/*M///////////////////////////////////////////////////////////////////////////////////////
//
//  IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
//
//  By downloading, copying, installing or using the software you agree to this license.
//  If you do not agree to this license, do not download, install,
//  copy or use the software.
//
//
//                        Intel License Agreement
//                For Open Source Computer Vision Library
//
// Copyright (C) 2000, Intel Corporation, all rights reserved.
// Third party copyrights are property of their respective owners.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
//   * Redistribution's of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//
//   * Redistribution's 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.
//
//   * The name of Intel Corporation may not 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
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// In no event shall the Intel Corporation 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.
//
//M*/

#include "_highgui.h"
#include "grfmt_jpeg.h"

// JPEG filter factory

GrFmtJpeg::GrFmtJpeg()
{
    m_sign_len = 3;
    m_signature = "\xFF\xD8\xFF";
    m_description = "JPEG files (*.jpeg;*.jpg;*.jpe)";
}


GrFmtJpeg::~GrFmtJpeg()
{
}


GrFmtReader* GrFmtJpeg::NewReader( const char* filename )
{
    return new GrFmtJpegReader( filename );
}


GrFmtWriter* GrFmtJpeg::NewWriter( const char* filename )
{
    return new GrFmtJpegWriter( filename );
}


#ifdef HAVE_JPEG

/****************************************************************************************\
    This part of the file implements JPEG codec on base of IJG libjpeg library,
    in particular, this is the modified example.doc from libjpeg package.
    See otherlibs/_graphics/readme.txt for copyright notice.
\****************************************************************************************/

#include <stdio.h>
#include <setjmp.h>

#ifdef WIN32

#define XMD_H // prevent redefinition of INT32
#undef FAR  // prevent FAR redefinition

#endif

#if defined WIN32 && defined __GNUC__
typedef unsigned char boolean;
#endif

extern "C" {
#include "jpeglib.h"
}

/////////////////////// Error processing /////////////////////

typedef struct GrFmtJpegErrorMgr
{
    struct jpeg_error_mgr pub;    /* "parent" structure */
    jmp_buf setjmp_buffer;        /* jump label */
}
GrFmtJpegErrorMgr;


METHODDEF(void)
error_exit( j_common_ptr cinfo )
{
    GrFmtJpegErrorMgr* err_mgr = (GrFmtJpegErrorMgr*)(cinfo->err);
    
    /* Return control to the setjmp point */
    longjmp( err_mgr->setjmp_buffer, 1 );
}


/////////////////////// GrFmtJpegReader ///////////////////


GrFmtJpegReader::GrFmtJpegReader( const char* filename ) : GrFmtReader( filename )
{
    m_cinfo = 0;
    m_f = 0;
}


GrFmtJpegReader::~GrFmtJpegReader()
{
}


void  GrFmtJpegReader::Close()
{
    if( m_f )
    {
        fclose( m_f );
        m_f = 0;
    }

    if( m_cinfo )
    {
        jpeg_decompress_struct* cinfo = (jpeg_decompress_struct*)m_cinfo;
        GrFmtJpegErrorMgr* jerr = (GrFmtJpegErrorMgr*)m_jerr;

        jpeg_destroy_decompress( cinfo );
        delete cinfo;
        delete jerr;
        m_cinfo = 0;
        m_jerr = 0;
    }
    GrFmtReader::Close();
}


bool  GrFmtJpegReader::ReadHeader()
{
    bool result = false;
    Close();

    jpeg_decompress_struct* cinfo = new jpeg_decompress_struct;
    GrFmtJpegErrorMgr* jerr = new GrFmtJpegErrorMgr;

    cinfo->err = jpeg_std_error(&jerr->pub);
    jerr->pub.error_exit = error_exit;

    m_cinfo = cinfo;
    m_jerr = jerr;

    if( setjmp( jerr->setjmp_buffer ) == 0 )
    {
        jpeg_create_decompress( cinfo );

        m_f = fopen( m_filename, "rb" );
        if( m_f )
        {
            jpeg_stdio_src( cinfo, m_f );
            jpeg_read_header( cinfo, TRUE );

            m_width = cinfo->image_width;
            m_height = cinfo->image_height;
            m_iscolor = cinfo->num_components > 1;

            result = true;
        }
    }

    if( !result )
        Close();

    return result;
}


bool  GrFmtJpegReader::ReadData( uchar* data, int step, int color )
{
    bool result = false;

    color = color > 0 || (m_iscolor && color < 0);
    
    if( m_cinfo && m_jerr && m_width && m_height )
    {
        jpeg_decompress_struct* cinfo = (jpeg_decompress_struct*)m_cinfo;
        GrFmtJpegErrorMgr* jerr = (GrFmtJpegErrorMgr*)m_jerr;
        JSAMPARRAY buffer = 0;
        
        if( setjmp( jerr->setjmp_buffer ) == 0 )
        {
            int planes = m_iscolor ? 3 : 1;
            int width_n = m_width * planes;

            jpeg_start_decompress( cinfo );

            buffer = (*cinfo->mem->alloc_sarray)((j_common_ptr)cinfo,
                                              JPOOL_IMAGE, width_n, 1 );

            for( ; m_height--; data += step )
            {
                jpeg_read_scanlines( cinfo, buffer, 1 );
                if( color )
                {
                    if( m_iscolor )
                        icvCvt_RGB2BGR_8u_C3R( buffer[0], 0, data, 0, cvSize(m_width,1) );
                    else
                        icvCvt_Gray2BGR_8u_C1C3R( buffer[0], 0, data, 0, cvSize(m_width,1) );
                }
                else
                {
                    if( m_iscolor )
                        icvCvt_BGR2Gray_8u_C3C1R( buffer[0], 0, data, 0, cvSize(m_width,1), 2 );
                    else
                        memcpy( data, buffer[0], m_width );
                }
            }
            result = true;
        }

        jpeg_finish_decompress( cinfo );
    }

    Close();
    return result;
}


/////////////////////// GrFmtJpegWriter ///////////////////

GrFmtJpegWriter::GrFmtJpegWriter( const char* filename ) : GrFmtWriter( filename )
{
}


