfx, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
339	43.1k	zgfx->OutputCount += count;
340	43.1k	}
341	1.07k	else
342	1.07k	{
343		/* Unencoded */
344	1.07k	zgfx_GetBits(zgfx, 15);
345	1.07k	count = zgfx->bits;
346	1.07k	zgfx->cBitsRemaining -= zgfx->cBitsCurrent;
347	1.07k	zgfx->cBitsCurrent = 0;
348	1.07k	zgfx->BitsCurrent = 0;
349
350	1.07k	if (count > sizeof(zgfx->OutputBuffer) - zgfx->OutputCount)
351	2	return FALSE;
352	1.07k	else if (count > zgfx->cBitsRemaining / 8)
353	24	return FALSE;
354	1.04k	else if (zgfx->pbInputCurrent + count > zgfx->pbInputEnd)
355	24	return FALSE;
356
357	1.02k	CopyMemory(&(zgfx->OutputBuffer[zgfx->OutputCount]), zgfx->pbInputCurrent,
358	1.02k	count);
359	1.02k	zgfx_history_buffer_ring_write(zgfx, zgfx->pbInputCurrent, count);
360	1.02k	zgfx->pbInputCurrent += count;
361	1.02k	zgfx->cBitsRemaining -= (8 * count);
362	1.02k	zgfx->OutputCount += count;
363	1.02k	}
364	44.2k	}
365
366	23.0M	break;
367	23.0M	}
368	37.4M	}
369	23.0M	}
370
371	1.80k	return TRUE;
372	2.30k	}
373
374		/* Allocate the buffers a bit larger.
375		*
376		* Due to optimizations some h264 decoders will read data beyond
377		* the actual available data, so ensure that it will never be a
378		* out of bounds read.
379		*/
380		static BYTE* aligned_zgfx_malloc(size_t size)
381	0	{
382	0	return malloc(size + 64);
383	0	}
384
385		static BOOL zgfx_append(ZGFX_CONTEXT* zgfx, BYTE** ppConcatenated, size_t uncompressedSize,
386		size_t* pUsed)
387	2.01k	{
388	2.01k	WINPR_ASSERT(zgfx);
389	2.01k	WINPR_ASSERT(ppConcatenated);
390	2.01k	WINPR_ASSERT(pUsed);
391
392	2.01k	const size_t used = *pUsed;
393	2.01k	if (zgfx->OutputCount > UINT32_MAX - used)
394	0	return FALSE;
395
396	2.01k	if (used + zgfx->OutputCount > uncompressedSize)
397	19	return FALSE;
398
399	1.99k	BYTE* tmp = realloc(*ppConcatenated, used + zgfx->OutputCount + 64ull);
400	1.99k	if (!tmp)
401	0	return FALSE;
402	1.99k	*ppConcatenated = tmp;
403	1.99k	CopyMemory(&tmp[used], zgfx->OutputBuffer, zgfx->OutputCount);
404	1.99k	*pUsed = used + zgfx->OutputCount;
405	1.99k	return TRUE;
406	1.99k	}
407
408		int zgfx_decompress(ZGFX_CONTEXT* zgfx, const BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData,
409		UINT32* pDstSize, UINT32 flags)
410	5.71k	{
411	5.71k	int status = -1;
412	5.71k	BYTE descriptor = 0;
413	5.71k	wStream sbuffer = { 0 };
414	5.71k	size_t used = 0;
415	5.71k	BYTE* pConcatenated = NULL;
416	5.71k	wStream* stream = Stream_StaticConstInit(&sbuffer, pSrcData, SrcSize);
417
418	5.71k	WINPR_ASSERT(zgfx);
419	5.71k	WINPR_ASSERT(stream);
420	5.71k	WINPR_ASSERT(ppDstData);
421	5.71k	WINPR_ASSERT(pDstSize);
422
423	5.71k	*ppDstData = NULL;
424	5.71k	*pDstSize = 0;
425
426	5.71k	if (!Stream_CheckAndLogRequiredLength(TAG, stream, 1))
427	0	goto fail;
428
429	5.71k	Stream_Read_UINT8(stream, descriptor); /* descriptor (1 byte) */
430
