/src/FreeRDP/libfreerdp/codec/mppc.c

Source
/**
 * 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.
 */

#include <winpr/assert.h>
#include <freerdp/config.h>

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

#include <freerdp/log.h>
#include "mppc.h"

#define TAG FREERDP_TAG("codec.mppc")

//#define DEBUG_MPPC  1

#define MPPC_MATCH_INDEX(_sym1, _sym2, _sym3)                             \
  ((((MPPC_MATCH_TABLE[_sym3] << 16) + (MPPC_MATCH_TABLE[_sym2] << 8) + \
     MPPC_MATCH_TABLE[_sym1]) &                                         \
    0x07FFF000) >>                                                      \
   12)

struct s_MPPC_CONTEXT
{
  ALIGN64 wBitStream* bs;
  ALIGN64 BOOL Compressor;
  ALIGN64 BYTE* HistoryPtr;
  ALIGN64 UINT32 HistoryOffset;
  ALIGN64 UINT32 HistoryBufferSize;
  ALIGN64 BYTE HistoryBuffer[65536];
  ALIGN64 UINT16 MatchBuffer[32768];
  ALIGN64 UINT32 CompressionLevel;
};

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
};

int mppc_decompress(MPPC_CONTEXT* mppc, const BYTE* pSrcData, UINT32 SrcSize,
                    const BYTE** ppDstData, UINT32* pDstSize, UINT32 flags)
{
  BYTE Literal = 0;
  UINT32 CopyOffset = 0;
  UINT32 LengthOfMatch = 0;
  UINT32 accumulator = 0;
  BYTE* HistoryPtr = nullptr;
  BYTE* HistoryBuffer = nullptr;
  BYTE* HistoryBufferEnd = nullptr;
  UINT32 HistoryBufferSize = 0;
  UINT32 CompressionLevel = 0;
  wBitStream* bs = nullptr;

  WINPR_ASSERT(mppc);
  WINPR_ASSERT(pSrcData);
  WINPR_ASSERT(ppDstData);
  WINPR_ASSERT(pDstSize);

  bs = mppc->bs;
  WINPR_ASSERT(bs);

  HistoryBuffer = mppc->HistoryBuffer;
  WINPR_ASSERT(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;
    }

#if defined(DEBUG_MPPC)
    WLog_DBG(TAG, "<%" PRIu32 ",%" PRIu32 ">", CopyOffset, LengthOfMatch);
#endif

    if ((HistoryPtr + LengthOfMatch - 1) > HistoryBufferEnd)
    {
      WLog_ERR(TAG, "history buffer overflow");
      return -1005;
    }

    const BYTE* SrcPtr = &HistoryBuffer[(HistoryPtr - HistoryBuffer - CopyOffset) &
                                        (CompressionLevel ? 0xFFFF : 0x1FFF)];
    if ((SrcPtr < HistoryBuffer) || (SrcPtr + LengthOfMatch > HistoryBufferEnd))
    {
      WLog_ERR(TAG, "CopyOffset %" PRIu32 " target is out of bounds", CopyOffset);
      return -1006;
    }

    do
    {
      *HistoryPtr++ = *SrcPtr++;
    } while (--LengthOfMatch);
  }

  *pDstSize = (UINT32)(HistoryPtr - mppc->HistoryPtr);
  *ppDstData = mppc->HistoryPtr;
  mppc->HistoryPtr = HistoryPtr;
  return 1;
}

int mppc_compress(MPPC_CONTEXT* mppc, const BYTE* pSrcData, UINT32 SrcSize, BYTE* pDstBuffer,
                  const BYTE** ppDstData, UINT32* pDstSize, UINT32* pFlags)
{
  const BYTE* pSrcPtr = nullptr;
  const BYTE* pSrcEnd = nullptr;
  BYTE* MatchPtr = nullptr;
  UINT32 DstSize = 0;
  BYTE* pDstData = nullptr;
  UINT32 MatchIndex = 0;
  UINT32 accumulator = 0;
  BOOL PacketFlushed = 0;
  BOOL PacketAtFront = 0;
  DWORD CopyOffset = 0;
  DWORD LengthOfMatch = 0;
  BYTE* HistoryBuffer = nullptr;
  BYTE* HistoryPtr = nullptr;
  UINT32 HistoryOffset = 0;
  UINT32 HistoryBufferSize = 0;
  BYTE Sym1 = 0;
  BYTE Sym2 = 0;
  BYTE Sym3 = 0;
  UINT32 CompressionLevel = 0;
  wBitStream* bs = nullptr;

  WINPR_ASSERT(mppc);
  WINPR_ASSERT(pSrcData);
  WINPR_ASSERT(pDstBuffer);
  WINPR_ASSERT(ppDstData);
  WINPR_ASSERT(pDstSize);
  WINPR_ASSERT(pFlags);

  bs = mppc->bs;
  WINPR_ASSERT(bs);

  HistoryBuffer = mppc->HistoryBuffer;
  WINPR_ASSERT(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 = pDstBuffer;
  *ppDstData = pDstBuffer;

  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;
#if defined(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++;
      }

#if defined(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;
#if defined(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;
  const intptr_t diff = HistoryPtr - HistoryBuffer;
  if (diff > UINT32_MAX)
    return -1;
  mppc->HistoryOffset = (UINT32)diff;
  return 1;
}

void mppc_set_compression_level(MPPC_CONTEXT* mppc, DWORD CompressionLevel)
{
  WINPR_ASSERT(mppc);

  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)
{
  WINPR_ASSERT(mppc);

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

  if (flush)
  {
    mppc->HistoryOffset = mppc->HistoryBufferSize + 1;
    mppc->HistoryPtr = mppc->HistoryBuffer;
  }
  else
  {
    mppc->HistoryOffset = 0;
    mppc->HistoryPtr = &(mppc->HistoryBuffer[mppc->HistoryOffset]);
  }
}

MPPC_CONTEXT* mppc_context_new(DWORD CompressionLevel, BOOL Compressor)
{
  MPPC_CONTEXT* mppc = calloc(1, sizeof(MPPC_CONTEXT));

  if (!mppc)
    goto fail;

  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)
    goto fail;

  mppc_context_reset(mppc, FALSE);

  return mppc;

fail:
  mppc_context_free(mppc);
  return nullptr;
}

void mppc_context_free(MPPC_CONTEXT* mppc)
{
  if (mppc)
  {
    BitStream_Free(mppc->bs);
    free(mppc);
  }
}

Coverage Report

Created: 2026-07-16 07:09