GrFmtJpegWriter::~GrFmtJpegWriter()
{
}


bool  GrFmtJpegWriter::WriteImage( const uchar* data, int step,
                                   int width, int height, int _channels )
{
    const int default_quality = 90;
    struct jpeg_compress_struct cinfo;
    GrFmtJpegErrorMgr jerr;

    bool result = false;
    FILE* f = 0;
    int channels = _channels > 1 ? 3 : 1;
    uchar* buffer = 0; // temporary buffer for row flipping
    
    cinfo.err = jpeg_std_error(&jerr.pub);
    jerr.pub.error_exit = error_exit;

    if( setjmp( jerr.setjmp_buffer ) == 0 )
    {
        jpeg_create_compress(&cinfo);
        f = fopen( m_filename, "wb" );

        if( f )
        {
            jpeg_stdio_dest( &cinfo, f );

            cinfo.image_width = width;
            cinfo.image_height = height;
            cinfo.input_components = channels;
            cinfo.in_color_space = channels > 1 ? JCS_RGB : JCS_GRAYSCALE;

            jpeg_set_defaults( &cinfo );
            jpeg_set_quality( &cinfo, default_quality,
                              TRUE /* limit to baseline-JPEG values */ );
            jpeg_start_compress( &cinfo, TRUE );

            if( channels > 1 )
                buffer = new uchar[width*channels];

            for( ; height--; data += step )
            {
                uchar* ptr = (uchar*)data;
            
                if( _channels == 3 )
                {
                    icvCvt_BGR2RGB_8u_C3R( data, 0, buffer, 0, cvSize(width,1) );
                    ptr = buffer;
                }
                else if( _channels == 4 )
                {
                    icvCvt_BGRA2BGR_8u_C4C3R( data, 0, buffer, 0, cvSize(width,1), 2 );
                    ptr = buffer;
                }

                jpeg_write_scanlines( &cinfo, &ptr, 1 );
            }

            jpeg_finish_compress( &cinfo );
            result = true;
        }
    }

    if(f) fclose(f);
    jpeg_destroy_compress( &cinfo );

    delete[] buffer;
    return result;
}

#else

//////////////////////  JPEG-oriented two-level bitstream ////////////////////////

RJpegBitStream::RJpegBitStream()
{
}

RJpegBitStream::~RJpegBitStream()
{
    Close();
}


bool  RJpegBitStream::Open( const char* filename )
{
    Close();
    Allocate();
    
    m_is_opened = m_low_strm.Open( filename );
    if( m_is_opened ) SetPos(0);
    return m_is_opened;
}


void  RJpegBitStream::Close()
{
    m_low_strm.Close();
    m_is_opened = false;
}


void  RJpegBitStream::ReadBlock()
{
    uchar* end = m_start + m_block_size;
    uchar* current = m_start;

    if( setjmp( m_low_strm.JmpBuf()) == 0 )
    {
        int sz = m_unGetsize;
        memmove( current - sz, m_end - sz, sz );
        while( current < end )
        {
            int val = m_low_strm.GetByte();
            if( val != 0xff )
            {
                *current++ = (uchar)val;
            }
            else
            {
                val = m_low_strm.GetByte();
                if( val == 0 )
                    *current++ = 0xFF;
                else if( !(0xD0 <= val && val <= 0xD7) )
                {
                    m_low_strm.SetPos( m_low_strm.GetPos() - 2 );
                    goto fetch_end;
                }
            }
        }
fetch_end: ;
    }
    else
    {
        if( current == m_start && m_jmp_set )
            longjmp( m_jmp_buf, RBS_THROW_EOS );
    }
    m_current = m_start;
    m_end = m_start + (((current - m_start) + 3) & -4);
    if( !bsIsBigEndian() )
        bsBSwapBlock( m_start, m_end );
}


void  RJpegBitStream::Flush()
{
    m_end = m_start + m_block_size;
    m_current = m_end - 4;
    m_bit_idx = 0;
}

void  RJpegBitStream::AlignOnByte()
{
    m_bit_idx &= -8;
}

int  RJpegBitStream::FindMarker()
{
    int code = m_low_strm.GetWord();
    while( (code & 0xFF00) != 0xFF00 || (code == 0xFFFF || code == 0xFF00 ))
    {
        code = ((code&255) << 8) | m_low_strm.GetByte();
    }
    return code;
}


/****************************** JPEG (JFIF) reader ***************************/

// zigzag & IDCT prescaling (AAN algorithm) tables
static const uchar zigzag[] =
{
  0,  8,  1,  2,  9, 16, 24, 17, 10,  3,  4, 11, 18, 25, 32, 40,
 33, 26, 19, 12,  5,  6, 13, 20, 27, 34, 41, 48, 56, 49, 42, 35,
 28, 21, 14,  7, 15, 22, 29, 36, 43, 50, 57, 58, 51, 44, 37, 30,
 23, 31, 38, 45, 52, 59, 60, 53, 46, 39, 47, 54, 61, 62, 55, 63,
 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63
};


static const int idct_prescale[] =
{
    16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
    22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
    21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
    19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
    16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
    12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
     8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
     4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
};


#define fixb         14
#define fix(x, n)    (int)((x)*(1 << (n)) + .5)
#define fix1(x, n)   (x)
#define fixmul(x)    (x)

#define C0_707     fix( 0.707106781f, fixb )
#define C0_924     fix( 0.923879533f, fixb )
#define C0_541     fix( 0.541196100f, fixb )
#define C0_382     fix( 0.382683432f, fixb )
#define C1_306     fix( 1.306562965f, fixb )

#define C1_082     fix( 1.082392200f, fixb )
#define C1_414     fix( 1.414213562f, fixb )
#define C1_847     fix( 1.847759065f, fixb )
#define C2_613     fix( 2.613125930f, fixb )

