/usr/include/ZenLib/BitStream_Fast.h is in libzen-dev 0.4.34-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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*
* Use of this source code is governed by a zlib-style license that can
* be found in the License.txt file in the root of the source tree.
*/
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//
// Read a stream bit per bit
// Can read up to 32 bits at once
//
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//---------------------------------------------------------------------------
#ifndef ZenBitStream_FastH
#define ZenBitStream_FastH
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
#include "ZenLib/Conf.h"
//---------------------------------------------------------------------------
namespace ZenLib
{
#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif
class BitStream_Fast
{
public:
BitStream_Fast () {Buffer=NULL;
Buffer_Size=Buffer_Size_Init=0;
BufferUnderRun=false;}
BitStream_Fast (const int8u* Buffer_, size_t Size_) {Buffer=Buffer_;
Buffer_Size=Buffer_Size_Init=Size_*8; //Size is in bits
BufferUnderRun=false;}
~BitStream_Fast () {}
void Attach(const int8u* Buffer_, size_t Size_)
{
Buffer=Buffer_;
Buffer_Size=Buffer_Size_Init=Size_*8; //Size is in bits
BufferUnderRun=false;
}
bool GetB ()
{
if (Buffer_Size%8)
{
Buffer_Size--;
return ((LastByte>>(Buffer_Size%8))&0x1)?true:false;
}
if (!Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return false;
}
LastByte=*Buffer;
Buffer++;
Buffer_Size--;
return (LastByte&0x80)?true:false;
}
int8u Get1 (int8u HowMany)
{
int8u ToReturn;
static const int8u Mask[9]=
{
0x00,
0x01, 0x03, 0x07, 0x0f,
0x1f, 0x3f, 0x7f, 0xff,
};
if (HowMany<=(Buffer_Size%8))
{
Buffer_Size-=HowMany;
return (LastByte>>(Buffer_Size%8))&Mask[HowMany];
}
if (HowMany>Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return 0;
}
int8u NewBits=HowMany-(Buffer_Size%8);
if (NewBits==8)
ToReturn=0;
else
ToReturn=LastByte<<NewBits;
LastByte=*Buffer;
Buffer++;
Buffer_Size-=HowMany;
ToReturn|=(LastByte>>(Buffer_Size%8))&Mask[NewBits];
return ToReturn&Mask[HowMany];
}
int16u Get2 (int8u HowMany)
{
int16u ToReturn;
static const int16u Mask[17]=
{
0x0000,
0x0001, 0x0003, 0x0007, 0x000f,
0x001f, 0x003f, 0x007f, 0x00ff,
0x01ff, 0x03ff, 0x07ff, 0x0fff,
0x1fff, 0x3fff, 0x7fff, 0xffff,
};
if (HowMany<=(Buffer_Size%8))
{
Buffer_Size-=HowMany;
return (LastByte>>(Buffer_Size%8))&Mask[HowMany];
}
if (HowMany>Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return 0;
}
int8u NewBits=HowMany-(Buffer_Size%8);
if (NewBits==16)
ToReturn=0;
else
ToReturn=LastByte<<NewBits;
if ((NewBits-1)>>3)
{
NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
}
LastByte=*Buffer;
Buffer++;
Buffer_Size-=HowMany;
ToReturn|=(LastByte>>(Buffer_Size%8))&Mask[NewBits];
return ToReturn&Mask[HowMany];
}
int32u Get4 (int8u HowMany)
{
int32u ToReturn;
static const int32u Mask[33]=
{
0x00000000,
0x00000001, 0x00000003, 0x00000007, 0x0000000f,
0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff,
0x01ffffff, 0x03ffffff, 0x07ffffff, 0x0fffffff,
0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffff,
};
if (HowMany<=(Buffer_Size%8))
{
Buffer_Size-=HowMany;
return (LastByte>>(Buffer_Size%8))&Mask[HowMany];
}
if (HowMany>Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return 0;
}
int8u NewBits=HowMany-(Buffer_Size%8);
if (NewBits==32)
ToReturn=0;
else
ToReturn=LastByte<<NewBits;
switch ((NewBits-1)>>3)
{
case 3 : NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
case 2 : NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
case 1 : NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
default: ;
}
LastByte=*Buffer;
Buffer++;
Buffer_Size-=HowMany;
