OSG::BitUnpacker Class Reference

#include <OSGNFIOBitPacker.h>


Public Types
Types

typedef std::vector< UInt8 >	BufferType
Public Member Functions
Constructor

	BitUnpacker (const BufferType &buffer, UInt32 max)
Unpack

UInt32	unpack (void)
Private Attributes
UInt32	_numBitsToUnpack
Int32	_numBitsRemaining
Int32	_nextBit
const BufferType &	_buffer

Detailed Description

Definition at line 94 of file OSGNFIOBitPacker.h.

Member Typedef Documentation

typedef std::vector<UInt8> OSG::BitUnpacker::BufferType

Definition at line 102 of file OSGNFIOBitPacker.h.

Constructor & Destructor Documentation

BitUnpacker::BitUnpacker	(	const BufferType &	buffer,
		UInt32	max
	)

Definition at line 161 of file OSGNFIOBitPacker.cpp.

References _numBitsToUnpack.

00161                                                                    :
00162     _numBitsToUnpack (1                ),
00163     _numBitsRemaining(buffer.size() * 8),
00164     _nextBit         (0                ),
00165     _buffer          (buffer           )
00166 {
00167     while(true)
00168     {
00169         UInt32 maxValue = (UInt32) (1 << _numBitsToUnpack) - 1;
00170         if (maxValue >= max)
00171             break;
00172 
00173         ++_numBitsToUnpack;
00174     }
00175 }

Member Function Documentation

UInt32 BitUnpacker::unpack ( void )

Definition at line 177 of file OSGNFIOBitPacker.cpp.

References _buffer, _nextBit, _numBitsRemaining, and _numBitsToUnpack.

Referenced by OSG::NFIOGeometry::readPackedIndices(), and OSG::OSBGeometryHelper::readPackedIntegralProperty().

00178 {
00179     UInt32 result          = 0;
00180     UInt32 numBitsToUnpack = _numBitsToUnpack;
00181 
00182     while(numBitsToUnpack)
00183     {
00184         UInt32 byteIndex = (_nextBit / 8);
00185         UInt32 bitIndex  = (_nextBit % 8);
00186         UInt32 srcMask   = (1 << (7 - bitIndex));
00187         UInt32 destMask  = (1 << (numBitsToUnpack - 1));
00188 
00189         if(_buffer[byteIndex] & srcMask)
00190             result |= destMask;
00191         numBitsToUnpack--;
00192         _nextBit++;
00193     }
00194 
00195     _numBitsRemaining -= numBitsToUnpack;
00196 
00197     return result;
00198 }