compress.c

Next BIOS Source code : Extensible Firmware Interface

    u &= ~PERC_FLAG;
    if (u >= mPos) {
      u -= WNDSIZ;
    }
    if (u > s) {
      s = u;
    }
    mPosition[q] = (INT16)(s | WNDSIZ);
    q = mParent[q];
  }
  if (q < WNDSIZ) {
    if (u >= mPos) {
      u -= WNDSIZ;
    }
    if (u > s) {
      s = u;
    }
    mPosition[q] = (INT16)(s | WNDSIZ | PERC_FLAG);
  }
  s = Child(r, mText[t + mLevel[r]]);
  t = mPrev[s];
  u = mNext[s];
  mNext[t] = u;
  mPrev[u] = t;
  t = mPrev[r];
  mNext[t] = s;
  mPrev[s] = t;
  t = mNext[r];
  mPrev[t] = s;
  mNext[s] = t;
  mParent[s] = mParent[r];
  mParent[r] = NIL;
  mNext[r] = mAvail;
  mAvail = r;
}

STATIC 
VOID 
GetNextMatch ()
/*++

Routine Description:

  Advance the current position (read in new data if needed).
  Delete outdated string info. Find a match string for current position.

Arguments: (VOID)

Returns: (VOID)

--*/
{
  INT32 n;

  mRemainder--;
  if (++mPos == WNDSIZ * 2) {
    memmove(&mText[0], &mText[WNDSIZ], WNDSIZ + MAXMATCH);
    n = FreadCrc(&mText[WNDSIZ + MAXMATCH], WNDSIZ);
    mRemainder += n;
    mPos = WNDSIZ;
  }
  DeleteNode();
  InsertNode();
}

STATIC
EFI_STATUS
Encode ()
/*++

Routine Description:

  The main controlling routine for compression process.

Arguments: (VOID)

Returns:
  
  EFI_SUCCESS           - The compression is successful
  EFI_OUT_0F_RESOURCES  - Not enough memory for compression process

--*/
{
  EFI_STATUS  Status;
  INT32       LastMatchLen;
  NODE        LastMatchPos;

  Status = AllocateMemory();
  if (EFI_ERROR(Status)) {
    FreeMemory();
    return Status;
  }

  InitSlide();
  
  HufEncodeStart();

  mRemainder = FreadCrc(&mText[WNDSIZ], WNDSIZ + MAXMATCH);
  
  mMatchLen = 0;
  mPos = WNDSIZ;
  InsertNode();
  if (mMatchLen > mRemainder) {
    mMatchLen = mRemainder;
  }
  while (mRemainder > 0) {
    LastMatchLen = mMatchLen;
    LastMatchPos = mMatchPos;
    GetNextMatch();
    if (mMatchLen > mRemainder) {
      mMatchLen = mRemainder;
    }
    
    if (mMatchLen > LastMatchLen || LastMatchLen < THRESHOLD) {
      
      //
      // Not enough benefits are gained by outputting a pointer,
      // so just output the original character
      //
      
      Output(mText[mPos - 1], 0);
    } else {
      
      //
      // Outputting a pointer is beneficial enough, do it.
      //
      
      Output(LastMatchLen + (UINT8_MAX + 1 - THRESHOLD),
             (mPos - LastMatchPos - 2) & (WNDSIZ - 1));
      while (--LastMatchLen > 0) {
        GetNextMatch();
      }
      if (mMatchLen > mRemainder) {
        mMatchLen = mRemainder;
      }
    }
  }
  
  HufEncodeEnd();
  FreeMemory();
  return EFI_SUCCESS;
}

STATIC 
VOID 
CountTFreq ()
/*++

Routine Description:

  Count the frequencies for the Extra Set
  
Arguments: (VOID)

Returns: (VOID)

--*/
{
  INT32 i, k, n, Count;

  for (i = 0; i < NT; i++) {
    mTFreq[i] = 0;
  }
  n = NC;
  while (n > 0 && mCLen[n - 1] == 0) {
    n--;
  }
  i = 0;
  while (i < n) {
    k = mCLen[i++];
    if (k == 0) {
      Count = 1;
      while (i < n && mCLen[i] == 0) {
        i++;
        Count++;
      }
      if (Count <= 2) {
        mTFreq[0] = (UINT16)(mTFreq[0] + Count);
      } else if (Count <= 18) {
        mTFreq[1]++;
      } else if (Count == 19) {
        mTFreq[0]++;
        mTFreq[1]++;
      } else {
        mTFreq[2]++;
      }
    } else {
      mTFreq[k + 2]++;
    }
  }
}

STATIC 
VOID 
WritePTLen (
  IN INT32 n, 
  IN INT32 nbit, 
  IN INT32 Special
  )
/*++

Routine Description:

  Outputs the code length array for the Extra Set or the Position Set.
  
