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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 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 #include "base/metrics/bucket_ranges.h" | 5 #include "base/metrics/bucket_ranges.h" |
6 | 6 |
7 #include <cmath> | 7 #include <cmath> |
8 | 8 |
9 #include "base/logging.h" | 9 #include "base/logging.h" |
10 | 10 |
11 namespace base { | 11 namespace base { |
12 | 12 |
13 // Static table of checksums for all possible 8 bit bytes. | 13 // Static table of checksums for all possible 8 bit bytes. |
14 const uint32 kCrcTable[256] = { 0x0, 0x77073096L, 0xee0e612cL, | 14 const uint32_t kCrcTable[256] = { |
15 0x990951baL, 0x76dc419L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0xedb8832L, | 15 0x0, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x76dc419L, |
16 0x79dcb8a4L, 0xe0d5e91eL, 0x97d2d988L, 0x9b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, | 16 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0xedb8832L, 0x79dcb8a4L, |
17 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, 0x1adad47dL, | 17 0xe0d5e91eL, 0x97d2d988L, 0x9b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, |
18 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, 0x646ba8c0L, 0xfd62f97aL, | 18 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, |
19 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, | 19 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, |
20 0x4c69105eL, 0xd56041e4L, 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, | 20 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, |
21 0xa50ab56bL, 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L, | 21 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, |
22 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, 0xc8d75180L, | 22 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL, |
23 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, 0xb8bda50fL, 0x2802b89eL, | 23 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L, |
24 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, | 24 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, |
25 0xb6662d3dL, 0x76dc4190L, 0x1db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, | 25 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, |
26 0x6b6b51fL, 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0xf00f934L, 0x9609a88eL, | 26 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, |
27 0xe10e9818L, 0x7f6a0dbbL, 0x86d3d2dL, 0x91646c97L, 0xe6635c01L, 0x6b6b51f4L, | 27 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L, |
28 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, 0x1b01a57bL, 0x8208f4c1L, | 28 0x1db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x6b6b51fL, |
29 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, | 29 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0xf00f934L, 0x9609a88eL, |
30 0x15da2d49L, 0x8cd37cf3L, 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, | 30 0xe10e9818L, 0x7f6a0dbbL, 0x86d3d2dL, 0x91646c97L, 0xe6635c01L, |
31 0xd4bb30e2L, 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL, | 31 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, |
32 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, 0xaa0a4c5fL, | 32 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, |
33 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, 0xc90c2086L, 0x5768b525L, | 33 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, |
34 0x206f85b3L, 0xb966d409L, 0xce61e49fL, 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, | 34 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L, |
35 0xc7d7a8b4L, 0x59b33d17L, 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, | 35 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL, |
36 0x9abfb3b6L, 0x3b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x4db2615L, | 36 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, |
37 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0xd6d6a3eL, 0x7a6a5aa8L, 0xe40ecf0bL, | 37 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, |
38 0x9309ff9dL, 0xa00ae27L, 0x7d079eb1L, 0xf00f9344L, 0x8708a3d2L, 0x1e01f268L, | 38 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL, |
39 0x6906c2feL, 0xf762575dL, 0x806567cbL, 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, | 39 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L, |
40 0x89d32be0L, 0x10da7a5aL, 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, | 40 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L, |
