/** @file
  UEFI Decompress Library.

  Copyright (c) 2006, Intel Corporation
  All rights reserved. This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

  Module Name:  UefiDecompressLib.c

**/

//
// Decompression algorithm begins here
//
#define BITBUFSIZ 32
#define MAXMATCH  256
#define THRESHOLD 3
#define CODE_BIT  16
#define BAD_TABLE - 1

//
// C: Char&Len Set; P: Position Set; T: exTra Set
//
#define NC      (0xff + MAXMATCH + 2 - THRESHOLD)
#define CBIT    9
#define MAXPBIT 5
#define TBIT    5
#define MAXNP   ((1U << MAXPBIT) - 1)
#define NT      (CODE_BIT + 3)
#if NT > MAXNP
#define NPT NT
#else
#define NPT MAXNP
#endif

typedef struct {
  UINT8   *mSrcBase;  ///< Starting address of compressed data
  UINT8   *mDstBase;  ///< Starting address of decompressed data
  UINT32  mOutBuf;
  UINT32  mInBuf;

  UINT16  mBitCount;
  UINT32  mBitBuf;
  UINT32  mSubBitBuf;
  UINT16  mBlockSize;
  UINT32  mCompSize;
  UINT32  mOrigSize;

  UINT16  mBadTableFlag;

  UINT16  mLeft[2 * NC - 1];
  UINT16  mRight[2 * NC - 1];
  UINT8   mCLen[NC];
  UINT8   mPTLen[NPT];
  UINT16  mCTable[4096];
  UINT16  mPTTable[256];

  ///
  /// The length of the field 'Position Set Code Length Array Size' in Block Header.
  /// For EFI 1.1 de/compression algorithm, mPBit = 4
  /// For Tiano de/compression algorithm, mPBit = 5
  ///
  UINT8   mPBit;
} SCRATCH_DATA;

/**
  Shift mBitBuf NumOfBits left. Read in NumOfBits of bits from source.

  @param  Sd The global scratch data
  @param  NumOfBits The number of bits to shift and read.

**/
VOID
FillBuf (
  IN  SCRATCH_DATA  *Sd,
  IN  UINT16        NumOfBits
  )
{
  Sd->mBitBuf = (UINT32) (Sd->mBitBuf << NumOfBits);

  while (NumOfBits > Sd->mBitCount) {

    Sd->mBitBuf |= (UINT32) (Sd->mSubBitBuf << (NumOfBits = (UINT16) (NumOfBits - Sd->mBitCount)));

    if (Sd->mCompSize > 0) {
      //
      // Get 1 byte into SubBitBuf
      //
      Sd->mCompSize--;
      Sd->mSubBitBuf  = 0;
      Sd->mSubBitBuf  = Sd->mSrcBase[Sd->mInBuf++];
      Sd->mBitCount   = 8;

    } else {
      //
      // No more bits from the source, just pad zero bit.
      //
      Sd->mSubBitBuf  = 0;
      Sd->mBitCount   = 8;

    }
  }

  Sd->mBitCount = (UINT16) (Sd->mBitCount - NumOfBits);
  Sd->mBitBuf |= Sd->mSubBitBuf >> Sd->mBitCount;
}

/**
  Get NumOfBits of bits out from mBitBuf. Fill mBitBuf with subsequent 
  NumOfBits of bits from source. Returns NumOfBits of bits that are 
  popped out.

  @param  Sd The global scratch data.
  @param  NumOfBits The number of bits to pop and read.

  @return The bits that are popped out.

**/
UINT32
GetBits (
  IN  SCRATCH_DATA  *Sd,
  IN  UINT16        NumOfBits
  )
{
  UINT32  OutBits;

  OutBits = (UINT32) (Sd->mBitBuf >> (BITBUFSIZ - NumOfBits));

  FillBuf (Sd, NumOfBits);

  return OutBits;
}

/**
  Creates Huffman Code mapping table according to code length array.

  @param  Sd The global scratch data
  @param  NumOfChar Number of symbols in the symbol set
  @param  BitLen Code length array
  @param  TableBits The width of the mapping table
  @param  Table The table

  @retval  0 OK.
  @retval  BAD_TABLE The table is corrupted.

