1//===----------------------------------------------------------------------===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8 9// Copyright (c) Microsoft Corporation. 10// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 11 12// Copyright 2018 Ulf Adams 13// Copyright (c) Microsoft Corporation. All rights reserved. 14 15// Boost Software License - Version 1.0 - August 17th, 2003 16 17// Permission is hereby granted, free of charge, to any person or organization 18// obtaining a copy of the software and accompanying documentation covered by 19// this license (the "Software") to use, reproduce, display, distribute, 20// execute, and transmit the Software, and to prepare derivative works of the 21// Software, and to permit third-parties to whom the Software is furnished to 22// do so, all subject to the following: 23 24// The copyright notices in the Software and this entire statement, including 25// the above license grant, this restriction and the following disclaimer, 26// must be included in all copies of the Software, in whole or in part, and 27// all derivative works of the Software, unless such copies or derivative 28// works are solely in the form of machine-executable object code generated by 29// a source language processor. 30 31// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 32// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 33// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT 34// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE 35// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, 36// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 37// DEALINGS IN THE SOFTWARE. 38 39// Avoid formatting to keep the changes with the original code minimal. 40// clang-format off 41 42#include <__assert> 43#include <__config> 44#include <charconv> 45#include <cstring> 46#include <system_error> 47 48#include "include/ryu/common.h" 49#include "include/ryu/d2fixed.h" 50#include "include/ryu/d2fixed_full_table.h" 51#include "include/ryu/d2s.h" 52#include "include/ryu/d2s_intrinsics.h" 53#include "include/ryu/digit_table.h" 54 55_LIBCPP_BEGIN_NAMESPACE_STD 56 57inline constexpr int __POW10_ADDITIONAL_BITS = 120; 58 59#ifdef _LIBCPP_INTRINSIC128 60// Returns the low 64 bits of the high 128 bits of the 256-bit product of a and b. 61[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint64_t __umul256_hi128_lo64( 62 const uint64_t __aHi, const uint64_t __aLo, const uint64_t __bHi, const uint64_t __bLo) { 63 uint64_t __b00Hi; 64 const uint64_t __b00Lo = __ryu_umul128(__aLo, __bLo, &__b00Hi); 65 uint64_t __b01Hi; 66 const uint64_t __b01Lo = __ryu_umul128(__aLo, __bHi, &__b01Hi); 67 uint64_t __b10Hi; 68 const uint64_t __b10Lo = __ryu_umul128(__aHi, __bLo, &__b10Hi); 69 uint64_t __b11Hi; 70 const uint64_t __b11Lo = __ryu_umul128(__aHi, __bHi, &__b11Hi); 71 (void) __b00Lo; // unused 72 (void) __b11Hi; // unused 73 const uint64_t __temp1Lo = __b10Lo + __b00Hi; 74 const uint64_t __temp1Hi = __b10Hi + (__temp1Lo < __b10Lo); 75 const uint64_t __temp2Lo = __b01Lo + __temp1Lo; 76 const uint64_t __temp2Hi = __b01Hi + (__temp2Lo < __b01Lo); 77 return __b11Lo + __temp1Hi + __temp2Hi; 78} 79 80[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __uint128_mod1e9(const uint64_t __vHi, const uint64_t __vLo) { 81 // After multiplying, we're going to shift right by 29, then truncate to uint32_t. 82 // This means that we need only 29 + 32 = 61 bits, so we can truncate to uint64_t before shifting. 