source: 3DVCSoftware/trunk/source/Lib/TLibCommon/TComBitStream.h

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1/* The copyright in this software is being made available under the BSD
2 * License, included below. This software may be subject to other third party
3 * and contributor rights, including patent rights, and no such rights are
4 * granted under this license.
5 *
6 * Copyright (c) 2010-2017, ITU/ISO/IEC
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions are met:
11 *
12 *  * Redistributions of source code must retain the above copyright notice,
13 *    this list of conditions and the following disclaimer.
14 *  * Redistributions in binary form must reproduce the above copyright notice,
15 *    this list of conditions and the following disclaimer in the documentation
16 *    and/or other materials provided with the distribution.
17 *  * Neither the name of the ITU/ISO/IEC nor the names of its contributors may
18 *    be used to endorse or promote products derived from this software without
19 *    specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
22 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS
25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
31 * THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34/** \file     TComBitStream.h
35    \brief    class for handling bitstream (header)
36*/
37
38#ifndef __TCOMBITSTREAM__
39#define __TCOMBITSTREAM__
40
41#if _MSC_VER > 1000
42#pragma once
43#endif // _MSC_VER > 1000
44
45#include <stdint.h>
46#include <vector>
47#include <stdio.h>
48#include "CommonDef.h"
49
50//! \ingroup TLibCommon
51//! \{
52
53// ====================================================================================================================
54// Class definition
55// ====================================================================================================================
56
57/// pure virtual class for basic bit handling
58class TComBitIf
59{
60public:
61  virtual Void        writeAlignOne         () {};
62  virtual Void        writeAlignZero        () {};
63  virtual Void        write                 ( UInt uiBits, UInt uiNumberOfBits )  = 0;
64  virtual Void        resetBits             ()                                    = 0;
65  virtual UInt getNumberOfWrittenBits() const = 0;
66  virtual Int         getNumBitsUntilByteAligned() const = 0;
67  virtual ~TComBitIf() {}
68};
69
70/**
71 * Model of a writable bitstream that accumulates bits to produce a
72 * bytestream.
73 */
74class TComOutputBitstream : public TComBitIf
75{
76  /**
77   * FIFO for storage of bytes.  Use:
78   *  - fifo.push_back(x) to append words
79   *  - fifo.clear() to empty the FIFO
80   *  - &fifo.front() to get a pointer to the data array.
81   *    NB, this pointer is only valid until the next push_back()/clear()
82   */
83  std::vector<uint8_t> m_fifo;
84
85  UInt m_num_held_bits; /// number of bits not flushed to bytestream.
86  UChar m_held_bits; /// the bits held and not flushed to bytestream.
87                             /// this value is always msb-aligned, bigendian.
88public:
89  // create / destroy
90  TComOutputBitstream();
91  ~TComOutputBitstream();
92
93  // interface for encoding
94  /**
95   * append uiNumberOfBits least significant bits of uiBits to
96   * the current bitstream
97   */
98  Void        write           ( UInt uiBits, UInt uiNumberOfBits );
99
100  /** insert one bits until the bitstream is byte-aligned */
101  Void        writeAlignOne   ();
102
103  /** insert zero bits until the bitstream is byte-aligned */
104  Void        writeAlignZero  ();
105
106  /** this function should never be called */
107  Void resetBits() { assert(0); }
108
109  // utility functions
110
111  /**
112   * Return a pointer to the start of the byte-stream buffer.
113   * Pointer is valid until the next write/flush/reset call.
114   * NB, data is arranged such that subsequent bytes in the
115   * bytestream are stored in ascending addresses.
116   */
117  UChar* getByteStream() const;
118
119  /**
120   * Return the number of valid bytes available from  getByteStream()
121   */
122  UInt getByteStreamLength();
123
124  /**
125   * Reset all internal state.
126   */
127  Void clear();
128
129  /**
130   * returns the number of bits that need to be written to
131   * achieve byte alignment.
