GitOrigin-RevId: d89dba27e3
Change-Id: I0eae80578a93a580820bc90d42e6b42faf7fde0a
lts_2018_06_20
20180600
Abseil Team
7 years ago
committed by
Shaindel Schwartz
parent
e5be80532b
commit
6c7de165d1
217 changed files with 5284 additions and 175 deletions
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# Long Term Support (LTS) Branches |
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|
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This repository contains periodic snapshots of the Abseil codebase that are |
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Long Term Support (LTS) branches. An LTS branch allows you to use a known |
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version of Abseil without interfering with other projects which may also, in |
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turn, use Abseil. (For more information about our releases, see the |
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[Abseil Release Management](https://abseil.io/about/releases) guide.) |
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|
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## LTS Branches |
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The following lists LTS branches and the dates on which they have been released: |
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* [LTS Branch June 20, 2018](https://github.com/abseil/abseil-cpp/tree/lts_2018_06_20/) |
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// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
|
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// you may not use this file except in compliance with the License.
|
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// You may obtain a copy of the License at
|
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//
|
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
|
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// distributed under the License is distributed on an "AS IS" BASIS,
|
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
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// See the License for the specific language governing permissions and
|
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// limitations under the License.
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|
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#include "absl/memory/memory.h" |
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#include "gtest/gtest.h" |
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#include "absl/base/internal/exception_safety_testing.h" |
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|
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namespace absl { |
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inline namespace lts_2018_06_20 { |
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namespace { |
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using Thrower = ::testing::ThrowingValue<>; |
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TEST(MakeUnique, CheckForLeaks) { |
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constexpr int kValue = 321; |
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constexpr size_t kLength = 10; |
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auto tester = testing::MakeExceptionSafetyTester() |
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.WithInitialValue(Thrower(kValue)) |
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// Ensures make_unique does not modify the input. The real
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// test, though, is ConstructorTracker checking for leaks.
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.WithInvariants(testing::strong_guarantee); |
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EXPECT_TRUE(tester.Test([](Thrower* thrower) { |
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static_cast<void>(absl::make_unique<Thrower>(*thrower)); |
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})); |
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|
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EXPECT_TRUE(tester.Test([](Thrower* thrower) { |
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static_cast<void>(absl::make_unique<Thrower>(std::move(*thrower))); |
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})); |
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|
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// Test T[n] overload
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EXPECT_TRUE(tester.Test([&](Thrower*) { |
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static_cast<void>(absl::make_unique<Thrower[]>(kLength)); |
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})); |
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} |
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|
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} // namespace
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} // inline namespace lts_2018_06_20
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} // namespace absl
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@ -0,0 +1,984 @@ |
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// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
|
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// you may not use this file except in compliance with the License.
|
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// You may obtain a copy of the License at
|
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//
|
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
|
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// distributed under the License is distributed on an "AS IS" BASIS,
|
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
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// See the License for the specific language governing permissions and
|
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// limitations under the License.
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|
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#include "absl/strings/charconv.h" |
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#include <algorithm> |
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#include <cassert> |
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#include <cmath> |
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#include <cstring> |
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#include "absl/base/casts.h" |
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#include "absl/numeric/int128.h" |
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#include "absl/strings/internal/bits.h" |
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#include "absl/strings/internal/charconv_bigint.h" |
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#include "absl/strings/internal/charconv_parse.h" |
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|
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// The macro ABSL_BIT_PACK_FLOATS is defined on x86-64, where IEEE floating
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// point numbers have the same endianness in memory as a bitfield struct
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// containing the corresponding parts.
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//
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// When set, we replace calls to ldexp() with manual bit packing, which is
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// faster and is unaffected by floating point environment.
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#ifdef ABSL_BIT_PACK_FLOATS |
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#error ABSL_BIT_PACK_FLOATS cannot be directly set |
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#elif defined(__x86_64__) || defined(_M_X64) |
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#define ABSL_BIT_PACK_FLOATS 1 |
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#endif |
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|
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// A note about subnormals:
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//
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// The code below talks about "normals" and "subnormals". A normal IEEE float
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// has a fixed-width mantissa and power of two exponent. For example, a normal
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// `double` has a 53-bit mantissa. Because the high bit is always 1, it is not
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// stored in the representation. The implicit bit buys an extra bit of
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// resolution in the datatype.
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//
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// The downside of this scheme is that there is a large gap between DBL_MIN and
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// zero. (Large, at least, relative to the different between DBL_MIN and the
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// next representable number). This gap is softened by the "subnormal" numbers,
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// which have the same power-of-two exponent as DBL_MIN, but no implicit 53rd
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// bit. An all-bits-zero exponent in the encoding represents subnormals. (Zero
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// is represented as a subnormal with an all-bits-zero mantissa.)
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//
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// The code below, in calculations, represents the mantissa as a uint64_t. The
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// end result normally has the 53rd bit set. It represents subnormals by using
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// narrower mantissas.
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|
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namespace absl { |
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inline namespace lts_2018_06_20 { |
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namespace { |
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template <typename FloatType> |
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struct FloatTraits; |
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template <> |
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struct FloatTraits<double> { |
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// The number of mantissa bits in the given float type. This includes the
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// implied high bit.
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static constexpr int kTargetMantissaBits = 53; |
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// The largest supported IEEE exponent, in our integral mantissa
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// representation.
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//
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// If `m` is the largest possible int kTargetMantissaBits bits wide, then
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// m * 2**kMaxExponent is exactly equal to DBL_MAX.
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static constexpr int kMaxExponent = 971; |
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|
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// The smallest supported IEEE normal exponent, in our integral mantissa
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// representation.
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//
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// If `m` is the smallest possible int kTargetMantissaBits bits wide, then
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// m * 2**kMinNormalExponent is exactly equal to DBL_MIN.
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static constexpr int kMinNormalExponent = -1074; |
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static double MakeNan(const char* tagp) { |
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// Support nan no matter which namespace it's in. Some platforms
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// incorrectly don't put it in namespace std.
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using namespace std; // NOLINT
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return nan(tagp); |
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} |
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|
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// Builds a nonzero floating point number out of the provided parts.
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//
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// This is intended to do the same operation as ldexp(mantissa, exponent),
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// but using purely integer math, to avoid -ffastmath and floating
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// point environment issues. Using type punning is also faster. We fall back
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// to ldexp on a per-platform basis for portability.
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//
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// `exponent` must be between kMinNormalExponent and kMaxExponent.
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//
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// `mantissa` must either be exactly kTargetMantissaBits wide, in which case
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// a normal value is made, or it must be less narrow than that, in which case
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// `exponent` must be exactly kMinNormalExponent, and a subnormal value is
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// made.
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static double Make(uint64_t mantissa, int exponent, bool sign) { |
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#ifndef ABSL_BIT_PACK_FLOATS |
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// Support ldexp no matter which namespace it's in. Some platforms
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// incorrectly don't put it in namespace std.
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using namespace std; // NOLINT
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return sign ? -ldexp(mantissa, exponent) : ldexp(mantissa, exponent); |
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#else |
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constexpr uint64_t kMantissaMask = |
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(uint64_t(1) << (kTargetMantissaBits - 1)) - 1; |
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uint64_t dbl = static_cast<uint64_t>(sign) << 63; |
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if (mantissa > kMantissaMask) { |
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// Normal value.
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// Adjust by 1023 for the exponent representation bias, and an additional
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// 52 due to the implied decimal point in the IEEE mantissa represenation.
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dbl += uint64_t{exponent + 1023u + kTargetMantissaBits - 1} << 52; |
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mantissa &= kMantissaMask; |
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} else { |
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// subnormal value
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assert(exponent == kMinNormalExponent); |
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} |
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dbl += mantissa; |
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return absl::bit_cast<double>(dbl); |
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#endif // ABSL_BIT_PACK_FLOATS
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} |
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}; |
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|
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// Specialization of floating point traits for the `float` type. See the
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// FloatTraits<double> specialization above for meaning of each of the following
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// members and methods.
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template <> |
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struct FloatTraits<float> { |
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static constexpr int kTargetMantissaBits = 24; |
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static constexpr int kMaxExponent = 104; |
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static constexpr int kMinNormalExponent = -149; |
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static float MakeNan(const char* tagp) { |
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// Support nanf no matter which namespace it's in. Some platforms
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// incorrectly don't put it in namespace std.
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using namespace std; // NOLINT
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return nanf(tagp); |
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} |
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static float Make(uint32_t mantissa, int exponent, bool sign) { |
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#ifndef ABSL_BIT_PACK_FLOATS |
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// Support ldexpf no matter which namespace it's in. Some platforms
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// incorrectly don't put it in namespace std.
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using namespace std; // NOLINT
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return sign ? -ldexpf(mantissa, exponent) : ldexpf(mantissa, exponent); |
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#else |
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constexpr uint32_t kMantissaMask = |
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(uint32_t(1) << (kTargetMantissaBits - 1)) - 1; |
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uint32_t flt = static_cast<uint32_t>(sign) << 31; |
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if (mantissa > kMantissaMask) { |
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// Normal value.
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// Adjust by 127 for the exponent representation bias, and an additional
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// 23 due to the implied decimal point in the IEEE mantissa represenation.
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flt += uint32_t{exponent + 127u + kTargetMantissaBits - 1} << 23; |
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mantissa &= kMantissaMask; |
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} else { |
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// subnormal value
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assert(exponent == kMinNormalExponent); |
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} |
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flt += mantissa; |
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return absl::bit_cast<float>(flt); |
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#endif // ABSL_BIT_PACK_FLOATS
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} |
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}; |
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// Decimal-to-binary conversions require coercing powers of 10 into a mantissa
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// and a power of 2. The two helper functions Power10Mantissa(n) and
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// Power10Exponent(n) perform this task. Together, these represent a hand-
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// rolled floating point value which is equal to or just less than 10**n.
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//
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// The return values satisfy two range guarantees:
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//
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// Power10Mantissa(n) * 2**Power10Exponent(n) <= 10**n
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// < (Power10Mantissa(n) + 1) * 2**Power10Exponent(n)
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//
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// 2**63 <= Power10Mantissa(n) < 2**64.
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//
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// Lookups into the power-of-10 table must first check the Power10Overflow() and
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// Power10Underflow() functions, to avoid out-of-bounds table access.
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//
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// Indexes into these tables are biased by -kPower10TableMin, and the table has
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// values in the range [kPower10TableMin, kPower10TableMax].
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extern const uint64_t kPower10MantissaTable[]; |
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extern const int16_t kPower10ExponentTable[]; |
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// The smallest allowed value for use with the Power10Mantissa() and
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// Power10Exponent() functions below. (If a smaller exponent is needed in
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// calculations, the end result is guaranteed to underflow.)
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constexpr int kPower10TableMin = -342; |
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// The largest allowed value for use with the Power10Mantissa() and
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// Power10Exponent() functions below. (If a smaller exponent is needed in
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// calculations, the end result is guaranteed to overflow.)
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constexpr int kPower10TableMax = 308; |
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uint64_t Power10Mantissa(int n) { |
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return kPower10MantissaTable[n - kPower10TableMin]; |
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} |
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int Power10Exponent(int n) { |
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return kPower10ExponentTable[n - kPower10TableMin]; |
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} |
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// Returns true if n is large enough that 10**n always results in an IEEE
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// overflow.
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bool Power10Overflow(int n) { return n > kPower10TableMax; } |
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// Returns true if n is small enough that 10**n times a ParsedFloat mantissa
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// always results in an IEEE underflow.
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bool Power10Underflow(int n) { return n < kPower10TableMin; } |
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// Returns true if Power10Mantissa(n) * 2**Power10Exponent(n) is exactly equal
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// to 10**n numerically. Put another way, this returns true if there is no
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// truncation error in Power10Mantissa(n).
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bool Power10Exact(int n) { return n >= 0 && n <= 27; } |
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// Sentinel exponent values for representing numbers too large or too close to
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// zero to represent in a double.
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constexpr int kOverflow = 99999; |
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constexpr int kUnderflow = -99999; |
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// Struct representing the calculated conversion result of a positive (nonzero)
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// floating point number.
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//
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// The calculated number is mantissa * 2**exponent (mantissa is treated as an
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// integer.) `mantissa` is chosen to be the correct width for the IEEE float
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// representation being calculated. (`mantissa` will always have the same bit
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// width for normal values, and narrower bit widths for subnormals.)
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//
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// If the result of conversion was an underflow or overflow, exponent is set
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// to kUnderflow or kOverflow.
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struct CalculatedFloat { |
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uint64_t mantissa = 0; |
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int exponent = 0; |
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}; |
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// Returns the bit width of the given uint128. (Equivalently, returns 128
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// minus the number of leading zero bits.)
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int BitWidth(uint128 value) { |
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if (Uint128High64(value) == 0) { |
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return 64 - strings_internal::CountLeadingZeros64(Uint128Low64(value)); |
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} |
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return 128 - strings_internal::CountLeadingZeros64(Uint128High64(value)); |
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} |
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// Calculates how far to the right a mantissa needs to be shifted to create a
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// properly adjusted mantissa for an IEEE floating point number.
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//
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// `mantissa_width` is the bit width of the mantissa to be shifted, and
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// `binary_exponent` is the exponent of the number before the shift.
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//
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// This accounts for subnormal values, and will return a larger-than-normal
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// shift if binary_exponent would otherwise be too low.
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template <typename FloatType> |
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int NormalizedShiftSize(int mantissa_width, int binary_exponent) { |
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const int normal_shift = |
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mantissa_width - FloatTraits<FloatType>::kTargetMantissaBits; |
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const int minimum_shift = |
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FloatTraits<FloatType>::kMinNormalExponent - binary_exponent; |
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return std::max(normal_shift, minimum_shift); |
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} |
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|
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// Right shifts a uint128 so that it has the requested bit width. (The
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// resulting value will have 128 - bit_width leading zeroes.) The initial
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// `value` must be wider than the requested bit width.
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//
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// Returns the number of bits shifted.
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int TruncateToBitWidth(int bit_width, uint128* value) { |
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const int current_bit_width = BitWidth(*value); |
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const int shift = current_bit_width - bit_width; |
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*value >>= shift; |
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return shift; |
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} |
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|
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// Checks if the given ParsedFloat represents one of the edge cases that are
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// not dependent on number base: zero, infinity, or NaN. If so, sets *value
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// the appropriate double, and returns true.
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template <typename FloatType> |
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bool HandleEdgeCase(const strings_internal::ParsedFloat& input, bool negative, |
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FloatType* value) { |
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if (input.type == strings_internal::FloatType::kNan) { |
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// A bug in both clang and gcc would cause the compiler to optimize away the
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// buffer we are building below. Declaring the buffer volatile avoids the
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// issue, and has no measurable performance impact in microbenchmarks.
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//
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// https://bugs.llvm.org/show_bug.cgi?id=37778
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// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86113
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constexpr ptrdiff_t kNanBufferSize = 128; |
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volatile char n_char_sequence[kNanBufferSize]; |
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if (input.subrange_begin == nullptr) { |
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n_char_sequence[0] = '\0'; |
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} else { |
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ptrdiff_t nan_size = input.subrange_end - input.subrange_begin; |
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nan_size = std::min(nan_size, kNanBufferSize - 1); |
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std::copy_n(input.subrange_begin, nan_size, n_char_sequence); |
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n_char_sequence[nan_size] = '\0'; |
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} |
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char* nan_argument = const_cast<char*>(n_char_sequence); |
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*value = negative ? -FloatTraits<FloatType>::MakeNan(nan_argument) |
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: FloatTraits<FloatType>::MakeNan(nan_argument); |
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return true; |
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} |
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if (input.type == strings_internal::FloatType::kInfinity) { |
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*value = negative ? -std::numeric_limits<FloatType>::infinity() |
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: std::numeric_limits<FloatType>::infinity(); |
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return true; |
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} |
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if (input.mantissa == 0) { |
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*value = negative ? -0.0 : 0.0; |
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return true; |
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} |
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return false; |
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} |
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|
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// Given a CalculatedFloat result of a from_chars conversion, generate the
|
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// correct output values.