83 const uint64_t __multiplied = __umul256_hi128_lo64(__vHi, __vLo, 0x89705F4136B4A597u, 0x31680A88F8953031u); 84 85 // For uint32_t truncation, see the __mod1e9() comment in d2s_intrinsics.h. 86 const uint32_t __shifted = static_cast<uint32_t>(__multiplied >> 29); 87 88 return static_cast<uint32_t>(__vLo) - 1000000000 * __shifted; 89} 90#endif // ^^^ intrinsics available ^^^ 91 92[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __mulShift_mod1e9(const uint64_t __m, const uint64_t* const __mul, const int32_t __j) { 93 uint64_t __high0; // 64 94 const uint64_t __low0 = __ryu_umul128(__m, __mul[0], &__high0); // 0 95 uint64_t __high1; // 128 96 const uint64_t __low1 = __ryu_umul128(__m, __mul[1], &__high1); // 64 97 uint64_t __high2; // 192 98 const uint64_t __low2 = __ryu_umul128(__m, __mul[2], &__high2); // 128 99 const uint64_t __s0low = __low0; // 0 100 (void) __s0low; // unused 101 const uint64_t __s0high = __low1 + __high0; // 64 102 const uint32_t __c1 = __s0high < __low1; 103 const uint64_t __s1low = __low2 + __high1 + __c1; // 128 104 const uint32_t __c2 = __s1low < __low2; // __high1 + __c1 can't overflow, so compare against __low2 105 const uint64_t __s1high = __high2 + __c2; // 192 106 _LIBCPP_ASSERT(__j >= 128, ""); 107 _LIBCPP_ASSERT(__j <= 180, ""); 108#ifdef _LIBCPP_INTRINSIC128 109 const uint32_t __dist = static_cast<uint32_t>(__j - 128); // __dist: [0, 52] 110 const uint64_t __shiftedhigh = __s1high >> __dist; 111 const uint64_t __shiftedlow = __ryu_shiftright128(__s1low, __s1high, __dist); 112 return __uint128_mod1e9(__shiftedhigh, __shiftedlow); 113#else // ^^^ intrinsics available ^^^ / vvv intrinsics unavailable vvv 114 if (__j < 160) { // __j: [128, 160) 115 const uint64_t __r0 = __mod1e9(__s1high); 116 const uint64_t __r1 = __mod1e9((__r0 << 32) | (__s1low >> 32)); 117 const uint64_t __r2 = ((__r1 << 32) | (__s1low & 0xffffffff)); 118 return __mod1e9(__r2 >> (__j - 128)); 119 } else { // __j: [160, 192) 120 const uint64_t __r0 = __mod1e9(__s1high); 121 const uint64_t __r1 = ((__r0 << 32) | (__s1low >> 32)); 122 return __mod1e9(__r1 >> (__j - 160)); 123 } 124#endif // ^^^ intrinsics unavailable ^^^ 125} 126 127void __append_n_digits(const uint32_t __olength, uint32_t __digits, char* const __result) { 128 uint32_t __i = 0; 129 while (__digits >= 10000) { 130#ifdef __clang__ // TRANSITION, LLVM-38217 131 const uint32_t __c = __digits - 10000 * (__digits / 10000); 132#else 133 const uint32_t __c = __digits % 10000; 134#endif 135 __digits /= 10000; 136 const uint32_t __c0 = (__c % 100) << 1; 137 const uint32_t __c1 = (__c / 100) << 1; 138 _VSTD::memcpy(__result + __olength - __i - 2, __DIGIT_TABLE + __c0, 2); 139 _VSTD::memcpy(__result + __olength - __i - 4, __DIGIT_TABLE + __c1, 2); 140 __i += 4; 141 } 142 if (__digits >= 100) { 143 const uint32_t __c = (__digits % 100) << 1; 144 __digits /= 100; 145 _VSTD::memcpy(__result + __olength - __i - 2, __DIGIT_TABLE + __c, 2); 146 __i += 2; 147 } 148 if (__digits >= 10) { 149 const uint32_t __c = __digits << 1; 150 _VSTD::memcpy(__result + __olength - __i - 2, __DIGIT_TABLE + __c, 2); 151 } else { 152 __result[0] = static_cast<char>('0' + __digits); 153 } 154} 155 156_LIBCPP_HIDE_FROM_ABI inline void __append_d_digits(const uint32_t __olength, uint32_t __digits, char* const __result) { 157 uint32_t __i = 0; 158 while (__digits >= 10000) { 159#ifdef __clang__ // TRANSITION, LLVM-38217 160 const uint32_t __c = __digits - 10000 * (__digits / 10000); 161#else 162 const uint32_t __c = __digits % 10000; 163#endif 164 __digits /= 10000; 165 const uint32_t __c0 = (__c % 100) << 1; 166 const uint32_t __c1 = (__c / 100) << 1; 167 _VSTD::memcpy(__result + __olength + 1 - __i - 2, __DIGIT_TABLE + __c0, 2); 168 _VSTD::memcpy(__result + __olength + 1 - __i - 4, __DIGIT_TABLE + __c1, 2); 169 __i += 4; 170 } 171 if (__digits >= 100) { 172 const uint32_t __c = (__digits % 100) << 1; 173 __digits /= 100; 174 _VSTD::memcpy(__result + __olength + 1 - __i - 2, __DIGIT_TABLE + __c, 2); 175 __i += 2; 176 } 177 if (__digits >= 10) { 178 const uint32_t __c = __digits << 1; 179 __result[2] = __DIGIT_TABLE[__c + 1]; 180 __result[1] = '.'; 181 __result[0] = __DIGIT_TABLE[__c]; 182 } else { 183 __result[1] = '.'; 184 __result[0] = static_cast<char>('0' + __digits); 185 } 186} 187 188_LIBCPP_HIDE_FROM_ABI inline void __append_c_digits(const uint32_t __count, uint32_t __digits, char* const __result) { 189 uint32_t __i = 0; 190 for (; __i < __count - 1; __i += 2) { 191 const uint32_t __c = (__digits % 100) << 1; 192 __digits /= 100; 193 _VSTD::memcpy(__result + __count - __i - 2, __DIGIT_TABLE + __c, 2); 194 } 195 if (__i < __count) { 196 const char __c = static_cast<char>('0' + (__digits % 10)); 197 __result[__count - __i - 1] = __c; 198 } 199} 200 201void __append_nine_digits(uint32_t __digits, char* const __result) { 202 if (__digits == 0) { 203 _VSTD::memset(__result, '0', 9); 204 return; 205 } 206 207 for (uint32_t __i = 0; __i < 5; __i += 4) { 208#ifdef __clang__ // TRANSITION, LLVM-38217 209 const uint32_t __c = __digits - 10000 * (__digits / 10000); 210#else 211 const uint32_t __c = __digits % 10000; 212#endif 213 __digits /= 10000; 214 const uint32_t __c0 = (__c % 100) << 1; 215 const uint32_t __c1 = (__c / 100) << 1; 216 _VSTD::memcpy(__result + 7 - __i, __DIGIT_TABLE + __c0, 2); 217 _VSTD::memcpy(__result + 5 - __i, __DIGIT_TABLE + __c1, 2); 218 } 219 __result[0] = static_cast<char>('0' + __digits); 220} 221 222[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __indexForExponent(const uint32_t __e) { 223 return (__e + 15) / 16; 224} 225 226[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __pow10BitsForIndex(const uint32_t __idx) { 227 return 16 * __idx + __POW10_ADDITIONAL_BITS; 228} 229 230[[nodiscard]] _LIBCPP_HIDE_FROM_ABI inline uint32_t __lengthForIndex(const uint32_t __idx) { 231 // +1 for ceil, +16 for mantissa, +8 to round up when dividing by 9 232 return (__log10Pow2(16 * static_cast<int32_t>(__idx)) + 1 + 16 + 8) / 9; 233} 234 235[[nodiscard]] to_chars_result __d2fixed_buffered_n(char* _First, char* const _Last, const double __d, 236 const uint32_t __precision) { 237 char* const _Original_first = _First; 238 239 const uint64_t __bits = __double_to_bits(__d); 240 241 // Case distinction; exit early for the easy cases. 242 if (__bits == 0) { 243 const int32_t _Total_zero_length = 1 // leading zero 244 + static_cast<int32_t>(__precision != 0) // possible decimal point 245 + static_cast<int32_t>(__precision); // zeroes after decimal point 246 247 if (_Last - _First < _Total_zero_length) { 248 return { _Last, errc::value_too_large }; 249 } 250 251 *_First++ = '0'; 252 if (__precision > 0) { 253 *_First++ = '.'; 254 _VSTD::memset(_First, '0', __precision); 255 _First += __precision; 256 } 257 return { _First, errc{} }; 258 } 259 260 // Decode __bits into mantissa and exponent. 