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/***************************************************************************** * Copyright (C) 2013 x265 project * * Author: Steve Borho 
   
     * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA. * * This program is also available under a commercial proprietary license. * For more information, contact us at license @ x265.com. *****************************************************************************/#ifndef X265_BITSTREAM_H#define X265_BITSTREAM_H 1namespace x265 {// private namespaceclass BitInterface{public:    virtual void     write(uint32_t val, uint32_t numBits)  = 0;    virtual void     writeByte(uint32_t val)                = 0;    virtual void     resetBits()                            = 0;    virtual uint32_t getNumberOfWrittenBits() const         = 0;    virtual void     writeAlignOne()                        = 0;    virtual void     writeAlignZero()                       = 0;    virtual ~BitInterface() {}};class BitCounter : public BitInterface{protected:    uint32_t  m_bitCounter;public:    BitCounter() : m_bitCounter(0) {}    void     write(uint32_t, uint32_t num)  { m_bitCounter += num; }    void     writeByte(uint32_t)            { m_bitCounter += 8;   }    void     resetBits()                    { m_bitCounter = 0;    }    uint32_t getNumberOfWrittenBits() const { return m_bitCounter; }    void     writeAlignOne()                { }    void     writeAlignZero()               { }};class Bitstream : public BitInterface{public:    Bitstream();    ~Bitstream()                             { X265_FREE(m_fifo); }    void     resetBits()                     { m_partialByteBits = m_byteOccupancy = 0; m_partialByte = 0; }    uint32_t getNumberOfWrittenBytes() const { return m_byteOccupancy; }    uint32_t getNumberOfWrittenBits()  const { return m_byteOccupancy * 8 + m_partialByteBits; }    const uint8_t* getFIFO() const           { return m_fifo; }    void     write(uint32_t val, uint32_t numBits);    void     writeByte(uint32_t val);    void     writeAlignOne();      // insert one bits until the bitstream is byte-aligned    void     writeAlignZero();     // insert zero bits until the bitstream is byte-aligned    void     writeByteAlignment(); // insert 1 bit, then pad to byte-align with zeroprivate:    uint8_t *m_fifo;    uint32_t m_byteAlloc;    uint32_t m_byteOccupancy;    uint32_t m_partialByteBits;    uint8_t  m_partialByte;    void     push_back(uint8_t val);};/*无符号指数哥伦布码占用的位数 (注意：实际编码中需要对原有数字加一 再获得指数哥伦布码，所以必须加一才是实际占用的位数)指数哥伦布编码分为：无符号和有符号：无符号哥伦布编码：有前缀和后缀的概念：1 先将要编码的数值写成二进制：0x6 ==> 0b1102 以最高位为界(左边第一个1的位置)，后面的就是后缀（就是二进制10了），总共两位，所以前缀也是两位，而且必须是0，3 得出数值6编码后的二进制表示为：00110解码就是反过程：从高位开始统计0的个数直至非零位, 假设0的个数是k, 那后面k+1位就是要找的数值了**/static const uint8_t bitSize[256] ={    1, 1, 3, 3, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 7, 7,    9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,    11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,    11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,    13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,    13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,    13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,    13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,    15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,};/** 函数功能             ： 获取无符号指数哥伦布码占用的位数* \参数 val              ： 当前待编码的值* \返回                  ： 无符号指数哥伦布码占用的位数 * */static inline int bs_size_ue(unsigned int val){    return bitSize[val + 1];//因为实际编码中需要先加一，固加一获得时间占用的位数}static inline int bs_size_ue_big(unsigned int val){    if (val < 255)        return bitSize[val + 1];    else        return bitSize[(val + 1) >> 8] + 16;}/*无符号指数哥伦布码先将编码系数映射为整数-10 -->  20-9 -->  18-8 -->  16-7 -->  14-6 -->  12-5 -->  10-4 -->   8-3 -->   6-2 -->   4-1 -->   20 -->   01 -->   12 -->   33 -->   54 -->   75 -->   96 -->  117 -->  138 -->  159 -->  1710 -->  19再调用无符号指数哥伦布码**//** 函数功能             ： 获取有符号指数哥伦布码占用的位数* \参数 val              ： 当前待编码的值* \返回                  ： 有符号指数哥伦布码占用的位数 * */static inline int bs_size_se(int val){    int tmp = 1 - val * 2;//这里：正数变负 负数变正  如果是负数 刚好就是对应val值+1    if (tmp < 0) tmp = val * 2;//说明当前是正数  直接乘以2 刚好是对应val值+1  如10 对应为19 19+1=20    if (tmp < 256)        return bitSize[tmp];//获取bits (也是加一后数字)    else        return bitSize[tmp >> 8] + 16;//大于256情况}class SyntaxElementWriter{public:    BitInterface* m_bitIf;    SyntaxElementWriter() : m_bitIf(NULL) {}    /* silently discard the name of the syntax element */    inline void WRITE_CODE(uint32_t code, uint32_t length, const char *) { writeCode(code, length); }    inline void WRITE_UVLC(uint32_t code,                  const char *) { writeUvlc(code); }    inline void WRITE_SVLC(int32_t  code,                  const char *) { writeSvlc(code); }    inline void WRITE_FLAG(bool flag,                      const char *) { writeFlag(flag); }    void writeCode(uint32_t code, uint32_t length) { m_bitIf->write(code, length); }    void writeUvlc(uint32_t code);    void writeSvlc(int32_t code)                   { uint32_t ucode = (code <= 0) ? -code << 1 : (code << 1) - 1; writeUvlc(ucode); }    void writeFlag(bool code)                      { m_bitIf->write(code, 1); }};}#endif // ifndef X265_BITSTREAM_H
   

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