bitpack.h
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上传日期:2021-03-01
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- /**
- * @file bitpack.h
- * @brief Convert data to packed bit stream
- *
- * $LicenseInfo:firstyear=2000&license=viewergpl$
- *
- * Copyright (c) 2000-2010, Linden Research, Inc.
- *
- * Second Life Viewer Source Code
- * The source code in this file ("Source Code") is provided by Linden Lab
- * to you under the terms of the GNU General Public License, version 2.0
- * ("GPL"), unless you have obtained a separate licensing agreement
- * ("Other License"), formally executed by you and Linden Lab. Terms of
- * the GPL can be found in doc/GPL-license.txt in this distribution, or
- * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
- *
- * There are special exceptions to the terms and conditions of the GPL as
- * it is applied to this Source Code. View the full text of the exception
- * in the file doc/FLOSS-exception.txt in this software distribution, or
- * online at
- * http://secondlifegrid.net/programs/open_source/licensing/flossexception
- *
- * By copying, modifying or distributing this software, you acknowledge
- * that you have read and understood your obligations described above,
- * and agree to abide by those obligations.
- *
- * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
- * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
- * COMPLETENESS OR PERFORMANCE.
- * $/LicenseInfo$
- */
- #ifndef LL_BITPACK_H
- #define LL_BITPACK_H
- #include "llerror.h"
- const U32 MAX_DATA_BITS = 8;
- class LLBitPack
- {
- public:
- LLBitPack(U8 *buffer, U32 max_size) : mBuffer(buffer), mBufferSize(0), mLoad(0), mLoadSize(0), mTotalBits(0), mMaxSize(max_size)
- {
- }
- ~LLBitPack()
- {
- }
- void resetBitPacking()
- {
- mLoad = 0;
- mLoadSize = 0;
- mTotalBits = 0;
- mBufferSize = 0;
- }
- U32 bitPack(U8 *total_data, U32 total_dsize)
- {
- U32 dsize;
- U8 data;
- while (total_dsize > 0)
- {
- if (total_dsize > MAX_DATA_BITS)
- {
- dsize = MAX_DATA_BITS;
- total_dsize -= MAX_DATA_BITS;
- }
- else
- {
- dsize = total_dsize;
- total_dsize = 0;
- }
- data = *total_data++;
- data <<= (MAX_DATA_BITS - dsize);
- while (dsize > 0)
- {
- if (mLoadSize == MAX_DATA_BITS)
- {
- *(mBuffer + mBufferSize++) = mLoad;
- if (mBufferSize > mMaxSize)
- {
- llerror("mBufferSize exceeding mMaxSize!", 0);
- }
- mLoadSize = 0;
- mLoad = 0x00;
- }
- mLoad <<= 1;
- mLoad |= (data >> (MAX_DATA_BITS - 1));
- data <<= 1;
- mLoadSize++;
- mTotalBits++;
- dsize--;
- }
- }
- return mBufferSize;
- }
- U32 bitCopy(U8 *total_data, U32 total_dsize)
- {
- U32 dsize;
- U8 data;
- while (total_dsize > 0)
- {
- if (total_dsize > MAX_DATA_BITS)
- {
- dsize = MAX_DATA_BITS;
- total_dsize -= MAX_DATA_BITS;
- }
- else
- {
- dsize = total_dsize;
- total_dsize = 0;
- }
- data = *total_data++;
- while (dsize > 0)
- {
- if (mLoadSize == MAX_DATA_BITS)
- {
- *(mBuffer + mBufferSize++) = mLoad;
- if (mBufferSize > mMaxSize)
- {
- llerror("mBufferSize exceeding mMaxSize!", 0);
- }
- mLoadSize = 0;
- mLoad = 0x00;
- }
- mLoad <<= 1;
- mLoad |= (data >> (MAX_DATA_BITS - 1));
- data <<= 1;
- mLoadSize++;
- mTotalBits++;
- dsize--;
- }
- }
- return mBufferSize;
- }
- U32 bitUnpack(U8 *total_retval, U32 total_dsize)
- {
- U32 dsize;
- U8 *retval;
- while (total_dsize > 0)
- {
- if (total_dsize > MAX_DATA_BITS)
- {
- dsize = MAX_DATA_BITS;
- total_dsize -= MAX_DATA_BITS;
- }
- else
- {
- dsize = total_dsize;
- total_dsize = 0;
- }
- retval = total_retval++;
- *retval = 0x00;
- while (dsize > 0)
- {
- if (mLoadSize == 0)
- {
- #ifdef _DEBUG
- if (mBufferSize > mMaxSize)
- {
- llerrs << "mBufferSize exceeding mMaxSize" << llendl;
- llerrs << mBufferSize << " > " << mMaxSize << llendl;
- }
- #endif
- mLoad = *(mBuffer + mBufferSize++);
- mLoadSize = MAX_DATA_BITS;
- }
- *retval <<= 1;
- *retval |= (mLoad >> (MAX_DATA_BITS - 1));
- mLoadSize--;
- mLoad <<= 1;
- dsize--;
- }
- }
- return mBufferSize;
- }
- U32 flushBitPack()
- {
- if (mLoadSize)
- {
- mLoad <<= (MAX_DATA_BITS - mLoadSize);
- *(mBuffer + mBufferSize++) = mLoad;
- if (mBufferSize > mMaxSize)
- {
- llerror("mBufferSize exceeding mMaxSize!", 0);
- }
- mLoadSize = 0;
- }
- return mBufferSize;
- }
- U8 *mBuffer;
- U32 mBufferSize;
- U8 mLoad;
- U32 mLoadSize;
- U32 mTotalBits;
- U32 mMaxSize;
- };
- #endif