261 const uint64_t __ieeeMantissa = __bits & ((1ull << __DOUBLE_MANTISSA_BITS) - 1); 262 const uint32_t __ieeeExponent = static_cast<uint32_t>(__bits >> __DOUBLE_MANTISSA_BITS); 263 264 int32_t __e2; 265 uint64_t __m2; 266 if (__ieeeExponent == 0) { 267 __e2 = 1 - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS; 268 __m2 = __ieeeMantissa; 269 } else { 270 __e2 = static_cast<int32_t>(__ieeeExponent) - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS; 271 __m2 = (1ull << __DOUBLE_MANTISSA_BITS) | __ieeeMantissa; 272 } 273 274 bool __nonzero = false; 275 if (__e2 >= -52) { 276 const uint32_t __idx = __e2 < 0 ? 0 : __indexForExponent(static_cast<uint32_t>(__e2)); 277 const uint32_t __p10bits = __pow10BitsForIndex(__idx); 278 const int32_t __len = static_cast<int32_t>(__lengthForIndex(__idx)); 279 for (int32_t __i = __len - 1; __i >= 0; --__i) { 280 const uint32_t __j = __p10bits - __e2; 281 // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is 282 // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers. 283 const uint32_t __digits = __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT[__POW10_OFFSET[__idx] + __i], 284 static_cast<int32_t>(__j + 8)); 285 if (__nonzero) { 286 if (_Last - _First < 9) { 287 return { _Last, errc::value_too_large }; 288 } 289 __append_nine_digits(__digits, _First); 290 _First += 9; 291 } else if (__digits != 0) { 292 const uint32_t __olength = __decimalLength9(__digits); 293 if (_Last - _First < static_cast<ptrdiff_t>(__olength)) { 294 return { _Last, errc::value_too_large }; 295 } 296 __append_n_digits(__olength, __digits, _First); 297 _First += __olength; 298 __nonzero = true; 299 } 300 } 301 } 302 if (!__nonzero) { 303 if (_First == _Last) { 304 return { _Last, errc::value_too_large }; 305 } 306 *_First++ = '0'; 307 } 308 if (__precision > 0) { 309 if (_First == _Last) { 310 return { _Last, errc::value_too_large }; 311 } 312 *_First++ = '.'; 313 } 314 if (__e2 < 0) { 315 const int32_t __idx = -__e2 / 16; 316 const uint32_t __blocks = __precision / 9 + 1; 317 // 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd. 318 int __roundUp = 0; 319 uint32_t __i = 0; 320 if (__blocks <= __MIN_BLOCK_2[__idx]) { 321 __i = __blocks; 322 if (_Last - _First < static_cast<ptrdiff_t>(__precision)) { 323 return { _Last, errc::value_too_large }; 324 } 325 _VSTD::memset(_First, '0', __precision); 326 _First += __precision; 327 } else if (__i < __MIN_BLOCK_2[__idx]) { 328 __i = __MIN_BLOCK_2[__idx]; 329 if (_Last - _First < static_cast<ptrdiff_t>(9 * __i)) { 330 return { _Last, errc::value_too_large }; 331 } 332 _VSTD::memset(_First, '0', 9 * __i); 333 _First += 9 * __i; 334 } 335 for (; __i < __blocks; ++__i) { 336 const int32_t __j = __ADDITIONAL_BITS_2 + (-__e2 - 16 * __idx); 337 const uint32_t __p = __POW10_OFFSET_2[__idx] + __i - __MIN_BLOCK_2[__idx]; 338 if (__p >= __POW10_OFFSET_2[__idx + 1]) { 339 // If the remaining digits are all 0, then we might as well use memset. 