431	5.71k	if (descriptor == ZGFX_SEGMENTED_SINGLE)
432	656	{
433	656	if (!zgfx_decompress_segment(zgfx, stream, Stream_GetRemainingLength(stream)))
434	533	goto fail;
435
436	123	if (zgfx->OutputCount > 0)
437	118	{
438	118	if (!zgfx_append(zgfx, &pConcatenated, zgfx->OutputCount, &used))
439	0	goto fail;
440	118	if (used != zgfx->OutputCount)
441	0	goto fail;
442	118	*ppDstData = pConcatenated;
443	118	*pDstSize = zgfx->OutputCount;
444	118	}
445	123	}
446	5.05k	else if (descriptor == ZGFX_SEGMENTED_MULTIPART)
447	344	{
448	344	UINT32 segmentSize = 0;
449	344	UINT16 segmentNumber = 0;
450	344	UINT16 segmentCount = 0;
451	344	UINT32 uncompressedSize = 0;
452
453	344	if (!Stream_CheckAndLogRequiredLength(TAG, stream, 6))
454	37	goto fail;
455
456	307	Stream_Read_UINT16(stream, segmentCount); /* segmentCount (2 bytes) */
457	307	Stream_Read_UINT32(stream, uncompressedSize); /* uncompressedSize (4 bytes) */
458
459	2.18k	for (segmentNumber = 0; segmentNumber < segmentCount; segmentNumber++)
460	2.14k	{
461	2.14k	if (!Stream_CheckAndLogRequiredLength(TAG, stream, sizeof(UINT32)))
462	84	goto fail;
463
464	2.06k	Stream_Read_UINT32(stream, segmentSize); /* segmentSize (4 bytes) */
465
466	2.06k	if (!zgfx_decompress_segment(zgfx, stream, segmentSize))
467	172	goto fail;
468
469	1.89k	if (!zgfx_append(zgfx, &pConcatenated, uncompressedSize, &used))
470	19	goto fail;
471	1.89k	}
472
473	32	if (used != uncompressedSize)
474	31	goto fail;
475
476	1	*ppDstData = pConcatenated;
477	1	*pDstSize = uncompressedSize;
478	1	}
479	4.71k	else
480	4.71k	{
481	4.71k	goto fail;
482	4.71k	}
483
484	124	status = 1;
485	5.71k	fail:
486	5.71k	if (status < 0)
487	5.59k	free(pConcatenated);
488	5.71k	return status;
489	124	}
490
491		static BOOL zgfx_compress_segment(ZGFX_CONTEXT* zgfx, wStream* s, const BYTE* pSrcData,
492		UINT32 SrcSize, UINT32* pFlags)
493	0	{
494		/* FIXME: Currently compression not implemented. Just copy the raw source */
495	0	if (!Stream_EnsureRemainingCapacity(s, SrcSize + 1))
496	0	{
497	0	WLog_ERR(TAG, "Stream_EnsureRemainingCapacity failed!");
498	0	return FALSE;
499	0	}
500
501	0	(pFlags) \|= ZGFX_PACKET_COMPR_TYPE_RDP8; / RDP 8.0 compression format */
502	0	Stream_Write_UINT8(s, (pFlags)); / header (1 byte) */
503	0	Stream_Write(s, pSrcData, SrcSize);
504	0	return TRUE;
505	0	}
506
507		int zgfx_compress_to_stream(ZGFX_CONTEXT* zgfx, wStream* sDst, const BYTE* pUncompressed,
508		UINT32 uncompressedSize, UINT32* pFlags)
509	0	{
510	0	int fragment = 0;
511	0	UINT16 maxLength = 0;
512	0	UINT32 totalLength = 0;
513	0	size_t posSegmentCount = 0;
514	0	const BYTE* pSrcData = NULL;
515	0	int status = 0;
516	0	maxLength = ZGFX_SEGMENTED_MAXSIZE;
517	0	totalLength = uncompressedSize;
518	0	pSrcData = pUncompressed;
519
520	0	for (; (totalLength > 0) \|\| (fragment == 0); fragment++)
521	0	{
522	0	UINT32 SrcSize = 0;
