1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 // Copyright (c) Microsoft Corporation.
11 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
12 
13 
14 // Copyright 2018 Ulf Adams
15 // Copyright (c) Microsoft Corporation. All rights reserved.
16 
17 // Boost Software License - Version 1.0 - August 17th, 2003
18 
19 // Permission is hereby granted, free of charge, to any person or organization
20 // obtaining a copy of the software and accompanying documentation covered by
21 // this license (the "Software") to use, reproduce, display, distribute,
22 // execute, and transmit the Software, and to prepare derivative works of the
23 // Software, and to permit third-parties to whom the Software is furnished to
24 // do so, all subject to the following:
25 
26 // The copyright notices in the Software and this entire statement, including
27 // the above license grant, this restriction and the following disclaimer,
28 // must be included in all copies of the Software, in whole or in part, and
29 // all derivative works of the Software, unless such copies or derivative
30 // works are solely in the form of machine-executable object code generated by
31 // a source language processor.
32 
33 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
34 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
35 // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
36 // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
37 // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
38 // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
39 // DEALINGS IN THE SOFTWARE.
40 
41 #ifndef _LIBCPP_SRC_INCLUDE_RYU_RYU_H
42 #define _LIBCPP_SRC_INCLUDE_RYU_RYU_H
43 
44 // Avoid formatting to keep the changes with the original code minimal.
45 // clang-format off
46 
47 #include <__charconv/chars_format.h>
48 #include <__charconv/to_chars_result.h>
49 #include <__config>
50 #include <__debug>
51 #include <__errc>
52 #include <cstdint>
53 #include <cstring>
54 #include <type_traits>
55 
56 #include "include/ryu/f2s.h"
57 #include "include/ryu/d2s.h"
58 #include "include/ryu/d2fixed.h"
59 
60 #if defined(_MSC_VER)
61 #include <intrin.h> // for _umul128(), __shiftright128(), _BitScanForward{,64}
62 #endif // defined(_MSC_VER)
63 
64 #if defined(_WIN64) || defined(_M_AMD64) || defined(__x86_64__) ||  defined(__aarch64__)
65 #define _LIBCPP_64_BIT
66 #endif
67 
68 _LIBCPP_BEGIN_NAMESPACE_STD
69 
70 // https://github.com/ulfjack/ryu/tree/59661c3/ryu
71 
72 #if !defined(_MSC_VER)
73 _LIBCPP_HIDE_FROM_ABI inline unsigned char _BitScanForward64(unsigned long* __index, unsigned long long __mask) {
74   if (__mask == 0) {
75     return false;
76   }
77   *__index = __builtin_ctzll(__mask);
78   return true;
79 }
80 
81 _LIBCPP_HIDE_FROM_ABI inline unsigned char _BitScanForward(unsigned long* __index, unsigned int __mask) {
82   if (__mask == 0) {
83     return false;
84   }
85   *__index = __builtin_ctz(__mask);
86   return true;
87 }
88 #endif  // !_MSC_VER
89 
90 template <class _Floating>
91 [[nodiscard]] to_chars_result _Floating_to_chars_ryu(
92     char* const _First, char* const _Last, const _Floating _Value, const chars_format _Fmt) noexcept {
93     if constexpr (_IsSame<_Floating, float>::value) {
94         return __f2s_buffered_n(_First, _Last, _Value, _Fmt);
95     } else {
96         return __d2s_buffered_n(_First, _Last, _Value, _Fmt);
97     }
98 }
99 
100 template <class _Floating>
101 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI to_chars_result _Floating_to_chars_scientific_precision(
102     char* const _First, char* const _Last, const _Floating _Value, int _Precision) noexcept {
103 
104     // C11 7.21.6.1 "The fprintf function"/5:
105     // "A negative precision argument is taken as if the precision were omitted."
106     // /8: "e,E [...] if the precision is missing, it is taken as 6"
107 
108     if (_Precision < 0) {
109         _Precision = 6;
110     } else if (_Precision < 1'000'000'000) { // Match ' to fix compilation with GCC in C++11 mode
111         // _Precision is ok.
112     } else {
113         // Avoid integer overflow.
114         // (This defensive check is slightly nonconformant; it can be carefully improved in the future.)
115         return {_Last, errc::value_too_large};
116     }
117 
118     return __d2exp_buffered_n(_First, _Last, _Value, static_cast<uint32_t>(_Precision));
119 }
120 
121 template <class _Floating>
122 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI to_chars_result _Floating_to_chars_fixed_precision(
123     char* const _First, char* const _Last, const _Floating _Value, int _Precision) noexcept {
124 
125     // C11 7.21.6.1 "The fprintf function"/5:
126     // "A negative precision argument is taken as if the precision were omitted."
127     // /8: "f,F [...] If the precision is missing, it is taken as 6"
128 
129     if (_Precision < 0) {
130         _Precision = 6;
131     } else if (_Precision < 1'000'000'000) { // Match ' to fix compilation with GCC in C++11 mode
132         // _Precision is ok.
133     } else {
134         // Avoid integer overflow.
135         // (This defensive check is slightly nonconformant; it can be carefully improved in the future.)
136         return {_Last, errc::value_too_large};
137     }
138 
139     return __d2fixed_buffered_n(_First, _Last, _Value, static_cast<uint32_t>(_Precision));
140 }
141 
142 #undef _LIBCPP_64_BIT
143 #undef _LIBCPP_INTRINSIC128
144 
145 _LIBCPP_END_NAMESPACE_STD
146 
147 // clang-format on
148 
149 #endif // _LIBCPP_SRC_INCLUDE_RYU_RYU_H
150