#define fixc       10
#define b_cb       fix( 1.772, fixc )
#define g_cb      -fix( 0.34414, fixc )
#define g_cr      -fix( 0.71414, fixc )
#define r_cr       fix( 1.402, fixc )

#define y_r        fix( 0.299, fixc )
#define y_g        fix( 0.587, fixc )
#define y_b        fix( 0.114, fixc )

#define cb_r      -fix( 0.1687, fixc )
#define cb_g      -fix( 0.3313, fixc )
#define cb_b       fix( 0.5,    fixc )

#define cr_r       fix( 0.5,    fixc )
#define cr_g      -fix( 0.4187, fixc )
#define cr_b      -fix( 0.0813, fixc )


// IDCT without prescaling
static void aan_idct8x8( int *src, int *dst, int step )
{
    int   workspace[64], *work = workspace;
    int   i;

    /* Pass 1: process rows */
    for( i = 8; i > 0; i--, src += 8, work += 8 )
    {
        /* Odd part */
        int  x0 = src[5], x1 = src[3];
        int  x2 = src[1], x3 = src[7];

        int  x4 = x0 + x1; x0 -= x1;

        x1 = x2 + x3; x2 -= x3;
        x3 = x1 + x4; x1 -= x4;

        x4 = (x0 + x2)*C1_847;
        x0 = descale( x4 - x0*C2_613, fixb);
        x2 = descale( x2*C1_082 - x4, fixb);
        x1 = descale( x1*C1_414, fixb);

        x0 -= x3;
        x1 -= x0;
        x2 += x1;

        work[7] = x3; work[6] = x0;
        work[5] = x1; work[4] = x2;

        /* Even part */
        x2 = src[2]; x3 = src[6];
        x0 = src[0]; x1 = src[4];

        x4 = x2 + x3;
        x2 = descale((x2-x3)*C1_414, fixb) - x4;

        x3 = x0 + x1; x0 -= x1;
        x1 = x3 + x4; x3 -= x4;
        x4 = x0 + x2; x0 -= x2;

        x2 = work[7];
        x1 -= x2; x2 = 2*x2 + x1;
        work[7] = x1; work[0] = x2;

        x2 = work[6];
        x1 = x4 + x2; x4 -= x2;
        work[1] = x1; work[6] = x4;

        x1 = work[5]; x2 = work[4];
        x4 = x0 + x1; x0 -= x1;
        x1 = x3 + x2; x3 -= x2;

        work[2] = x4; work[5] = x0;
        work[3] = x3; work[4] = x1;
    }

    /* Pass 2: process columns */
    work = workspace;
    for( i = 8; i > 0; i--, dst += step, work++ )
    {
        /* Odd part */
        int  x0 = work[8*5], x1 = work[8*3];
        int  x2 = work[8*1], x3 = work[8*7];

        int  x4 = x0 + x1; x0 -= x1;
        x1 = x2 + x3; x2 -= x3;
        x3 = x1 + x4; x1 -= x4;

        x4 = (x0 + x2)*C1_847;
        x0 = descale( x4 - x0*C2_613, fixb);
        x2 = descale( x2*C1_082 - x4, fixb);
        x1 = descale( x1*C1_414, fixb);

        x0 -= x3;
        x1 -= x0;
        x2 += x1;

        dst[7] = x3; dst[6] = x0;
        dst[5] = x1; dst[4] = x2;

        /* Even part */
        x2 = work[8*2]; x3 = work[8*6];
        x0 = work[8*0]; x1 = work[8*4];

        x4 = x2 + x3;
        x2 = descale((x2-x3)*C1_414, fixb) - x4;

        x3 = x0 + x1; x0 -= x1;
        x1 = x3 + x4; x3 -= x4;
        x4 = x0 + x2; x0 -= x2;

        x2 = dst[7];
        x1 -= x2; x2 = 2*x2 + x1;
        x1 = descale(x1,3);
        x2 = descale(x2,3);

        dst[7] = x1; dst[0] = x2;

        x2 = dst[6];
        x1 = descale(x4 + x2,3);
        x4 = descale(x4 - x2,3);
        dst[1] = x1; dst[6] = x4;

        x1 = dst[5]; x2 = dst[4];

        x4 = descale(x0 + x1,3);
        x0 = descale(x0 - x1,3);
        x1 = descale(x3 + x2,3);
        x3 = descale(x3 - x2,3);
       
        dst[2] = x4; dst[5] = x0;
        dst[3] = x3; dst[4] = x1;
    }
}


static const int max_dec_htable_size = 1 << 12;
static const int first_table_bits = 9;

GrFmtJpegReader::GrFmtJpegReader( const char* filename ) : GrFmtReader( filename )
{
    m_planes= -1;
    m_offset= -1;

    int i;
    for( i = 0; i < 4; i++ )
    {
        m_td[i] = new short[max_dec_htable_size];
        m_ta[i] = new short[max_dec_htable_size];
    }
}


GrFmtJpegReader::~GrFmtJpegReader()
{
    for( int i = 0; i < 4; i++ )
    {
        delete[] m_td[i];
        m_td[i] = 0;
        delete[] m_ta[i];
        m_ta[i] = 0;
    }
}


void  GrFmtJpegReader::Close()
{
    m_strm.Close();
    GrFmtReader::Close();
}


bool GrFmtJpegReader::ReadHeader()
{
    char buffer[16];
    int  i;
    bool result = false, is_sof = false, 
         is_qt = false, is_ht = false, is_sos = false;
    
    assert( strlen(m_filename) != 0 );
    if( !m_strm.Open( m_filename )) return false;

    memset( m_is_tq, 0, sizeof(m_is_tq));
    memset( m_is_td, 0, sizeof(m_is_td));
    memset( m_is_ta, 0, sizeof(m_is_ta));
    m_MCUs = 0;

    if( setjmp( m_strm.JmpBuf()) == 0 )
    {
        RMByteStream& lstrm = m_strm.m_low_strm;
        
        lstrm.Skip( 2 ); // skip SOI marker
        
        for(;;)
        {
            int marker = m_strm.FindMarker() & 255;

