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LASreadItemCompressed_GPSTIME11_v2.cs
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LASreadItemCompressed_GPSTIME11_v2.cs
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//===============================================================================
//
// FILE: lasreaditemcompressed_gpstime11_v2.cs
//
// CONTENTS:
//
// Implementation of LASreadItemCompressed for GPSTime11 items (version 2).
//
// PROGRAMMERS:
//
// martin.isenburg@rapidlasso.com - http://rapidlasso.com
//
// COPYRIGHT:
//
// (c) 2005-2012, martin isenburg, rapidlasso - tools to catch reality
// (c) of the C# port 2014 by Shinta <shintadono@googlemail.com>
//
// This is free software; you can redistribute and/or modify it under the
// terms of the GNU Lesser General Licence as published by the Free Software
// Foundation. See the COPYING file for more information.
//
// This software is distributed WITHOUT ANY WARRANTY and without even the
// implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//
// CHANGE HISTORY: omitted for easier Copy&Paste (pls see the original)
//
//===============================================================================
using System.Diagnostics;
namespace laszip.net
{
class LASreadItemCompressed_GPSTIME11_v2 : LASreadItemCompressed
{
const int LASZIP_GPSTIME_MULTI=500;
const int LASZIP_GPSTIME_MULTI_MINUS=-10;
const int LASZIP_GPSTIME_MULTI_UNCHANGED=(LASZIP_GPSTIME_MULTI-LASZIP_GPSTIME_MULTI_MINUS+1);
const int LASZIP_GPSTIME_MULTI_CODE_FULL=(LASZIP_GPSTIME_MULTI-LASZIP_GPSTIME_MULTI_MINUS+2);
const int LASZIP_GPSTIME_MULTI_TOTAL=(LASZIP_GPSTIME_MULTI-LASZIP_GPSTIME_MULTI_MINUS+6);
public LASreadItemCompressed_GPSTIME11_v2(ArithmeticDecoder dec)
{
// set decoder
Debug.Assert(dec!=null);
this.dec=dec;
// create entropy models and integer compressors
m_gpstime_multi=dec.createSymbolModel(LASZIP_GPSTIME_MULTI_TOTAL);
m_gpstime_0diff=dec.createSymbolModel(6);
ic_gpstime=new IntegerCompressor(dec, 32, 9); // 32 bits, 9 contexts
}
public override bool init(laszip_point item)
{
// init state
last=0; next=0;
last_gpstime_diff[0]=0;
last_gpstime_diff[1]=0;
last_gpstime_diff[2]=0;
last_gpstime_diff[3]=0;
multi_extreme_counter[0]=0;
multi_extreme_counter[1]=0;
multi_extreme_counter[2]=0;
multi_extreme_counter[3]=0;
// init models and integer compressors
dec.initSymbolModel(m_gpstime_multi);
dec.initSymbolModel(m_gpstime_0diff);
ic_gpstime.initDecompressor();
// init last item
last_gpstime[0].f64=item.gps_time;
last_gpstime[1].u64=0;
last_gpstime[2].u64=0;
last_gpstime[3].u64=0;
return true;
}
public override void read(laszip_point item)
{
if(last_gpstime_diff[last]==0) // if the last integer difference was zero
{
int multi=(int)dec.decodeSymbol(m_gpstime_0diff);
if(multi==1) // the difference can be represented with 32 bits
{
last_gpstime_diff[last]=ic_gpstime.decompress(0, 0);
last_gpstime[last].i64+=last_gpstime_diff[last];
multi_extreme_counter[last]=0;
}
else if(multi==2) // the difference is huge
{
next=(next+1)&3;
last_gpstime[next].u64=(ulong)ic_gpstime.decompress((int)(last_gpstime[last].u64>>32), 8);
last_gpstime[next].u64=last_gpstime[next].u64<<32;
last_gpstime[next].u64|=dec.readInt();
last=next;
last_gpstime_diff[last]=0;
multi_extreme_counter[last]=0;
}
else if(multi>2) // we switch to another sequence
{
last=(uint)(last+multi-2)&3;
read(item);
}
}
else
{
int multi=(int)dec.decodeSymbol(m_gpstime_multi);
if(multi==1)
{
last_gpstime[last].i64+=ic_gpstime.decompress(last_gpstime_diff[last], 1); ;
multi_extreme_counter[last]=0;
}
else if(multi<LASZIP_GPSTIME_MULTI_UNCHANGED)
{
int gpstime_diff;
if(multi==0)
{
gpstime_diff=ic_gpstime.decompress(0, 7);
multi_extreme_counter[last]++;
if(multi_extreme_counter[last]>3)
{
last_gpstime_diff[last]=gpstime_diff;
multi_extreme_counter[last]=0;
}
}
else if(multi<LASZIP_GPSTIME_MULTI)
{
if(multi<10)
gpstime_diff=ic_gpstime.decompress(multi*last_gpstime_diff[last], 2);
else
gpstime_diff=ic_gpstime.decompress(multi*last_gpstime_diff[last], 3);
}
else if(multi==LASZIP_GPSTIME_MULTI)
{
gpstime_diff=ic_gpstime.decompress(LASZIP_GPSTIME_MULTI*last_gpstime_diff[last], 4);
multi_extreme_counter[last]++;
if(multi_extreme_counter[last]>3)
{
last_gpstime_diff[last]=gpstime_diff;
multi_extreme_counter[last]=0;
}
}
else
{
multi=LASZIP_GPSTIME_MULTI-multi;
if(multi>LASZIP_GPSTIME_MULTI_MINUS)
{
gpstime_diff=ic_gpstime.decompress(multi*last_gpstime_diff[last], 5);
}
else
{
gpstime_diff=ic_gpstime.decompress(LASZIP_GPSTIME_MULTI_MINUS*last_gpstime_diff[last], 6);
multi_extreme_counter[last]++;
if(multi_extreme_counter[last]>3)
{
last_gpstime_diff[last]=gpstime_diff;
multi_extreme_counter[last]=0;
}
}
}
last_gpstime[last].i64+=gpstime_diff;
}
else if(multi==LASZIP_GPSTIME_MULTI_CODE_FULL)
{
next=(next+1)&3;
last_gpstime[next].u64=(ulong)ic_gpstime.decompress((int)(last_gpstime[last].u64>>32), 8);
last_gpstime[next].u64=last_gpstime[next].u64<<32;
last_gpstime[next].u64|=dec.readInt();
last=next;
last_gpstime_diff[last]=0;
multi_extreme_counter[last]=0;
}
else if(multi>=LASZIP_GPSTIME_MULTI_CODE_FULL)
{
last=(uint)(last+multi-LASZIP_GPSTIME_MULTI_CODE_FULL)&3;
read(item);
}
}
item.gps_time=last_gpstime[last].f64;
}
ArithmeticDecoder dec;
uint last, next;
U64I64F64[] last_gpstime=new U64I64F64[4];
int[] last_gpstime_diff=new int[4];
int[] multi_extreme_counter=new int[4];
ArithmeticModel m_gpstime_multi;
ArithmeticModel m_gpstime_0diff;
IntegerCompressor ic_gpstime;
}
}