340 // No rounding required in this case. 341 const uint32_t __fill = __precision - 9 * __i; 342 if (_Last - _First < static_cast<ptrdiff_t>(__fill)) { 343 return { _Last, errc::value_too_large }; 344 } 345 _VSTD::memset(_First, '0', __fill); 346 _First += __fill; 347 break; 348 } 349 // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is 350 // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers. 351 uint32_t __digits = __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT_2[__p], __j + 8); 352 if (__i < __blocks - 1) { 353 if (_Last - _First < 9) { 354 return { _Last, errc::value_too_large }; 355 } 356 __append_nine_digits(__digits, _First); 357 _First += 9; 358 } else { 359 const uint32_t __maximum = __precision - 9 * __i; 360 uint32_t __lastDigit = 0; 361 for (uint32_t __k = 0; __k < 9 - __maximum; ++__k) { 362 __lastDigit = __digits % 10; 363 __digits /= 10; 364 } 365 if (__lastDigit != 5) { 366 __roundUp = __lastDigit > 5; 367 } else { 368 // Is m * 10^(additionalDigits + 1) / 2^(-__e2) integer? 369 const int32_t __requiredTwos = -__e2 - static_cast<int32_t>(__precision) - 1; 370 const bool __trailingZeros = __requiredTwos <= 0 371 || (__requiredTwos < 60 && __multipleOfPowerOf2(__m2, static_cast<uint32_t>(__requiredTwos))); 372 __roundUp = __trailingZeros ? 2 : 1; 373 } 374 if (__maximum > 0) { 375 if (_Last - _First < static_cast<ptrdiff_t>(__maximum)) { 376 return { _Last, errc::value_too_large }; 377 } 378 __append_c_digits(__maximum, __digits, _First); 379 _First += __maximum; 380 } 381 break; 382 } 383 } 384 if (__roundUp != 0) { 385 char* _Round = _First; 386 char* _Dot = _Last; 387 while (true) { 388 if (_Round == _Original_first) { 389 _Round[0] = '1'; 390 if (_Dot != _Last) { 391 _Dot[0] = '0'; 392 _Dot[1] = '.'; 393 } 394 if (_First == _Last) { 395 return { _Last, errc::value_too_large }; 396 } 397 *_First++ = '0'; 398 break; 399 } 400 --_Round; 401 const char __c = _Round[0]; 402 if (__c == '.') { 403 _Dot = _Round; 404 } else if (__c == '9') { 405 _Round[0] = '0'; 406 __roundUp = 1; 407 } else { 408 if (__roundUp == 1 || __c % 2 != 0) { 409 _Round[0] = __c + 1; 410 } 411 break; 412 } 413 } 414 } 415 } else { 416 if (_Last - _First < static_cast<ptrdiff_t>(__precision)) { 417 return { _Last, errc::value_too_large }; 418 } 419 _VSTD::memset(_First, '0', __precision); 420 _First += __precision; 421 } 422 return { _First, errc{} }; 423} 424 425[[nodiscard]] to_chars_result __d2exp_buffered_n(char* _First, char* const _Last, const double __d, 426 uint32_t __precision) { 427 char* const _Original_first = _First; 428 429 const uint64_t __bits = __double_to_bits(__d); 430 431 // Case distinction; exit early for the easy cases. 432 if (__bits == 0) { 433 const int32_t _Total_zero_length = 1 // leading zero 434 + static_cast<int32_t>(__precision != 0) // possible decimal point 435 + static_cast<int32_t>(__precision) // zeroes after decimal point 436 + 4; // "e+00" 437 if (_Last - _First < _Total_zero_length) { 438 return { _Last, errc::value_too_large }; 439 } 440 *_First++ = '0'; 441 if (__precision > 0) { 442 *_First++ = '.'; 443 _VSTD::memset(_First, '0', __precision); 444 _First += __precision; 445 } 446 _VSTD::memcpy(_First, "e+00", 4); 447 _First += 4; 448 return { _First, errc{} }; 449 } 450 451 // Decode __bits into mantissa and exponent. 