19a21ec41a2007f01ba18cf5fa48f7987e40e5109ulan@chromium.org// Copyright 2012 the V8 project authors. All rights reserved. 2b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// Redistribution and use in source and binary forms, with or without 3b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// modification, are permitted provided that the following conditions are 4b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// met: 5b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// 6b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// * Redistributions of source code must retain the above copyright 7b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// notice, this list of conditions and the following disclaimer. 8b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// * Redistributions in binary form must reproduce the above 9b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// copyright notice, this list of conditions and the following 10b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// disclaimer in the documentation and/or other materials provided 11b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// with the distribution. 12b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// * Neither the name of Google Inc. nor the names of its 13b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// contributors may be used to endorse or promote products derived 14b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// from this software without specific prior written permission. 15b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// 16b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 28b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org#include <stdarg.h> 2977ca49ac05d25684c89442029c22f5b2bce94395ulan@chromium.org#include <cmath> 30b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 3155ee80713569ab0324fc8dcedcb5518501daa6a6ricow@chromium.org#include "globals.h" 32ddda9e81d3175130f2029c0e1205d265a00c32edjkummerow@chromium.org#include "utils.h" 33b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org#include "strtod.h" 3401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org#include "bignum.h" 35303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org#include "cached-powers.h" 36303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org#include "double.h" 37b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 38b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.orgnamespace v8 { 39b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.orgnamespace internal { 40b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 41b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// 2^53 = 9007199254740992. 42b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// Any integer with at most 15 decimal digits will hence fit into a double 43b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org// (which has a 53bit significand) without loss of precision. 44b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.orgstatic const int kMaxExactDoubleIntegerDecimalDigits = 15; 45303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// 2^64 = 18446744073709551616 > 10^19 46b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.orgstatic const int kMaxUint64DecimalDigits = 19; 47303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 4842841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org// Max double: 1.7976931348623157 x 10^308 4942841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org// Min non-zero double: 4.9406564584124654 x 10^-324 5042841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org// Any x >= 10^309 is interpreted as +infinity. 5142841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org// Any x <= 10^-324 is interpreted as 0. 5242841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org// Note that 2.5e-324 (despite being smaller than the min double) will be read 5342841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org// as non-zero (equal to the min non-zero double). 5442841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.orgstatic const int kMaxDecimalPower = 309; 5542841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.orgstatic const int kMinDecimalPower = -324; 56b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 57303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// 2^64 = 18446744073709551616 58303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.orgstatic const uint64_t kMaxUint64 = V8_2PART_UINT64_C(0xFFFFFFFF, FFFFFFFF); 59303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 60303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 61b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.orgstatic const double exact_powers_of_ten[] = { 62b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1.0, // 10^0 63b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10.0, 64b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 100.0, 65b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1000.0, 66b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10000.0, 67b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 100000.0, 68b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1000000.0, 69b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10000000.0, 70b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 100000000.0, 71b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1000000000.0, 72b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10000000000.0, // 10^10 73b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 100000000000.0, 74b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1000000000000.0, 75b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10000000000000.0, 76b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 100000000000000.0, 77b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1000000000000000.0, 78b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10000000000000000.0, 79b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 100000000000000000.0, 80b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1000000000000000000.0, 81b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10000000000000000000.0, 82b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 100000000000000000000.0, // 10^20 83b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 1000000000000000000000.0, 84b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // 10^22 = 0x21e19e0c9bab2400000 = 0x878678326eac9 * 2^22 85b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 10000000000000000000000.0 86b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org}; 87b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.orgstatic const int kExactPowersOfTenSize = ARRAY_SIZE(exact_powers_of_ten); 88b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 8901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// Maximum number of significant digits in the decimal representation. 9001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// In fact the value is 772 (see conversions.cc), but to give us some margin 9101fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// we round up to 780. 9201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.orgstatic const int kMaxSignificantDecimalDigits = 780; 93b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 9442841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.orgstatic Vector<const char> TrimLeadingZeros(Vector<const char> buffer) { 9542841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org for (int i = 0; i < buffer.length(); i++) { 9642841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org if (buffer[i] != '0') { 97303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org return buffer.SubVector(i, buffer.length()); 9842841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org } 9942841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org } 10042841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org return Vector<const char>(buffer.start(), 0); 10142841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org} 10242841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org 10342841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org 10442841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.orgstatic Vector<const char> TrimTrailingZeros(Vector<const char> buffer) { 105b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org for (int i = buffer.length() - 1; i >= 0; --i) { 106b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org if (buffer[i] != '0') { 107303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org return buffer.SubVector(0, i + 1); 108b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org } 109b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org } 11042841968c3c92e3b07bcd67e79eb6ba3f83032c1vegorov@chromium.org return Vector<const char>(buffer.start(), 0); 111b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org} 112b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 113b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 11401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.orgstatic void TrimToMaxSignificantDigits(Vector<const char> buffer, 11501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org int exponent, 11601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org char* significant_buffer, 11701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org int* significant_exponent) { 11801fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org for (int i = 0; i < kMaxSignificantDecimalDigits - 1; ++i) { 11901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org significant_buffer[i] = buffer[i]; 12001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } 12101fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // The input buffer has been trimmed. Therefore the last digit must be 12201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // different from '0'. 12301fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org ASSERT(buffer[buffer.length() - 1] != '0'); 12401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // Set the last digit to be non-zero. This is sufficient to guarantee 12501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // correct rounding. 