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 #ifndef _LIBCPP___CHARCONV_TO_CHARS_BASE_10_H 11 #define _LIBCPP___CHARCONV_TO_CHARS_BASE_10_H 12 13 #include <__algorithm/copy_n.h> 14 #include <__charconv/tables.h> 15 #include <__config> 16 #include <cstdint> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 #ifndef _LIBCPP_CXX03_LANG 25 26 namespace __itoa { 27 28 _LIBCPP_HIDE_FROM_ABI inline char* __append1(char* __first, uint32_t __value) noexcept { 29 *__first = '0' + static_cast<char>(__value); 30 return __first + 1; 31 } 32 33 _LIBCPP_HIDE_FROM_ABI inline char* __append2(char* __first, uint32_t __value) noexcept { 34 return std::copy_n(&__table<>::__digits_base_10[__value * 2], 2, __first); 35 } 36 37 _LIBCPP_HIDE_FROM_ABI inline char* __append3(char* __first, uint32_t __value) noexcept { 38 return __itoa::__append2(__itoa::__append1(__first, __value / 100), __value % 100); 39 } 40 41 _LIBCPP_HIDE_FROM_ABI inline char* __append4(char* __first, uint32_t __value) noexcept { 42 return __itoa::__append2(__itoa::__append2(__first, __value / 100), __value % 100); 43 } 44 45 _LIBCPP_HIDE_FROM_ABI inline char* __append5(char* __first, uint32_t __value) noexcept { 46 return __itoa::__append4(__itoa::__append1(__first, __value / 10000), __value % 10000); 47 } 48 49 _LIBCPP_HIDE_FROM_ABI inline char* __append6(char* __first, uint32_t __value) noexcept { 50 return __itoa::__append4(__itoa::__append2(__first, __value / 10000), __value % 10000); 51 } 52 53 _LIBCPP_HIDE_FROM_ABI inline char* __append7(char* __first, uint32_t __value) noexcept { 54 return __itoa::__append6(__itoa::__append1(__first, __value / 1000000), __value % 1000000); 55 } 56 57 _LIBCPP_HIDE_FROM_ABI inline char* __append8(char* __first, uint32_t __value) noexcept { 58 return __itoa::__append6(__itoa::__append2(__first, __value / 1000000), __value % 1000000); 59 } 60 61 _LIBCPP_HIDE_FROM_ABI inline char* __append9(char* __first, uint32_t __value) noexcept { 62 return __itoa::__append8(__itoa::__append1(__first, __value / 100000000), __value % 100000000); 63 } 64 65 // This function is used for uint32_t and uint64_t. 66 template <class _Tp> 67 _LIBCPP_HIDE_FROM_ABI char* __append10(char* __first, _Tp __value) noexcept { 68 return __itoa::__append8(__itoa::__append2(__first, static_cast<uint32_t>(__value / 100000000)), 69 static_cast<uint32_t>(__value % 100000000)); 70 } 71 72 _LIBCPP_HIDE_FROM_ABI inline char* __base_10_u32(char* __first, uint32_t __value) noexcept { 73 if (__value < 1000000) { 74 if (__value < 10000) { 75 if (__value < 100) { 76 // 0 <= __value < 100 77 if (__value < 10) 78 return __itoa::__append1(__first, __value); 79 return __itoa::__append2(__first, __value); 80 } 81 // 100 <= __value < 10'000 82 if (__value < 1000) 83 return __itoa::__append3(__first, __value); 84 return __itoa::__append4(__first, __value); 85 } 86 87 // 10'000 <= __value < 1'000'000 88 if (__value < 100000) 89 return __itoa::__append5(__first, __value); 90 return __itoa::__append6(__first, __value); 91 } 92 93 // __value => 1'000'000 94 if (__value < 100000000) { 95 // 1'000'000 <= __value < 100'000'000 96 if (__value < 10000000) 97 return __itoa::__append7(__first, __value); 98 return __itoa::__append8(__first, __value); 99 } 100 101 // 100'000'000 <= __value < max 102 if (__value < 1000000000) 103 return __itoa::__append9(__first, __value); 104 return __itoa::__append10(__first, __value); 105 } 106 107 _LIBCPP_HIDE_FROM_ABI inline char* __base_10_u64(char* __buffer, uint64_t __value) noexcept { 108 if (__value <= UINT32_MAX) 109 return __itoa::__base_10_u32(__buffer, static_cast<uint32_t>(__value)); 110 111 // Numbers in the range UINT32_MAX <= val < 10'000'000'000 always contain 10 112 // digits and are outputted after this if statement. 113 if (__value >= 10000000000) { 114 // This function properly deterimines the first non-zero leading digit. 115 __buffer = __itoa::__base_10_u32(__buffer, static_cast<uint32_t>(__value / 10000000000)); 116 __value %= 10000000000; 117 } 118 return __itoa::__append10(__buffer, __value); 119 } 120 121 } // namespace __itoa 122 123 #endif // _LIBCPP_CXX03_LANG 124 125 _LIBCPP_END_NAMESPACE_STD 126 127 #endif // _LIBCPP___CHARCONV_TO_CHARS_BASE_10_H 128