UncompressTFD.c

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#include                "libFireBird.h"
#include                "FBLib_compression.h"
 
// UncompressTFD() is a function wrapper that decodes 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 includeing header (word)
// 2 - CRC-16 (word)
// 4 - block type
// 6 - uncompressed size (word)
// 8 .. (compressed size + 5) - compressed data (byte array)
dword UncompressTFD(byte *pSrc, byte *pDest, void *pPercentFinishedCallback)
{
  TRACEENTER();
 
  word                  compSize = 0, uncompSize = 0, NrBlocks = 0;
  dword                 outSize = 0, i;
 
  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;
 
  if(LOAD_WORD(pSrc) != 8)
  {
    //Invalid header
    TRACEEXIT();
    return 0;
  }
 
  if(CRC16 (0, pSrc + 4, 6) != LOAD_WORD(pSrc + 2))
  {
    //Invalid header CRC
    TRACEEXIT();
    return 0;
  }
 
  if(LOAD_WORD(pSrc + 6) != 1)
  {
    //Invalid file version
    TRACEEXIT();
    return 0;
  }
 
  NrBlocks = LOAD_WORD(pSrc + 8);
 
  pSrc += 10;
 
  for(i = 0; i < NrBlocks; i++)
  {
    if(PercentFinishedCallback) PercentFinishedCallback(i * 100 / NrBlocks);
 
    compSize   = LOAD_WORD(pSrc) - 6;
    uncompSize = LOAD_WORD(pSrc + 6);
 
    if(uncompSize > 0x7ffa)
    {
      //Size of uncompressed block too large
      TRACEEXIT();
 
      return 0;
    }
 
    pSrc += 8;
 
    if(compSize == uncompSize)
    {
      // not compressed data, copy it directly
      if(pDest) memcpy(pDest, pSrc, uncompSize);
    }
    else
    {
      // compressed data, uncompress it
      if(!UncompressBlock(pSrc, compSize, pDest, uncompSize))
      {
        //Uncompress failed
        TRACEEXIT();
        return 0;
      }
    }
 
    if(pDest) pDest += uncompSize;
    pSrc += compSize;
    outSize += uncompSize;
  }
  if(PercentFinishedCallback) PercentFinishedCallback(100);
 
  TRACEEXIT();
  return outSize;
}