452 const uint64_t __ieeeMantissa = __bits & ((1ull << __DOUBLE_MANTISSA_BITS) - 1); 453 const uint32_t __ieeeExponent = static_cast<uint32_t>(__bits >> __DOUBLE_MANTISSA_BITS); 454 455 int32_t __e2; 456 uint64_t __m2; 457 if (__ieeeExponent == 0) { 458 __e2 = 1 - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS; 459 __m2 = __ieeeMantissa; 460 } else { 461 __e2 = static_cast<int32_t>(__ieeeExponent) - __DOUBLE_BIAS - __DOUBLE_MANTISSA_BITS; 462 __m2 = (1ull << __DOUBLE_MANTISSA_BITS) | __ieeeMantissa; 463 } 464 465 const bool __printDecimalPoint = __precision > 0; 466 ++__precision; 467 uint32_t __digits = 0; 468 uint32_t __printedDigits = 0; 469 uint32_t __availableDigits = 0; 470 int32_t __exp = 0; 471 if (__e2 >= -52) { 472 const uint32_t __idx = __e2 < 0 ? 0 : __indexForExponent(static_cast<uint32_t>(__e2)); 473 const uint32_t __p10bits = __pow10BitsForIndex(__idx); 474 const int32_t __len = static_cast<int32_t>(__lengthForIndex(__idx)); 475 for (int32_t __i = __len - 1; __i >= 0; --__i) { 476 const uint32_t __j = __p10bits - __e2; 477 // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is 478 // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers. 479 __digits = __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT[__POW10_OFFSET[__idx] + __i], 480 static_cast<int32_t>(__j + 8)); 481 if (__printedDigits != 0) { 482 if (__printedDigits + 9 > __precision) { 483 __availableDigits = 9; 484 break; 485 } 486 if (_Last - _First < 9) { 487 return { _Last, errc::value_too_large }; 488 } 489 __append_nine_digits(__digits, _First); 490 _First += 9; 491 __printedDigits += 9; 492 } else if (__digits != 0) { 493 __availableDigits = __decimalLength9(__digits); 494 __exp = __i * 9 + static_cast<int32_t>(__availableDigits) - 1; 495 if (__availableDigits > __precision) { 496 break; 497 } 498 if (__printDecimalPoint) { 499 if (_Last - _First < static_cast<ptrdiff_t>(__availableDigits + 1)) { 500 return { _Last, errc::value_too_large }; 501 } 502 __append_d_digits(__availableDigits, __digits, _First); 503 _First += __availableDigits + 1; // +1 for decimal point 504 } else { 505 if (_First == _Last) { 506 return { _Last, errc::value_too_large }; 507 } 508 *_First++ = static_cast<char>('0' + __digits); 509 } 510 __printedDigits = __availableDigits; 511 __availableDigits = 0; 512 } 513 } 514 } 515 516 if (__e2 < 0 && __availableDigits == 0) { 517 const int32_t __idx = -__e2 / 16; 518 for (int32_t __i = __MIN_BLOCK_2[__idx]; __i < 200; ++__i) { 519 const int32_t __j = __ADDITIONAL_BITS_2 + (-__e2 - 16 * __idx); 520 const uint32_t __p = __POW10_OFFSET_2[__idx] + static_cast<uint32_t>(__i) - __MIN_BLOCK_2[__idx]; 521 // Temporary: __j is usually around 128, and by shifting a bit, we push it to 128 or above, which is 522 // a slightly faster code path in __mulShift_mod1e9. Instead, we can just increase the multipliers. 523 __digits = (__p >= __POW10_OFFSET_2[__idx + 1]) ? 0 : __mulShift_mod1e9(__m2 << 8, __POW10_SPLIT_2[__p], __j + 8); 524 if (__printedDigits != 0) { 525 if (__printedDigits + 9 > __precision) { 526 __availableDigits = 9; 527 break; 528 } 529 if (_Last - _First < 9) { 530 return { _Last, errc::value_too_large }; 531 } 532 __append_nine_digits(__digits, _First); 533 _First += 9; 534 __printedDigits += 9; 535 } else if (__digits != 0) { 536 __availableDigits = __decimalLength9(__digits); 537 __exp = -(__i + 1) * 9 + static_cast<int32_t>(__availableDigits) - 1; 538 if (__availableDigits > __precision) { 539 break; 540 } 541 if (__printDecimalPoint) { 542 if (_Last - _First < static_cast<ptrdiff_t>(__availableDigits + 1)) { 543 return { _Last, errc::value_too_large }; 544 } 545 __append_d_digits(__availableDigits, __digits, _First); 