            // check for standalone markers
            if( marker != 0xD8 /* SOI */ && marker != 0xD9 /* EOI */ &&
                marker != 0x01 /* TEM */ && !( 0xD0 <= marker && marker <= 0xD7 ))
            {
                int pos    = lstrm.GetPos();
                int length = lstrm.GetWord();
            
                switch( marker )
                {
                case 0xE0: // APP0
                    lstrm.GetBytes( buffer, 5 );
                    if( strcmp(buffer, "JFIF") == 0 ) // JFIF identification
                    {
                        m_version = lstrm.GetWord();
                        //is_jfif = true;
                    }
                    break;

                case 0xC0: // SOF0
                    m_precision = lstrm.GetByte();
                    m_height = lstrm.GetWord();
                    m_width = lstrm.GetWord();
                    m_planes = lstrm.GetByte();

                    if( m_width == 0 || m_height == 0 || // DNL not supported
                       (m_planes != 1 && m_planes != 3)) goto parsing_end;

                    m_iscolor = m_planes == 3;
                
                    memset( m_ci, -1, sizeof(m_ci));

                    for( i = 0; i < m_planes; i++ )
                    {
                        int idx = lstrm.GetByte();

                        if( idx < 1 || idx > m_planes ) // wrong index
                        {
                            idx = i+1; // hack
                        }
                        cmp_info& ci = m_ci[idx-1];
                        
                        if( ci.tq > 0 /* duplicated description */) goto parsing_end;

                        ci.h = (char)lstrm.GetByte();
                        ci.v = (char)(ci.h & 15);
                        ci.h >>= 4;
                        ci.tq = (char)lstrm.GetByte();
                        if( !((ci.h == 1 || ci.h == 2 || ci.h == 4) &&
                              (ci.v == 1 || ci.v == 2 || ci.v == 4) &&
                              ci.tq < 3) ||
                            // chroma mcu-parts should have equal sizes and
                            // be non greater then luma sizes
                            !( i != 2 || (ci.h == m_ci[1].h && ci.v == m_ci[1].v &&
                                          ci.h <= m_ci[0].h && ci.v <= m_ci[0].v)))
                            goto parsing_end;
                    }
                    is_sof = true;
                    m_type = marker - 0xC0;
                    break;

                case 0xDB: // DQT
                    if( !LoadQuantTables( length )) goto parsing_end;
                    is_qt = true;
                    break;

                case 0xC4: // DHT
                    if( !LoadHuffmanTables( length )) goto parsing_end;
                    is_ht = true;
                    break;

                case 0xDA: // SOS
                    is_sos = true;
                    m_offset = pos - 2;
                    goto parsing_end;

                case 0xDD: // DRI
                    m_MCUs = lstrm.GetWord();
                    break;
                }
                lstrm.SetPos( pos + length );
            }
        }
parsing_end: ;
    }

    result = /*is_jfif &&*/ is_sof && is_qt && is_ht && is_sos;
    if( !result )
    {
        m_width = m_height = -1;
        m_offset = -1;
        m_strm.Close();
    }
    return result;
}


bool GrFmtJpegReader::LoadQuantTables( int length )
{
    uchar buffer[128];
    int  i, tq_size;
    
    RMByteStream& lstrm = m_strm.m_low_strm;
    length -= 2;

    while( length > 0 )
    {
        int tq = lstrm.GetByte();
        int size = tq >> 4;
        tq &= 15;

        tq_size = (64<<size) + 1; 
        if( tq > 3 || size > 1 || length < tq_size ) return false;
        length -= tq_size;

        lstrm.GetBytes( buffer, tq_size - 1 );
        
        if( size == 0 ) // 8 bit quant factors
        {
            for( i = 0; i < 64; i++ )
            {
                int idx = zigzag[i];
                m_tq[tq][idx] = buffer[i] * 16 * idct_prescale[idx];
            }
        }
        else // 16 bit quant factors
        {
            for( i = 0; i < 64; i++ )
            {
                int idx = zigzag[i];
                m_tq[tq][idx] = ((unsigned short*)buffer)[i] * idct_prescale[idx];
            }
        }
        m_is_tq[tq] = true;
    }

    return true;
}


bool GrFmtJpegReader::LoadHuffmanTables( int length )
{
    const int max_bits = 16;
    uchar buffer[1024];
    int  buffer2[1024];

    int  i, ht_size;
    RMByteStream& lstrm = m_strm.m_low_strm;
    length -= 2;

    while( length > 0 )
    {
        int t = lstrm.GetByte();
        int hclass = t >> 4;
        t &= 15;

        if( t > 3 || hclass > 1 || length < 17 ) return false;
        length -= 17;

        lstrm.GetBytes( buffer, max_bits );
        for( i = 0, ht_size = 0; i < max_bits; i++ ) ht_size += buffer[i];

        if( length < ht_size ) return false;
        length -= ht_size;

        lstrm.GetBytes( buffer + max_bits, ht_size );
        
        if( !::bsCreateDecodeHuffmanTable( 
                  ::bsCreateSourceHuffmanTable( 
                        buffer, buffer2, max_bits, first_table_bits ),
                        hclass == 0 ? m_td[t] : m_ta[t], 
                        max_dec_htable_size )) return false;
        if( hclass == 0 )
            m_is_td[t] = true;
        else
            m_is_ta[t] = true;
    }
    return true;
}


bool GrFmtJpegReader::ReadData( uchar* data, int step, int color )
{
    if( m_offset < 0 || !m_strm.IsOpened())
        return false;

    if( setjmp( m_strm.JmpBuf()) == 0 )
    {
        RMByteStream& lstrm = m_strm.m_low_strm;
        lstrm.SetPos( m_offset );

        for(;;)
        {
            int marker = m_strm.FindMarker() & 255;

            if( marker == 0xD8 /* SOI */ || marker == 0xD9 /* EOI */ )
                goto decoding_end;