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//
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// CalculatedFloat can represent an underflow or overflow, in which case the
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// error code in *result is set. Otherwise, the calculated floating point
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// number is stored in *value.
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template <typename FloatType> |
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void EncodeResult(const CalculatedFloat& calculated, bool negative, |
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absl::from_chars_result* result, FloatType* value) { |
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if (calculated.exponent == kOverflow) { |
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result->ec = std::errc::result_out_of_range; |
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*value = negative ? -std::numeric_limits<FloatType>::max() |
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: std::numeric_limits<FloatType>::max(); |
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return; |
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} else if (calculated.mantissa == 0 || calculated.exponent == kUnderflow) { |
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result->ec = std::errc::result_out_of_range; |
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*value = negative ? -0.0 : 0.0; |
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return; |
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} |
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*value = FloatTraits<FloatType>::Make(calculated.mantissa, |
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calculated.exponent, negative); |
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} |
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|
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// Returns the given uint128 shifted to the right by `shift` bits, and rounds
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// the remaining bits using round_to_nearest logic. The value is returned as a
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// uint64_t, since this is the type used by this library for storing calculated
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// floating point mantissas.
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//
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// It is expected that the width of the input value shifted by `shift` will
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// be the correct bit-width for the target mantissa, which is strictly narrower
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// than a uint64_t.
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//
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// If `input_exact` is false, then a nonzero error epsilon is assumed. For
|
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// rounding purposes, the true value being rounded is strictly greater than the
|
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// input value. The error may represent a single lost carry bit.
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//
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// When input_exact, shifted bits of the form 1000000... represent a tie, which
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// is broken by rounding to even -- the rounding direction is chosen so the low
|
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// bit of the returned value is 0.
|
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//
|
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// When !input_exact, shifted bits of the form 10000000... represent a value
|
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// strictly greater than one half (due to the error epsilon), and so ties are
|
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// always broken by rounding up.
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//
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// When !input_exact, shifted bits of the form 01111111... are uncertain;
|
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// the true value may or may not be greater than 10000000..., due to the
|
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// possible lost carry bit. The correct rounding direction is unknown. In this
|
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// case, the result is rounded down, and `output_exact` is set to false.
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//
|
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// Zero and negative values of `shift` are accepted, in which case the word is
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// shifted left, as necessary.
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uint64_t ShiftRightAndRound(uint128 value, int shift, bool input_exact, |
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bool* output_exact) { |
||||
if (shift <= 0) { |
||||
*output_exact = input_exact; |
||||
return static_cast<uint64_t>(value << -shift); |
||||
} |
||||
if (shift >= 128) { |
||||
// Exponent is so small that we are shifting away all significant bits.
|
||||
// Answer will not be representable, even as a subnormal, so return a zero
|
||||
// mantissa (which represents underflow).
|
||||
*output_exact = true; |
||||
return 0; |
||||
} |
||||
|
||||
*output_exact = true; |
||||
const uint128 shift_mask = (uint128(1) << shift) - 1; |
||||
const uint128 halfway_point = uint128(1) << (shift - 1); |
||||
|
||||
const uint128 shifted_bits = value & shift_mask; |
||||
value >>= shift; |
||||
if (shifted_bits > halfway_point) { |
||||
// Shifted bits greater than 10000... require rounding up.
|
||||
return static_cast<uint64_t>(value + 1); |
||||
} |
||||
if (shifted_bits == halfway_point) { |
||||
// In exact mode, shifted bits of 10000... mean we're exactly halfway
|
||||
// between two numbers, and we must round to even. So only round up if
|
||||
// the low bit of `value` is set.
|
||||
//
|
||||
// In inexact mode, the nonzero error means the actual value is greater
|
||||
// than the halfway point and we must alway round up.
|
||||
if ((value & 1) == 1 || !input_exact) { |
||||
++value; |
||||
} |
||||
return static_cast<uint64_t>(value); |
||||
} |
||||
if (!input_exact && shifted_bits == halfway_point - 1) { |
||||
// Rounding direction is unclear, due to error.
|
||||
*output_exact = false; |
||||
} |
||||
// Otherwise, round down.
|
||||
return static_cast<uint64_t>(value); |
||||
} |
||||
|
||||
// Checks if a floating point guess needs to be rounded up, using high precision
|
||||
// math.
|
||||
//
|
||||
// `guess_mantissa` and `guess_exponent` represent a candidate guess for the
|
||||
// number represented by `parsed_decimal`.
|
||||
//
|
||||
// The exact number represented by `parsed_decimal` must lie between the two
|
||||
// numbers:
|
||||
// A = `guess_mantissa * 2**guess_exponent`
|
||||
// B = `(guess_mantissa + 1) * 2**guess_exponent`
|
||||
//
|
||||
// This function returns false if `A` is the better guess, and true if `B` is
|
||||
// the better guess, with rounding ties broken by rounding to even.
|
||||
bool MustRoundUp(uint64_t guess_mantissa, int guess_exponent, |
||||
const strings_internal::ParsedFloat& parsed_decimal) { |
||||
// 768 is the number of digits needed in the worst case. We could determine a
|
||||
// better limit dynamically based on the value of parsed_decimal.exponent.
|
||||
// This would optimize pathological input cases only. (Sane inputs won't have
|
||||
// hundreds of digits of mantissa.)
|
||||
absl::strings_internal::BigUnsigned<84> exact_mantissa; |
||||
int exact_exponent = exact_mantissa.ReadFloatMantissa(parsed_decimal, 768); |
||||
|
||||
// Adjust the `guess` arguments to be halfway between A and B.
|
||||
guess_mantissa = guess_mantissa * 2 + 1; |
||||
guess_exponent -= 1; |
||||
|
||||
// In our comparison:
|
||||
// lhs = exact = exact_mantissa * 10**exact_exponent
|
||||
// = exact_mantissa * 5**exact_exponent * 2**exact_exponent
|
||||
// rhs = guess = guess_mantissa * 2**guess_exponent
|
||||
//
|
||||
// Because we are doing integer math, we can't directly deal with negative
|
||||
// exponents. We instead move these to the other side of the inequality.
|
||||
absl::strings_internal::BigUnsigned<84>& lhs = exact_mantissa; |
||||
int comparison; |
||||
if (exact_exponent >= 0) { |
||||
lhs.MultiplyByFiveToTheNth(exact_exponent); |
||||
absl::strings_internal::BigUnsigned<84> rhs(guess_mantissa); |
||||
// There are powers of 2 on both sides of the inequality; reduce this to
|
||||
// a single bit-shift.
|
||||
if (exact_exponent > guess_exponent) { |
||||
lhs.ShiftLeft(exact_exponent - guess_exponent); |
||||
} else { |
||||
rhs.ShiftLeft(guess_exponent - exact_exponent); |
||||
} |
||||
comparison = Compare(lhs, rhs); |
||||
} else { |
||||
// Move the power of 5 to the other side of the equation, giving us:
|
||||
// lhs = exact_mantissa * 2**exact_exponent
|
||||
// rhs = guess_mantissa * 5**(-exact_exponent) * 2**guess_exponent
|
||||
absl::strings_internal::BigUnsigned<84> rhs = |
||||
absl::strings_internal::BigUnsigned<84>::FiveToTheNth(-exact_exponent); |
||||
rhs.MultiplyBy(guess_mantissa); |
||||
if (exact_exponent > guess_exponent) { |
||||
lhs.ShiftLeft(exact_exponent - guess_exponent); |
||||
} else { |
||||
rhs.ShiftLeft(guess_exponent - exact_exponent); |
||||
} |
||||
comparison = Compare(lhs, rhs); |
||||
} |
||||
if (comparison < 0) { |
||||
return false; |
||||
} else if (comparison > 0) { |
||||
return true; |
||||
} else { |
||||
// When lhs == rhs, the decimal input is exactly between A and B.
|
||||
// Round towards even -- round up only if the low bit of the initial
|
||||
// `guess_mantissa` was a 1. We shifted guess_mantissa left 1 bit at
|
||||
// the beginning of this function, so test the 2nd bit here.
|
||||
return (guess_mantissa & 2) == 2; |
||||
} |
||||
} |
||||
|
||||
// Constructs a CalculatedFloat from a given mantissa and exponent, but
|
||||
// with the following normalizations applied:
|
||||
//
|
||||
// If rounding has caused mantissa to increase just past the allowed bit
|
||||
// width, shift and adjust exponent.
|
||||
//
|
||||
// If exponent is too high, sets kOverflow.
|
||||
//
|
||||
// If mantissa is zero (representing a non-zero value not representable, even
|
||||
// as a subnormal), sets kUnderflow.
|
||||
template <typename FloatType> |
||||
CalculatedFloat CalculatedFloatFromRawValues(uint64_t mantissa, int exponent) { |
||||
CalculatedFloat result; |
||||
if (mantissa == uint64_t(1) << FloatTraits<FloatType>::kTargetMantissaBits) { |
||||
mantissa >>= 1; |
||||
exponent += 1; |
||||
} |
||||
if (exponent > FloatTraits<FloatType>::kMaxExponent) { |
||||
result.exponent = kOverflow; |
||||
} else if (mantissa == 0) { |
||||
result.exponent = kUnderflow; |
||||
} else { |
||||
result.exponent = exponent; |
||||
result.mantissa = mantissa; |
||||
} |
||||
return result; |
||||
} |
||||
|
||||
template <typename FloatType> |
||||
CalculatedFloat CalculateFromParsedHexadecimal( |
||||
const strings_internal::ParsedFloat& parsed_hex) { |
||||
uint64_t mantissa = parsed_hex.mantissa; |
||||
int exponent = parsed_hex.exponent; |
||||
int mantissa_width = 64 - strings_internal::CountLeadingZeros64(mantissa); |
||||
const int shift = NormalizedShiftSize<FloatType>(mantissa_width, exponent); |
||||
bool result_exact; |
||||
exponent += shift; |
||||
mantissa = ShiftRightAndRound(mantissa, shift, |
||||
/* input exact= */ true, &result_exact); |
||||
// ParseFloat handles rounding in the hexadecimal case, so we don't have to
|
||||
// check `result_exact` here.
|
||||
return CalculatedFloatFromRawValues<FloatType>(mantissa, exponent); |
||||
} |
||||
|
||||
template <typename FloatType> |
||||
CalculatedFloat CalculateFromParsedDecimal( |
||||
const strings_internal::ParsedFloat& parsed_decimal) { |
||||
CalculatedFloat result; |
||||
|
||||
// Large or small enough decimal exponents will always result in overflow
|
||||
// or underflow.
|
||||
if (Power10Underflow(parsed_decimal.exponent)) { |
||||
result.exponent = kUnderflow; |
||||
return result; |
||||
} else if (Power10Overflow(parsed_decimal.exponent)) { |
||||
result.exponent = kOverflow; |
||||
return result; |
||||
} |
||||
|
||||
// Otherwise convert our power of 10 into a power of 2 times an integer
|
||||
// mantissa, and multiply this by our parsed decimal mantissa.
|
||||
uint128 wide_binary_mantissa = parsed_decimal.mantissa; |
||||
wide_binary_mantissa *= Power10Mantissa(parsed_decimal.exponent); |
||||
int binary_exponent = Power10Exponent(parsed_decimal.exponent); |
||||
|
||||
// Discard bits that are inaccurate due to truncation error. The magic
|
||||
// `mantissa_width` constants below are justified in charconv_algorithm.md.
|
||||
// They represent the number of bits in `wide_binary_mantissa` that are
|
||||
// guaranteed to be unaffected by error propagation.
|
||||
bool mantissa_exact; |
||||
int mantissa_width; |
||||
if (parsed_decimal.subrange_begin) { |
||||
// Truncated mantissa
|
||||
mantissa_width = 58; |
||||
mantissa_exact = false; |
||||
binary_exponent += |
||||
TruncateToBitWidth(mantissa_width, &wide_binary_mantissa); |
||||
} else if (!Power10Exact(parsed_decimal.exponent)) { |
||||
// Exact mantissa, truncated power of ten
|
||||
mantissa_width = 63; |
||||
mantissa_exact = false; |
||||
binary_exponent += |
||||
TruncateToBitWidth(mantissa_width, &wide_binary_mantissa); |
||||
} else { |
||||
// Product is exact
|
||||
mantissa_width = BitWidth(wide_binary_mantissa); |
||||
mantissa_exact = true; |
||||
} |
||||
|
||||
// Shift into an FloatType-sized mantissa, and round to nearest.
|
||||
const int shift = |
||||
NormalizedShiftSize<FloatType>(mantissa_width, binary_exponent); |
||||
bool result_exact; |
||||
binary_exponent += shift; |
||||
uint64_t binary_mantissa = ShiftRightAndRound(wide_binary_mantissa, shift, |
||||
mantissa_exact, &result_exact); |
||||
if (!result_exact) { |
||||
// We could not determine the rounding direction using int128 math. Use
|
||||
// full resolution math instead.
|
||||
if (MustRoundUp(binary_mantissa, binary_exponent, parsed_decimal)) { |
||||
binary_mantissa += 1; |
||||
} |
||||
} |
||||
|
||||
return CalculatedFloatFromRawValues<FloatType>(binary_mantissa, |
||||
binary_exponent); |
||||
} |
||||
|
||||
template <typename FloatType> |
||||
from_chars_result FromCharsImpl(const char* first, const char* last, |
||||
FloatType& value, chars_format fmt_flags) { |
||||
from_chars_result result; |
||||
result.ptr = first; // overwritten on successful parse
|
||||
result.ec = std::errc(); |
||||
|
||||
bool negative = false; |
||||
if (first != last && *first == '-') { |
||||
++first; |
||||
negative = true; |
||||
} |
||||
// If the `hex` flag is *not* set, then we will accept a 0x prefix and try
|
||||
// to parse a hexadecimal float.
|
||||
if ((fmt_flags & chars_format::hex) == chars_format{} && last - first >= 2 && |
||||
*first == '0' && (first[1] == 'x' || first[1] == 'X')) { |
||||
const char* hex_first = first + 2; |
||||
strings_internal::ParsedFloat hex_parse = |
||||
strings_internal::ParseFloat<16>(hex_first, last, fmt_flags); |
||||
if (hex_parse.end == nullptr || |
||||
hex_parse.type != strings_internal::FloatType::kNumber) { |
||||
// Either we failed to parse a hex float after the "0x", or we read
|
||||
// "0xinf" or "0xnan" which we don't want to match.
|
||||
//
|
||||
// However, a std::string that begins with "0x" also begins with "0", which
|
||||
// is normally a valid match for the number zero. So we want these
|
||||
// strings to match zero unless fmt_flags is `scientific`. (This flag
|
||||
// means an exponent is required, which the std::string "0" does not have.)
