VecCompressor.h

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// -*- C++ -*-

// VecCompressor.h
// Copyright (C) 2001 Pascal Vincent
// Copyright (C) 2002 Pascal Vincent, Julien Keable, Xavier Saint-Mleux
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// 
//  1. Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
// 
//  2. Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//     documentation and/or other materials provided with the distribution.
// 
//  3. The name of the authors may not be used to endorse or promote
//     products derived from this software without specific prior written
//     permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
// NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// 
// This file is part of the PLearn library. For more information on the PLearn
// library, go to the PLearn Web site at www.plearn.org


/* *******************************************************      
   * $Id: VecCompressor.h,v 1.2 2004/02/20 21:11:46 chrish42 Exp $
   ******************************************************* */


#ifndef VecCompressor_INC
#define VecCompressor_INC

#include "TMat.h"

namespace PLearn {
using namespace std;
 

class VecCompressor
{
protected:

  static inline bool issmallint(real x)
  { int intx = int(x); return floor(x)==x && intx<=127 && intx>=-127; }

  static inline bool is0(real x)
  { return x==0.; }

  static inline bool isI(real x)
  { return x!=0. && issmallint(x); }

  static inline bool isF(real x)
  { return x!=0. && !issmallint(x); }
  
public:
  static signed char* compressVec(const Vec& v, signed char* data);

  static void uncompressVec(signed char* data, const Vec& v);  

  static void writeCompressedVec(ostream& out, const Vec& v);

  static void readCompressedVec(istream& in, const Vec& v); 

  static size_t worstCaseSize(int n)
  { return 2+4*n+n/128; }
};

} // end of namespcae PLearn
#endif

---