**/
UINT16
MakeTable (
  IN  SCRATCH_DATA  *Sd,
  IN  UINT16        NumOfChar,
  IN  UINT8         *BitLen,
  IN  UINT16        TableBits,
  OUT UINT16        *Table
  )
{
  UINT16  Count[17];
  UINT16  Weight[17];
  UINT16  Start[18];
  UINT16  *Pointer;
  UINT16  Index3;
  volatile UINT16  Index;
  UINT16  Len;
  UINT16  Char;
  UINT16  JuBits;
  UINT16  Avail;
  UINT16  NextCode;
  UINT16  Mask;

  for (Index = 1; Index <= 16; Index++) {
    Count[Index] = 0;
  }

  for (Index = 0; Index < NumOfChar; Index++) {
    Count[BitLen[Index]]++;
  }

  Start[1] = 0;

  for (Index = 1; Index <= 16; Index++) {
    Start[Index + 1] = (UINT16) (Start[Index] + (Count[Index] << (16 - Index)));
  }

  if (Start[17] != 0) {
    /*(1U << 16)*/
    return (UINT16) BAD_TABLE;
  }

  JuBits = (UINT16) (16 - TableBits);

  for (Index = 1; Index <= TableBits; Index++) {
    Start[Index] >>= JuBits;
    Weight[Index] = (UINT16) (1U << (TableBits - Index));
  }

  while (Index <= 16) {
    Weight[Index] = (UINT16) (1U << (16 - Index));
    Index++;    
  }

  Index = (UINT16) (Start[TableBits + 1] >> JuBits);

  if (Index != 0) {
    Index3 = (UINT16) (1U << TableBits);
    while (Index != Index3) {
      Table[Index++] = 0;
    }
  }

  Avail = NumOfChar;
  Mask  = (UINT16) (1U << (15 - TableBits));

  for (Char = 0; Char < NumOfChar; Char++) {

    Len = BitLen[Char];
    if (Len == 0) {
      continue;
    }

    NextCode = (UINT16) (Start[Len] + Weight[Len]);

    if (Len <= TableBits) {

      for (Index = Start[Len]; Index < NextCode; Index++) {
        Table[Index] = Char;
      }

    } else {

      Index3  = Start[Len];
      Pointer = &Table[Index3 >> JuBits];
      Index   = (UINT16) (Len - TableBits);

      while (Index != 0) {
        if (*Pointer == 0) {
          Sd->mRight[Avail]                     = Sd->mLeft[Avail] = 0;
          *Pointer = Avail++;
        }

        if (Index3 & Mask) {
          Pointer = &Sd->mRight[*Pointer];
        } else {
          Pointer = &Sd->mLeft[*Pointer];
        }

        Index3 <<= 1;
        Index--;
      }

      *Pointer = Char;

    }

    Start[Len] = NextCode;
  }
  //
  // Succeeds
  //
  return 0;
}

/**
  Decodes a position value.

  @param  Sd the global scratch data

  @return The position value decoded.

**/
UINT32
DecodeP (
  IN  SCRATCH_DATA  *Sd
  )
{
  UINT16  Val;
  UINT32  Mask;
  UINT32  Pos;

  Val = Sd->mPTTable[Sd->mBitBuf >> (BITBUFSIZ - 8)];

  if (Val >= MAXNP) {
    Mask = 1U << (BITBUFSIZ - 1 - 8);

    do {

      if (Sd->mBitBuf & Mask) {
        Val = Sd->mRight[Val];
      } else {
        Val = Sd->mLeft[Val];
      }

      Mask >>= 1;
    } while (Val >= MAXNP);
  }
  //
  // Advance what we have read
  //
  FillBuf (Sd, Sd->mPTLen[Val]);

  Pos = Val;
  if (Val > 1) {
    Pos = (UINT32) ((1U << (Val - 1)) + GetBits (Sd, (UINT16) (Val - 1)));
  }

  return Pos;
}

/**
  Reads code lengths for the Extra Set or the Position Set.

  @param  Sd The global scratch data.
  @param  nn Number of symbols.
  @param  nbit Number of bits needed to represent nn.
  @param  Special The special symbol that needs to be taken care of.

  @retval  0 OK.
  @retval  BAD_TABLE Table is corrupted.

**/
UINT16
ReadPTLen (
  IN  SCRATCH_DATA  *Sd,
  IN  UINT16        nn,
  IN  UINT16        nbit,
  IN  UINT16        Special
  )
{
  UINT16  Number;
  UINT16  CharC;
  volatile UINT16  Index;
  UINT32  Mask;

  Number = (UINT16) GetBits (Sd, nbit);

  if (Number == 0) {
    CharC = (UINT16) GetBits (Sd, nbit);

    for (Index = 0; Index < 256; Index++) {
      Sd->mPTTable[Index] = CharC;
    }

    for (Index = 0; Index < nn; Index++) {
      Sd->mPTLen[Index] = 0;
    }

    return 0;
  }

  Index = 0;

  while (Index < Number) {

    CharC = (UINT16) (Sd->mBitBuf >> (BITBUFSIZ - 3));

    if (CharC == 7) {
      Mask = 1U << (BITBUFSIZ - 1 - 3);
      while (Mask & Sd->mBitBuf) {
        Mask >>= 1;
        CharC += 1;
      }
    }