            // check for standalone markers
            if( marker != 0x01 /* TEM */ && !( 0xD0 <= marker && marker <= 0xD7 ))
            {
                int pos    = lstrm.GetPos();
                int length = lstrm.GetWord();
            
                switch( marker )
                {
                case 0xC4: // DHT
                    if( !LoadHuffmanTables( length )) goto decoding_end;
                    break;

                case 0xDA: // SOS
                    // read scan header
                    {
                        int idx[3] = { -1, -1, -1 };
                        int i, ns = lstrm.GetByte();
                        int sum = 0, a; // spectral selection & approximation

                        if( ns != m_planes ) goto decoding_end;
                        for( i = 0; i < ns; i++ )
                        {
                            int td, ta, c = lstrm.GetByte() - 1;
                            if( c < 0 || m_planes <= c )
                            {
                                c = i; // hack
                            }
                            
                            if( idx[c] != -1 ) goto decoding_end;
                            idx[i] = c;
                            td = lstrm.GetByte();
                            ta = td & 15;
                            td >>= 4;
                            if( !(ta <= 3 && m_is_ta[ta] && 
                                  td <= 3 && m_is_td[td] &&
                                  m_is_tq[m_ci[c].tq]) )
                                goto decoding_end;

                            m_ci[c].td = (char)td;
                            m_ci[c].ta = (char)ta;

                            sum += m_ci[c].h*m_ci[c].v;
                        }

                        if( sum > 10 ) goto decoding_end;

                        m_ss = lstrm.GetByte();
                        m_se = lstrm.GetByte();

                        a = lstrm.GetByte();
                        m_al = a & 15;
                        m_ah = a >> 4;

                        ProcessScan( idx, ns, data, step, color );
                        goto decoding_end; // only single scan case is supported now
                    }

                    //m_offset = pos - 2;
                    //break;

                case 0xDD: // DRI
                    m_MCUs = lstrm.GetWord();
                    break;
                }
                
                if( marker != 0xDA ) lstrm.SetPos( pos + length );
            }
        }
decoding_end: ;
    }

    return true;
}


void  GrFmtJpegReader::ResetDecoder()
{
    m_ci[0].dc_pred = m_ci[1].dc_pred = m_ci[2].dc_pred = 0; 
}

void  GrFmtJpegReader::ProcessScan( int* idx, int ns, uchar* data, int step, int color )
{
    int   i, s = 0, mcu, x1 = 0, y1 = 0;
    int   temp[64];
    int   blocks[10][64];
    int   pos[3], h[3], v[3];
    int   x_shift = 0, y_shift = 0;
    int   nch = color ? 3 : 1;

    assert( ns == m_planes && m_ss == 0 && m_se == 63 &&
            m_al == 0 && m_ah == 0 ); // sequental & single scan

    assert( idx[0] == 0 && (ns ==1 || (idx[1] == 1 && idx[2] == 2)));

    for( i = 0; i < ns; i++ )
    {
        int c = idx[i];
        h[c] = m_ci[c].h*8;
        v[c] = m_ci[c].v*8;
        pos[c] = s >> 6;
        s += h[c]*v[c];
    }

    if( ns == 3 )
    {
        x_shift = h[0]/(h[1]*2);
        y_shift = v[0]/(v[1]*2);
    }

    m_strm.Flush();
    ResetDecoder();

    for( mcu = 0;; mcu++ )
    {
        int  x2, y2, x, y;
        int* cmp;
        uchar* data1;
        
        if( mcu == m_MCUs && m_MCUs != 0 )
        {
            ResetDecoder();
            m_strm.AlignOnByte();
            mcu = 0;
        }

        // Get mcu
        for( i = 0; i < ns; i++ )
        {
            int  c = idx[i];
            cmp = blocks[pos[c]];
            for( y = 0; y < v[c]; y += 8, cmp += h[c]*8 )
                for( x = 0; x < h[c]; x += 8 )
                {
                    GetBlock( temp, c );
                    if( i < (color ? 3 : 1))
                    {
                        aan_idct8x8( temp, cmp + x, h[c] );
                    }
                }
        }

        y2 = v[0];
        x2 = h[0];

        if( y1 + y2 > m_height ) y2 = m_height - y1;
        if( x1 + x2 > m_width ) x2 = m_width - x1;

        cmp = blocks[0];
        data1 = data + x1*nch;

        if( ns == 1 )
            for( y = 0; y < y2; y++, data1 += step, cmp += h[0] )
            {
                if( color )
                {
                    for( x = 0; x < x2; x++ )
                    {
                        int val = descale( cmp[x] + 128*4, 2 );
                        data1[x*3] = data1[x*3 + 1] = data1[x*3 + 2] = saturate( val );
                    }
                }
                else
                {
                    for( x = 0; x < x2; x++ )
                    {
                        int val = descale( cmp[x] + 128*4, 2 );
                        data1[x] = saturate( val );
                    }
                }
            }
        else
        {
            for( y = 0; y < y2; y++, data1 += step, cmp += h[0] )
            {
                if( color )
                {
                    int  shift = h[1]*(y >> y_shift);
                    int* cmpCb = blocks[pos[1]] + shift; 
                    int* cmpCr = blocks[pos[2]] + shift;
                    for( x = 0; x < x2; x++ )
                    {
                        int Y  = (cmp[x] + 128*4) << fixc;
                        int Cb = cmpCb[x >> x_shift];
                        int Cr = cmpCr[x >> x_shift];
                        int t = (Y + Cb*b_cb) >> (fixc + 2);
                        data1[x*3] = saturate(t);
                        t = (Y + Cb*g_cb + Cr*g_cr) >> (fixc + 2);
                        data1[x*3 + 1] = saturate(t);
                        t = (Y + Cr*r_cr) >> (fixc + 2);
                        data1[x*3 + 2] = saturate(t);
                    }
                }
                else
                {
                    for( x = 0; x < x2; x++ )
                    {
                        int val = descale( cmp[x] + 128*4, 2 );
                        data1[x] = saturate(val);
                    }
                }
            }
        }

        x1 += h[0];
        if( x1 >= m_width )
        {
            x1 = 0;
            y1 += v[0];
            data += v[0]*step;
            if( y1 >= m_height ) break;
        }
    }
}


void  GrFmtJpegReader::GetBlock( int* block, int c )
{
    memset( block, 0, 64*sizeof(block[0]) );

    assert( 0 <= c && c < 3 );
    const short* td = m_td[m_ci[c].td];
    const short* ta = m_ta[m_ci[c].ta];
    const int* tq = m_tq[m_ci[c].tq];