41 0x60b08ed5L, 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L, | 41 0x3b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x4db2615L, |
42 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, 0x36034af6L, | 42 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0xd6d6a3eL, 0x7a6a5aa8L, |
43 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, 0x4669be79L, 0xcb61b38cL, | 43 0xe40ecf0bL, 0x9309ff9dL, 0xa00ae27L, 0x7d079eb1L, 0xf00f9344L, |
44 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, | 44 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL, |
45 0x5505262fL, 0xc5ba3bbeL, 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, | 45 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, |
46 0xb5d0cf31L, 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, | 46 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L, |
47 0x26d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x5005713L, 0x95bf4a82L, | 47 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L, |
48 0xe2b87a14L, 0x7bb12baeL, 0xcb61b38L, 0x92d28e9bL, 0xe5d5be0dL, 0x7cdcefb7L, | 48 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, |
49 0xbdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, | 49 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, |
50 0xf6b9265bL, 0x6fb077e1L, 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, | 50 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, |
51 0x11010b5cL, 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L, | 51 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL, |
52 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, 0x4969474dL, | 52 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L, |
53 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, 0x37d83bf0L, 0xa9bcae53L, | 53 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, |
54 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, | 54 0x26d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x5005713L, |
55 0x24b4a3a6L, 0xbad03605L, 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, | 55 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0xcb61b38L, 0x92d28e9bL, |
56 0xc4614ab8L, 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, | 56 0xe5d5be0dL, 0x7cdcefb7L, 0xbdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, |
57 0x2d02ef8dL, | 57 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, |
| 58 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL, |
| 59 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L, |
| 60 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, |
| 61 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, |
| 62 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, |
| 63 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L, |
| 64 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L, |
| 65 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, |
| 66 0x2d02ef8dL, |
58 }; | 67 }; |
59 | 68 |
60 // We generate the CRC-32 using the low order bits to select whether to XOR in | 69 // We generate the CRC-32 using the low order bits to select whether to XOR in |
61 // the reversed polynomial 0xedb88320L. This is nice and simple, and allows us | 70 // the reversed polynomial 0xedb88320L. This is nice and simple, and allows us |
62 // to keep the quotient in a uint32. Since we're not concerned about the nature | 71 // to keep the quotient in a uint32_t. Since we're not concerned about the |
63 // of corruptions (i.e., we don't care about bit sequencing, since we are | 72 // nature of corruptions (i.e., we don't care about bit sequencing, since we are |
64 // handling memory changes, which are more grotesque) so we don't bother to | 73 // handling memory changes, which are more grotesque) so we don't bother to get |
65 // get the CRC correct for big-endian vs little-ending calculations. All we | 74 // the CRC correct for big-endian vs little-ending calculations. All we need is |
66 // need is a nice hash, that tends to depend on all the bits of the sample, with | 75 // a nice hash, that tends to depend on all the bits of the sample, with very |
67 // very little chance of changes in one place impacting changes in another | 76 // little chance of changes in one place impacting changes in another place. |
68 // place. | 77 static uint32_t Crc32(uint32_t sum, HistogramBase::Sample value) { |
69 static uint32 Crc32(uint32 sum, HistogramBase::Sample value) { | |
70 // TODO(jar): Switch to false and watch stats. | 78 // TODO(jar): Switch to false and watch stats. |
