///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// *       Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// *       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.
// *       Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "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 COPYRIGHT
// OWNER OR CONTRIBUTORS 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.
//
///////////////////////////////////////////////////////////////////////////



//-----------------------------------------------------------------------------
//
//	class ZipCompressor
//
//-----------------------------------------------------------------------------

#include <ImfZipCompressor.h>
#include <Iex.h>
#include <zlib.h>

namespace Imf {


ZipCompressor::ZipCompressor
    (const Header &hdr,
     int maxScanLineSize,
     int numScanLines)
:
    Compressor (hdr),
    _maxScanLineSize (maxScanLineSize),
    _numScanLines (numScanLines),
    _tmpBuffer (0),
    _outBuffer (0)
{
    _tmpBuffer = new char [maxScanLineSize * numScanLines];
    _outBuffer = new char [maxScanLineSize * numScanLines * 3 / 2];
}


ZipCompressor::~ZipCompressor ()
{
    delete [] _tmpBuffer;
    delete [] _outBuffer;
}


int
ZipCompressor::numScanLines () const
{
    return _numScanLines;
}


int
ZipCompressor::compress (const char *inPtr,
			 int inSize,
			 int minY,
			 const char *&outPtr)
{
    //
    // Special case ­- empty input buffer
    //

    if (inSize == 0)
    {
	outPtr = _outBuffer;
	return 0;
    }

    //
    // Reorder the pixel data.
    //

    {
	char *t1 = _tmpBuffer;
	char *t2 = _tmpBuffer + (inSize + 1) / 2;
	const char *stop = inPtr + inSize;

	while (true)
	{
	    if (inPtr < stop)
		*(t1++) = *(inPtr++);
	    else
		break;

	    if (inPtr < stop)
		*(t2++) = *(inPtr++);
	    else
		break;
	}
    }

    //
    // Predictor.
    //

    {
	unsigned char *t = (unsigned char *) _tmpBuffer + 1;
	unsigned char *stop = (unsigned char *) _tmpBuffer + inSize;
	int p = t[-1];

	while (t < stop)
	{
	    int d = int (t[0]) - p + (128 + 256);
	    p = t[0];
	    t[0] = d;
	    ++t;
	}
    }

    //
    // Compress the data using zlib
    //

    uLongf outSize = inSize * 3 / 2;

    if (Z_OK != ::compress ((Bytef *)_outBuffer, &outSize,
			    (const Bytef *) _tmpBuffer, inSize))
    {
	throw Iex::BaseExc ("Data compression (zlib) failed.");
    }

    outPtr = _outBuffer;
    return outSize;
}


int
ZipCompressor::uncompress (const char *inPtr,
			   int inSize,
			   int minY,
			   const char *&outPtr)
{
    //
    // Special case ­- empty input buffer
    //

    if (inSize == 0)
    {
	outPtr = _outBuffer;
	return 0;
    }

    //
    // Decompress the data using zlib
    //

    uLongf outSize = _maxScanLineSize * _numScanLines;

    if (Z_OK != ::uncompress ((Bytef *)_tmpBuffer, &outSize,
			      (const Bytef *) inPtr, inSize))
    {
	throw Iex::BaseExc ("Data decompression (zlib) failed.");
    }

    //
    // Predictor.
    //

    {
	unsigned char *t = (unsigned char *) _tmpBuffer + 1;
	unsigned char *stop = (unsigned char *) _tmpBuffer + outSize;

	while (t < stop)
	{
	    int d = int (t[-1]) + int (t[0]) - 128;
	    t[0] = d;
	    ++t;
	}
    }

    //
    // Reorder the pixel data.
    //

    {
	const char *t1 = _tmpBuffer;
	const char *t2 = _tmpBuffer + (outSize + 1) / 2;
	char *s = _outBuffer;
	char *stop = s + outSize;

	while (true)
	{
	    if (s < stop)
		*(s++) = *(t1++);
	    else
		break;

	    if (s < stop)
		*(s++) = *(t2++);
	    else
		break;
	}
    }

    outPtr = _outBuffer;
    return outSize;
}


} // namespace Imf