|
||||
if (fmt_flags == chars_format::scientific) { |
||||
result.ec = std::errc::invalid_argument; |
||||
} else { |
||||
result.ptr = first + 1; |
||||
value = negative ? -0.0 : 0.0; |
||||
} |
||||
return result; |
||||
} |
||||
// We matched a value.
|
||||
result.ptr = hex_parse.end; |
||||
if (HandleEdgeCase(hex_parse, negative, &value)) { |
||||
return result; |
||||
} |
||||
CalculatedFloat calculated = |
||||
CalculateFromParsedHexadecimal<FloatType>(hex_parse); |
||||
EncodeResult(calculated, negative, &result, &value); |
||||
return result; |
||||
} |
||||
// Otherwise, we choose the number base based on the flags.
|
||||
if ((fmt_flags & chars_format::hex) == chars_format::hex) { |
||||
strings_internal::ParsedFloat hex_parse = |
||||
strings_internal::ParseFloat<16>(first, last, fmt_flags); |
||||
if (hex_parse.end == nullptr) { |
||||
result.ec = std::errc::invalid_argument; |
||||
return result; |
||||
} |
||||
result.ptr = hex_parse.end; |
||||
if (HandleEdgeCase(hex_parse, negative, &value)) { |
||||
return result; |
||||
} |
||||
CalculatedFloat calculated = |
||||
CalculateFromParsedHexadecimal<FloatType>(hex_parse); |
||||
EncodeResult(calculated, negative, &result, &value); |
||||
return result; |
||||
} else { |
||||
strings_internal::ParsedFloat decimal_parse = |
||||
strings_internal::ParseFloat<10>(first, last, fmt_flags); |
||||
if (decimal_parse.end == nullptr) { |
||||
result.ec = std::errc::invalid_argument; |
||||
return result; |
||||
} |
||||
result.ptr = decimal_parse.end; |
||||
if (HandleEdgeCase(decimal_parse, negative, &value)) { |
||||
return result; |
||||
} |
||||
CalculatedFloat calculated = |
||||
CalculateFromParsedDecimal<FloatType>(decimal_parse); |
||||
EncodeResult(calculated, negative, &result, &value); |
||||
return result; |
||||
} |
||||
return result; |
||||
} |
||||
} // namespace
|
||||
|
||||
from_chars_result from_chars(const char* first, const char* last, double& value, |
||||
chars_format fmt) { |
||||
return FromCharsImpl(first, last, value, fmt); |
||||
} |
||||
|
||||
from_chars_result from_chars(const char* first, const char* last, float& value, |
||||
chars_format fmt) { |
||||
return FromCharsImpl(first, last, value, fmt); |
||||
} |
||||
|
||||
namespace { |
||||
|
||||
// Table of powers of 10, from kPower10TableMin to kPower10TableMax.
|
||||
//
|
||||
// kPower10MantissaTable[i - kPower10TableMin] stores the 64-bit mantissa (high
|
||||
// bit always on), and kPower10ExponentTable[i - kPower10TableMin] stores the
|
||||
// power-of-two exponent. For a given number i, this gives the unique mantissa
|
||||
// and exponent such that mantissa * 2**exponent <= 10**i < (mantissa + 1) *
|
||||
// 2**exponent.
|
||||
|
||||
const uint64_t kPower10MantissaTable[] = { |
||||
0xeef453d6923bd65aU, 0x9558b4661b6565f8U, 0xbaaee17fa23ebf76U, |
||||
0xe95a99df8ace6f53U, 0x91d8a02bb6c10594U, 0xb64ec836a47146f9U, |
||||
0xe3e27a444d8d98b7U, 0x8e6d8c6ab0787f72U, 0xb208ef855c969f4fU, |
||||
0xde8b2b66b3bc4723U, 0x8b16fb203055ac76U, 0xaddcb9e83c6b1793U, |
||||
0xd953e8624b85dd78U, 0x87d4713d6f33aa6bU, 0xa9c98d8ccb009506U, |
||||
0xd43bf0effdc0ba48U, 0x84a57695fe98746dU, 0xa5ced43b7e3e9188U, |
||||
0xcf42894a5dce35eaU, 0x818995ce7aa0e1b2U, 0xa1ebfb4219491a1fU, |
||||
0xca66fa129f9b60a6U, 0xfd00b897478238d0U, 0x9e20735e8cb16382U, |
||||
0xc5a890362fddbc62U, 0xf712b443bbd52b7bU, 0x9a6bb0aa55653b2dU, |
||||
0xc1069cd4eabe89f8U, 0xf148440a256e2c76U, 0x96cd2a865764dbcaU, |
||||
0xbc807527ed3e12bcU, 0xeba09271e88d976bU, 0x93445b8731587ea3U, |
||||
0xb8157268fdae9e4cU, 0xe61acf033d1a45dfU, 0x8fd0c16206306babU, |
||||
0xb3c4f1ba87bc8696U, 0xe0b62e2929aba83cU, 0x8c71dcd9ba0b4925U, |
||||
0xaf8e5410288e1b6fU, 0xdb71e91432b1a24aU, 0x892731ac9faf056eU, |
||||
0xab70fe17c79ac6caU, 0xd64d3d9db981787dU, 0x85f0468293f0eb4eU, |
||||
0xa76c582338ed2621U, 0xd1476e2c07286faaU, 0x82cca4db847945caU, |
||||
0xa37fce126597973cU, 0xcc5fc196fefd7d0cU, 0xff77b1fcbebcdc4fU, |
||||
0x9faacf3df73609b1U, 0xc795830d75038c1dU, 0xf97ae3d0d2446f25U, |
||||
0x9becce62836ac577U, 0xc2e801fb244576d5U, 0xf3a20279ed56d48aU, |
||||
0x9845418c345644d6U, 0xbe5691ef416bd60cU, 0xedec366b11c6cb8fU, |
||||
0x94b3a202eb1c3f39U, 0xb9e08a83a5e34f07U, 0xe858ad248f5c22c9U, |
||||
0x91376c36d99995beU, 0xb58547448ffffb2dU, 0xe2e69915b3fff9f9U, |
||||
0x8dd01fad907ffc3bU, 0xb1442798f49ffb4aU, 0xdd95317f31c7fa1dU, |
||||
0x8a7d3eef7f1cfc52U, 0xad1c8eab5ee43b66U, 0xd863b256369d4a40U, |
||||
0x873e4f75e2224e68U, 0xa90de3535aaae202U, 0xd3515c2831559a83U, |
||||
0x8412d9991ed58091U, 0xa5178fff668ae0b6U, 0xce5d73ff402d98e3U, |
||||
0x80fa687f881c7f8eU, 0xa139029f6a239f72U, 0xc987434744ac874eU, |
||||
0xfbe9141915d7a922U, 0x9d71ac8fada6c9b5U, 0xc4ce17b399107c22U, |
||||
0xf6019da07f549b2bU, 0x99c102844f94e0fbU, 0xc0314325637a1939U, |
||||
0xf03d93eebc589f88U, 0x96267c7535b763b5U, 0xbbb01b9283253ca2U, |
||||
0xea9c227723ee8bcbU, 0x92a1958a7675175fU, 0xb749faed14125d36U, |
||||
0xe51c79a85916f484U, 0x8f31cc0937ae58d2U, 0xb2fe3f0b8599ef07U, |
||||
0xdfbdcece67006ac9U, 0x8bd6a141006042bdU, 0xaecc49914078536dU, |
||||
0xda7f5bf590966848U, 0x888f99797a5e012dU, 0xaab37fd7d8f58178U, |
||||
0xd5605fcdcf32e1d6U, 0x855c3be0a17fcd26U, 0xa6b34ad8c9dfc06fU, |
||||
0xd0601d8efc57b08bU, 0x823c12795db6ce57U, 0xa2cb1717b52481edU, |
||||
0xcb7ddcdda26da268U, 0xfe5d54150b090b02U, 0x9efa548d26e5a6e1U, |
||||
0xc6b8e9b0709f109aU, 0xf867241c8cc6d4c0U, 0x9b407691d7fc44f8U, |
||||
0xc21094364dfb5636U, 0xf294b943e17a2bc4U, 0x979cf3ca6cec5b5aU, |
||||
0xbd8430bd08277231U, 0xece53cec4a314ebdU, 0x940f4613ae5ed136U, |
||||
0xb913179899f68584U, 0xe757dd7ec07426e5U, 0x9096ea6f3848984fU, |
||||
0xb4bca50b065abe63U, 0xe1ebce4dc7f16dfbU, 0x8d3360f09cf6e4bdU, |
||||
0xb080392cc4349decU, 0xdca04777f541c567U, 0x89e42caaf9491b60U, |
||||
0xac5d37d5b79b6239U, 0xd77485cb25823ac7U, 0x86a8d39ef77164bcU, |
||||
0xa8530886b54dbdebU, 0xd267caa862a12d66U, 0x8380dea93da4bc60U, |
||||
0xa46116538d0deb78U, 0xcd795be870516656U, 0x806bd9714632dff6U, |
||||
0xa086cfcd97bf97f3U, 0xc8a883c0fdaf7df0U, 0xfad2a4b13d1b5d6cU, |
||||
0x9cc3a6eec6311a63U, 0xc3f490aa77bd60fcU, 0xf4f1b4d515acb93bU, |
||||
0x991711052d8bf3c5U, 0xbf5cd54678eef0b6U, 0xef340a98172aace4U, |
||||
0x9580869f0e7aac0eU, 0xbae0a846d2195712U, 0xe998d258869facd7U, |
||||
0x91ff83775423cc06U, 0xb67f6455292cbf08U, 0xe41f3d6a7377eecaU, |
||||
0x8e938662882af53eU, 0xb23867fb2a35b28dU, 0xdec681f9f4c31f31U, |
||||
0x8b3c113c38f9f37eU, 0xae0b158b4738705eU, 0xd98ddaee19068c76U, |
||||
0x87f8a8d4cfa417c9U, 0xa9f6d30a038d1dbcU, 0xd47487cc8470652bU, |
||||
0x84c8d4dfd2c63f3bU, 0xa5fb0a17c777cf09U, 0xcf79cc9db955c2ccU, |
||||
0x81ac1fe293d599bfU, 0xa21727db38cb002fU, 0xca9cf1d206fdc03bU, |
||||
0xfd442e4688bd304aU, 0x9e4a9cec15763e2eU, 0xc5dd44271ad3cdbaU, |
||||
0xf7549530e188c128U, 0x9a94dd3e8cf578b9U, 0xc13a148e3032d6e7U, |
||||
0xf18899b1bc3f8ca1U, 0x96f5600f15a7b7e5U, 0xbcb2b812db11a5deU, |
||||
0xebdf661791d60f56U, 0x936b9fcebb25c995U, 0xb84687c269ef3bfbU, |
||||
0xe65829b3046b0afaU, 0x8ff71a0fe2c2e6dcU, 0xb3f4e093db73a093U, |
||||
0xe0f218b8d25088b8U, 0x8c974f7383725573U, 0xafbd2350644eeacfU, |
||||
0xdbac6c247d62a583U, 0x894bc396ce5da772U, 0xab9eb47c81f5114fU, |
||||
0xd686619ba27255a2U, 0x8613fd0145877585U, 0xa798fc4196e952e7U, |
||||
0xd17f3b51fca3a7a0U, 0x82ef85133de648c4U, 0xa3ab66580d5fdaf5U, |
||||
0xcc963fee10b7d1b3U, 0xffbbcfe994e5c61fU, 0x9fd561f1fd0f9bd3U, |
||||
0xc7caba6e7c5382c8U, 0xf9bd690a1b68637bU, 0x9c1661a651213e2dU, |
||||
0xc31bfa0fe5698db8U, 0xf3e2f893dec3f126U, 0x986ddb5c6b3a76b7U, |
||||
0xbe89523386091465U, 0xee2ba6c0678b597fU, 0x94db483840b717efU, |
||||
0xba121a4650e4ddebU, 0xe896a0d7e51e1566U, 0x915e2486ef32cd60U, |
||||
0xb5b5ada8aaff80b8U, 0xe3231912d5bf60e6U, 0x8df5efabc5979c8fU, |
||||
0xb1736b96b6fd83b3U, 0xddd0467c64bce4a0U, 0x8aa22c0dbef60ee4U, |
||||
0xad4ab7112eb3929dU, 0xd89d64d57a607744U, 0x87625f056c7c4a8bU, |
||||
0xa93af6c6c79b5d2dU, 0xd389b47879823479U, 0x843610cb4bf160cbU, |
||||
0xa54394fe1eedb8feU, 0xce947a3da6a9273eU, 0x811ccc668829b887U, |
||||
0xa163ff802a3426a8U, 0xc9bcff6034c13052U, 0xfc2c3f3841f17c67U, |
||||
0x9d9ba7832936edc0U, 0xc5029163f384a931U, 0xf64335bcf065d37dU, |
||||
0x99ea0196163fa42eU, 0xc06481fb9bcf8d39U, 0xf07da27a82c37088U, |
||||
0x964e858c91ba2655U, 0xbbe226efb628afeaU, 0xeadab0aba3b2dbe5U, |
||||
0x92c8ae6b464fc96fU, 0xb77ada0617e3bbcbU, 0xe55990879ddcaabdU, |
||||
0x8f57fa54c2a9eab6U, 0xb32df8e9f3546564U, 0xdff9772470297ebdU, |
||||
0x8bfbea76c619ef36U, 0xaefae51477a06b03U, 0xdab99e59958885c4U, |
||||
0x88b402f7fd75539bU, 0xaae103b5fcd2a881U, 0xd59944a37c0752a2U, |
||||
0x857fcae62d8493a5U, 0xa6dfbd9fb8e5b88eU, 0xd097ad07a71f26b2U, |
||||
0x825ecc24c873782fU, 0xa2f67f2dfa90563bU, 0xcbb41ef979346bcaU, |
||||
0xfea126b7d78186bcU, 0x9f24b832e6b0f436U, 0xc6ede63fa05d3143U, |
||||
0xf8a95fcf88747d94U, 0x9b69dbe1b548ce7cU, 0xc24452da229b021bU, |
||||
0xf2d56790ab41c2a2U, 0x97c560ba6b0919a5U, 0xbdb6b8e905cb600fU, |
||||
0xed246723473e3813U, 0x9436c0760c86e30bU, 0xb94470938fa89bceU, |
||||
0xe7958cb87392c2c2U, 0x90bd77f3483bb9b9U, 0xb4ecd5f01a4aa828U, |
||||
0xe2280b6c20dd5232U, 0x8d590723948a535fU, 0xb0af48ec79ace837U, |
||||
0xdcdb1b2798182244U, 0x8a08f0f8bf0f156bU, 0xac8b2d36eed2dac5U, |
||||
0xd7adf884aa879177U, 0x86ccbb52ea94baeaU, 0xa87fea27a539e9a5U, |
||||
0xd29fe4b18e88640eU, 0x83a3eeeef9153e89U, 0xa48ceaaab75a8e2bU, |
||||
0xcdb02555653131b6U, 0x808e17555f3ebf11U, 0xa0b19d2ab70e6ed6U, |
||||
0xc8de047564d20a8bU, 0xfb158592be068d2eU, 0x9ced737bb6c4183dU, |
||||
0xc428d05aa4751e4cU, 0xf53304714d9265dfU, 0x993fe2c6d07b7fabU, |
||||
0xbf8fdb78849a5f96U, 0xef73d256a5c0f77cU, 0x95a8637627989aadU, |
||||
0xbb127c53b17ec159U, 0xe9d71b689dde71afU, 0x9226712162ab070dU, |
||||
0xb6b00d69bb55c8d1U, 0xe45c10c42a2b3b05U, 0x8eb98a7a9a5b04e3U, |
||||
0xb267ed1940f1c61cU, 0xdf01e85f912e37a3U, 0x8b61313bbabce2c6U, |
||||
0xae397d8aa96c1b77U, 0xd9c7dced53c72255U, 0x881cea14545c7575U, |
||||
0xaa242499697392d2U, 0xd4ad2dbfc3d07787U, 0x84ec3c97da624ab4U, |
||||
0xa6274bbdd0fadd61U, 0xcfb11ead453994baU, 0x81ceb32c4b43fcf4U, |
||||
0xa2425ff75e14fc31U, 0xcad2f7f5359a3b3eU, 0xfd87b5f28300ca0dU, |
||||
0x9e74d1b791e07e48U, 0xc612062576589ddaU, 0xf79687aed3eec551U, |
||||
0x9abe14cd44753b52U, 0xc16d9a0095928a27U, 0xf1c90080baf72cb1U, |
||||
0x971da05074da7beeU, 0xbce5086492111aeaU, 0xec1e4a7db69561a5U, |
||||
0x9392ee8e921d5d07U, 0xb877aa3236a4b449U, 0xe69594bec44de15bU, |
||||
0x901d7cf73ab0acd9U, 0xb424dc35095cd80fU, 0xe12e13424bb40e13U, |
||||
0x8cbccc096f5088cbU, 0xafebff0bcb24aafeU, 0xdbe6fecebdedd5beU, |
||||
0x89705f4136b4a597U, 0xabcc77118461cefcU, 0xd6bf94d5e57a42bcU, |
||||
0x8637bd05af6c69b5U, 0xa7c5ac471b478423U, 0xd1b71758e219652bU, |
||||
