| /*=========================================================================== |
| FILE: |
| BitParser.h |
| |
| DESCRIPTION: |
| Declaration of cBitParser class |
| |
| PUBLIC CLASSES AND METHODS: |
| cBitParser |
| This class extracts bits from 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. |
| ===========================================================================*/ |
| |
| //--------------------------------------------------------------------------- |
| // Pragmas |
| //--------------------------------------------------------------------------- |
| #pragma once |
| |
| //--------------------------------------------------------------------------- |
| // Definitions |
| //--------------------------------------------------------------------------- |
| |
| // Number of bits in a byte |
| const ULONG BITS_PER_BYTE = 8; |
| |
| // Maximum number of bits we will parse for any supported type |
| const ULONG MAX_TYPE_BITS = (ULONG)sizeof(ULONGLONG) * BITS_PER_BYTE; |
| |
| /*=========================================================================== |
| METHOD: |
| ByteSwap (Inline Public Method) |
| |
| DESCRIPTION: |
| Changes little-endian values to big-endian, and vice versa |
| |
| PARAMETERS: |
| data [ I ] - Data being byte-swapped |
| |
| RETURN VALUE: |
| None |
| ===========================================================================*/ |
| template <class T> |
| void ByteSwap( T & data ) |
| { |
| // Just reverse the order of the bytes |
| PBYTE pL; |
| PBYTE pR; |
| |
| for (pL = (PBYTE)&data, pR = pL + sizeof( T ) - 1; pL < pR; ++pL, --pR) |
| { |
| *pL = *pL ^ *pR; |
| *pR = *pL ^ *pR; |
| *pL = *pL ^ *pR; |
| } |
| }; |
| |
| /*=========================================================================*/ |
| // Class cBitParser |
| // |
| // Class to assist in parsing a buffer into bit/byte specified fields |
| /*=========================================================================*/ |
| class cBitParser |
| { |
| public: |
| // Constructor (default) |
| cBitParser(); |
| |
| // Constructor (from a buffer) |
| cBitParser( |
| const BYTE * pData, |
| ULONG dataBitSize ); |
| |
| // Destructor |
| ~cBitParser(); |
| |
| // (Inline) Returns the number of bits left in the buffer (from the |
| // current working bit offset) |
| ULONG GetNumBitsLeft() const |
| { |
| return (mMaxOffset - mOffset); |
| }; |
| |
| // (Inline) Returns the number of bits in the buffer that have been |
| // processed (essentially the current working bit offset) |
| ULONG GetNumBitsParsed() const |
| { |
| return (mOffset); |
| }; |
| |
| // (Inline) Set current working bit offset |
| void SetOffset( ULONG offset ) |
| { |
| mOffset = offset; |
| if (mOffset > mMaxOffset) |
| { |
| mOffset = mMaxOffset; |
| } |
| }; |
| |
| // (Inline) Are we parsing LSB -> MSB (the default)? |
| bool GetLSBMode() |
| { |
| return mbLSB; |
| }; |
| |
| // (Inline) Parse LSB -> MSB (if true) or MSB -> LSB |
| void SetLSBMode( bool bLSB ) |
| { |
| mbLSB = bLSB; |
| }; |
| |
| // Return 'numBits' as a CHAR (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| CHAR & dataOut ); |
| |
| // Return 'numBits' as a SHORT (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| SHORT & dataOut ); |
| |
| // Return 'numBits' as a LONG (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| LONG & dataOut ); |
| |
| // Return 'numBits' as a LONGLONG (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| LONGLONG & dataOut ); |
| |
| // Return 'numBits' as a UCHAR (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| UCHAR & dataOut ); |
| |
| // Return 'numBits' as a USHORT (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| USHORT & dataOut ); |
| |
| // Return 'numBits' as a ULONG (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| ULONG & dataOut ); |
| |
| // Return 'numBits' as a ULONGLONG (advances offset) |
| DWORD Get( |
| ULONG numBits, |
| ULONGLONG & dataOut ); |
| |
| // Release the data being parsed |
| void ReleaseData(); |
| |
| // Set the data being parsed |
| void SetData( |
| const BYTE * pData, |
| ULONG dataBitSize ); |
| |
| protected: |
| /* Data buffer */ |
| const BYTE * mpData; |
| |
| /* Current bit-specified offset */ |
| ULONG mOffset; |
| |
| /* Maximum bit-specified offset */ |
| ULONG mMaxOffset; |
| |
| /* Are we parsing LSB -> MSB (the default)? */ |
| bool mbLSB; |
| }; |