132   */
133  Int getNumBitsUntilByteAligned() const { return (8 - m_num_held_bits) & 0x7; }
134
135  /**
136   * Return the number of bits that have been written since the last clear()
137   */
138  UInt getNumberOfWrittenBits() const { return UInt(m_fifo.size()) * 8 + m_num_held_bits; }
139
140  Void insertAt(const TComOutputBitstream& src, UInt pos);
141
142  /**
143   * Return a reference to the internal fifo
144   */
145  std::vector<uint8_t>& getFIFO() { return m_fifo; }
146
147  UChar getHeldBits  ()          { return m_held_bits;          }
148
149  //TComOutputBitstream& operator= (const TComOutputBitstream& src);
150  /** Return a reference to the internal fifo */
151  const std::vector<uint8_t>& getFIFO() const { return m_fifo; }
152
153  Void          addSubstream    ( TComOutputBitstream* pcSubstream );
154  Void writeByteAlignment();
155
156  //! returns the number of start code emulations contained in the current buffer
157  Int countStartCodeEmulations();
158};
159
160/**
161 * Model of an input bitstream that extracts bits from a predefined
162 * bytestream.
163 */
164class TComInputBitstream
165{
166protected:
167  std::vector<uint8_t> m_fifo; /// FIFO for storage of complete bytes
168  std::vector<UInt> m_emulationPreventionByteLocation;
169
170  UInt m_fifo_idx; /// Read index into m_fifo
171
172  UInt m_num_held_bits;
173  UChar m_held_bits;
174  UInt  m_numBitsRead;
175
176public:
177  /**
178   * Create a new bitstream reader object that reads from buf.
179   */
180  TComInputBitstream();
181  virtual ~TComInputBitstream() { }
182  TComInputBitstream(const TComInputBitstream &src);
183
184  Void resetToStart();
185
186  // interface for decoding
187  Void        pseudoRead      ( UInt uiNumberOfBits, UInt& ruiBits );
188  Void        read            ( UInt uiNumberOfBits, UInt& ruiBits );
189  Void        readByte        ( UInt &ruiBits )
190  {
191    assert(m_fifo_idx < m_fifo.size());
192    ruiBits = m_fifo[m_fifo_idx++];
193  }
194
195  Void        peekPreviousByte( UInt &byte )
196  {
197    assert(m_fifo_idx > 0);
198    byte = m_fifo[m_fifo_idx - 1];
199  }
200
201  UInt        readOutTrailingBits ();
202  UChar getHeldBits  ()          { return m_held_bits;          }
203  TComOutputBitstream& operator= (const TComOutputBitstream& src);
204  UInt  getByteLocation              ( )                     { return m_fifo_idx                    ; }
205
206  // Peek at bits in word-storage. Used in determining if we have completed reading of current bitstream and therefore slice in LCEC.
207  UInt        peekBits (UInt uiBits) { UInt tmp; pseudoRead(uiBits, tmp); return tmp; }
208
209  // utility functions
210  UInt read(UInt numberOfBits) { UInt tmp; read(numberOfBits, tmp); return tmp; }
211  UInt     readByte() { UInt tmp; readByte( tmp ); return tmp; }
212  UInt getNumBitsUntilByteAligned() { return m_num_held_bits & (0x7); }
213  UInt getNumBitsLeft() { return 8*((UInt)m_fifo.size() - m_fifo_idx) + m_num_held_bits; }
214  TComInputBitstream *extractSubstream( UInt uiNumBits ); // Read the nominated number of bits, and return as a bitstream.
215  UInt  getNumBitsRead() { return m_numBitsRead; }
216  UInt readByteAlignment();
217
218  Void      pushEmulationPreventionByteLocation ( UInt pos )                  { m_emulationPreventionByteLocation.push_back( pos ); }
219  UInt      numEmulationPreventionBytesRead     ()                            { return (UInt) m_emulationPreventionByteLocation.size();    }
220  const std::vector<UInt> &getEmulationPreventionByteLocation  () const              { return m_emulationPreventionByteLocation;           }
221  UInt      getEmulationPreventionByteLocation  ( UInt idx )                  { return m_emulationPreventionByteLocation[ idx ];    }
222  Void      clearEmulationPreventionByteLocation()                            { m_emulationPreventionByteLocation.clear();          }
223  Void      setEmulationPreventionByteLocation  ( const std::vector<UInt> &vec )     { m_emulationPreventionByteLocation = vec;            }
224
225  const std::vector<uint8_t> &getFifo() const { return m_fifo; }
226        std::vector<uint8_t> &getFifo()       { return m_fifo; }
227};
228
229//! \}
230
231#endif
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