Arguments:

  n       - the number of symbols
  nbit    - the number of bits needed to represent 'n'
  Special - the special symbol that needs to be take care of
  
Returns: (VOID)

--*/
{
  INT32 i, k;

  while (n > 0 && mPTLen[n - 1] == 0) {
    n--;
  }
  PutBits(nbit, n);
  i = 0;
  while (i < n) {
    k = mPTLen[i++];
    if (k <= 6) {
      PutBits(3, k);
    } else {
      PutBits(k - 3, (1U << (k - 3)) - 2);
    }
    if (i == Special) {
      while (i < 6 && mPTLen[i] == 0) {
        i++;
      }
      PutBits(2, (i - 3) & 3);
    }
  }
}

STATIC 
VOID 
WriteCLen ()
/*++

Routine Description:

  Outputs the code length array for Char&Length Set
  
Arguments: (VOID)

Returns: (VOID)

--*/
{
  INT32 i, k, n, Count;

  n = NC;
  while (n > 0 && mCLen[n - 1] == 0) {
    n--;
  }
  PutBits(CBIT, n);
  i = 0;
  while (i < n) {
    k = mCLen[i++];
    if (k == 0) {
      Count = 1;
      while (i < n && mCLen[i] == 0) {
        i++;
        Count++;
      }
      if (Count <= 2) {
        for (k = 0; k < Count; k++) {
          PutBits(mPTLen[0], mPTCode[0]);
        }
      } else if (Count <= 18) {
        PutBits(mPTLen[1], mPTCode[1]);
        PutBits(4, Count - 3);
      } else if (Count == 19) {
        PutBits(mPTLen[0], mPTCode[0]);
        PutBits(mPTLen[1], mPTCode[1]);
        PutBits(4, 15);
      } else {
        PutBits(mPTLen[2], mPTCode[2]);
        PutBits(CBIT, Count - 20);
      }
    } else {
      PutBits(mPTLen[k + 2], mPTCode[k + 2]);
    }
  }
}

STATIC 
VOID 
EncodeC (
  IN INT32 c
  )
{
  PutBits(mCLen[c], mCCode[c]);
}

STATIC 
VOID 
EncodeP (
  IN UINT32 p
  )
{
  UINT32 c, q;

  c = 0;
  q = p;
  while (q) {
    q >>= 1;
    c++;
  }
  PutBits(mPTLen[c], mPTCode[c]);
  if (c > 1) {
    PutBits(c - 1, p & (0xFFFFU >> (17 - c)));
  }
}

STATIC 
VOID 
SendBlock ()
/*++

Routine Description:

  Huffman code the block and output it.
  
Argument: (VOID)

Returns: (VOID)

--*/
{
  UINT32 i, k, Flags, Root, Pos, Size;
  Flags = 0;

  Root = MakeTree(NC, mCFreq, mCLen, mCCode);
  Size = mCFreq[Root];
  PutBits(16, Size);
  if (Root >= NC) {
    CountTFreq();
    Root = MakeTree(NT, mTFreq, mPTLen, mPTCode);
    if (Root >= NT) {
      WritePTLen(NT, TBIT, 3);
    } else {
      PutBits(TBIT, 0);
      PutBits(TBIT, Root);
    }
    WriteCLen();
  } else {
    PutBits(TBIT, 0);
    PutBits(TBIT, 0);
    PutBits(CBIT, 0);
    PutBits(CBIT, Root);
  }
  Root = MakeTree(NP, mPFreq, mPTLen, mPTCode);
  if (Root >= NP) {
    WritePTLen(NP, PBIT, -1);
  } else {
    PutBits(PBIT, 0);
    PutBits(PBIT, Root);
  }
  Pos = 0;
  for (i = 0; i < Size; i++) {
    if (i % UINT8_BIT == 0) {
      Flags = mBuf[Pos++];
    } else {
      Flags <<= 1;
    }
    if (Flags & (1U << (UINT8_BIT - 1))) {
      EncodeC(mBuf[Pos++] + (1U << UINT8_BIT));
      k = mBuf[Pos++] << UINT8_BIT;
      k += mBuf[Pos++];
      EncodeP(k);
    } else {
      EncodeC(mBuf[Pos++]);
    }
  }
  for (i = 0; i < NC; i++) {
    mCFreq[i] = 0;
  }
  for (i = 0; i < NP; i++) {
    mPFreq[i] = 0;
  }
}