ToReturn|=(LastByte>>(Buffer_Size%8))&Mask[NewBits];
return ToReturn&Mask[HowMany];
}
int64u Get8 (int8u HowMany)
{
if (HowMany>64)
return 0; //Not supported
int8u HowMany1, HowMany2;
int64u Value1, Value2;
if (HowMany>32)
HowMany1=HowMany-32;
else
HowMany1=0;
HowMany2=HowMany-HowMany1;
Value1=Get4(HowMany1);
Value2=Get4(HowMany2);
if (BufferUnderRun)
return 0;
return Value1*0x100000000LL+Value2;
}
void Skip (size_t HowMany)
{
if (HowMany<=(Buffer_Size%8))
{
Buffer_Size-=HowMany;
return;
}
if (HowMany>Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return;
}
Buffer+=(HowMany-(Buffer_Size%8)-1)>>3;
LastByte=*Buffer;
Buffer++;
Buffer_Size-=HowMany;
}
bool PeekB()
{
if (Buffer_Size%8)
return ((LastByte>>((Buffer_Size-1)%8))&0x1)?true:false;
if (!Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return false;
}
return ((*Buffer)&0x80)?true:false;
}
int8u Peek1(int8u HowMany)
{
int8u ToReturn;
static const int8u Mask[9]=
{
0x00,
0x01, 0x03, 0x07, 0x0f,
0x1f, 0x3f, 0x7f, 0xff,
};
if (HowMany<=(Buffer_Size%8))
return (LastByte>>((Buffer_Size-HowMany)%8))&Mask[HowMany];
if (HowMany>Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return 0;
}
int8u NewBits=HowMany-(Buffer_Size%8);
if (NewBits==8)
ToReturn=0;
else
ToReturn=LastByte<<NewBits;
ToReturn|=((*Buffer)>>((Buffer_Size-HowMany)%8))&Mask[NewBits];
return ToReturn&Mask[HowMany];
}
int16u Peek2(int8u HowMany)
{
int16u ToReturn;
static const int16u Mask[17]=
{
0x0000,
0x0001, 0x0003, 0x0007, 0x000f,
0x001f, 0x003f, 0x007f, 0x00ff,
0x01ff, 0x03ff, 0x07ff, 0x0fff,
0x1fff, 0x3fff, 0x7fff, 0xffff,
};
if (HowMany<=(Buffer_Size%8))
return (LastByte>>((Buffer_Size-HowMany)%8))&Mask[HowMany];
if (HowMany>Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return 0;
}
const int8u* Buffer_Save=Buffer;
int8u NewBits=HowMany-(Buffer_Size%8);
if (NewBits==16)
ToReturn=0;
else
ToReturn=LastByte<<NewBits;
if ((NewBits-1)>>3)
{
NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
}
ToReturn|=((*Buffer)>>((Buffer_Size-HowMany)%8))&Mask[NewBits];
Buffer=Buffer_Save;
return ToReturn&Mask[HowMany];
}
int32u Peek4(int8u HowMany)
{
int32u ToReturn;
static const int32u Mask[33]=
{
0x00000000,
0x00000001, 0x00000003, 0x00000007, 0x0000000f,
0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff,
0x01ffffff, 0x03ffffff, 0x07ffffff, 0x0fffffff,
0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffff,
};
if (HowMany<=(Buffer_Size%8))
return (LastByte>>((Buffer_Size-HowMany)%8))&Mask[HowMany];
if (HowMany>Buffer_Size)
{
Buffer_Size=0;
BufferUnderRun=true;
return 0;
}
const int8u* Buffer_Save=Buffer;
int8u NewBits=HowMany-(Buffer_Size%8);
if (NewBits==32)
ToReturn=0;
else
ToReturn=LastByte<<NewBits;
switch ((NewBits-1)>>3)
{
case 3 : NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
case 2 : NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
case 1 : NewBits-=8;
ToReturn|=*Buffer<<NewBits;
Buffer++;
default: ;
}
ToReturn|=((*Buffer)>>((Buffer_Size-HowMany)%8))&Mask[NewBits];
Buffer=Buffer_Save;
return ToReturn&Mask[HowMany];
}
int64u Peek8(int8u HowMany)
{
return (int64u)Peek4(HowMany); //Not yet implemented
}
inline size_t Remain () const //How many bits remain?
{
return Buffer_Size;
}
inline void Byte_Align()
{
Skip (Buffer_Size%8);
}
inline size_t Offset_Get() const
{
return (Buffer_Size_Init-Buffer_Size)/8;
}
inline size_t BitOffset_Get() const
{
return Buffer_Size%8;
}
inline size_t OffsetBeforeLastCall_Get() const //No more valid
{
return Buffer_Size%8;
}
private :
const int8u* Buffer;
size_t Buffer_Size;
size_t Buffer_Size_Init;
int8u LastByte;
public :
bool BufferUnderRun;
};
} //namespace ZenLib
#endif
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