    // Get DC coefficient
    int i = 0, cat  = m_strm.GetHuff( td );
    int mask = bs_bit_mask[cat];
    int val  = m_strm.Get( cat );

    val -= (val*2 <= mask ? mask : 0);
    m_ci[c].dc_pred = val += m_ci[c].dc_pred;
    
    block[0] = descale(val * tq[0],16);

    // Get AC coeffs
    for(;;)
    {
        cat = m_strm.GetHuff( ta );
        if( cat == 0 ) break; // end of block

        i += (cat >> 4) + 1;
        cat &= 15;
        mask = bs_bit_mask[cat];
        val  = m_strm.Get( cat );
        cat  = zigzag[i];
        val -= (val*2 <= mask ? mask : 0);
        block[cat] = descale(val * tq[cat], 16);
        assert( i <= 63 );
        if( i >= 63 ) break;
    }
}

////////////////////// WJpegStream ///////////////////////

WJpegBitStream::WJpegBitStream()
{
}


WJpegBitStream::~WJpegBitStream()
{
    Close();
    m_is_opened = false;
}



bool  WJpegBitStream::Open( const char* filename )
{
    Close();
    Allocate();
    
    m_is_opened = m_low_strm.Open( filename );
    if( m_is_opened )
    {
        m_block_pos = 0;
        ResetBuffer();
    }
    return m_is_opened;
}


void  WJpegBitStream::Close()
{
    if( m_is_opened )
    {
        Flush();
        m_low_strm.Close();
        m_is_opened = false;
    }
}


void  WJpegBitStream::Flush()
{
    Put( -1, m_bit_idx & 31 );
    *((ulong*&)m_current)++ = m_val;
    WriteBlock();
    ResetBuffer();
}


void  WJpegBitStream::WriteBlock()
{
    uchar* ptr = m_start;
    if( !bsIsBigEndian() )
        bsBSwapBlock( m_start, m_current );

    while( ptr < m_current )
    {
        int val = *ptr++;
        m_low_strm.PutByte( val );
        if( val == 0xff )
        {
            m_low_strm.PutByte( 0 );
        }
    }
    
    m_current = m_start;
}


/////////////////////// GrFmtJpegWriter ///////////////////

GrFmtJpegWriter::GrFmtJpegWriter( const char* filename ) : GrFmtWriter( filename )
{
}

GrFmtJpegWriter::~GrFmtJpegWriter()
{
}

//  Standard JPEG quantization tables
static const uchar jpegTableK1_T[] =
{
    16, 12, 14, 14,  18,  24,  49,  72,
    11, 12, 13, 17,  22,  35,  64,  92,
    10, 14, 16, 22,  37,  55,  78,  95,
    16, 19, 24, 29,  56,  64,  87,  98,
    24, 26, 40, 51,  68,  81, 103, 112,
    40, 58, 57, 87, 109, 104, 121, 100,
    51, 60, 69, 80, 103, 113, 120, 103,
    61, 55, 56, 62,  77,  92, 101,  99
};


static const uchar jpegTableK2_T[] =
{
    17, 18, 24, 47, 99, 99, 99, 99,
    18, 21, 26, 66, 99, 99, 99, 99,
    24, 26, 56, 99, 99, 99, 99, 99,
    47, 66, 99, 99, 99, 99, 99, 99,
    99, 99, 99, 99, 99, 99, 99, 99,
    99, 99, 99, 99, 99, 99, 99, 99,
    99, 99, 99, 99, 99, 99, 99, 99,
    99, 99, 99, 99, 99, 99, 99, 99
};


// Standard Huffman tables

// ... for luma DCs.
static const uchar jpegTableK3[] =
{
    0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0,
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
};


// ... for chroma DCs.
static const uchar jpegTableK4[] =
{
    0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
};


// ... for luma ACs.
static const uchar jpegTableK5[] =
{
    0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 125,
    0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
    0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
    0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
    0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
    0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
    0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
    0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
    0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
    0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
    0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
    0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
    0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
    0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
    0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
    0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
    0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
    0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
    0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
    0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
    0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
    0xf9, 0xfa
};

// ... for chroma ACs  
static const uchar jpegTableK6[] =
{
    0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 119,
    0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
    0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
    0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
    0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
    0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
    0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
    0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
    0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
    0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
    0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
    0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
    0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
    0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
    0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
    0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
    0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
    0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
    0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
    0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
    0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
    0xf9, 0xfa
};


static const char jpegHeader[] = 
    "\xFF\xD8"  // SOI  - start of image
    "\xFF\xE0"  // APP0 - jfif extention
    "\x00\x10"  // 2 bytes: length of APP0 segment
    "JFIF\x00"  // JFIF signature
    "\x01\x02"  // version of JFIF
    "\x00"      // units = pixels ( 1 - inch, 2 - cm )
    "\x00\x01\x00\x01" // 2 2-bytes values: x density & y density
    "\x00\x00"; // width & height of thumbnail: ( 0x0 means no thumbnail)

#define postshift 14

// FDCT with postscaling
static void aan_fdct8x8( int *src, int *dst,
                         int step, const int *postscale )
{
    int  workspace[64], *work = workspace;
    int  i;