    FillBuf (Sd, (UINT16) ((CharC < 7) ? 3 : CharC - 3));

    Sd->mPTLen[Index++] = (UINT8) CharC;

    if (Index == Special) {
      CharC = (UINT16) GetBits (Sd, 2);
      while ((INT16) (--CharC) >= 0) {
        Sd->mPTLen[Index++] = 0;
      }
    }
  }

  while (Index < nn) {
    Sd->mPTLen[Index++] = 0;
  }

  return MakeTable (Sd, nn, Sd->mPTLen, 8, Sd->mPTTable);
}

/**
  Reads code lengths for Char&Len Set.

  @param  Sd the global scratch data

**/
VOID
ReadCLen (
  SCRATCH_DATA  *Sd
  )
{
  UINT16  Number;
  UINT16  CharC;
  volatile UINT16  Index;
  UINT32  Mask;

  Number = (UINT16) GetBits (Sd, CBIT);

  if (Number == 0) {
    CharC = (UINT16) GetBits (Sd, CBIT);

    for (Index = 0; Index < NC; Index++) {
      Sd->mCLen[Index] = 0;
    }

    for (Index = 0; Index < 4096; Index++) {
      Sd->mCTable[Index] = CharC;
    }

    return ;
  }

  Index = 0;
  while (Index < Number) {

    CharC = Sd->mPTTable[Sd->mBitBuf >> (BITBUFSIZ - 8)];
    if (CharC >= NT) {
      Mask = 1U << (BITBUFSIZ - 1 - 8);

      do {

        if (Mask & Sd->mBitBuf) {
          CharC = Sd->mRight[CharC];
        } else {
          CharC = Sd->mLeft[CharC];
        }

        Mask >>= 1;

      } while (CharC >= NT);
    }
    //
    // Advance what we have read
    //
    FillBuf (Sd, Sd->mPTLen[CharC]);

    if (CharC <= 2) {

      if (CharC == 0) {
        CharC = 1;
      } else if (CharC == 1) {
        CharC = (UINT16) (GetBits (Sd, 4) + 3);
      } else if (CharC == 2) {
        CharC = (UINT16) (GetBits (Sd, CBIT) + 20);
      }

      while ((INT16) (--CharC) >= 0) {
        Sd->mCLen[Index++] = 0;
      }

    } else {

      Sd->mCLen[Index++] = (UINT8) (CharC - 2);

    }
  }

  while (Index < NC) {
    Sd->mCLen[Index++] = 0;
  }

  MakeTable (Sd, NC, Sd->mCLen, 12, Sd->mCTable);

  return ;
}

/**
  Decode a character/length value.

  @param  Sd The global scratch data.

  @return The value decoded.

**/
UINT16
DecodeC (
  SCRATCH_DATA  *Sd
  )
{
  UINT16  Index2;
  UINT32  Mask;

  if (Sd->mBlockSize == 0) {
    //
    // Starting a new block
    //
    Sd->mBlockSize    = (UINT16) GetBits (Sd, 16);
    Sd->mBadTableFlag = ReadPTLen (Sd, NT, TBIT, 3);
    if (Sd->mBadTableFlag != 0) {
      return 0;
    }

    ReadCLen (Sd);

    Sd->mBadTableFlag = ReadPTLen (Sd, MAXNP, Sd->mPBit, (UINT16) (-1));
    if (Sd->mBadTableFlag != 0) {
      return 0;
    }
  }

  Sd->mBlockSize--;
  Index2 = Sd->mCTable[Sd->mBitBuf >> (BITBUFSIZ - 12)];

  if (Index2 >= NC) {
    Mask = 1U << (BITBUFSIZ - 1 - 12);

    do {
      if (Sd->mBitBuf & Mask) {
        Index2 = Sd->mRight[Index2];
      } else {
        Index2 = Sd->mLeft[Index2];
      }

      Mask >>= 1;
    } while (Index2 >= NC);
  }
  //
  // Advance what we have read
  //
  FillBuf (Sd, Sd->mCLen[Index2]);

  return Index2;
}

/**
  Decode the source data and put the resulting data into the destination buffer.

