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Side by Side Diff: media/base/bit_reader_core.h

Issue 1534273002: Switch to standard integer types in media/. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: more Created 5 years ago
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1 // Copyright 2014 The Chromium Authors. All rights reserved. 1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #ifndef MEDIA_BASE_BIT_READER_CORE_H_ 5 #ifndef MEDIA_BASE_BIT_READER_CORE_H_
6 #define MEDIA_BASE_BIT_READER_CORE_H_ 6 #define MEDIA_BASE_BIT_READER_CORE_H_
7 7
8 #include "base/basictypes.h"
9 #include "base/logging.h" 8 #include "base/logging.h"
10 #include "media/base/media_export.h" 9 #include "media/base/media_export.h"
11 10
12 namespace media { 11 namespace media {
13 12
14 class MEDIA_EXPORT BitReaderCore { 13 class MEDIA_EXPORT BitReaderCore {
15 public: 14 public:
16 class ByteStreamProvider { 15 class ByteStreamProvider {
17 public: 16 public:
18 ByteStreamProvider(); 17 ByteStreamProvider();
19 virtual ~ByteStreamProvider(); 18 virtual ~ByteStreamProvider();
20 19
21 // Consume at most the following |max_n| bytes of the stream 20 // Consume at most the following |max_n| bytes of the stream
22 // and return the number n of bytes actually consumed. 21 // and return the number n of bytes actually consumed.
23 // Set |*array| to point to a memory buffer containing those n bytes. 22 // Set |*array| to point to a memory buffer containing those n bytes.
24 // Note: |*array| must be valid until the next call to GetBytes 23 // Note: |*array| must be valid until the next call to GetBytes
25 // but there is no guarantee it is valid after. 24 // but there is no guarantee it is valid after.
26 virtual int GetBytes(int max_n, const uint8** array) = 0; 25 virtual int GetBytes(int max_n, const uint8_t** array) = 0;
27 }; 26 };
28 27
29 // Lifetime of |byte_stream_provider| must be longer than BitReaderCore. 28 // Lifetime of |byte_stream_provider| must be longer than BitReaderCore.
30 explicit BitReaderCore(ByteStreamProvider* byte_stream_provider); 29 explicit BitReaderCore(ByteStreamProvider* byte_stream_provider);
31 ~BitReaderCore(); 30 ~BitReaderCore();
32 31
33 // Read one bit from the stream and return it as a boolean in |*out|. 32 // Read one bit from the stream and return it as a boolean in |*out|.
34 // Remark: we do not use the template version for reading a bool 33 // Remark: we do not use the template version for reading a bool
35 // since it generates some optimization warnings during compilation 34 // since it generates some optimization warnings during compilation
36 // on Windows platforms. 35 // on Windows platforms.
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47 // - |num_bits| cannot be larger than the bits the type can hold. 46 // - |num_bits| cannot be larger than the bits the type can hold.
48 // - From the above description, passing a signed type in |T| does not 47 // - From the above description, passing a signed type in |T| does not
49 // mean the first bit read from the stream gives the sign of the value. 48 // mean the first bit read from the stream gives the sign of the value.
50 // Return false if the given number of bits cannot be read (not enough 49 // Return false if the given number of bits cannot be read (not enough
51 // bits in the stream), true otherwise. When return false, the stream will 50 // bits in the stream), true otherwise. When return false, the stream will
52 // enter a state where further ReadBits/SkipBits operations will always 51 // enter a state where further ReadBits/SkipBits operations will always
53 // return false unless |num_bits| is 0. The type |T| has to be a primitive 52 // return false unless |num_bits| is 0. The type |T| has to be a primitive
54 // integer type. 53 // integer type.
55 template<typename T> bool ReadBits(int num_bits, T* out) { 54 template<typename T> bool ReadBits(int num_bits, T* out) {
56 DCHECK_LE(num_bits, static_cast<int>(sizeof(T) * 8)); 55 DCHECK_LE(num_bits, static_cast<int>(sizeof(T) * 8));
57 uint64 temp; 56 uint64_t temp;
58 bool ret = ReadBitsInternal(num_bits, &temp); 57 bool ret = ReadBitsInternal(num_bits, &temp);
59 *out = static_cast<T>(temp); 58 *out = static_cast<T>(temp);
60 return ret; 59 return ret;
61 } 60 }
62 61
63 // Read one bit from the stream and return it as a boolean in |*flag|. 62 // Read one bit from the stream and return it as a boolean in |*flag|.
64 bool ReadFlag(bool* flag); 63 bool ReadFlag(bool* flag);
65 64
66 // Retrieve some bits without actually consuming them. 65 // Retrieve some bits without actually consuming them.
