/*=========================================================================== FILE: BitPacker.cpp DESCRIPTION: Implementation of cBitPacker class PUBLIC CLASSES AND METHODS: cBitPacker This class packs bits into a buffer Copyright (c) 2011, Code Aurora Forum. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions 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. * Neither the name of Code Aurora Forum nor the names of its contributors may 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 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER 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. ===========================================================================*/ //--------------------------------------------------------------------------- // Include Files //--------------------------------------------------------------------------- #include "StdAfx.h" #include "BitPacker.h" #include <list> //--------------------------------------------------------------------------- // Definitions //--------------------------------------------------------------------------- /*=========================================================================*/ // Free Methods /*=========================================================================*/ /*=========================================================================== METHOD: SetUnsignedVal (Public Method) DESCRIPTION: Set an unsigned value in the bit source (writing least significant bits first) PARAMETERS: pData [ O ] - Data buffer to write to currentOffset [I/O] - Current bit offset into above buffer maxOffset [ I ] - Maximum bit offset into above buffer numBits [ I ] - Number of bits to write dataIn [ I ] - Input value to write bLSB [ I ] - Pack LSB -> MSB? RETURN VALUE: DWORD ===========================================================================*/ template <class T> DWORD SetUnsignedVal( BYTE * pData, ULONG & currentOffset, ULONG maxOffset, ULONG numBits, T dataIn, bool bLSB = true ) { ASSERT( pData != 0 ); // Number of bits in the passed in type const ULONG TYPE_BIT_COUNT = (ULONG)(sizeof( T ) * BITS_PER_BYTE); ASSERT( numBits > 0 && numBits <= TYPE_BIT_COUNT); // Requesting too much? if (currentOffset < maxOffset) { ULONG bitsToGo = maxOffset - currentOffset; if (bitsToGo < numBits) { return ERROR_NOT_ENOUGH_MEMORY; } } else if (currentOffset == maxOffset) { // Silly rabbit, don't bother to call us if you don't want any bits! return ERROR_INVALID_PARAMETER; } else { return ERROR_NOT_ENOUGH_MEMORY; } // Advance to first valid byte pData += (currentOffset / BITS_PER_BYTE); // Since we don't really care about performance for bit packing // (we do not anticipate this being called as frequently as bit // parsing) we always use the generic approach // Reduce input to a bit array BYTE bits[MAX_TYPE_BITS]; ULONG bitsExtracted = 0; while (bitsExtracted < numBits) { if (bLSB == true) { BYTE bit = (BYTE)(dataIn & (T)1); bits[bitsExtracted++] = bit; } else { BYTE bit = (BYTE)(dataIn & (T)1); bits[numBits - ++bitsExtracted] = bit; } dataIn >>= 1; } // Store current offset ULONG offset = currentOffset; // Add in each bit - one at a time bitsExtracted = 0; while (bitsExtracted != numBits) { // How many bits are left in the current byte? ULONG bitsLeft = BITS_PER_BYTE - (offset % BITS_PER_BYTE); // Shift input bit over to desired destination BYTE tmp = bits[bitsExtracted++]; if (bLSB == true) { tmp <<= (BITS_PER_BYTE - bitsLeft); } else { tmp <<= bitsLeft - 1; } *pData |= tmp; // Advance to next byte in buffer? offset++; if (offset % BITS_PER_BYTE == 0) { pData++; } } currentOffset += numBits; return NO_ERROR; } /*=========================================================================*/ // cBitPacker Methods /*=========================================================================*/ /*=========================================================================== METHOD: cBitPacker (Public Method) DESCRIPTION: Constructor (default) RETURN VALUE: None ===========================================================================*/ cBitPacker::cBitPacker() : mpData( 0 ), mOffset( 0 ), mMaxAttainedOffset( 0 ), mMaxOffset( 0 ), mbLSB( true ) { // Nothing to do } /*=========================================================================== METHOD: cBitPacker (Public Method) DESCRIPTION: Constructor (from a buffer) PARAMETERS: pData [ I ] - Data buffer dataBitSize [ I ] - Size of above data buffer (in bits) RETURN VALUE: None ===========================================================================*/ cBitPacker::cBitPacker( BYTE * pData, ULONG dataBitSize ) : mpData( 0 ), mOffset( 0 ), mMaxAttainedOffset( 0 ), mMaxOffset( 0 ), mbLSB( true ) { SetData( pData, dataBitSize ); } /*=========================================================================== METHOD: ~cBitPacker (Public Method) DESCRIPTION: Destructor RETURN VALUE: None ===========================================================================*/ cBitPacker::~cBitPacker() { // Nothing to do } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a CHAR (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, CHAR dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a SHORT (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, SHORT dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a LONG (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, LONG dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a LONGLONG (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, LONGLONG dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a UCHAR (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, UCHAR dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a USHORT (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, USHORT dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a ULONG (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, ULONG dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: Set (Public Method) DESCRIPTION: Write 'numBits' from a ULONGLONG (advances offset) PARAMETERS: numBits [ I ] - Number of bits to write dataIn [ I ] - Value to write RETURN VALUE: DWORD ===========================================================================*/ DWORD cBitPacker::Set( ULONG numBits, ULONGLONG dataIn ) { DWORD rc = SetUnsignedVal( mpData, mOffset, mMaxOffset, numBits, dataIn, mbLSB ); if (rc == NO_ERROR && mOffset > mMaxAttainedOffset) { mMaxAttainedOffset = mOffset; } return rc; } /*=========================================================================== METHOD: ReleaseData (Public Method) DESCRIPTION: Release the data being parsed RETURN VALUE: None ===========================================================================*/ void cBitPacker::ReleaseData() { // Clear out current buffer mpData = 0; mOffset = 0; mMaxAttainedOffset = 0; mMaxOffset = 0; }; /*=========================================================================== METHOD: SetData (Public Method) DESCRIPTION: Set the data being parsed PARAMETERS: pData [ I ] - Data buffer dataBitSize [ I ] - Size of above data buffer (in bits) RETURN VALUE: None ===========================================================================*/ void cBitPacker::SetData( BYTE * pData, ULONG dataBitSize ) { // Release current buffer ReleaseData(); // Anything to parse? if (pData != 0) { // Yes mpData = pData; mMaxOffset = dataBitSize; } else { // No ASSERT( mpData != 0 ); } }