4e5f8b4d8d
Use expm1f(x) = exp(x) - 1 for |x| > ln(2). For |x| <= ln(2), divide it into 3 subintervals: [-ln2, -1/8], [-1/8, 1/8], [1/8, ln2] and use a degree-6 polynomial approximation generated by Sollya's fpminmax for each interval. Errors < 1.5 ULPs when we use fma to evaluate the polynomials. Differential Revision: https://reviews.llvm.org/D101134
70 lines
2.2 KiB
C++
70 lines
2.2 KiB
C++
//===-- Bit patterns of common floating point numbers -----------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_UTILS_FPUTIL_BIT_PATTERNS_H
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#define LLVM_LIBC_UTILS_FPUTIL_BIT_PATTERNS_H
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#include "FloatProperties.h"
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#include <float.h>
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static_assert(
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FLT_RADIX == 2,
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"LLVM libc only supports radix 2 IEEE 754 floating point formats.");
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namespace __llvm_libc {
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namespace fputil {
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template <typename T> struct BitPatterns {};
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template <> struct BitPatterns<float> {
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using BitsType = FloatProperties<float>::BitsType;
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static constexpr BitsType inf = 0x7f800000U;
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static constexpr BitsType negInf = 0xff800000U;
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static constexpr BitsType zero = 0x0;
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static constexpr BitsType negZero = 0x80000000U;
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static constexpr BitsType one = 0x3f800000U;
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static constexpr BitsType negOne = 0xbf800000U;
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// Examples of quiet NAN.
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static constexpr BitsType aQuietNaN = 0x7fc00000U;
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static constexpr BitsType aNegativeQuietNaN = 0xffc00000U;
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// Examples of signalling NAN.
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static constexpr BitsType aSignallingNaN = 0x7f800001U;
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static constexpr BitsType aNegativeSignallingNaN = 0xff800001U;
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};
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template <> struct BitPatterns<double> {
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using BitsType = FloatProperties<double>::BitsType;
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static constexpr BitsType inf = 0x7ff0000000000000ULL;
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static constexpr BitsType negInf = 0xfff0000000000000ULL;
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static constexpr BitsType zero = 0x0ULL;
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static constexpr BitsType negZero = 0x8000000000000000ULL;
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static constexpr BitsType one = 0x3FF0000000000000ULL;
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// Examples of quiet NAN.
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static constexpr BitsType aQuietNaN = 0x7ff8000000000000ULL;
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static constexpr BitsType aNegativeQuietNaN = 0xfff8000000000000ULL;
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// Examples of signalling NAN.
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static constexpr BitsType aSignallingNaN = 0x7ff0000000000001ULL;
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static constexpr BitsType aNegativeSignallingNaN = 0xfff0000000000001ULL;
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};
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} // namespace fputil
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} // namespace __llvm_libc
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#endif // LLVM_LIBC_UTILS_FPUTIL_BIT_PATTERNS_H
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