STATIC 
VOID 
Output (
  IN UINT32 c, 
  IN UINT32 p
  )
/*++

Routine Description:

  Outputs an Original Character or a Pointer

Arguments:

  c     - The original character or the 'String Length' element of a Pointer
  p     - The 'Position' field of a Pointer

Returns: (VOID)

--*/
{
  STATIC UINT32 CPos;

  if ((mOutputMask >>= 1) == 0) {
    mOutputMask = 1U << (UINT8_BIT - 1);
    if (mOutputPos >= mBufSiz - 3 * UINT8_BIT) {
      SendBlock();
      mOutputPos = 0;
    }
    CPos = mOutputPos++;  
    mBuf[CPos] = 0;
  }
  mBuf[mOutputPos++] = (UINT8) c;
  mCFreq[c]++;
  if (c >= (1U << UINT8_BIT)) {
    mBuf[CPos] |= mOutputMask;
    mBuf[mOutputPos++] = (UINT8)(p >> UINT8_BIT);
    mBuf[mOutputPos++] = (UINT8) p;
    c = 0;
    while (p) {
      p >>= 1;
      c++;
    }
    mPFreq[c]++;
  }
}

STATIC
VOID
HufEncodeStart ()
{
  INT32 i;

  for (i = 0; i < NC; i++) {
    mCFreq[i] = 0;
  }
  for (i = 0; i < NP; i++) {
    mPFreq[i] = 0;
  }
  mOutputPos = mOutputMask = 0;
  InitPutBits();
  return;
}

STATIC 
VOID 
HufEncodeEnd ()
{
  SendBlock();
  
  //
  // Flush remaining bits
  //
  PutBits(UINT8_BIT - 1, 0);
  
  return;
}


STATIC 
VOID 
MakeCrcTable ()
{
  UINT32 i, j, r;

  for (i = 0; i <= UINT8_MAX; i++) {
    r = i;
    for (j = 0; j < UINT8_BIT; j++) {
      if (r & 1) {
        r = (r >> 1) ^ CRCPOLY;
      } else {
        r >>= 1;
      }
    }
    mCrcTable[i] = (UINT16)r;    
  }
}

STATIC 
VOID 
PutBits (
  IN INT32 n, 
  IN UINT32 x
  )
/*++

Routine Description:

  Outputs rightmost n bits of x

Argments:

  n   - the rightmost n bits of the data is used
  x   - the data 

Returns: (VOID)

--*/
{
  UINT8 Temp;  
  
  if (n < mBitCount) {
    mSubBitBuf |= x << (mBitCount -= n);
  } else {
      
    Temp = (UINT8)(mSubBitBuf | (x >> (n -= mBitCount)));
    if (mDst < mDstUpperLimit) {
      *mDst++ = Temp;
    }
    mCompSize++;

    if (n < UINT8_BIT) {
      mSubBitBuf = x << (mBitCount = UINT8_BIT - n);
    } else {
        
      Temp = (UINT8)(x >> (n - UINT8_BIT));
      if (mDst < mDstUpperLimit) {
        *mDst++ = Temp;
      }
      mCompSize++;
      
      mSubBitBuf = x << (mBitCount = 2 * UINT8_BIT - n);
    }
  }
}

STATIC 
INT32 
FreadCrc (
  OUT UINT8 *p, 
  IN  INT32 n
  )
/*++

Routine Description:

  Read in source data
  
Arguments:

  p   - the buffer to hold the data
  n   - number of bytes to read

Returns:

  number of bytes actually read
  
--*/
{
  INT32 i;

  for (i = 0; mSrc < mSrcUpperLimit && i < n; i++) {
    *p++ = *mSrc++;
  }
  n = i;

  p -= n;
  mOrigSize += n;
  while (--i >= 0) {
    UPDATE_CRC(*p++);
  }
  return n;
}


STATIC 
VOID 
InitPutBits ()
{
  mBitCount = UINT8_BIT;  
  mSubBitBuf = 0;
}

STATIC 
VOID 
CountLen (
  IN INT32 i
  )
/*++

Routine Description:

  Count the number of each code length for a Huffman tree.
  