0x83126e978d4fdf3bU, 0xa3d70a3d70a3d70aU, 0xccccccccccccccccU, |
||||
0x8000000000000000U, 0xa000000000000000U, 0xc800000000000000U, |
||||
0xfa00000000000000U, 0x9c40000000000000U, 0xc350000000000000U, |
||||
0xf424000000000000U, 0x9896800000000000U, 0xbebc200000000000U, |
||||
0xee6b280000000000U, 0x9502f90000000000U, 0xba43b74000000000U, |
||||
0xe8d4a51000000000U, 0x9184e72a00000000U, 0xb5e620f480000000U, |
||||
0xe35fa931a0000000U, 0x8e1bc9bf04000000U, 0xb1a2bc2ec5000000U, |
||||
0xde0b6b3a76400000U, 0x8ac7230489e80000U, 0xad78ebc5ac620000U, |
||||
0xd8d726b7177a8000U, 0x878678326eac9000U, 0xa968163f0a57b400U, |
||||
0xd3c21bcecceda100U, 0x84595161401484a0U, 0xa56fa5b99019a5c8U, |
||||
0xcecb8f27f4200f3aU, 0x813f3978f8940984U, 0xa18f07d736b90be5U, |
||||
0xc9f2c9cd04674edeU, 0xfc6f7c4045812296U, 0x9dc5ada82b70b59dU, |
||||
0xc5371912364ce305U, 0xf684df56c3e01bc6U, 0x9a130b963a6c115cU, |
||||
0xc097ce7bc90715b3U, 0xf0bdc21abb48db20U, 0x96769950b50d88f4U, |
||||
0xbc143fa4e250eb31U, 0xeb194f8e1ae525fdU, 0x92efd1b8d0cf37beU, |
||||
0xb7abc627050305adU, 0xe596b7b0c643c719U, 0x8f7e32ce7bea5c6fU, |
||||
0xb35dbf821ae4f38bU, 0xe0352f62a19e306eU, 0x8c213d9da502de45U, |
||||
0xaf298d050e4395d6U, 0xdaf3f04651d47b4cU, 0x88d8762bf324cd0fU, |
||||
0xab0e93b6efee0053U, 0xd5d238a4abe98068U, 0x85a36366eb71f041U, |
||||
0xa70c3c40a64e6c51U, 0xd0cf4b50cfe20765U, 0x82818f1281ed449fU, |
||||
0xa321f2d7226895c7U, 0xcbea6f8ceb02bb39U, 0xfee50b7025c36a08U, |
||||
0x9f4f2726179a2245U, 0xc722f0ef9d80aad6U, 0xf8ebad2b84e0d58bU, |
||||
0x9b934c3b330c8577U, 0xc2781f49ffcfa6d5U, 0xf316271c7fc3908aU, |
||||
0x97edd871cfda3a56U, 0xbde94e8e43d0c8ecU, 0xed63a231d4c4fb27U, |
||||
0x945e455f24fb1cf8U, 0xb975d6b6ee39e436U, 0xe7d34c64a9c85d44U, |
||||
0x90e40fbeea1d3a4aU, 0xb51d13aea4a488ddU, 0xe264589a4dcdab14U, |
||||
0x8d7eb76070a08aecU, 0xb0de65388cc8ada8U, 0xdd15fe86affad912U, |
||||
0x8a2dbf142dfcc7abU, 0xacb92ed9397bf996U, 0xd7e77a8f87daf7fbU, |
||||
0x86f0ac99b4e8dafdU, 0xa8acd7c0222311bcU, 0xd2d80db02aabd62bU, |
||||
0x83c7088e1aab65dbU, 0xa4b8cab1a1563f52U, 0xcde6fd5e09abcf26U, |
||||
0x80b05e5ac60b6178U, 0xa0dc75f1778e39d6U, 0xc913936dd571c84cU, |
||||
0xfb5878494ace3a5fU, 0x9d174b2dcec0e47bU, 0xc45d1df942711d9aU, |
||||
0xf5746577930d6500U, 0x9968bf6abbe85f20U, 0xbfc2ef456ae276e8U, |
||||
0xefb3ab16c59b14a2U, 0x95d04aee3b80ece5U, 0xbb445da9ca61281fU, |
||||
0xea1575143cf97226U, 0x924d692ca61be758U, 0xb6e0c377cfa2e12eU, |
||||
0xe498f455c38b997aU, 0x8edf98b59a373fecU, 0xb2977ee300c50fe7U, |
||||
0xdf3d5e9bc0f653e1U, 0x8b865b215899f46cU, 0xae67f1e9aec07187U, |
||||
0xda01ee641a708de9U, 0x884134fe908658b2U, 0xaa51823e34a7eedeU, |
||||
0xd4e5e2cdc1d1ea96U, 0x850fadc09923329eU, 0xa6539930bf6bff45U, |
||||
0xcfe87f7cef46ff16U, 0x81f14fae158c5f6eU, 0xa26da3999aef7749U, |
||||
0xcb090c8001ab551cU, 0xfdcb4fa002162a63U, 0x9e9f11c4014dda7eU, |
||||
0xc646d63501a1511dU, 0xf7d88bc24209a565U, 0x9ae757596946075fU, |
||||
0xc1a12d2fc3978937U, 0xf209787bb47d6b84U, 0x9745eb4d50ce6332U, |
||||
0xbd176620a501fbffU, 0xec5d3fa8ce427affU, 0x93ba47c980e98cdfU, |
||||
0xb8a8d9bbe123f017U, 0xe6d3102ad96cec1dU, 0x9043ea1ac7e41392U, |
||||
0xb454e4a179dd1877U, 0xe16a1dc9d8545e94U, 0x8ce2529e2734bb1dU, |
||||
0xb01ae745b101e9e4U, 0xdc21a1171d42645dU, 0x899504ae72497ebaU, |
||||
0xabfa45da0edbde69U, 0xd6f8d7509292d603U, 0x865b86925b9bc5c2U, |
||||
0xa7f26836f282b732U, 0xd1ef0244af2364ffU, 0x8335616aed761f1fU, |
||||
0xa402b9c5a8d3a6e7U, 0xcd036837130890a1U, 0x802221226be55a64U, |
||||
0xa02aa96b06deb0fdU, 0xc83553c5c8965d3dU, 0xfa42a8b73abbf48cU, |
||||
0x9c69a97284b578d7U, 0xc38413cf25e2d70dU, 0xf46518c2ef5b8cd1U, |
||||
0x98bf2f79d5993802U, 0xbeeefb584aff8603U, 0xeeaaba2e5dbf6784U, |
||||
0x952ab45cfa97a0b2U, 0xba756174393d88dfU, 0xe912b9d1478ceb17U, |
||||
0x91abb422ccb812eeU, 0xb616a12b7fe617aaU, 0xe39c49765fdf9d94U, |
||||
0x8e41ade9fbebc27dU, 0xb1d219647ae6b31cU, 0xde469fbd99a05fe3U, |
||||
0x8aec23d680043beeU, 0xada72ccc20054ae9U, 0xd910f7ff28069da4U, |
||||
0x87aa9aff79042286U, 0xa99541bf57452b28U, 0xd3fa922f2d1675f2U, |
||||
0x847c9b5d7c2e09b7U, 0xa59bc234db398c25U, 0xcf02b2c21207ef2eU, |
||||
0x8161afb94b44f57dU, 0xa1ba1ba79e1632dcU, 0xca28a291859bbf93U, |
||||
0xfcb2cb35e702af78U, 0x9defbf01b061adabU, 0xc56baec21c7a1916U, |
||||
0xf6c69a72a3989f5bU, 0x9a3c2087a63f6399U, 0xc0cb28a98fcf3c7fU, |
||||
0xf0fdf2d3f3c30b9fU, 0x969eb7c47859e743U, 0xbc4665b596706114U, |
||||
0xeb57ff22fc0c7959U, 0x9316ff75dd87cbd8U, 0xb7dcbf5354e9beceU, |
||||
0xe5d3ef282a242e81U, 0x8fa475791a569d10U, 0xb38d92d760ec4455U, |
||||
0xe070f78d3927556aU, 0x8c469ab843b89562U, 0xaf58416654a6babbU, |
||||
0xdb2e51bfe9d0696aU, 0x88fcf317f22241e2U, 0xab3c2fddeeaad25aU, |
||||
0xd60b3bd56a5586f1U, 0x85c7056562757456U, 0xa738c6bebb12d16cU, |
||||
0xd106f86e69d785c7U, 0x82a45b450226b39cU, 0xa34d721642b06084U, |
||||
0xcc20ce9bd35c78a5U, 0xff290242c83396ceU, 0x9f79a169bd203e41U, |
||||
0xc75809c42c684dd1U, 0xf92e0c3537826145U, 0x9bbcc7a142b17ccbU, |
||||
0xc2abf989935ddbfeU, 0xf356f7ebf83552feU, 0x98165af37b2153deU, |
||||
0xbe1bf1b059e9a8d6U, 0xeda2ee1c7064130cU, 0x9485d4d1c63e8be7U, |
||||
0xb9a74a0637ce2ee1U, 0xe8111c87c5c1ba99U, 0x910ab1d4db9914a0U, |
||||
0xb54d5e4a127f59c8U, 0xe2a0b5dc971f303aU, 0x8da471a9de737e24U, |
||||
0xb10d8e1456105dadU, 0xdd50f1996b947518U, 0x8a5296ffe33cc92fU, |
||||
0xace73cbfdc0bfb7bU, 0xd8210befd30efa5aU, 0x8714a775e3e95c78U, |
||||
0xa8d9d1535ce3b396U, 0xd31045a8341ca07cU, 0x83ea2b892091e44dU, |
||||
0xa4e4b66b68b65d60U, 0xce1de40642e3f4b9U, 0x80d2ae83e9ce78f3U, |
||||
0xa1075a24e4421730U, 0xc94930ae1d529cfcU, 0xfb9b7cd9a4a7443cU, |
||||
0x9d412e0806e88aa5U, 0xc491798a08a2ad4eU, 0xf5b5d7ec8acb58a2U, |
||||
0x9991a6f3d6bf1765U, 0xbff610b0cc6edd3fU, 0xeff394dcff8a948eU, |
||||
0x95f83d0a1fb69cd9U, 0xbb764c4ca7a4440fU, 0xea53df5fd18d5513U, |
||||
0x92746b9be2f8552cU, 0xb7118682dbb66a77U, 0xe4d5e82392a40515U, |
||||
0x8f05b1163ba6832dU, 0xb2c71d5bca9023f8U, 0xdf78e4b2bd342cf6U, |
||||
0x8bab8eefb6409c1aU, 0xae9672aba3d0c320U, 0xda3c0f568cc4f3e8U, |
||||
0x8865899617fb1871U, 0xaa7eebfb9df9de8dU, 0xd51ea6fa85785631U, |
||||
0x8533285c936b35deU, 0xa67ff273b8460356U, 0xd01fef10a657842cU, |
||||
0x8213f56a67f6b29bU, 0xa298f2c501f45f42U, 0xcb3f2f7642717713U, |
||||
0xfe0efb53d30dd4d7U, 0x9ec95d1463e8a506U, 0xc67bb4597ce2ce48U, |
||||
0xf81aa16fdc1b81daU, 0x9b10a4e5e9913128U, 0xc1d4ce1f63f57d72U, |
||||
0xf24a01a73cf2dccfU, 0x976e41088617ca01U, 0xbd49d14aa79dbc82U, |
||||
0xec9c459d51852ba2U, 0x93e1ab8252f33b45U, 0xb8da1662e7b00a17U, |
||||
0xe7109bfba19c0c9dU, 0x906a617d450187e2U, 0xb484f9dc9641e9daU, |
||||
0xe1a63853bbd26451U, 0x8d07e33455637eb2U, 0xb049dc016abc5e5fU, |
||||
0xdc5c5301c56b75f7U, 0x89b9b3e11b6329baU, 0xac2820d9623bf429U, |
||||
0xd732290fbacaf133U, 0x867f59a9d4bed6c0U, 0xa81f301449ee8c70U, |
||||
0xd226fc195c6a2f8cU, 0x83585d8fd9c25db7U, 0xa42e74f3d032f525U, |
||||
0xcd3a1230c43fb26fU, 0x80444b5e7aa7cf85U, 0xa0555e361951c366U, |
||||
0xc86ab5c39fa63440U, 0xfa856334878fc150U, 0x9c935e00d4b9d8d2U, |
||||
0xc3b8358109e84f07U, 0xf4a642e14c6262c8U, 0x98e7e9cccfbd7dbdU, |
||||
0xbf21e44003acdd2cU, 0xeeea5d5004981478U, 0x95527a5202df0ccbU, |
||||
0xbaa718e68396cffdU, 0xe950df20247c83fdU, 0x91d28b7416cdd27eU, |
||||
0xb6472e511c81471dU, 0xe3d8f9e563a198e5U, 0x8e679c2f5e44ff8fU, |
||||
}; |
||||
|
||||
const int16_t kPower10ExponentTable[] = { |
||||
-1200, -1196, -1193, -1190, -1186, -1183, -1180, -1176, -1173, -1170, -1166, |
||||
-1163, -1160, -1156, -1153, -1150, -1146, -1143, -1140, -1136, -1133, -1130, |
||||
-1127, -1123, -1120, -1117, -1113, -1110, -1107, -1103, -1100, -1097, -1093, |
||||
-1090, -1087, -1083, -1080, -1077, -1073, -1070, -1067, -1063, -1060, -1057, |
||||
-1053, -1050, -1047, -1043, -1040, -1037, -1034, -1030, -1027, -1024, -1020, |
||||
-1017, -1014, -1010, -1007, -1004, -1000, -997, -994, -990, -987, -984, |
||||
-980, -977, -974, -970, -967, -964, -960, -957, -954, -950, -947, |
||||
-944, -940, -937, -934, -931, -927, -924, -921, -917, -914, -911, |
||||
-907, -904, -901, -897, -894, -891, -887, -884, -881, -877, -874, |
||||
-871, -867, -864, -861, -857, -854, -851, -847, -844, -841, -838, |
||||
-834, -831, -828, -824, -821, -818, -814, -811, -808, -804, -801, |
||||
-798, -794, -791, -788, -784, -781, -778, -774, -771, -768, -764, |
||||
-761, -758, -754, -751, -748, -744, -741, -738, -735, -731, -728, |
||||
-725, -721, -718, -715, -711, -708, -705, -701, -698, -695, -691, |
||||
-688, -685, -681, -678, -675, -671, -668, -665, -661, -658, -655, |
||||
-651, -648, -645, -642, -638, -635, -632, -628, -625, -622, -618, |
||||
-615, -612, -608, -605, -602, -598, -595, -592, -588, -585, -582, |
||||
-578, -575, -572, -568, -565, -562, -558, -555, -552, -549, -545, |
||||
-542, -539, -535, -532, -529, -525, -522, -519, -515, -512, -509, |
||||
-505, -502, -499, -495, -492, -489, -485, -482, -479, -475, -472, |
||||
-469, -465, -462, -459, -455, -452, -449, -446, -442, -439, -436, |
||||
-432, -429, -426, -422, -419, -416, -412, -409, -406, -402, -399, |
||||
-396, -392, -389, -386, -382, -379, -376, -372, -369, -366, -362, |
||||
-359, -356, -353, -349, -346, -343, -339, -336, -333, -329, -326, |
||||
-323, -319, -316, -313, -309, -306, -303, -299, -296, -293, -289, |
||||
-286, -283, -279, -276, -273, -269, -266, -263, -259, -256, -253, |
||||
-250, -246, -243, -240, -236, -233, -230, -226, -223, -220, -216, |
||||
-213, -210, -206, -203, -200, -196, -193, -190, -186, -183, -180, |
||||
-176, -173, -170, -166, -163, -160, -157, -153, -150, -147, -143, |
||||
-140, -137, -133, -130, -127, -123, -120, -117, -113, -110, -107, |
||||
-103, -100, -97, -93, -90, -87, -83, -80, -77, -73, -70, |
||||
-67, -63, -60, -57, -54, -50, -47, -44, -40, -37, -34, |
||||
-30, -27, -24, -20, -17, -14, -10, -7, -4, 0, 3, |
||||
6, 10, 13, 16, 20, 23, 26, 30, 33, 36, 39, |
||||
43, 46, 49, 53, 56, 59, 63, 66, 69, 73, 76, |
||||
79, 83, 86, 89, 93, 96, 99, 103, 106, 109, 113, |
||||
116, 119, 123, 126, 129, 132, 136, 139, 142, 146, 149, |
||||
152, 156, 159, 162, 166, 169, 172, 176, 179, 182, 186, |
||||
189, 192, 196, 199, 202, 206, 209, 212, 216, 219, 222, |
||||
226, 229, 232, 235, 239, 242, 245, 249, 252, 255, 259, |
||||
262, 265, 269, 272, 275, 279, 282, 285, 289, 292, 295, |
||||
299, 302, 305, 309, 312, 315, 319, 322, 325, 328, 332, |
||||
335, 338, 342, 345, 348, 352, 355, 358, 362, 365, 368, |
||||
372, 375, 378, 382, 385, 388, 392, 395, 398, 402, 405, |
||||
408, 412, 415, 418, 422, 425, 428, 431, 435, 438, 441, |
||||
445, 448, 451, 455, 458, 461, 465, 468, 471, 475, 478, |
||||
481, 485, 488, 491, 495, 498, 501, 505, 508, 511, 515, |
||||
518, 521, 524, 528, 531, 534, 538, 541, 544, 548, 551, |
||||
554, 558, 561, 564, 568, 571, 574, 578, 581, 584, 588, |