  @param  Sd The global scratch data

**/
VOID
Decode (
  SCRATCH_DATA  *Sd
  )
{
  UINT16  BytesRemain;
  UINT32  DataIdx;
  UINT16  CharC;

  BytesRemain = (UINT16) (-1);

  DataIdx     = 0;

  for (;;) {
    CharC = DecodeC (Sd);
    if (Sd->mBadTableFlag != 0) {
      return ;
    }

    if (CharC < 256) {
      //
      // Process an Original character
      //
      if (Sd->mOutBuf >= Sd->mOrigSize) {
        return ;
      } else {
        Sd->mDstBase[Sd->mOutBuf++] = (UINT8) CharC;
      }

    } else {
      //
      // Process a Pointer
      //
      CharC       = (UINT16) (CharC - (UINT8_MAX + 1 - THRESHOLD));

      BytesRemain = CharC;

      DataIdx     = Sd->mOutBuf - DecodeP (Sd) - 1;

      BytesRemain--;
      while ((INT16) (BytesRemain) >= 0) {
        Sd->mDstBase[Sd->mOutBuf++] = Sd->mDstBase[DataIdx++];
        if (Sd->mOutBuf >= Sd->mOrigSize) {
          return ;
        }

        BytesRemain--;
      }
    }
  }

  return ;
}

/**
  The internal implementation of *_DECOMPRESS_PROTOCOL.GetInfo().

  @param  Source The source buffer containing the compressed data.
  @param  SourceSize The size of source buffer
  @param  DestinationSize The size of destination buffer.
  @param  ScratchSize The size of scratch buffer.

  @retval  RETURN_SUCCESS The size of destination buffer and the size of scratch buffer are successull retrieved.
  @retval  RETURN_INVALID_PARAMETER The source data is corrupted

**/
RETURN_STATUS
EFIAPI
UefiDecompressGetInfo (
  IN  CONST VOID  *Source,
  IN  UINT32      SourceSize,
  OUT UINT32      *DestinationSize,
  OUT UINT32      *ScratchSize
  )
{
  UINT32  CompressedSize;

  ASSERT (Source != NULL);
  ASSERT (DestinationSize != NULL);
  ASSERT (ScratchSize != NULL);

  *ScratchSize  = sizeof (SCRATCH_DATA);

  if (SourceSize < 8) {
    return RETURN_INVALID_PARAMETER;
  }

  CopyMem (&CompressedSize, Source, sizeof (UINT32));
  CopyMem (DestinationSize, (VOID *)((UINT8 *)Source + 4), sizeof (UINT32));

  if (SourceSize < (CompressedSize + 8)) {
    return RETURN_INVALID_PARAMETER;
  }

  return RETURN_SUCCESS;
}

/**
  The internal implementation of *_DECOMPRESS_PROTOCOL.Decompress().

  @param  Source The source buffer containing the compressed data.
  @param  Destination The destination buffer to store the decompressed data
  @param  Scratch The buffer used internally by the decompress routine. This  buffer is needed to store intermediate data.

  @retval  RETURN_SUCCESS Decompression is successfull
  @retval  RETURN_INVALID_PARAMETER The source data is corrupted

**/
RETURN_STATUS
EFIAPI
UefiDecompress (
  IN CONST VOID  *Source,
  IN OUT VOID    *Destination,
  IN OUT VOID    *Scratch
  )
{
  volatile UINT32  Index;
  UINT32           CompSize;
  UINT32           OrigSize;
  SCRATCH_DATA     *Sd;
  CONST UINT8      *Src;
  UINT8            *Dst;

  ASSERT (Source != NULL);
  ASSERT (Destination != NULL);
  ASSERT (Scratch != NULL);

  Src     = Source;
  Dst     = Destination;

  Sd = (SCRATCH_DATA *) Scratch;

  CompSize  = Src[0] + (Src[1] << 8) + (Src[2] << 16) + (Src[3] << 24);
  OrigSize  = Src[4] + (Src[5] << 8) + (Src[6] << 16) + (Src[7] << 24);

  //
  // If compressed file size is 0, return
  //
  if (OrigSize == 0) {
    return RETURN_SUCCESS;
  }

  Src = Src + 8;

  for (Index = 0; Index < sizeof (SCRATCH_DATA); Index++) {
    ((UINT8 *) Sd)[Index] = 0;
  }
  //
  // The length of the field 'Position Set Code Length Array Size' in Block Header.
  // For EFI 1.1 de/compression algorithm(Version 1), mPBit = 4
  // For Tiano de/compression algorithm(Version 2), mPBit = 5
  //
  Sd->mPBit     = 4;
  Sd->mSrcBase  = (UINT8 *)Src;
  Sd->mDstBase  = Dst;
  Sd->mCompSize = CompSize;
  Sd->mOrigSize = OrigSize;

  //
  // Fill the first BITBUFSIZ bits
  //
  FillBuf (Sd, BITBUFSIZ);

  //
  // Decompress it
  //
  Decode (Sd);

  if (Sd->mBadTableFlag != 0) {
    //
    // Something wrong with the source
    //
    return RETURN_INVALID_PARAMETER;
  }

  return RETURN_SUCCESS;
}