Arguments:

  i   - the top node
  
Returns: (VOID)

--*/
{
  STATIC INT32 Depth = 0;

  if (i < mN) {
    mLenCnt[(Depth < 16) ? Depth : 16]++;
  } else {
    Depth++;
    CountLen(mLeft [i]);
    CountLen(mRight[i]);
    Depth--;
  }
}

STATIC 
VOID 
MakeLen (
  IN INT32 Root
  )
/*++

Routine Description:

  Create code length array for a Huffman tree
  
Arguments:

  Root   - the root of the tree

--*/
{
  INT32 i, k;
  UINT32 Cum;

  for (i = 0; i <= 16; i++) {
    mLenCnt[i] = 0;
  }
  CountLen(Root);
  
  //
  // Adjust the length count array so that
  // no code will be generated longer than its designated length
  //
  
  Cum = 0;
  for (i = 16; i > 0; i--) {
    Cum += mLenCnt[i] << (16 - i);
  }
  while (Cum != (1U << 16)) {
    mLenCnt[16]--;
    for (i = 15; i > 0; i--) {
      if (mLenCnt[i] != 0) {
        mLenCnt[i]--;
        mLenCnt[i+1] += 2;
        break;
      }
    }
    Cum--;
  }
  for (i = 16; i > 0; i--) {
    k = mLenCnt[i];
    while (--k >= 0) {
      mLen[*mSortPtr++] = (UINT8)i;
    }
  }
}

STATIC 
VOID 
DownHeap (
  IN INT32 i
  )
{
  INT32 j, k;

  //
  // priority queue: send i-th entry down heap
  //
  
  k = mHeap[i];
  while ((j = 2 * i) <= mHeapSize) {
    if (j < mHeapSize && mFreq[mHeap[j]] > mFreq[mHeap[j + 1]]) {
      j++;
    }
    if (mFreq[k] <= mFreq[mHeap[j]]) {
      break;
    }
    mHeap[i] = mHeap[j];
    i = j;
  }
  mHeap[i] = (INT16)k;
}

STATIC 
VOID 
MakeCode (
  IN  INT32 n, 
  IN  UINT8 Len[], 
  OUT UINT16 Code[]
  )
/*++

Routine Description:

  Assign code to each symbol based on the code length array
  
Arguments:

  n     - number of symbols
  Len   - the code length array
  Code  - stores codes for each symbol

Returns: (VOID)

--*/
{
  INT32    i;
  UINT16   Start[18];

  Start[1] = 0;
  for (i = 1; i <= 16; i++) {
    Start[i + 1] = (UINT16)((Start[i] + mLenCnt[i]) << 1);
  }
  for (i = 0; i < n; i++) {
    Code[i] = Start[Len[i]]++;
  }
}

STATIC 
INT32 
MakeTree (
  IN  INT32   NParm, 
  IN  UINT16  FreqParm[], 
  OUT UINT8   LenParm[], 
  OUT UINT16  CodeParm[]
  )
/*++

Routine Description:

  Generates Huffman codes given a frequency distribution of symbols
  
Arguments:

  NParm    - number of symbols
  FreqParm - frequency of each symbol
  LenParm  - code length for each symbol
  CodeParm - code for each symbol
  
Returns:

  Root of the Huffman tree.
  
--*/
{
  INT32 i, j, k, Avail;
  
  //
  // make tree, calculate len[], return root
  //

  mN = NParm;
  mFreq = FreqParm;
  mLen = LenParm;
  Avail = mN;
  mHeapSize = 0;
  mHeap[1] = 0;
  for (i = 0; i < mN; i++) {
    mLen[i] = 0;
    if (mFreq[i]) {
      mHeap[++mHeapSize] = (INT16)i;
    }    
  }
  if (mHeapSize < 2) {
    CodeParm[mHeap[1]] = 0;
    return mHeap[1];
  }
  for (i = mHeapSize / 2; i >= 1; i--) {
    
    //
    // make priority queue 
    //
    DownHeap(i);
  }
  mSortPtr = CodeParm;
  do {
    i = mHeap[1];
    if (i < mN) {
      *mSortPtr++ = (UINT16)i;
    }
    mHeap[1] = mHeap[mHeapSize--];
    DownHeap(1);
    j = mHeap[1];
    if (j < mN) {
      *mSortPtr++ = (UINT16)j;
    }
    k = Avail++;
    mFreq[k] = (UINT16)(mFreq[i] + mFreq[j]);
    mHeap[1] = (INT16)k;
    DownHeap(1);
    mLeft[k] = (UINT16)i;
    mRight[k] = (UINT16)j;
  } while (mHeapSize > 1);
  
  mSortPtr = CodeParm;
  MakeLen(k);
  MakeCode(NParm, LenParm, CodeParm);
  
  //
  // return root
  //
  return k;
}