||||
591, 594, 598, 601, 604, 608, 611, 614, 617, 621, 624, |
||||
627, 631, 634, 637, 641, 644, 647, 651, 654, 657, 661, |
||||
664, 667, 671, 674, 677, 681, 684, 687, 691, 694, 697, |
||||
701, 704, 707, 711, 714, 717, 720, 724, 727, 730, 734, |
||||
737, 740, 744, 747, 750, 754, 757, 760, 764, 767, 770, |
||||
774, 777, 780, 784, 787, 790, 794, 797, 800, 804, 807, |
||||
810, 813, 817, 820, 823, 827, 830, 833, 837, 840, 843, |
||||
847, 850, 853, 857, 860, 863, 867, 870, 873, 877, 880, |
||||
883, 887, 890, 893, 897, 900, 903, 907, 910, 913, 916, |
||||
920, 923, 926, 930, 933, 936, 940, 943, 946, 950, 953, |
||||
956, 960, |
||||
}; |
||||
|
||||
} // namespace
|
||||
} // inline namespace lts_2018_06_20
|
||||
} // namespace absl
|
||||
@ -0,0 +1,117 @@ |
||||
// Copyright 2018 The Abseil Authors.
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
#ifndef ABSL_STRINGS_CHARCONV_H_ |
||||
#define ABSL_STRINGS_CHARCONV_H_ |
||||
|
||||
#include <system_error> // NOLINT(build/c++11) |
||||
|
||||
namespace absl { |
||||
inline namespace lts_2018_06_20 { |
||||
|
||||
// Workalike compatibilty version of std::chars_format from C++17.
|
||||
//
|
||||
// This is an bitfield enumerator which can be passed to absl::from_chars to
|
||||
// configure the std::string-to-float conversion.
|
||||
enum class chars_format { |
||||
scientific = 1, |
||||
fixed = 2, |
||||
hex = 4, |
||||
general = fixed | scientific, |
||||
}; |
||||
|
||||
// The return result of a std::string-to-number conversion.
|
||||
//
|
||||
// `ec` will be set to `invalid_argument` if a well-formed number was not found
|
||||
// at the start of the input range, `result_out_of_range` if a well-formed
|
||||
// number was found, but it was out of the representable range of the requested
|
||||
// type, or to std::errc() otherwise.
|
||||
//
|
||||
// If a well-formed number was found, `ptr` is set to one past the sequence of
|
||||
// characters that were successfully parsed. If none was found, `ptr` is set
|
||||
// to the `first` argument to from_chars.
|
||||
struct from_chars_result { |
||||
const char* ptr; |
||||
std::errc ec; |
||||
}; |
||||
|
||||
// Workalike compatibilty version of std::from_chars from C++17. Currently
|
||||
// this only supports the `double` and `float` types.
|
||||
//
|
||||
// This interface incorporates the proposed resolutions for library issues
|
||||
// DR 3800 and DR 3801. If these are adopted with different wording,
|
||||
// Abseil's behavior will change to match the standard. (The behavior most
|
||||
// likely to change is for DR 3801, which says what `value` will be set to in
|
||||
// the case of overflow and underflow. Code that wants to avoid possible
|
||||
// breaking changes in this area should not depend on `value` when the returned
|
||||
// from_chars_result indicates a range error.)
|
||||
//
|
||||
// Searches the range [first, last) for the longest matching pattern beginning
|
||||
// at `first` that represents a floating point number. If one is found, store
|
||||
// the result in `value`.
|
||||
//
|
||||
// The matching pattern format is almost the same as that of strtod(), except
|
||||
// that C locale is not respected, and an initial '+' character in the input
|
||||
// range will never be matched.
|
||||
//
|
||||
// If `fmt` is set, it must be one of the enumerator values of the chars_format.
|
||||
// (This is despite the fact that chars_format is a bitmask type.) If set to
|
||||
// `scientific`, a matching number must contain an exponent. If set to `fixed`,
|
||||
// then an exponent will never match. (For example, the std::string "1e5" will be
|
||||
// parsed as "1".) If set to `hex`, then a hexadecimal float is parsed in the
|
||||
// format that strtod() accepts, except that a "0x" prefix is NOT matched.
|
||||
// (In particular, in `hex` mode, the input "0xff" results in the largest
|
||||
// matching pattern "0".)
|
||||
absl::from_chars_result from_chars(const char* first, const char* last, |
||||
double& value, // NOLINT
|
||||
chars_format fmt = chars_format::general); |
||||
|
||||
absl::from_chars_result from_chars(const char* first, const char* last, |
||||
float& value, // NOLINT
|
||||
chars_format fmt = chars_format::general); |
||||
|
||||
// std::chars_format is specified as a bitmask type, which means the following
|
||||
// operations must be provided:
|
||||
inline constexpr chars_format operator&(chars_format lhs, chars_format rhs) { |
||||
return static_cast<chars_format>(static_cast<int>(lhs) & |
||||
static_cast<int>(rhs)); |
||||
} |
||||
inline constexpr chars_format operator|(chars_format lhs, chars_format rhs) { |
||||
return static_cast<chars_format>(static_cast<int>(lhs) | |
||||
static_cast<int>(rhs)); |
||||
} |
||||
inline constexpr chars_format operator^(chars_format lhs, chars_format rhs) { |
||||
return static_cast<chars_format>(static_cast<int>(lhs) ^ |
||||
static_cast<int>(rhs)); |
||||
} |
||||
inline constexpr chars_format operator~(chars_format arg) { |
||||
return static_cast<chars_format>(~static_cast<int>(arg)); |
||||
} |
||||
inline chars_format& operator&=(chars_format& lhs, chars_format rhs) { |
||||
lhs = lhs & rhs; |
||||
return lhs; |
||||
} |
||||
inline chars_format& operator|=(chars_format& lhs, chars_format rhs) { |
||||
lhs = lhs | rhs; |
||||
return lhs; |
||||
} |
||||
inline chars_format& operator^=(chars_format& lhs, chars_format rhs) { |
||||
lhs = lhs ^ rhs; |
||||
return lhs; |
||||
} |
||||
|
||||
} // inline namespace lts_2018_06_20
|
||||
} // namespace absl
|
||||
|
||||
#endif // ABSL_STRINGS_CHARCONV_H_
|
||||
@ -0,0 +1,204 @@ |
||||
// Copyright 2018 The Abseil Authors.
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
#include "absl/strings/charconv.h" |
||||
|
||||
#include <cstdlib> |
||||
#include <cstring> |
||||
#include <string> |
||||
|
||||
#include "benchmark/benchmark.h" |
||||
|
||||
namespace { |
||||
|
||||
void BM_Strtod_Pi(benchmark::State& state) { |
||||
const char* pi = "3.14159"; |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(pi); |
||||
benchmark::DoNotOptimize(strtod(pi, nullptr)); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Strtod_Pi); |
||||
|
||||
void BM_Absl_Pi(benchmark::State& state) { |
||||
const char* pi = "3.14159"; |
||||
const char* pi_end = pi + strlen(pi); |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(pi); |
||||
double v; |
||||
absl::from_chars(pi, pi_end, v); |
||||
benchmark::DoNotOptimize(v); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Absl_Pi); |
||||
|
||||
void BM_Strtod_Pi_float(benchmark::State& state) { |
||||
const char* pi = "3.14159"; |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(pi); |
||||
benchmark::DoNotOptimize(strtof(pi, nullptr)); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Strtod_Pi_float); |
||||
|
||||
void BM_Absl_Pi_float(benchmark::State& state) { |
||||
const char* pi = "3.14159"; |
||||
const char* pi_end = pi + strlen(pi); |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(pi); |
||||
float v; |
||||
absl::from_chars(pi, pi_end, v); |
||||
benchmark::DoNotOptimize(v); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Absl_Pi_float); |
||||
|
||||
void BM_Strtod_HardLarge(benchmark::State& state) { |
||||
const char* num = "272104041512242479.e200"; |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(num); |
||||
benchmark::DoNotOptimize(strtod(num, nullptr)); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Strtod_HardLarge); |
||||
|
||||
void BM_Absl_HardLarge(benchmark::State& state) { |
||||
const char* numstr = "272104041512242479.e200"; |
||||
const char* numstr_end = numstr + strlen(numstr); |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(numstr); |
||||
double v; |
||||
absl::from_chars(numstr, numstr_end, v); |
||||
benchmark::DoNotOptimize(v); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Absl_HardLarge); |
||||
|
||||
void BM_Strtod_HardSmall(benchmark::State& state) { |
||||
const char* num = "94080055902682397.e-242"; |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(num); |
||||
benchmark::DoNotOptimize(strtod(num, nullptr)); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Strtod_HardSmall); |
||||
|
||||
void BM_Absl_HardSmall(benchmark::State& state) { |
||||
const char* numstr = "94080055902682397.e-242"; |
||||
const char* numstr_end = numstr + strlen(numstr); |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(numstr); |
||||
double v; |
||||
absl::from_chars(numstr, numstr_end, v); |
||||
benchmark::DoNotOptimize(v); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Absl_HardSmall); |
||||
|
||||
void BM_Strtod_HugeMantissa(benchmark::State& state) { |
||||
std::string huge(200, '3'); |
||||
const char* num = huge.c_str(); |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(num); |
||||
benchmark::DoNotOptimize(strtod(num, nullptr)); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Strtod_HugeMantissa); |
||||
|
||||
void BM_Absl_HugeMantissa(benchmark::State& state) { |
||||
std::string huge(200, '3'); |
||||
const char* num = huge.c_str(); |
||||
const char* num_end = num + 200; |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(num); |
||||
double v; |
||||
absl::from_chars(num, num_end, v); |
||||
benchmark::DoNotOptimize(v); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Absl_HugeMantissa); |
||||
|
||||
std::string MakeHardCase(int length) { |
||||
// The number 1.1521...e-297 is exactly halfway between 12345 * 2**-1000 and
|
||||
// the next larger representable number. The digits of this number are in
|
||||
// the std::string below.
|
||||
const std::string digits = |
||||
"1." |
||||
"152113937042223790993097181572444900347587985074226836242307364987727724" |
||||
"831384300183638649152607195040591791364113930628852279348613864894524591" |
||||
"272746490313676832900762939595690019745859128071117417798540258114233761" |
||||
"012939937017879509401007964861774960297319002612457273148497158989073482" |
||||
"171377406078223015359818300988676687994537274548940612510414856761641652" |
||||
"513434981938564294004070500716200446656421722229202383105446378511678258" |
||||
"370570631774499359748259931676320916632111681001853983492795053244971606" |
||||
"922718923011680846577744433974087653954904214152517799883551075537146316" |
||||
"168973685866425605046988661997658648354773076621610279716804960009043764" |
||||
"038392994055171112475093876476783502487512538082706095923790634572014823" |
||||
"78877699375152587890625" + |
||||
std::string(5000, '0'); |
||||
// generate the hard cases on either side for the given length.
|
||||
// Lengths between 3 and 1000 are reasonable.