71 const bool kUseRealCrc = true; | 79 const bool kUseRealCrc = true; |
72 | 80 |
73 if (kUseRealCrc) { | 81 if (kUseRealCrc) { |
74 union { | 82 union { |
75 HistogramBase::Sample range; | 83 HistogramBase::Sample range; |
76 unsigned char bytes[sizeof(HistogramBase::Sample)]; | 84 unsigned char bytes[sizeof(HistogramBase::Sample)]; |
77 } converter; | 85 } converter; |
78 converter.range = value; | 86 converter.range = value; |
79 for (size_t i = 0; i < sizeof(converter); ++i) | 87 for (size_t i = 0; i < sizeof(converter); ++i) |
80 sum = kCrcTable[(sum & 0xff) ^ converter.bytes[i]] ^ (sum >> 8); | 88 sum = kCrcTable[(sum & 0xff) ^ converter.bytes[i]] ^ (sum >> 8); |
81 } else { | 89 } else { |
82 // Use hash techniques provided in ReallyFastHash, except we don't care | 90 // Use hash techniques provided in ReallyFastHash, except we don't care |
83 // about "avalanching" (which would worsten the hash, and add collisions), | 91 // about "avalanching" (which would worsten the hash, and add collisions), |
84 // and we don't care about edge cases since we have an even number of bytes. | 92 // and we don't care about edge cases since we have an even number of bytes. |
85 union { | 93 union { |
86 HistogramBase::Sample range; | 94 HistogramBase::Sample range; |
87 uint16 ints[sizeof(HistogramBase::Sample) / 2]; | 95 uint16_t ints[sizeof(HistogramBase::Sample) / 2]; |
88 } converter; | 96 } converter; |
89 DCHECK_EQ(sizeof(HistogramBase::Sample), sizeof(converter)); | 97 DCHECK_EQ(sizeof(HistogramBase::Sample), sizeof(converter)); |
90 converter.range = value; | 98 converter.range = value; |
91 sum += converter.ints[0]; | 99 sum += converter.ints[0]; |
92 sum = (sum << 16) ^ sum ^ (static_cast<uint32>(converter.ints[1]) << 11); | 100 sum = (sum << 16) ^ sum ^ (static_cast<uint32_t>(converter.ints[1]) << 11); |
93 sum += sum >> 11; | 101 sum += sum >> 11; |
94 } | 102 } |
95 return sum; | 103 return sum; |
96 } | 104 } |
97 | 105 |
98 BucketRanges::BucketRanges(size_t num_ranges) | 106 BucketRanges::BucketRanges(size_t num_ranges) |
99 : ranges_(num_ranges, 0), | 107 : ranges_(num_ranges, 0), |
100 checksum_(0) {} | 108 checksum_(0) {} |
101 | 109 |
102 BucketRanges::~BucketRanges() {} | 110 BucketRanges::~BucketRanges() {} |
103 | 111 |
104 void BucketRanges::set_range(size_t i, HistogramBase::Sample value) { | 112 void BucketRanges::set_range(size_t i, HistogramBase::Sample value) { |
105 DCHECK_LT(i, ranges_.size()); | 113 DCHECK_LT(i, ranges_.size()); |
106 CHECK_GE(value, 0); | 114 CHECK_GE(value, 0); |
107 ranges_[i] = value; | 115 ranges_[i] = value; |
108 } | 116 } |
109 | 117 |
110 uint32 BucketRanges::CalculateChecksum() const { | 118 uint32_t BucketRanges::CalculateChecksum() const { |
111 // Seed checksum. | 119 // Seed checksum. |
112 uint32 checksum = static_cast<uint32>(ranges_.size()); | 120 uint32_t checksum = static_cast<uint32_t>(ranges_.size()); |
113 | 121 |
114 for (size_t index = 0; index < ranges_.size(); ++index) | 122 for (size_t index = 0; index < ranges_.size(); ++index) |
115 checksum = Crc32(checksum, ranges_[index]); | 123 checksum = Crc32(checksum, ranges_[index]); |
116 return checksum; | 124 return checksum; |
117 } | 125 } |
118 | 126 |
119 bool BucketRanges::HasValidChecksum() const { | 127 bool BucketRanges::HasValidChecksum() const { |
120 return CalculateChecksum() == checksum_; | 128 return CalculateChecksum() == checksum_; |
121 } | 129 } |
122 | 130 |
123 void BucketRanges::ResetChecksum() { | 131 void BucketRanges::ResetChecksum() { |
124 checksum_ = CalculateChecksum(); | 132 checksum_ = CalculateChecksum(); |
125 } | 133 } |
126 | 134 |
127 bool BucketRanges::Equals(const BucketRanges* other) const { | 135 bool BucketRanges::Equals(const BucketRanges* other) const { |
128 if (checksum_ != other->checksum_) | 136 if (checksum_ != other->checksum_) |
129 return false; | 137 return false; |
130 if (ranges_.size() != other->ranges_.size()) | 138 if (ranges_.size() != other->ranges_.size()) |
131 return false; | 139 return false; |
132 for (size_t index = 0; index < ranges_.size(); ++index) { | 140 for (size_t index = 0; index < ranges_.size(); ++index) { |
133 if (ranges_[index] != other->ranges_[index]) | 141 if (ranges_[index] != other->ranges_[index]) |
134 return false; | 142 return false; |
135 } | 143 } |
136 return true; | 144 return true; |
137 } | 145 } |
138 | 146 |
139 } // namespace base | 147 } // namespace base |
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