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Side by Side Diff: src/base/division-by-constant.cc

Issue 2395553002: Reland "Turn libbase into a component" (Closed)
Patch Set: Created 4 years, 2 months ago
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1 // Copyright 2014 the V8 project authors. All rights reserved. 1 // Copyright 2014 the V8 project 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 "src/base/division-by-constant.h" 5 #include "src/base/division-by-constant.h"
6 6
7 #include <stdint.h> 7 #include <stdint.h>
8 8
9 #include "src/base/logging.h" 9 #include "src/base/logging.h"
10 #include "src/base/macros.h" 10 #include "src/base/macros.h"
11 11
12 namespace v8 { 12 namespace v8 {
13 namespace base { 13 namespace base {
14 14
15 template <class T> 15 template <class T>
16 bool MagicNumbersForDivision<T>::operator==(
17 const MagicNumbersForDivision& rhs) const {
18 return multiplier == rhs.multiplier && shift == rhs.shift && add == rhs.add;
19 }
20
21
22 template <class T>
23 MagicNumbersForDivision<T> SignedDivisionByConstant(T d) { 16 MagicNumbersForDivision<T> SignedDivisionByConstant(T d) {
24 STATIC_ASSERT(static_cast<T>(0) < static_cast<T>(-1)); 17 STATIC_ASSERT(static_cast<T>(0) < static_cast<T>(-1));
25 DCHECK(d != static_cast<T>(-1) && d != 0 && d != 1); 18 DCHECK(d != static_cast<T>(-1) && d != 0 && d != 1);
26 const unsigned bits = static_cast<unsigned>(sizeof(T)) * 8; 19 const unsigned bits = static_cast<unsigned>(sizeof(T)) * 8;
27 const T min = (static_cast<T>(1) << (bits - 1)); 20 const T min = (static_cast<T>(1) << (bits - 1));
28 const bool neg = (min & d) != 0; 21 const bool neg = (min & d) != 0;
29 const T ad = neg ? (0 - d) : d; 22 const T ad = neg ? (0 - d) : d;
30 const T t = min + (d >> (bits - 1)); 23 const T t = min + (d >> (bits - 1));
31 const T anc = t - 1 - t % ad; // Absolute value of nc 24 const T anc = t - 1 - t % ad; // Absolute value of nc
32 unsigned p = bits - 1; // Init. p. 25 unsigned p = bits - 1; // Init. p.
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93 } 86 }
94 delta = d - 1 - r2; 87 delta = d - 1 - r2;
95 } while (p < bits * 2 && (q1 < delta || (q1 == delta && r1 == 0))); 88 } while (p < bits * 2 && (q1 < delta || (q1 == delta && r1 == 0)));
96 return MagicNumbersForDivision<T>(q2 + 1, p - bits, a); 89 return MagicNumbersForDivision<T>(q2 + 1, p - bits, a);
97 } 90 }
98 91
99 92
100 // ----------------------------------------------------------------------------- 93 // -----------------------------------------------------------------------------
101 // Instantiations. 94 // Instantiations.
102 95
103 template struct MagicNumbersForDivision<uint32_t>;
104 template struct MagicNumbersForDivision<uint64_t>;
105
106 template MagicNumbersForDivision<uint32_t> SignedDivisionByConstant(uint32_t d); 96 template MagicNumbersForDivision<uint32_t> SignedDivisionByConstant(uint32_t d);
107 template MagicNumbersForDivision<uint64_t> SignedDivisionByConstant(uint64_t d); 97 template MagicNumbersForDivision<uint64_t> SignedDivisionByConstant(uint64_t d);
108 98
109 template MagicNumbersForDivision<uint32_t> UnsignedDivisionByConstant( 99 template MagicNumbersForDivision<uint32_t> UnsignedDivisionByConstant(
110 uint32_t d, unsigned leading_zeros); 100 uint32_t d, unsigned leading_zeros);
111 template MagicNumbersForDivision<uint64_t> UnsignedDivisionByConstant( 101 template MagicNumbersForDivision<uint64_t> UnsignedDivisionByConstant(
112 uint64_t d, unsigned leading_zeros); 102 uint64_t d, unsigned leading_zeros);
113 103
114 } // namespace base 104 } // namespace base
115 } // namespace v8 105 } // namespace v8
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