    // Pass 1: process rows
    for( i = 8; i > 0; i--, src += step, work += 8 )
    {
        int x0 = src[0], x1 = src[7];
        int x2 = src[3], x3 = src[4];

        int x4 = x0 + x1; x0 -= x1;
        x1 = x2 + x3; x2 -= x3;
    
        work[7] = x0; work[1] = x2;
        x2 = x4 + x1; x4 -= x1;

        x0 = src[1]; x3 = src[6];
        x1 = x0 + x3; x0 -= x3;
        work[5] = x0;

        x0 = src[2]; x3 = src[5];
        work[3] = x0 - x3; x0 += x3;

        x3 = x0 + x1; x0 -= x1;
        x1 = x2 + x3; x2 -= x3;

        work[0] = x1; work[4] = x2;

        x0 = descale((x0 - x4)*C0_707, fixb);
        x1 = x4 + x0; x4 -= x0;
        work[2] = x4; work[6] = x1;

        x0 = work[1]; x1 = work[3];
        x2 = work[5]; x3 = work[7];

        x0 += x1; x1 += x2; x2 += x3;
        x1 = descale(x1*C0_707, fixb);

        x4 = x1 + x3; x3 -= x1;
        x1 = (x0 - x2)*C0_382;
        x0 = descale(x0*C0_541 + x1, fixb);
        x2 = descale(x2*C1_306 + x1, fixb);

        x1 = x0 + x3; x3 -= x0;
        x0 = x4 + x2; x4 -= x2;

        work[5] = x1; work[1] = x0;
        work[7] = x4; work[3] = x3;
    }

    work = workspace;
    // pass 2: process columns
    for( i = 8; i > 0; i--, work++, postscale += 8, dst += 8 )
    {
        int  x0 = work[8*0], x1 = work[8*7];
        int  x2 = work[8*3], x3 = work[8*4];

        int  x4 = x0 + x1; x0 -= x1;
        x1 = x2 + x3; x2 -= x3;
    
        work[8*7] = x0; work[8*0] = x2;
        x2 = x4 + x1; x4 -= x1;

        x0 = work[8*1]; x3 = work[8*6];
        x1 = x0 + x3; x0 -= x3;
        work[8*4] = x0;

        x0 = work[8*2]; x3 = work[8*5];
        work[8*3] = x0 - x3; x0 += x3;

        x3 = x0 + x1; x0 -= x1;
        x1 = x2 + x3; x2 -= x3;

        dst[0] = descale(x1*postscale[0], postshift);
        dst[4] = descale(x2*postscale[4], postshift);

        x0 = descale((x0 - x4)*C0_707, fixb);
        x1 = x4 + x0; x4 -= x0;

        dst[2] = descale(x4*postscale[2], postshift);
        dst[6] = descale(x1*postscale[6], postshift);

        x0 = work[8*0]; x1 = work[8*3];
        x2 = work[8*4]; x3 = work[8*7];

        x0 += x1; x1 += x2; x2 += x3;
        x1 = descale(x1*C0_707, fixb);

        x4 = x1 + x3; x3 -= x1;
        x1 = (x0 - x2)*C0_382;
        x0 = descale(x0*C0_541 + x1, fixb);
        x2 = descale(x2*C1_306 + x1, fixb);

        x1 = x0 + x3; x3 -= x0;
        x0 = x4 + x2; x4 -= x2;

        dst[5] = descale(x1*postscale[5], postshift);
        dst[1] = descale(x0*postscale[1], postshift);
        dst[7] = descale(x4*postscale[7], postshift);
        dst[3] = descale(x3*postscale[3], postshift);
    }
}


bool  GrFmtJpegWriter::WriteImage( const uchar* data, int step,
                                   int width, int height, int _channels )
{
    assert( data && width > 0 && height > 0 );
    
    if( !m_strm.Open( m_filename ) ) return false;

    // encode the header and tables
    // for each mcu:
    //   convert rgb to yuv with downsampling (if color).
    //   for every block:
    //     calc dct and quantize
    //     encode block.
    int x, y;
    int i, j;
    const int max_quality = 10;
    int   quality = max_quality;
    WMByteStream& lowstrm = m_strm.m_low_strm;
    int   fdct_qtab[2][64];
    ulong huff_dc_tab[2][16];
    ulong huff_ac_tab[2][256];
    int  channels = _channels > 1 ? 3 : 1;
    int  x_scale = channels > 1 ? 2 : 1, y_scale = x_scale;
    int  dc_pred[] = { 0, 0, 0 };
    int  x_step = x_scale * 8;
    int  y_step = y_scale * 8;
    int  block[6][64];
    int  buffer[1024];
    int  luma_count = x_scale*y_scale;
    int  block_count = luma_count + channels - 1;
    int  Y_step = x_scale*8;
    const int UV_step = 16;
    double inv_quality;

    if( quality < 3 ) quality = 3;
    if( quality > max_quality ) quality = max_quality;

    inv_quality = 1./quality;

    // Encode header
    lowstrm.PutBytes( jpegHeader, sizeof(jpegHeader) - 1 );
    
    // Encode quantization tables
    for( i = 0; i < (channels > 1 ? 2 : 1); i++ )
    {
        const uchar* qtable = i == 0 ? jpegTableK1_T : jpegTableK2_T;
        int chroma_scale = i > 0 ? luma_count : 1;
        
        lowstrm.PutWord( 0xffdb );   // DQT marker
        lowstrm.PutWord( 2 + 65*1 ); // put single qtable
        lowstrm.PutByte( 0*16 + i ); // 8-bit table

        // put coefficients
        for( j = 0; j < 64; j++ )
        {
            int idx = zigzag[j];
            int qval = cvRound(qtable[idx]*inv_quality);
            if( qval < 1 )
                qval = 1;
            if( qval > 255 )
                qval = 255;
            fdct_qtab[i][idx] = cvRound((1 << (postshift + 9))/
                                      (qval*chroma_scale*idct_prescale[idx]));
            lowstrm.PutByte( qval );
        }
    }