523	0	size_t posDstSize = 0;
524	0	size_t posDataStart = 0;
525	0	UINT32 DstSize = 0;
526	0	SrcSize = (totalLength > maxLength) ? maxLength : totalLength;
527	0	posDstSize = 0;
528	0	totalLength -= SrcSize;
529
530		/* Ensure we have enough space for headers */
531	0	if (!Stream_EnsureRemainingCapacity(sDst, 12))
532	0	{
533	0	WLog_ERR(TAG, "Stream_EnsureRemainingCapacity failed!");
534	0	return -1;
535	0	}
536
537	0	if (fragment == 0)
538	0	{
539		/* First fragment */
540		/* descriptor (1 byte) */
541	0	Stream_Write_UINT8(sDst, (totalLength == 0) ? ZGFX_SEGMENTED_SINGLE
542	0	: ZGFX_SEGMENTED_MULTIPART);
543
544	0	if (totalLength > 0)
545	0	{
546	0	posSegmentCount = Stream_GetPosition(sDst); /* segmentCount (2 bytes) */
547	0	Stream_Seek(sDst, 2);
548	0	Stream_Write_UINT32(sDst, uncompressedSize); /* uncompressedSize (4 bytes) */
549	0	}
550	0	}
551
552	0	if (fragment > 0 \|\| totalLength > 0)
553	0	{
554		/* Multipart */
555	0	posDstSize = Stream_GetPosition(sDst); /* size (4 bytes) */
556	0	Stream_Seek(sDst, 4);
557	0	}
558
559	0	posDataStart = Stream_GetPosition(sDst);
560
561	0	if (!zgfx_compress_segment(zgfx, sDst, pSrcData, SrcSize, pFlags))
562	0	return -1;
563
564	0	if (posDstSize)
565	0	{
566		/* Fill segment data size */
567	0	DstSize = Stream_GetPosition(sDst) - posDataStart;
568	0	Stream_SetPosition(sDst, posDstSize);
569	0	Stream_Write_UINT32(sDst, DstSize);
570	0	Stream_SetPosition(sDst, posDataStart + DstSize);
571	0	}
572
573	0	pSrcData += SrcSize;
574	0	}
575
576	0	Stream_SealLength(sDst);
577
578		/* fill back segmentCount */
579	0	if (posSegmentCount)
580	0	{
581	0	Stream_SetPosition(sDst, posSegmentCount);
582	0	Stream_Write_UINT16(sDst, fragment);
583	0	Stream_SetPosition(sDst, Stream_Length(sDst));
584	0	}
585
586	0	return status;
587	0	}
588
589		int zgfx_compress(ZGFX_CONTEXT* zgfx, const BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData,
590		UINT32* pDstSize, UINT32* pFlags)
591	0	{
592	0	int status = 0;
593	0	wStream* s = Stream_New(NULL, SrcSize);
594	0	status = zgfx_compress_to_stream(zgfx, s, pSrcData, SrcSize, pFlags);
595	0	(*ppDstData) = Stream_Buffer(s);
596	0	(*pDstSize) = Stream_GetPosition(s);
597	0	Stream_Free(s, FALSE);
598	0	return status;
599	0	}
600
601		void zgfx_context_reset(ZGFX_CONTEXT* zgfx, BOOL flush)
602	5.71k	{
603	5.71k	zgfx->HistoryIndex = 0;
604	5.71k	}
605
606		ZGFX_CONTEXT* zgfx_context_new(BOOL Compressor)
607	5.71k	{
608	5.71k	ZGFX_CONTEXT* zgfx = NULL;
609	5.71k	zgfx = (ZGFX_CONTEXT*)calloc(1, sizeof(ZGFX_CONTEXT));
610
611	5.71k	if (zgfx)
612	5.71k	{
613	5.71k	zgfx->Compressor = Compressor;
614	5.71k	zgfx->HistoryBufferSize = sizeof(zgfx->HistoryBuffer);
615	5.71k	zgfx_context_reset(zgfx, FALSE);
616	5.71k	}
617
618	5.71k	return zgfx;
619	5.71k	}
620
621		void zgfx_context_free(ZGFX_CONTEXT* zgfx)
622	5.71k	{
623	5.71k	free(zgfx);
624	5.71k	}