546 _First += __availableDigits + 1; // +1 for decimal point 547 } else { 548 if (_First == _Last) { 549 return { _Last, errc::value_too_large }; 550 } 551 *_First++ = static_cast<char>('0' + __digits); 552 } 553 __printedDigits = __availableDigits; 554 __availableDigits = 0; 555 } 556 } 557 } 558 559 const uint32_t __maximum = __precision - __printedDigits; 560 if (__availableDigits == 0) { 561 __digits = 0; 562 } 563 uint32_t __lastDigit = 0; 564 if (__availableDigits > __maximum) { 565 for (uint32_t __k = 0; __k < __availableDigits - __maximum; ++__k) { 566 __lastDigit = __digits % 10; 567 __digits /= 10; 568 } 569 } 570 // 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd. 571 int __roundUp = 0; 572 if (__lastDigit != 5) { 573 __roundUp = __lastDigit > 5; 574 } else { 575 // Is m * 2^__e2 * 10^(__precision + 1 - __exp) integer? 576 // __precision was already increased by 1, so we don't need to write + 1 here. 577 const int32_t __rexp = static_cast<int32_t>(__precision) - __exp; 578 const int32_t __requiredTwos = -__e2 - __rexp; 579 bool __trailingZeros = __requiredTwos <= 0 580 || (__requiredTwos < 60 && __multipleOfPowerOf2(__m2, static_cast<uint32_t>(__requiredTwos))); 581 if (__rexp < 0) { 582 const int32_t __requiredFives = -__rexp; 583 __trailingZeros = __trailingZeros && __multipleOfPowerOf5(__m2, static_cast<uint32_t>(__requiredFives)); 584 } 585 __roundUp = __trailingZeros ? 2 : 1; 586 } 587 if (__printedDigits != 0) { 588 if (_Last - _First < static_cast<ptrdiff_t>(__maximum)) { 589 return { _Last, errc::value_too_large }; 590 } 591 if (__digits == 0) { 592 _VSTD::memset(_First, '0', __maximum); 593 } else { 594 __append_c_digits(__maximum, __digits, _First); 595 } 596 _First += __maximum; 597 } else { 598 if (__printDecimalPoint) { 599 if (_Last - _First < static_cast<ptrdiff_t>(__maximum + 1)) { 600 return { _Last, errc::value_too_large }; 601 } 602 __append_d_digits(__maximum, __digits, _First); 603 _First += __maximum + 1; // +1 for decimal point 604 } else { 605 if (_First == _Last) { 606 return { _Last, errc::value_too_large }; 607 } 608 *_First++ = static_cast<char>('0' + __digits); 609 } 610 } 611 if (__roundUp != 0) { 612 char* _Round = _First; 613 while (true) { 614 if (_Round == _Original_first) { 615 _Round[0] = '1'; 616 ++__exp; 617 break; 618 } 619 --_Round; 620 const char __c = _Round[0]; 621 if (__c == '.') { 622 // Keep going. 623 } else if (__c == '9') { 624 _Round[0] = '0'; 625 __roundUp = 1; 626 } else { 627 if (__roundUp == 1 || __c % 2 != 0) { 628 _Round[0] = __c + 1; 629 } 630 break; 631 } 632 } 633 } 634 635 char _Sign_character; 636 637 if (__exp < 0) { 638 _Sign_character = '-'; 639 __exp = -__exp; 640 } else { 641 _Sign_character = '+'; 642 } 643 644 const int _Exponent_part_length = __exp >= 100 645 ? 5 // "e+NNN" 646 : 4; // "e+NN" 647 648 if (_Last - _First < _Exponent_part_length) { 649 return { _Last, errc::value_too_large }; 650 } 651 652 *_First++ = 'e'; 653 *_First++ = _Sign_character; 654 655 if (__exp >= 100) { 656 const int32_t __c = __exp % 10; 657 _VSTD::memcpy(_First, __DIGIT_TABLE + 2 * (__exp / 10), 2); 658 _First[2] = static_cast<char>('0' + __c); 659 _First += 3; 660 } else { 661 _VSTD::memcpy(_First, __DIGIT_TABLE + 2 * __exp, 2); 662 _First += 2; 663 } 664 665 return { _First, errc{} }; 666} 667 668_LIBCPP_END_NAMESPACE_STD 669 670// clang-format on 671