|
||||
return digits.substr(0, length) + "1e-297"; |
||||
} |
||||
|
||||
void BM_Strtod_Big_And_Difficult(benchmark::State& state) { |
||||
std::string testcase = MakeHardCase(state.range(0)); |
||||
const char* begin = testcase.c_str(); |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(begin); |
||||
benchmark::DoNotOptimize(strtod(begin, nullptr)); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Strtod_Big_And_Difficult)->Range(3, 5000); |
||||
|
||||
void BM_Absl_Big_And_Difficult(benchmark::State& state) { |
||||
std::string testcase = MakeHardCase(state.range(0)); |
||||
const char* begin = testcase.c_str(); |
||||
const char* end = begin + testcase.size(); |
||||
for (auto s : state) { |
||||
benchmark::DoNotOptimize(begin); |
||||
double v; |
||||
absl::from_chars(begin, end, v); |
||||
benchmark::DoNotOptimize(v); |
||||
} |
||||
} |
||||
BENCHMARK(BM_Absl_Big_And_Difficult)->Range(3, 5000); |
||||
|
||||
} // namespace
|
||||
|
||||
// ------------------------------------------------------------------------
|
||||
// Benchmark Time CPU Iterations
|
||||
// ------------------------------------------------------------------------
|
||||
// BM_Strtod_Pi 96 ns 96 ns 6337454
|
||||
// BM_Absl_Pi 35 ns 35 ns 20031996
|
||||
// BM_Strtod_Pi_float 91 ns 91 ns 7745851
|
||||
// BM_Absl_Pi_float 35 ns 35 ns 20430298
|
||||
// BM_Strtod_HardLarge 133 ns 133 ns 5288341
|
||||
// BM_Absl_HardLarge 181 ns 181 ns 3855615
|
||||
// BM_Strtod_HardSmall 279 ns 279 ns 2517243
|
||||
// BM_Absl_HardSmall 287 ns 287 ns 2458744
|
||||
// BM_Strtod_HugeMantissa 433 ns 433 ns 1604293
|
||||
// BM_Absl_HugeMantissa 160 ns 160 ns 4403671
|
||||
// BM_Strtod_Big_And_Difficult/3 236 ns 236 ns 2942496
|
||||
// BM_Strtod_Big_And_Difficult/8 232 ns 232 ns 2983796
|
||||
// BM_Strtod_Big_And_Difficult/64 437 ns 437 ns 1591951
|
||||
// BM_Strtod_Big_And_Difficult/512 1738 ns 1738 ns 402519
|
||||
// BM_Strtod_Big_And_Difficult/4096 3943 ns 3943 ns 176128
|
||||
// BM_Strtod_Big_And_Difficult/5000 4397 ns 4397 ns 157878
|
||||
// BM_Absl_Big_And_Difficult/3 39 ns 39 ns 17799583
|
||||
// BM_Absl_Big_And_Difficult/8 43 ns 43 ns 16096859
|
||||
// BM_Absl_Big_And_Difficult/64 550 ns 550 ns 1259717
|
||||
// BM_Absl_Big_And_Difficult/512 4167 ns 4167 ns 171414
|
||||
// BM_Absl_Big_And_Difficult/4096 9160 ns 9159 ns 76297
|
||||
// BM_Absl_Big_And_Difficult/5000 9738 ns 9738 ns 70140
|
||||
@ -0,0 +1,766 @@ |
||||
// Copyright 2018 The Abseil Authors.
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
#include "absl/strings/charconv.h" |
||||
|
||||
#include <cstdlib> |
||||
#include <string> |
||||
|
||||
#include "gmock/gmock.h" |
||||
#include "gtest/gtest.h" |
||||
#include "absl/strings/str_cat.h" |
||||
|
||||
#ifdef _MSC_FULL_VER |
||||
#define ABSL_COMPILER_DOES_EXACT_ROUNDING 0 |
||||
#define ABSL_STRTOD_HANDLES_NAN_CORRECTLY 0 |
||||
#else |
||||
#define ABSL_COMPILER_DOES_EXACT_ROUNDING 1 |
||||
#define ABSL_STRTOD_HANDLES_NAN_CORRECTLY 1 |
||||
#endif |
||||
|
||||
namespace { |
||||
|
||||
#if ABSL_COMPILER_DOES_EXACT_ROUNDING |
||||
|
||||
// Tests that the given std::string is accepted by absl::from_chars, and that it
|
||||
// converts exactly equal to the given number.
|
||||
void TestDoubleParse(absl::string_view str, double expected_number) { |
||||
SCOPED_TRACE(str); |
||||
double actual_number = 0.0; |
||||
absl::from_chars_result result = |
||||
absl::from_chars(str.data(), str.data() + str.length(), actual_number); |
||||
EXPECT_EQ(result.ec, std::errc()); |
||||
EXPECT_EQ(result.ptr, str.data() + str.length()); |
||||
EXPECT_EQ(actual_number, expected_number); |
||||
} |
||||
|
||||
void TestFloatParse(absl::string_view str, float expected_number) { |
||||
SCOPED_TRACE(str); |
||||
float actual_number = 0.0; |
||||
absl::from_chars_result result = |
||||
absl::from_chars(str.data(), str.data() + str.length(), actual_number); |
||||
EXPECT_EQ(result.ec, std::errc()); |
||||
EXPECT_EQ(result.ptr, str.data() + str.length()); |
||||
EXPECT_EQ(actual_number, expected_number); |
||||
} |
||||
|
||||
// Tests that the given double or single precision floating point literal is
|
||||
// parsed correctly by absl::from_chars.
|
||||
//
|
||||
// These convenience macros assume that the C++ compiler being used also does
|
||||
// fully correct decimal-to-binary conversions.
|
||||
#define FROM_CHARS_TEST_DOUBLE(number) \ |
||||
{ \
|
||||
TestDoubleParse(#number, number); \
|
||||
TestDoubleParse("-" #number, -number); \
|
||||
} |
||||
|
||||
#define FROM_CHARS_TEST_FLOAT(number) \ |
||||
{ \
|
||||
TestFloatParse(#number, number##f); \
|
||||
TestFloatParse("-" #number, -number##f); \
|
||||
} |
||||
|
||||
TEST(FromChars, NearRoundingCases) { |
||||
// Cases from "A Program for Testing IEEE Decimal-Binary Conversion"
|
||||
// by Vern Paxson.
|
||||
|
||||
// Forms that should round towards zero. (These are the hardest cases for
|
||||
// each decimal mantissa size.)
|
||||
FROM_CHARS_TEST_DOUBLE(5.e125); |
||||
FROM_CHARS_TEST_DOUBLE(69.e267); |
||||
FROM_CHARS_TEST_DOUBLE(999.e-026); |
||||
FROM_CHARS_TEST_DOUBLE(7861.e-034); |
||||
FROM_CHARS_TEST_DOUBLE(75569.e-254); |
||||
FROM_CHARS_TEST_DOUBLE(928609.e-261); |
||||
FROM_CHARS_TEST_DOUBLE(9210917.e080); |
||||
FROM_CHARS_TEST_DOUBLE(84863171.e114); |
||||
FROM_CHARS_TEST_DOUBLE(653777767.e273); |
||||
FROM_CHARS_TEST_DOUBLE(5232604057.e-298); |
||||
FROM_CHARS_TEST_DOUBLE(27235667517.e-109); |
||||
FROM_CHARS_TEST_DOUBLE(653532977297.e-123); |
||||
FROM_CHARS_TEST_DOUBLE(3142213164987.e-294); |
||||
FROM_CHARS_TEST_DOUBLE(46202199371337.e-072); |
||||
FROM_CHARS_TEST_DOUBLE(231010996856685.e-073); |
||||
FROM_CHARS_TEST_DOUBLE(9324754620109615.e212); |
||||
FROM_CHARS_TEST_DOUBLE(78459735791271921.e049); |
||||
FROM_CHARS_TEST_DOUBLE(272104041512242479.e200); |
||||
FROM_CHARS_TEST_DOUBLE(6802601037806061975.e198); |
||||
FROM_CHARS_TEST_DOUBLE(20505426358836677347.e-221); |
||||
FROM_CHARS_TEST_DOUBLE(836168422905420598437.e-234); |
||||
FROM_CHARS_TEST_DOUBLE(4891559871276714924261.e222); |
||||
FROM_CHARS_TEST_FLOAT(5.e-20); |
||||
FROM_CHARS_TEST_FLOAT(67.e14); |
||||
FROM_CHARS_TEST_FLOAT(985.e15); |
||||
FROM_CHARS_TEST_FLOAT(7693.e-42); |
||||
FROM_CHARS_TEST_FLOAT(55895.e-16); |
||||
FROM_CHARS_TEST_FLOAT(996622.e-44); |
||||
FROM_CHARS_TEST_FLOAT(7038531.e-32); |
||||
FROM_CHARS_TEST_FLOAT(60419369.e-46); |
||||
FROM_CHARS_TEST_FLOAT(702990899.e-20); |
||||
FROM_CHARS_TEST_FLOAT(6930161142.e-48); |
||||
FROM_CHARS_TEST_FLOAT(25933168707.e-13); |
||||
FROM_CHARS_TEST_FLOAT(596428896559.e20); |
||||
|
||||
// Similarly, forms that should round away from zero.
|
||||
FROM_CHARS_TEST_DOUBLE(9.e-265); |
||||
FROM_CHARS_TEST_DOUBLE(85.e-037); |
||||
FROM_CHARS_TEST_DOUBLE(623.e100); |
||||
FROM_CHARS_TEST_DOUBLE(3571.e263); |
||||
FROM_CHARS_TEST_DOUBLE(81661.e153); |
||||
FROM_CHARS_TEST_DOUBLE(920657.e-023); |
||||
FROM_CHARS_TEST_DOUBLE(4603285.e-024); |
||||
FROM_CHARS_TEST_DOUBLE(87575437.e-309); |
||||
FROM_CHARS_TEST_DOUBLE(245540327.e122); |
||||
FROM_CHARS_TEST_DOUBLE(6138508175.e120); |
||||
FROM_CHARS_TEST_DOUBLE(83356057653.e193); |
||||
FROM_CHARS_TEST_DOUBLE(619534293513.e124); |
||||
FROM_CHARS_TEST_DOUBLE(2335141086879.e218); |
||||
FROM_CHARS_TEST_DOUBLE(36167929443327.e-159); |
||||
FROM_CHARS_TEST_DOUBLE(609610927149051.e-255); |
||||
FROM_CHARS_TEST_DOUBLE(3743626360493413.e-165); |
||||
FROM_CHARS_TEST_DOUBLE(94080055902682397.e-242); |
||||
FROM_CHARS_TEST_DOUBLE(899810892172646163.e283); |
||||
FROM_CHARS_TEST_DOUBLE(7120190517612959703.e120); |
||||
FROM_CHARS_TEST_DOUBLE(25188282901709339043.e-252); |
||||
FROM_CHARS_TEST_DOUBLE(308984926168550152811.e-052); |
||||
FROM_CHARS_TEST_DOUBLE(6372891218502368041059.e064); |
||||
FROM_CHARS_TEST_FLOAT(3.e-23); |
||||
FROM_CHARS_TEST_FLOAT(57.e18); |
||||
FROM_CHARS_TEST_FLOAT(789.e-35); |
||||
FROM_CHARS_TEST_FLOAT(2539.e-18); |
||||
FROM_CHARS_TEST_FLOAT(76173.e28); |
||||
FROM_CHARS_TEST_FLOAT(887745.e-11); |
||||
FROM_CHARS_TEST_FLOAT(5382571.e-37); |
||||
FROM_CHARS_TEST_FLOAT(82381273.e-35); |
||||
FROM_CHARS_TEST_FLOAT(750486563.e-38); |
||||
FROM_CHARS_TEST_FLOAT(3752432815.e-39); |
||||
FROM_CHARS_TEST_FLOAT(75224575729.e-45); |
||||
FROM_CHARS_TEST_FLOAT(459926601011.e15); |
||||
} |
||||
|
||||
#undef FROM_CHARS_TEST_DOUBLE |
||||
#undef FROM_CHARS_TEST_FLOAT |
||||
#endif |
||||
|
||||
float ToFloat(absl::string_view s) { |
||||
float f; |
||||
absl::from_chars(s.data(), s.data() + s.size(), f); |
||||
return f; |
||||
} |
||||
|
||||
double ToDouble(absl::string_view s) { |
||||
double d; |
||||
absl::from_chars(s.data(), s.data() + s.size(), d); |
||||
return d; |
||||
} |
||||
|
||||
// A duplication of the test cases in "NearRoundingCases" above, but with
|
||||
// expected values expressed with integers, using ldexp/ldexpf. These test
|
||||
// cases will work even on compilers that do not accurately round floating point
|
||||
// literals.
