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/*
* Copyright (C) 2007-2013 Xagasoft, All rights reserved.
*
* This file is part of the libgats library and is released under the
* terms of the license contained in the file LICENSE.
*/
using System.IO;
namespace Com.Xagasoft.Gats
{
/// <summary>
/// Encapsulates a single integer value.
/// </summary>
/// <remarks>
/// The GATS integer encoding is arbitrary precision, and only consumes as
/// many bytes as it needs to represent a given number. There is no such
/// thing as an unsigned GATS integer.
///
/// Internally the GatsInteger stores it's value in a long.
///
/// In encoding, the type specifier for a GATS integer is 'i'.
/// </remarks>
public class GatsInteger : GatsObject
{
public long Value { get; set; }
public GatsInteger( long val=0 )
{
Value = val;
}
public override string ToString()
{
return Value.ToString();
}
public override void Read( Stream s, char cType )
{
Value = ReadPackedInt( s );
}
public override void Write( Stream s )
{
s.WriteByte( (int)'i' );
WritePackedInt( s, Value );
}
public static long ReadPackedInt( Stream s )
{
int b;
long rOut = 0;
bool bNeg;
b = s.ReadByte();
if( b == -1 )
throw new GatsException( GatsException.Type.PrematureEnd );
bNeg = (b&0x40) == 0x40;
rOut |= ((long)b)&0x3F;
int c = 0;
while( (b&0x80) == 0x80 )
{
b = s.ReadByte();
if( b == -1 )
throw new GatsException( GatsException.Type.PrematureEnd );
rOut |= (long)(b&0x7F) << (6+7*(c++));
}
if( bNeg )
return -rOut;
return rOut;
}
public static void WritePackedInt( Stream s, long iIn )
{
byte b;
if( iIn < 0 )
{
iIn = -iIn;
b = (byte)(iIn&0x3F);
if( iIn > b )
b |= 0x80 | 0x40;
else
b |= 0x40;
}
else
{
b = (byte)(iIn&0x3F);
if( iIn > b )
b |= 0x80;
}
s.WriteByte( b );
iIn = iIn >> 6;
while( iIn > 0 )
{
b = (byte)(iIn&0x7F);
if( iIn > b )
b |= 0x80;
s.WriteByte( b );
iIn = iIn >> 7;
}
}
};
}
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