    // Encode huffman tables
    for( i = 0; i < (channels > 1 ? 4 : 2); i++ )
    {
        const uchar* htable = i == 0 ? jpegTableK3 : i == 1 ? jpegTableK5 :
                              i == 2 ? jpegTableK4 : jpegTableK6;
        int is_ac_tab = i & 1;
        int idx = i >= 2;
        int tableSize = 16 + (is_ac_tab ? 162 : 12);

        lowstrm.PutWord( 0xFFC4   );      // DHT marker
        lowstrm.PutWord( 3 + tableSize ); // define one huffman table
        lowstrm.PutByte( is_ac_tab*16 + idx ); // put DC/AC flag and table index
        lowstrm.PutBytes( htable, tableSize ); // put table

        bsCreateEncodeHuffmanTable( bsCreateSourceHuffmanTable(
            htable, buffer, 16, 9 ), is_ac_tab ? huff_ac_tab[idx] :
            huff_dc_tab[idx], is_ac_tab ? 256 : 16 );
    }

    // put frame header
    lowstrm.PutWord( 0xFFC0 );          // SOF0 marker
    lowstrm.PutWord( 8 + 3*channels );  // length of frame header
    lowstrm.PutByte( 8 );               // sample precision
    lowstrm.PutWord( height );
    lowstrm.PutWord( width );
    lowstrm.PutByte( channels );        // number of components

    for( i = 0; i < channels; i++ )
    {
        lowstrm.PutByte( i + 1 );  // (i+1)-th component id (Y,U or V)
        if( i == 0 )
            lowstrm.PutByte(x_scale*16 + y_scale); // chroma scale factors
        else
            lowstrm.PutByte(1*16 + 1);
        lowstrm.PutByte( i > 0 ); // quantization table idx
    }

    // put scan header
    lowstrm.PutWord( 0xFFDA );          // SOS marker
    lowstrm.PutWord( 6 + 2*channels );  // length of scan header
    lowstrm.PutByte( channels );        // number of components in the scan

    for( i = 0; i < channels; i++ )
    {
        lowstrm.PutByte( i+1 );             // component id
        lowstrm.PutByte( (i>0)*16 + (i>0) );// selection of DC & AC tables
    }

    lowstrm.PutWord(0*256 + 63);// start and end of spectral selection - for
                                // sequental DCT start is 0 and end is 63

    lowstrm.PutByte( 0 );  // successive approximation bit position 
                           // high & low - (0,0) for sequental DCT  

    // encode data
    for( y = 0; y < height; y += y_step, data += y_step*step )
    {
        for( x = 0; x < width; x += x_step )
        {
            int x_limit = x_step;
            int y_limit = y_step;
            const uchar* rgb_data = data + x*_channels;
            int* Y_data = block[0];

            if( x + x_limit > width ) x_limit = width - x;
            if( y + y_limit > height ) y_limit = height - y;

            memset( block, 0, block_count*64*sizeof(block[0][0]));
            
            if( channels > 1 )
            {
                int* UV_data = block[luma_count];

                for( i = 0; i < y_limit; i++, rgb_data += step, Y_data += Y_step )
                {
                    for( j = 0; j < x_limit; j++, rgb_data += _channels )
                    {
                        int r = rgb_data[2];
                        int g = rgb_data[1];
                        int b = rgb_data[0];

                        int Y = descale( r*y_r + g*y_g + b*y_b, fixc - 2) - 128*4;
                        int U = descale( r*cb_r + g*cb_g + b*cb_b, fixc - 2 );
                        int V = descale( r*cr_r + g*cr_g + b*cr_b, fixc - 2 );
                        int j2 = j >> (x_scale - 1); 

                        Y_data[j] = Y;
                        UV_data[j2] += U;
                        UV_data[j2 + 8] += V;
                    }

                    rgb_data -= x_limit*_channels;
                    if( ((i+1) & (y_scale - 1)) == 0 )
                    {
                        UV_data += UV_step;
                    }
                }
            }
            else
            {
                for( i = 0; i < y_limit; i++, rgb_data += step, Y_data += Y_step )
                {
                    for( j = 0; j < x_limit; j++ )
                        Y_data[j] = rgb_data[j]*4 - 128*4;
                }
            }

            for( i = 0; i < block_count; i++ )
            {
                int is_chroma = i >= luma_count;
                int src_step = x_scale * 8;
                int run = 0, val;
                int* src_ptr = block[i & -2] + (i & 1)*8;
                const ulong* htable = huff_ac_tab[is_chroma];

                aan_fdct8x8( src_ptr, buffer, src_step, fdct_qtab[is_chroma] );

                j = is_chroma + (i > luma_count);
                val = buffer[0] - dc_pred[j];
                dc_pred[j] = buffer[0];

                {
                float a = (float)val;
                int cat = (((int&)a >> 23) & 255) - (126 & (val ? -1 : 0));

                assert( cat <= 11 );
                m_strm.PutHuff( cat, huff_dc_tab[is_chroma] );
                m_strm.Put( val - (val < 0 ? 1 : 0), cat );
                }

                for( j = 1; j < 64; j++ )
                {
                    val = buffer[zigzag[j]];

                    if( val == 0 )
                    {
                        run++;
                    }
                    else
                    {
                        while( run >= 16 )
                        {
                            m_strm.PutHuff( 0xF0, htable ); // encode 16 zeros
                            run -= 16;
                        }

                        {
                        float a = (float)val;
                        int cat = (((int&)a >> 23) & 255) - (126 & (val ? -1 : 0));

                        assert( cat <= 10 );
                        m_strm.PutHuff( cat + run*16, htable );
                        m_strm.Put( val - (val < 0 ? 1 : 0), cat );
                        }

                        run = 0;
                    }
                }

                if( run )
                {
                    m_strm.PutHuff( 0x00, htable ); // encode EOB
                }
            }
        }
    }

    // Flush 
    m_strm.Flush();

    lowstrm.PutWord( 0xFFD9 ); // EOI marker
    m_strm.Close();

    return true;
}

#endif

/* End of file. */