|
||||
TEST(FromChars, NearRoundingCasesExplicit) { |
||||
EXPECT_EQ(ToDouble("5.e125"), ldexp(6653062250012735, 365)); |
||||
EXPECT_EQ(ToDouble("69.e267"), ldexp(4705683757438170, 841)); |
||||
EXPECT_EQ(ToDouble("999.e-026"), ldexp(6798841691080350, -129)); |
||||
EXPECT_EQ(ToDouble("7861.e-034"), ldexp(8975675289889240, -153)); |
||||
EXPECT_EQ(ToDouble("75569.e-254"), ldexp(6091718967192243, -880)); |
||||
EXPECT_EQ(ToDouble("928609.e-261"), ldexp(7849264900213743, -900)); |
||||
EXPECT_EQ(ToDouble("9210917.e080"), ldexp(8341110837370930, 236)); |
||||
EXPECT_EQ(ToDouble("84863171.e114"), ldexp(4625202867375927, 353)); |
||||
EXPECT_EQ(ToDouble("653777767.e273"), ldexp(5068902999763073, 884)); |
||||
EXPECT_EQ(ToDouble("5232604057.e-298"), ldexp(5741343011915040, -1010)); |
||||
EXPECT_EQ(ToDouble("27235667517.e-109"), ldexp(6707124626673586, -380)); |
||||
EXPECT_EQ(ToDouble("653532977297.e-123"), ldexp(7078246407265384, -422)); |
||||
EXPECT_EQ(ToDouble("3142213164987.e-294"), ldexp(8219991337640559, -988)); |
||||
EXPECT_EQ(ToDouble("46202199371337.e-072"), ldexp(5224462102115359, -246)); |
||||
EXPECT_EQ(ToDouble("231010996856685.e-073"), ldexp(5224462102115359, -247)); |
||||
EXPECT_EQ(ToDouble("9324754620109615.e212"), ldexp(5539753864394442, 705)); |
||||
EXPECT_EQ(ToDouble("78459735791271921.e049"), ldexp(8388176519442766, 166)); |
||||
EXPECT_EQ(ToDouble("272104041512242479.e200"), ldexp(5554409530847367, 670)); |
||||
EXPECT_EQ(ToDouble("6802601037806061975.e198"), ldexp(5554409530847367, 668)); |
||||
EXPECT_EQ(ToDouble("20505426358836677347.e-221"), |
||||
ldexp(4524032052079546, -722)); |
||||
EXPECT_EQ(ToDouble("836168422905420598437.e-234"), |
||||
ldexp(5070963299887562, -760)); |
||||
EXPECT_EQ(ToDouble("4891559871276714924261.e222"), |
||||
ldexp(6452687840519111, 757)); |
||||
EXPECT_EQ(ToFloat("5.e-20"), ldexpf(15474250, -88)); |
||||
EXPECT_EQ(ToFloat("67.e14"), ldexpf(12479722, 29)); |
||||
EXPECT_EQ(ToFloat("985.e15"), ldexpf(14333636, 36)); |
||||
EXPECT_EQ(ToFloat("7693.e-42"), ldexpf(10979816, -150)); |
||||
EXPECT_EQ(ToFloat("55895.e-16"), ldexpf(12888509, -61)); |
||||
EXPECT_EQ(ToFloat("996622.e-44"), ldexpf(14224264, -150)); |
||||
EXPECT_EQ(ToFloat("7038531.e-32"), ldexpf(11420669, -107)); |
||||
EXPECT_EQ(ToFloat("60419369.e-46"), ldexpf(8623340, -150)); |
||||
EXPECT_EQ(ToFloat("702990899.e-20"), ldexpf(16209866, -61)); |
||||
EXPECT_EQ(ToFloat("6930161142.e-48"), ldexpf(9891056, -150)); |
||||
EXPECT_EQ(ToFloat("25933168707.e-13"), ldexpf(11138211, -32)); |
||||
EXPECT_EQ(ToFloat("596428896559.e20"), ldexpf(12333860, 82)); |
||||
|
||||
|
||||
EXPECT_EQ(ToDouble("9.e-265"), ldexp(8168427841980010, -930)); |
||||
EXPECT_EQ(ToDouble("85.e-037"), ldexp(6360455125664090, -169)); |
||||
EXPECT_EQ(ToDouble("623.e100"), ldexp(6263531988747231, 289)); |
||||
EXPECT_EQ(ToDouble("3571.e263"), ldexp(6234526311072170, 833)); |
||||
EXPECT_EQ(ToDouble("81661.e153"), ldexp(6696636728760206, 472)); |
||||
EXPECT_EQ(ToDouble("920657.e-023"), ldexp(5975405561110124, -109)); |
||||
EXPECT_EQ(ToDouble("4603285.e-024"), ldexp(5975405561110124, -110)); |
||||
EXPECT_EQ(ToDouble("87575437.e-309"), ldexp(8452160731874668, -1053)); |
||||
EXPECT_EQ(ToDouble("245540327.e122"), ldexp(4985336549131723, 381)); |
||||
EXPECT_EQ(ToDouble("6138508175.e120"), ldexp(4985336549131723, 379)); |
||||
EXPECT_EQ(ToDouble("83356057653.e193"), ldexp(5986732817132056, 625)); |
||||
EXPECT_EQ(ToDouble("619534293513.e124"), ldexp(4798406992060657, 399)); |
||||
EXPECT_EQ(ToDouble("2335141086879.e218"), ldexp(5419088166961646, 713)); |
||||
EXPECT_EQ(ToDouble("36167929443327.e-159"), ldexp(8135819834632444, -536)); |
||||
EXPECT_EQ(ToDouble("609610927149051.e-255"), ldexp(4576664294594737, -850)); |
||||
EXPECT_EQ(ToDouble("3743626360493413.e-165"), ldexp(6898586531774201, -549)); |
||||
EXPECT_EQ(ToDouble("94080055902682397.e-242"), ldexp(6273271706052298, -800)); |
||||
EXPECT_EQ(ToDouble("899810892172646163.e283"), ldexp(7563892574477827, 947)); |
||||
EXPECT_EQ(ToDouble("7120190517612959703.e120"), ldexp(5385467232557565, 409)); |
||||
EXPECT_EQ(ToDouble("25188282901709339043.e-252"), |
||||
ldexp(5635662608542340, -825)); |
||||
EXPECT_EQ(ToDouble("308984926168550152811.e-052"), |
||||
ldexp(5644774693823803, -157)); |
||||
EXPECT_EQ(ToDouble("6372891218502368041059.e064"), |
||||
ldexp(4616868614322430, 233)); |
||||
|
||||
EXPECT_EQ(ToFloat("3.e-23"), ldexpf(9507380, -98)); |
||||
EXPECT_EQ(ToFloat("57.e18"), ldexpf(12960300, 42)); |
||||
EXPECT_EQ(ToFloat("789.e-35"), ldexpf(10739312, -130)); |
||||
EXPECT_EQ(ToFloat("2539.e-18"), ldexpf(11990089, -72)); |
||||
EXPECT_EQ(ToFloat("76173.e28"), ldexpf(9845130, 86)); |
||||
EXPECT_EQ(ToFloat("887745.e-11"), ldexpf(9760860, -40)); |
||||
EXPECT_EQ(ToFloat("5382571.e-37"), ldexpf(11447463, -124)); |
||||
EXPECT_EQ(ToFloat("82381273.e-35"), ldexpf(8554961, -113)); |
||||
EXPECT_EQ(ToFloat("750486563.e-38"), ldexpf(9975678, -120)); |
||||
EXPECT_EQ(ToFloat("3752432815.e-39"), ldexpf(9975678, -121)); |
||||
EXPECT_EQ(ToFloat("75224575729.e-45"), ldexpf(13105970, -137)); |
||||
EXPECT_EQ(ToFloat("459926601011.e15"), ldexpf(12466336, 65)); |
||||
} |
||||
|
||||
// Common test logic for converting a std::string which lies exactly halfway between
|
||||
// two target floats.
|
||||
//
|
||||
// mantissa and exponent represent the precise value between two floating point
|
||||
// numbers, `expected_low` and `expected_high`. The floating point
|
||||
// representation to parse in `StrCat(mantissa, "e", exponent)`.
|
||||
//
|
||||
// This function checks that an input just slightly less than the exact value
|
||||
// is rounded down to `expected_low`, and an input just slightly greater than
|
||||
// the exact value is rounded up to `expected_high`.
|
||||
//
|
||||
// The exact value should round to `expected_half`, which must be either
|
||||
// `expected_low` or `expected_high`.
|
||||
template <typename FloatType> |
||||
void TestHalfwayValue(const std::string& mantissa, int exponent, |
||||
FloatType expected_low, FloatType expected_high, |
||||
FloatType expected_half) { |
||||
std::string low_rep = mantissa; |
||||
low_rep[low_rep.size() - 1] -= 1; |
||||
absl::StrAppend(&low_rep, std::string(1000, '9'), "e", exponent); |
||||
|
||||
FloatType actual_low = 0; |
||||
absl::from_chars(low_rep.data(), low_rep.data() + low_rep.size(), actual_low); |
||||
EXPECT_EQ(expected_low, actual_low); |
||||
|
||||
std::string high_rep = absl::StrCat(mantissa, std::string(1000, '0'), "1e", exponent); |
||||
FloatType actual_high = 0; |
||||
absl::from_chars(high_rep.data(), high_rep.data() + high_rep.size(), |
||||
actual_high); |
||||
EXPECT_EQ(expected_high, actual_high); |
||||
|
||||
std::string halfway_rep = absl::StrCat(mantissa, "e", exponent); |
||||
FloatType actual_half = 0; |
||||
absl::from_chars(halfway_rep.data(), halfway_rep.data() + halfway_rep.size(), |
||||
actual_half); |
||||
EXPECT_EQ(expected_half, actual_half); |
||||
} |
||||
|
||||
TEST(FromChars, DoubleRounding) { |
||||
const double zero = 0.0; |
||||
const double first_subnormal = nextafter(zero, 1.0); |
||||
const double second_subnormal = nextafter(first_subnormal, 1.0); |
||||
|
||||
const double first_normal = DBL_MIN; |
||||
const double last_subnormal = nextafter(first_normal, 0.0); |
||||
const double second_normal = nextafter(first_normal, 1.0); |
||||
|
||||
const double last_normal = DBL_MAX; |
||||
const double penultimate_normal = nextafter(last_normal, 0.0); |
||||
|
||||
// Various test cases for numbers between two representable floats. Each
|
||||
// call to TestHalfwayValue tests a number just below and just above the
|
||||
// halfway point, as well as the number exactly between them.
|
||||
|
||||
// Test between zero and first_subnormal. Round-to-even tie rounds down.
|
||||
TestHalfwayValue( |
||||
"2." |
||||
"470328229206232720882843964341106861825299013071623822127928412503377536" |
||||
"351043759326499181808179961898982823477228588654633283551779698981993873" |
||||
"980053909390631503565951557022639229085839244910518443593180284993653615" |
||||
"250031937045767824921936562366986365848075700158576926990370631192827955" |
||||
"855133292783433840935197801553124659726357957462276646527282722005637400" |
||||
"648549997709659947045402082816622623785739345073633900796776193057750674" |
||||
"017632467360096895134053553745851666113422376667860416215968046191446729" |
||||
"184030053005753084904876539171138659164623952491262365388187963623937328" |
||||
"042389101867234849766823508986338858792562830275599565752445550725518931" |
||||
"369083625477918694866799496832404970582102851318545139621383772282614543" |
||||
"7693412532098591327667236328125", |
||||
-324, zero, first_subnormal, zero); |
||||
|
||||
// first_subnormal and second_subnormal. Round-to-even tie rounds up.
|
||||
TestHalfwayValue( |
||||
"7." |
||||
"410984687618698162648531893023320585475897039214871466383785237510132609" |
||||
"053131277979497545424539885696948470431685765963899850655339096945981621" |
||||
"940161728171894510697854671067917687257517734731555330779540854980960845" |
||||
"750095811137303474765809687100959097544227100475730780971111893578483867" |
||||
"565399878350301522805593404659373979179073872386829939581848166016912201" |
||||
"945649993128979841136206248449867871357218035220901702390328579173252022" |
||||
"052897402080290685402160661237554998340267130003581248647904138574340187" |
||||
"552090159017259254714629617513415977493871857473787096164563890871811984" |
||||
"127167305601704549300470526959016576377688490826798697257336652176556794" |
||||
"107250876433756084600398490497214911746308553955635418864151316847843631" |
||||
"3080237596295773983001708984375", |
||||
-324, first_subnormal, second_subnormal, second_subnormal); |
||||
|
||||
// last_subnormal and first_normal. Round-to-even tie rounds up.
|
||||
TestHalfwayValue( |
||||
"2." |
||||
"225073858507201136057409796709131975934819546351645648023426109724822222" |
||||
"021076945516529523908135087914149158913039621106870086438694594645527657" |
||||
"207407820621743379988141063267329253552286881372149012981122451451889849" |
||||
"057222307285255133155755015914397476397983411801999323962548289017107081" |
||||
"850690630666655994938275772572015763062690663332647565300009245888316433" |
||||
"037779791869612049497390377829704905051080609940730262937128958950003583" |
||||
"799967207254304360284078895771796150945516748243471030702609144621572289" |
||||
"880258182545180325707018860872113128079512233426288368622321503775666622" |
||||
"503982534335974568884423900265498198385487948292206894721689831099698365" |
||||
"846814022854243330660339850886445804001034933970427567186443383770486037" |
||||
"86162277173854562306587467901408672332763671875", |
||||
-308, last_subnormal, first_normal, first_normal); |
||||
|
||||
// first_normal and second_normal. Round-to-even tie rounds down.
|
||||
TestHalfwayValue( |
||||
"2." |
||||
"225073858507201630123055637955676152503612414573018013083228724049586647" |
||||
"606759446192036794116886953213985520549032000903434781884412325572184367" |
||||
"563347617020518175998922941393629966742598285899994830148971433555578567" |
||||
"693279306015978183162142425067962460785295885199272493577688320732492479" |
||||
"924816869232247165964934329258783950102250973957579510571600738343645738" |
||||
"494324192997092179207389919761694314131497173265255020084997973676783743" |
||||
"155205818804439163810572367791175177756227497413804253387084478193655533" |
||||
"073867420834526162513029462022730109054820067654020201547112002028139700" |
||||
"141575259123440177362244273712468151750189745559978653234255886219611516" |
||||
"335924167958029604477064946470184777360934300451421683607013647479513962" |
||||
"13837722826145437693412532098591327667236328125", |
||||
-308, first_normal, second_normal, first_normal); |
||||
|
||||
// penultimate_normal and last_normal. Round-to-even rounds down.
|
||||
TestHalfwayValue( |
||||
"1." |
||||
"797693134862315608353258760581052985162070023416521662616611746258695532" |
||||
"672923265745300992879465492467506314903358770175220871059269879629062776" |
||||
"047355692132901909191523941804762171253349609463563872612866401980290377" |
||||
"995141836029815117562837277714038305214839639239356331336428021390916694" |
||||
"57927874464075218944", |
||||
308, penultimate_normal, last_normal, penultimate_normal); |
||||
} |
||||
|
||||
// Same test cases as DoubleRounding, now with new and improved Much Smaller
|
||||
// Precision!
|
||||
TEST(FromChars, FloatRounding) { |
||||
const float zero = 0.0; |
||||
const float first_subnormal = nextafterf(zero, 1.0); |
||||
const float second_subnormal = nextafterf(first_subnormal, 1.0); |
||||
|
||||
const float first_normal = FLT_MIN; |
||||
const float last_subnormal = nextafterf(first_normal, 0.0); |
||||
const float second_normal = nextafterf(first_normal, 1.0); |
||||
|
||||
const float last_normal = FLT_MAX; |
||||
const float penultimate_normal = nextafterf(last_normal, 0.0); |
||||
|
||||
// Test between zero and first_subnormal. Round-to-even tie rounds down.
|
||||
TestHalfwayValue( |
||||
"7." |
||||
"006492321624085354618647916449580656401309709382578858785341419448955413" |
||||
"42930300743319094181060791015625", |
||||
-46, zero, first_subnormal, zero); |
||||
|
||||
// first_subnormal and second_subnormal. Round-to-even tie rounds up.
|
||||
TestHalfwayValue( |
||||
"2." |
||||
"101947696487225606385594374934874196920392912814773657635602425834686624" |
||||
"028790902229957282543182373046875", |
||||
-45, first_subnormal, second_subnormal, second_subnormal); |
||||
|
||||
// last_subnormal and first_normal. Round-to-even tie rounds up.
|
||||
TestHalfwayValue( |
||||
"1." |
||||
"175494280757364291727882991035766513322858992758990427682963118425003064" |
||||
"9651730385585324256680905818939208984375", |
||||
-38, last_subnormal, first_normal, first_normal); |
||||
|
||||
// first_normal and second_normal. Round-to-even tie rounds down.
|
||||
TestHalfwayValue( |
||||
"1." |
||||
"175494420887210724209590083408724842314472120785184615334540294131831453" |
||||
"9442813071445925743319094181060791015625", |
||||
-38, first_normal, second_normal, first_normal); |
||||
|
||||
// penultimate_normal and last_normal. Round-to-even rounds down.
|
||||
TestHalfwayValue("3.40282336497324057985868971510891282432", 38, |
||||
penultimate_normal, last_normal, penultimate_normal); |
||||
} |
||||
|
||||
TEST(FromChars, Underflow) { |
||||
// Check that underflow is handled correctly, according to the specification
|
||||
// in DR 3081.
|
||||
double d; |
||||
float f; |
||||
absl::from_chars_result result; |
||||
|
||||
std::string negative_underflow = "-1e-1000"; |
||||
const char* begin = negative_underflow.data(); |
||||
const char* end = begin + negative_underflow.size(); |
||||
d = 100.0; |
||||
result = absl::from_chars(begin, end, d); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_TRUE(std::signbit(d)); // negative
|
||||
EXPECT_GE(d, -std::numeric_limits<double>::min()); |
||||
f = 100.0; |
||||
result = absl::from_chars(begin, end, f); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_TRUE(std::signbit(f)); // negative
|
||||
EXPECT_GE(f, -std::numeric_limits<float>::min()); |
||||
|
||||
std::string positive_underflow = "1e-1000"; |
||||
begin = positive_underflow.data(); |
||||
end = begin + positive_underflow.size(); |
||||
d = -100.0; |
||||
result = absl::from_chars(begin, end, d); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_FALSE(std::signbit(d)); // positive
|
||||
EXPECT_LE(d, std::numeric_limits<double>::min()); |
||||
f = -100.0; |
||||
result = absl::from_chars(begin, end, f); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_FALSE(std::signbit(f)); // positive
|
||||
EXPECT_LE(f, std::numeric_limits<float>::min()); |
||||
} |
||||
|
||||
TEST(FromChars, Overflow) { |
||||
// Check that overflow is handled correctly, according to the specification
|
||||
// in DR 3081.
