CompressTFD.c

Go to the documentation of this file.

#include                "libFireBird.h"
#include                "FBLib_compression.h"
 
// CompressTFD() is a function wrapper that encodes data blocks
// encoded with AR002 algorithm. This type uses a header
 
// The expected block structure is as follows:
// 0 - header length (always 0x0008)
// 2 - header CRC16
// 4 - System ID
// 6 - file version (always 0x0001)
// 8 - number of compressed blocks
 
//Every block has the following header:
// 0 - compressed size including header (word)
// 2 - CRC-16 (word)
// 4 - block type
// 6 - uncompressed size (word)
// 8 .. (compressed size + 5) - compressed data (byte array)
dword CompressTFD(byte *pSrc, dword SourceBufferSize, byte *pDest, word TFDType, word SysID, void *pPercentFinishedCallback)
{
  TRACEENTER();
 
  word                  OrigSize, CompSize;
  dword                 OutBufferSize, NrBlocks = 0, FullSize = SourceBufferSize;
  byte                  *FileHeader;
 
  if(!pSrc || !pDest)
  {
    TRACEEXIT();
    return 0;
  }
 
  //PercentFinishedCallback is called for every block. PercentFinished contains a number between 0 and 100
  void (*PercentFinishedCallback) (dword PercentFinished) = pPercentFinishedCallback;
 
  //Build the tfd file header
  FileHeader = pDest;
  if(pDest)
  {
    STORE_WORD(pDest    , 0x0008);
    STORE_WORD(pDest + 4, SysID);
    STORE_WORD(pDest + 6, 0x0001);
    pDest += 10;
  }
  OutBufferSize = 10;
 
  while(SourceBufferSize)
  {
    if(PercentFinishedCallback) PercentFinishedCallback((FullSize - SourceBufferSize) * 100 / FullSize);
 
    NrBlocks++;
    OrigSize = (SourceBufferSize > 0x7ffa) ? 0x7ffa : SourceBufferSize;
 
    if(pDest)
    {
      CompSize = CompressBlock(pSrc, OrigSize, pDest + 8);
 
      //Build the block header
      STORE_WORD(pDest    , CompSize + 6);
      STORE_WORD(pDest + 4, TFDType);
      STORE_WORD(pDest + 6, OrigSize);
      STORE_WORD(pDest + 2, CRC16(0, pDest + 4, 4 + CompSize));
      pDest += CompSize + 8;
    }
    else CompSize = CompressBlock(pSrc, OrigSize, NULL);
 
    OutBufferSize    += CompSize + 8;
    SourceBufferSize -= OrigSize;
    pSrc             += OrigSize;
  }
 
  if(FileHeader)
  {
    STORE_WORD(FileHeader + 8, NrBlocks);
    STORE_WORD(FileHeader + 2, CRC16 (0, FileHeader + 4, 6));
  }
 
  if(PercentFinishedCallback) PercentFinishedCallback(100);
 
  TRACEEXIT();
  return OutBufferSize;
}