67 // Bits returned in |*out| are shifted so the most significant bit contains 66 // Bits returned in |*out| are shifted so the most significant bit contains
68 // the next bit that can be read from the stream. 67 // the next bit that can be read from the stream.
69 // Return the number of bits actually written in |out|. 68 // Return the number of bits actually written in |out|.
70 // Note: |num_bits| is just a suggestion of how many bits the caller 69 // Note: |num_bits| is just a suggestion of how many bits the caller
71 // wish to get in |*out| and must be less than 64: 70 // wish to get in |*out| and must be less than 64:
72 // - The number of bits returned can be more than |num_bits|. 71 // - The number of bits returned can be more than |num_bits|.
73 // - However, it will be strictly less than |num_bits| 72 // - However, it will be strictly less than |num_bits|
74 // if and only if there are not enough bits left in the stream. 73 // if and only if there are not enough bits left in the stream.
75 int PeekBitsMsbAligned(int num_bits, uint64* out); 74 int PeekBitsMsbAligned(int num_bits, uint64_t* out);
76 75
77 // Skip |num_bits| next bits from stream. Return false if the given number of 76 // Skip |num_bits| next bits from stream. Return false if the given number of
78 // bits cannot be skipped (not enough bits in the stream), true otherwise. 77 // bits cannot be skipped (not enough bits in the stream), true otherwise.
79 // When return false, the stream will enter a state where further 78 // When return false, the stream will enter a state where further
80 // ReadBits/ReadFlag/SkipBits operations 79 // ReadBits/ReadFlag/SkipBits operations
81 // will always return false unless |num_bits| is 0. 80 // will always return false unless |num_bits| is 0.
82 bool SkipBits(int num_bits); 81 bool SkipBits(int num_bits);
83 82
84 // Returns the number of bits read so far. 83 // Returns the number of bits read so far.
85 int bits_read() const; 84 int bits_read() const;
86 85
87 private: 86 private:
88 // This function can skip any number of bits but is more efficient 87 // This function can skip any number of bits but is more efficient
89 // for small numbers. Return false if the given number of bits cannot be 88 // for small numbers. Return false if the given number of bits cannot be
90 // skipped (not enough bits in the stream), true otherwise. 89 // skipped (not enough bits in the stream), true otherwise.
91 bool SkipBitsSmall(int num_bits); 90 bool SkipBitsSmall(int num_bits);
92 91
93 // Help function used by ReadBits to avoid inlining the bit reading logic. 92 // Help function used by ReadBits to avoid inlining the bit reading logic.
94 bool ReadBitsInternal(int num_bits, uint64* out); 93 bool ReadBitsInternal(int num_bits, uint64_t* out);
95 94
96 // Refill bit registers to have at least |min_nbits| bits available. 95 // Refill bit registers to have at least |min_nbits| bits available.
97 // Return true if the mininimum bit count condition is met after the refill. 96 // Return true if the mininimum bit count condition is met after the refill.
98 bool Refill(int min_nbits); 97 bool Refill(int min_nbits);
99 98
100 // Refill the current bit register from the next bit register. 99 // Refill the current bit register from the next bit register.
101 void RefillCurrentRegister(); 100 void RefillCurrentRegister();
102 101
103 ByteStreamProvider* const byte_stream_provider_; 102 ByteStreamProvider* const byte_stream_provider_;
104 103
105 // Number of bits read so far. 104 // Number of bits read so far.
106 int bits_read_; 105 int bits_read_;
107 106
108 // Number of bits in |reg_| that have not been consumed yet. 107 // Number of bits in |reg_| that have not been consumed yet.
109 // Note: bits are consumed from MSB to LSB. 108 // Note: bits are consumed from MSB to LSB.
110 int nbits_; 109 int nbits_;
111 uint64 reg_; 110 uint64_t reg_;
112 111
113 // Number of bits in |reg_next_| that have not been consumed yet. 112 // Number of bits in |reg_next_| that have not been consumed yet.
114 // Note: bits are consumed from MSB to LSB. 113 // Note: bits are consumed from MSB to LSB.
115 int nbits_next_; 114 int nbits_next_;
116 uint64 reg_next_; 115 uint64_t reg_next_;
117 116
118 DISALLOW_COPY_AND_ASSIGN(BitReaderCore); 117 DISALLOW_COPY_AND_ASSIGN(BitReaderCore);
119 }; 118 };
120 119
121 } // namespace media 120 } // namespace media
122 121
123 #endif // MEDIA_BASE_BIT_READER_CORE_H_ 122 #endif // MEDIA_BASE_BIT_READER_CORE_H_
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