|
||||
double d; |
||||
float f; |
||||
absl::from_chars_result result; |
||||
|
||||
std::string negative_overflow = "-1e1000"; |
||||
const char* begin = negative_overflow.data(); |
||||
const char* end = begin + negative_overflow.size(); |
||||
d = 100.0; |
||||
result = absl::from_chars(begin, end, d); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_TRUE(std::signbit(d)); // negative
|
||||
EXPECT_EQ(d, -std::numeric_limits<double>::max()); |
||||
f = 100.0; |
||||
result = absl::from_chars(begin, end, f); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_TRUE(std::signbit(f)); // negative
|
||||
EXPECT_EQ(f, -std::numeric_limits<float>::max()); |
||||
|
||||
std::string positive_overflow = "1e1000"; |
||||
begin = positive_overflow.data(); |
||||
end = begin + positive_overflow.size(); |
||||
d = -100.0; |
||||
result = absl::from_chars(begin, end, d); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_FALSE(std::signbit(d)); // positive
|
||||
EXPECT_EQ(d, std::numeric_limits<double>::max()); |
||||
f = -100.0; |
||||
result = absl::from_chars(begin, end, f); |
||||
EXPECT_EQ(result.ptr, end); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_FALSE(std::signbit(f)); // positive
|
||||
EXPECT_EQ(f, std::numeric_limits<float>::max()); |
||||
} |
||||
|
||||
TEST(FromChars, ReturnValuePtr) { |
||||
// Check that `ptr` points one past the number scanned, even if that number
|
||||
// is not representable.
|
||||
double d; |
||||
absl::from_chars_result result; |
||||
|
||||
std::string normal = "3.14@#$%@#$%"; |
||||
result = absl::from_chars(normal.data(), normal.data() + normal.size(), d); |
||||
EXPECT_EQ(result.ec, std::errc()); |
||||
EXPECT_EQ(result.ptr - normal.data(), 4); |
||||
|
||||
std::string overflow = "1e1000@#$%@#$%"; |
||||
result = absl::from_chars(overflow.data(), |
||||
overflow.data() + overflow.size(), d); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_EQ(result.ptr - overflow.data(), 6); |
||||
|
||||
std::string garbage = "#$%@#$%"; |
||||
result = absl::from_chars(garbage.data(), |
||||
garbage.data() + garbage.size(), d); |
||||
EXPECT_EQ(result.ec, std::errc::invalid_argument); |
||||
EXPECT_EQ(result.ptr - garbage.data(), 0); |
||||
} |
||||
|
||||
// Check for a wide range of inputs that strtod() and absl::from_chars() exactly
|
||||
// agree on the conversion amount.
|
||||
//
|
||||
// This test assumes the platform's strtod() uses perfect round_to_nearest
|
||||
// rounding.
|
||||
TEST(FromChars, TestVersusStrtod) { |
||||
for (int mantissa = 1000000; mantissa <= 9999999; mantissa += 501) { |
||||
for (int exponent = -300; exponent < 300; ++exponent) { |
||||
std::string candidate = absl::StrCat(mantissa, "e", exponent); |
||||
double strtod_value = strtod(candidate.c_str(), nullptr); |
||||
double absl_value = 0; |
||||
absl::from_chars(candidate.data(), candidate.data() + candidate.size(), |
||||
absl_value); |
||||
ASSERT_EQ(strtod_value, absl_value) << candidate; |
||||
} |
||||
} |
||||
} |
||||
|
||||
// Check for a wide range of inputs that strtof() and absl::from_chars() exactly
|
||||
// agree on the conversion amount.
|
||||
//
|
||||
// This test assumes the platform's strtof() uses perfect round_to_nearest
|
||||
// rounding.
|
||||
TEST(FromChars, TestVersusStrtof) { |
||||
for (int mantissa = 1000000; mantissa <= 9999999; mantissa += 501) { |
||||
for (int exponent = -43; exponent < 32; ++exponent) { |
||||
std::string candidate = absl::StrCat(mantissa, "e", exponent); |
||||
float strtod_value = strtof(candidate.c_str(), nullptr); |
||||
float absl_value = 0; |
||||
absl::from_chars(candidate.data(), candidate.data() + candidate.size(), |
||||
absl_value); |
||||
ASSERT_EQ(strtod_value, absl_value) << candidate; |
||||
} |
||||
} |
||||
} |
||||
|
||||
// Tests if two floating point values have identical bit layouts. (EXPECT_EQ
|
||||
// is not suitable for NaN testing, since NaNs are never equal.)
|
||||
template <typename Float> |
||||
bool Identical(Float a, Float b) { |
||||
return 0 == memcmp(&a, &b, sizeof(Float)); |
||||
} |
||||
|
||||
// Check that NaNs are parsed correctly. The spec requires that
|
||||
// std::from_chars on "NaN(123abc)" return the same value as std::nan("123abc").
|
||||
// How such an n-char-sequence affects the generated NaN is unspecified, so we
|
||||
// just test for symmetry with std::nan and strtod here.
|
||||
//
|
||||
// (In Linux, this parses the value as a number and stuffs that number into the
|
||||
// free bits of a quiet NaN.)
|
||||
TEST(FromChars, NaNDoubles) { |
||||
for (std::string n_char_sequence : |
||||
{"", "1", "2", "3", "fff", "FFF", "200000", "400000", "4000000000000", |
||||
"8000000000000", "abc123", "legal_but_unexpected", |
||||
"99999999999999999999999", "_"}) { |
||||
std::string input = absl::StrCat("nan(", n_char_sequence, ")"); |
||||
SCOPED_TRACE(input); |
||||
double from_chars_double; |
||||
absl::from_chars(input.data(), input.data() + input.size(), |
||||
from_chars_double); |
||||
double std_nan_double = std::nan(n_char_sequence.c_str()); |
||||
EXPECT_TRUE(Identical(from_chars_double, std_nan_double)); |
||||
|
||||
// Also check that we match strtod()'s behavior. This test assumes that the
|
||||
// platform has a compliant strtod().
|
||||
#if ABSL_STRTOD_HANDLES_NAN_CORRECTLY |
||||
double strtod_double = strtod(input.c_str(), nullptr); |
||||
EXPECT_TRUE(Identical(from_chars_double, strtod_double)); |
||||
#endif // ABSL_STRTOD_HANDLES_NAN_CORRECTLY
|
||||
|
||||
// Check that we can parse a negative NaN
|
||||
std::string negative_input = "-" + input; |
||||
double negative_from_chars_double; |
||||
absl::from_chars(negative_input.data(), |
||||
negative_input.data() + negative_input.size(), |
||||
negative_from_chars_double); |
||||
EXPECT_TRUE(std::signbit(negative_from_chars_double)); |
||||
EXPECT_FALSE(Identical(negative_from_chars_double, from_chars_double)); |
||||
from_chars_double = std::copysign(from_chars_double, -1.0); |
||||
EXPECT_TRUE(Identical(negative_from_chars_double, from_chars_double)); |
||||
} |
||||
} |
||||
|
||||
TEST(FromChars, NaNFloats) { |
||||
for (std::string n_char_sequence : |
||||
{"", "1", "2", "3", "fff", "FFF", "200000", "400000", "4000000000000", |
||||
"8000000000000", "abc123", "legal_but_unexpected", |
||||
"99999999999999999999999", "_"}) { |
||||
std::string input = absl::StrCat("nan(", n_char_sequence, ")"); |
||||
SCOPED_TRACE(input); |
||||
float from_chars_float; |
||||
absl::from_chars(input.data(), input.data() + input.size(), |
||||
from_chars_float); |
||||
float std_nan_float = std::nanf(n_char_sequence.c_str()); |
||||
EXPECT_TRUE(Identical(from_chars_float, std_nan_float)); |
||||
|
||||
// Also check that we match strtof()'s behavior. This test assumes that the
|
||||
// platform has a compliant strtof().
|
||||
#if ABSL_STRTOD_HANDLES_NAN_CORRECTLY |
||||
float strtof_float = strtof(input.c_str(), nullptr); |
||||
EXPECT_TRUE(Identical(from_chars_float, strtof_float)); |
||||
#endif // ABSL_STRTOD_HANDLES_NAN_CORRECTLY
|
||||
|
||||
// Check that we can parse a negative NaN
|
||||
std::string negative_input = "-" + input; |
||||
float negative_from_chars_float; |
||||
absl::from_chars(negative_input.data(), |
||||
negative_input.data() + negative_input.size(), |
||||
negative_from_chars_float); |
||||
EXPECT_TRUE(std::signbit(negative_from_chars_float)); |
||||
EXPECT_FALSE(Identical(negative_from_chars_float, from_chars_float)); |
||||
from_chars_float = std::copysign(from_chars_float, -1.0); |
||||
EXPECT_TRUE(Identical(negative_from_chars_float, from_chars_float)); |
||||
} |
||||
} |
||||
|
||||
// Returns an integer larger than step. The values grow exponentially.
|
||||
int NextStep(int step) { |
||||
return step + (step >> 2) + 1; |
||||
} |
||||
|
||||
// Test a conversion on a family of input strings, checking that the calculation
|
||||
// is correct for in-bounds values, and that overflow and underflow are done
|
||||
// correctly for out-of-bounds values.
|
||||
//
|
||||
// input_generator maps from an integer index to a std::string to test.
|
||||
// expected_generator maps from an integer index to an expected Float value.
|
||||
// from_chars conversion of input_generator(i) should result in
|
||||
// expected_generator(i).
|
||||
//
|
||||
// lower_bound and upper_bound denote the smallest and largest values for which
|
||||
// the conversion is expected to succeed.
|
||||
template <typename Float> |
||||
void TestOverflowAndUnderflow( |
||||
const std::function<std::string(int)>& input_generator, |
||||
const std::function<Float(int)>& expected_generator, int lower_bound, |
||||
int upper_bound) { |
||||
// test legal values near lower_bound
|
||||
int index, step; |
||||
for (index = lower_bound, step = 1; index < upper_bound; |
||||
index += step, step = NextStep(step)) { |
||||
std::string input = input_generator(index); |
||||
SCOPED_TRACE(input); |
||||
Float expected = expected_generator(index); |
||||
Float actual; |
||||
auto result = |
||||
absl::from_chars(input.data(), input.data() + input.size(), actual); |
||||
EXPECT_EQ(result.ec, std::errc()); |
||||
EXPECT_EQ(expected, actual); |
||||
} |
||||
// test legal values near upper_bound
|
||||
for (index = upper_bound, step = 1; index > lower_bound; |
||||
index -= step, step = NextStep(step)) { |
||||
std::string input = input_generator(index); |
||||
SCOPED_TRACE(input); |
||||
Float expected = expected_generator(index); |
||||
Float actual; |
||||
auto result = |
||||
absl::from_chars(input.data(), input.data() + input.size(), actual); |
||||
EXPECT_EQ(result.ec, std::errc()); |
||||
EXPECT_EQ(expected, actual); |
||||
} |
||||
// Test underflow values below lower_bound
|
||||
for (index = lower_bound - 1, step = 1; index > -1000000; |
||||
index -= step, step = NextStep(step)) { |
||||
std::string input = input_generator(index); |
||||
SCOPED_TRACE(input); |
||||
Float actual; |
||||
auto result = |
||||
absl::from_chars(input.data(), input.data() + input.size(), actual); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_LT(actual, 1.0); // check for underflow
|
||||
} |
||||
// Test overflow values above upper_bound
|
||||
for (index = upper_bound + 1, step = 1; index < 1000000; |
||||
index += step, step = NextStep(step)) { |
||||
std::string input = input_generator(index); |
||||
SCOPED_TRACE(input); |
||||
Float actual; |
||||
auto result = |
||||
absl::from_chars(input.data(), input.data() + input.size(), actual); |
||||
EXPECT_EQ(result.ec, std::errc::result_out_of_range); |
||||
EXPECT_GT(actual, 1.0); // check for overflow
|
||||
} |
||||
} |
||||
|
||||
// Check that overflow and underflow are caught correctly for hex doubles.
|
||||
//
|
||||
// The largest representable double is 0x1.fffffffffffffp+1023, and the
|
||||
// smallest representable subnormal is 0x0.0000000000001p-1022, which equals
|
||||
// 0x1p-1074. Therefore 1023 and -1074 are the limits of acceptable exponents
|
||||
// in this test.
|
||||
TEST(FromChars, HexdecimalDoubleLimits) { |
||||
auto input_gen = [](int index) { return absl::StrCat("0x1.0p", index); }; |
||||
auto expected_gen = [](int index) { return std::ldexp(1.0, index); }; |
||||
TestOverflowAndUnderflow<double>(input_gen, expected_gen, -1074, 1023); |
||||
} |
||||
|
||||
// Check that overflow and underflow are caught correctly for hex floats.
|
||||
//
|
||||
// The largest representable float is 0x1.fffffep+127, and the smallest
|
||||
// representable subnormal is 0x0.000002p-126, which equals 0x1p-149.
|
||||
// Therefore 127 and -149 are the limits of acceptable exponents in this test.
|
||||
TEST(FromChars, HexdecimalFloatLimits) { |
||||
auto input_gen = [](int index) { return absl::StrCat("0x1.0p", index); }; |
||||
auto expected_gen = [](int index) { return std::ldexp(1.0f, index); }; |
||||
TestOverflowAndUnderflow<float>(input_gen, expected_gen, -149, 127); |
||||
} |
||||
|
||||
// Check that overflow and underflow are caught correctly for decimal doubles.
|
||||
//
|
||||
// The largest representable double is about 1.8e308, and the smallest
|
||||
// representable subnormal is about 5e-324. '1e-324' therefore rounds away from
|
||||
// the smallest representable positive value. -323 and 308 are the limits of
|
||||
// acceptable exponents in this test.
|
||||
TEST(FromChars, DecimalDoubleLimits) { |
||||
auto input_gen = [](int index) { return absl::StrCat("1.0e", index); }; |
||||
auto expected_gen = [](int index) { return std::pow(10.0, index); }; |
||||
TestOverflowAndUnderflow<double>(input_gen, expected_gen, -323, 308); |
||||
} |
||||
|
||||
// Check that overflow and underflow are caught correctly for decimal floats.
|
||||
//
|
||||
// The largest representable float is about 3.4e38, and the smallest
|
||||
// representable subnormal is about 1.45e-45. '1e-45' therefore rounds towards
|
||||
// the smallest representable positive value. -45 and 38 are the limits of
|
||||
// acceptable exponents in this test.
|
||||
TEST(FromChars, DecimalFloatLimits) { |
||||
auto input_gen = [](int index) { return absl::StrCat("1.0e", index); }; |
||||
auto expected_gen = [](int index) { return std::pow(10.0, index); }; |
||||
TestOverflowAndUnderflow<float>(input_gen, expected_gen, -45, 38); |
||||
} |
||||
|
||||
} // namespace
|
||||
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