dcmdata/include/dcrledec.h

/*
 *
 *  Copyright (C) 1994-2003, OFFIS
 *
 *  This software and supporting documentation were developed by
 *
 *    Kuratorium OFFIS e.V.
 *    Healthcare Information and Communication Systems
 *    Escherweg 2
 *    D-26121 Oldenburg, Germany
 *
 *  THIS SOFTWARE IS MADE AVAILABLE,  AS IS,  AND OFFIS MAKES NO  WARRANTY
 *  REGARDING  THE  SOFTWARE,  ITS  PERFORMANCE,  ITS  MERCHANTABILITY  OR
 *  FITNESS FOR ANY PARTICULAR USE, FREEDOM FROM ANY COMPUTER DISEASES  OR
 *  ITS CONFORMITY TO ANY SPECIFICATION. THE ENTIRE RISK AS TO QUALITY AND
 *  PERFORMANCE OF THE SOFTWARE IS WITH THE USER.
 *
 *  Module:  dcmdata
 *
 *  Author:  Marco Eichelberg
 *
 *  Purpose: RLE decompressor
 *
 *  Last Update:      $Author: meichel $
 *  Update Date:      $Date: 2003/08/14 09:00:56 $
 *  Source File:      $Source: /share/dicom/cvs-depot/dcmtk/dcmdata/include/dcrledec.h,v $
 *  CVS/RCS Revision: $Revision: 1.3 $
 *  Status:           $State: Exp $
 *
 *  CVS/RCS Log at end of file
 *
 */

#ifndef DCRLEDEC_H
#define DCRLEDEC_H

#include "osconfig.h"
#include "dcerror.h"

class DcmRLEDecoder
{
public:

  DcmRLEDecoder(size_t outputBufferSize)
  : fail_(0)
  , outputBufferSize_(outputBufferSize)
  , outputBuffer_(NULL)
  , offset_(0)
  , suspendInfo_(128)
  {
    if (outputBufferSize_ == 0) fail_ = 1;
    else
    {
      outputBuffer_ = new unsigned char[outputBufferSize_];
      if (outputBuffer_ == NULL) fail_ = 1;
    }
  }

  ~DcmRLEDecoder()
  {
    delete[] outputBuffer_;
  }

  inline void clear()
  {
    offset_ = 0;
    suspendInfo_ = 128;
    if (outputBuffer_) fail_ = 0;
  }


  inline OFCondition decompress(void *compressedData, size_t compressedSize)
  {
    // we allow a call for zero bytes
    if (compressedSize == 0) return EC_Normal;

    OFCondition result = EC_IllegalCall;

    // check parameters passed by caller
    if (compressedData == NULL) fail_ = 1;

    if (! fail_)  // if fail_ is true, just ignore input
    {
      result = EC_Normal;
      unsigned char ch;
      unsigned char nbytes;
      unsigned char *cp = OFstatic_cast(unsigned char *, compressedData);

      // check if we suspended last time, clean up
      if (suspendInfo_ > 128)
      {
        // DICOM packbit scheme uses 257 - nbytes to represent replicate runs
        nbytes = OFstatic_cast(unsigned char, 257 - suspendInfo_);

        // suspended replicate run. compressedSize cannot be zero now.
        suspendInfo_ = 128;

        ch = *cp++;
        --compressedSize;
        replicate(ch, nbytes);
      }
      else if (suspendInfo_ < 128)
      {
        // suspended literal run
        nbytes = OFstatic_cast(unsigned char, (suspendInfo_ & 0x7f) + 1);
        suspendInfo_ = 128;
        if (compressedSize < nbytes)
        {
          // we're going to suspend again (oops?), prepare everything
          suspendInfo_ = OFstatic_cast(unsigned char, nbytes - compressedSize - 1);
          nbytes = OFstatic_cast(unsigned char, compressedSize);
          result = EC_StreamNotifyClient;
        }

        literal(cp, nbytes);
        compressedSize -= nbytes;
        cp += nbytes;
      }

      // continue with ordinary RLE decompression
      while (compressedSize && (! fail_))
      {
        ch = *cp++;
        --compressedSize;

        if (ch & 0x80)
        {
          // replicate run
          if (compressedSize)
          {
            // DICOM packbit scheme uses 257 - nbytes to represent replicate runs
            nbytes = OFstatic_cast(unsigned char, 257 - ch);
            ch = *cp++;
            --compressedSize;
            replicate(ch, nbytes);
          }
          else
          {
            // suspension: replicate run but second byte is in next block
            suspendInfo_ = ch;
            result = EC_StreamNotifyClient;
          }
        } 
        else
        {
          // literal run
          nbytes = OFstatic_cast(unsigned char, (ch & 0x7f) + 1);
          if (compressedSize < nbytes)
          {
            // we're going to suspend, prepare everything
            suspendInfo_ = OFstatic_cast(unsigned char, nbytes - compressedSize - 1);
            nbytes = OFstatic_cast(unsigned char, compressedSize);
            result = EC_StreamNotifyClient;
          }

          literal(cp, nbytes);
          compressedSize -= nbytes;
          cp += nbytes;
        }
      }

      // failure status at this point means output buffer overflow
      if (fail_) result = EC_CorruptedData;
    }

    return result;
  }


  inline size_t size() const
  {
    return offset_;
  }

  inline void *getOutputBuffer() const
  {
    return outputBuffer_;
  }

  inline OFBool fail() const
  {
    if (fail_) return OFTrue; else return OFFalse;
  }

private:

  DcmRLEDecoder(const DcmRLEDecoder&);

  DcmRLEDecoder& operator=(const DcmRLEDecoder&);


  inline void replicate(unsigned char ch, unsigned char nbytes)
  {
     if (offset_ + nbytes > outputBufferSize_)
     {
       // output buffer overflow
       fail_ = 1;
       nbytes = OFstatic_cast(unsigned char, outputBufferSize_ - offset_);
     }

     while (nbytes--) outputBuffer_[offset_++] = ch;
  }


  inline void literal(unsigned char *cp, unsigned char nbytes)
  {
     if (offset_ + nbytes > outputBufferSize_)
     {
       // output buffer overflow
       fail_ = 1;
       nbytes = OFstatic_cast(unsigned char, outputBufferSize_ - offset_);
     }

     while (nbytes--) outputBuffer_[offset_++] = *cp++;
  }

  /* member variables */

  int fail_;

  size_t outputBufferSize_;

  unsigned char *outputBuffer_;

  size_t offset_;

  unsigned char suspendInfo_;
};

#endif

/*
 * CVS/RCS Log
 * $Log: dcrledec.h,v $
 * Revision 1.3  2003/08/14 09:00:56  meichel
 * Adapted type casts to new-style typecast operators defined in ofcast.h
 *
 * Revision 1.2  2003/03/21 13:06:46  meichel
 * Minor code purifications for warnings reported by MSVC in Level 4
 *
 * Revision 1.1  2002/06/06 14:52:36  meichel
 * Initial release of the new RLE codec classes
 *   and the dcmcrle/dcmdrle tools in module dcmdata
 *
 *
 */

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