12601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org significant_buffer[kMaxSignificantDecimalDigits - 1] = '1'; 12701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org *significant_exponent = 12801fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org exponent + (buffer.length() - kMaxSignificantDecimalDigits); 12901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org} 13001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org 131e0e1b0d3e70c933d36ed381d511e9fda39f2a751mstarzinger@chromium.org 132303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// Reads digits from the buffer and converts them to a uint64. 133303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// Reads in as many digits as fit into a uint64. 134303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// When the string starts with "1844674407370955161" no further digit is read. 135303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// Since 2^64 = 18446744073709551616 it would still be possible read another 136303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// digit if it was less or equal than 6, but this would complicate the code. 137303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.orgstatic uint64_t ReadUint64(Vector<const char> buffer, 138303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int* number_of_read_digits) { 139b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org uint64_t result = 0; 140303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int i = 0; 141303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org while (i < buffer.length() && result <= (kMaxUint64 / 10 - 1)) { 142303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int digit = buffer[i++] - '0'; 143b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org ASSERT(0 <= digit && digit <= 9); 144b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org result = 10 * result + digit; 145b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org } 146303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *number_of_read_digits = i; 147b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org return result; 148b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org} 149b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 150b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 151303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// Reads a DiyFp from the buffer. 152303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// The returned DiyFp is not necessarily normalized. 153303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// If remaining_decimals is zero then the returned DiyFp is accurate. 154303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// Otherwise it has been rounded and has error of at most 1/2 ulp. 155303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.orgstatic void ReadDiyFp(Vector<const char> buffer, 156303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org DiyFp* result, 157303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int* remaining_decimals) { 158303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int read_digits; 159303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org uint64_t significand = ReadUint64(buffer, &read_digits); 160303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (buffer.length() == read_digits) { 161303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *result = DiyFp(significand, 0); 162303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *remaining_decimals = 0; 163303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } else { 164303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Round the significand. 165303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (buffer[read_digits] >= '5') { 166303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org significand++; 167303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 168303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Compute the binary exponent. 169303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int exponent = 0; 170303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *result = DiyFp(significand, exponent); 171303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *remaining_decimals = buffer.length() - read_digits; 172303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 173303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org} 174303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 175303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 1764a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.orgstatic bool DoubleStrtod(Vector<const char> trimmed, 1774a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org int exponent, 1784a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org double* result) { 179e0e1b0d3e70c933d36ed381d511e9fda39f2a751mstarzinger@chromium.org#if (V8_TARGET_ARCH_IA32 || defined(USE_SIMULATOR)) && !defined(_MSC_VER) 1804a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org // On x86 the floating-point stack can be 64 or 80 bits wide. If it is 1814a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org // 80 bits wide (as is the case on Linux) then double-rounding occurs and the 1824a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org // result is not accurate. 1839a21ec41a2007f01ba18cf5fa48f7987e40e5109ulan@chromium.org // We know that Windows32 with MSVC, unlike with MinGW32, uses 64 bits and is 1849a21ec41a2007f01ba18cf5fa48f7987e40e5109ulan@chromium.org // therefore accurate. 1859a21ec41a2007f01ba18cf5fa48f7987e40e5109ulan@chromium.org // Note that the ARM and MIPS simulators are compiled for 32bits. They 1869a21ec41a2007f01ba18cf5fa48f7987e40e5109ulan@chromium.org // therefore exhibit the same problem. 1874a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org return false; 1884a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org#endif 189b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org if (trimmed.length() <= kMaxExactDoubleIntegerDecimalDigits) { 190303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int read_digits; 191b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // The trimmed input fits into a double. 192b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // If the 10^exponent (resp. 10^-exponent) fits into a double too then we 193b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // can compute the result-double simply by multiplying (resp. dividing) the 194b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // two numbers. 195b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // This is possible because IEEE guarantees that floating-point operations 196b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // return the best possible approximation. 197b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org if (exponent < 0 && -exponent < kExactPowersOfTenSize) { 198b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // 10^-exponent fits into a double. 199303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *result = static_cast<double>(ReadUint64(trimmed, &read_digits)); 200303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(read_digits == trimmed.length()); 2014a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org *result /= exact_powers_of_ten[-exponent]; 2024a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org return true; 203b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org } 204b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org if (0 <= exponent && exponent < kExactPowersOfTenSize) { 205b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // 10^exponent fits into a double. 206303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *result = static_cast<double>(ReadUint64(trimmed, &read_digits)); 207303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(read_digits == trimmed.length()); 2084a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org *result *= exact_powers_of_ten[exponent]; 2094a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org return true; 210b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org } 211b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org int remaining_digits = 212b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org kMaxExactDoubleIntegerDecimalDigits - trimmed.length(); 213b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org if ((0 <= exponent) && 214b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org (exponent - remaining_digits < kExactPowersOfTenSize)) { 215b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // The trimmed string was short and we can multiply it with 216b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // 10^remaining_digits. As a result the remaining exponent now fits 217b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org // into a double too. 218303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *result = static_cast<double>(ReadUint64(trimmed, &read_digits)); 219303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(read_digits == trimmed.length()); 2204a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org *result *= exact_powers_of_ten[remaining_digits]; 2214a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org *result *= exact_powers_of_ten[exponent - remaining_digits]; 2224a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org return true; 223b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org } 224b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org } 2254a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org return false; 2264a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org} 2274a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org 2284a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org 229303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// Returns 10^exponent as an exact DiyFp. 230303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// The given exponent must be in the range [1; kDecimalExponentDistance[. 231303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.orgstatic DiyFp AdjustmentPowerOfTen(int exponent) { 232303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(0 < exponent); 233303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(exponent < PowersOfTenCache::kDecimalExponentDistance); 234303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Simply hardcode the remaining powers for the given decimal exponent 235303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // distance. 236303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(PowersOfTenCache::kDecimalExponentDistance == 8); 237303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org switch (exponent) { 238303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org case 1: return DiyFp(V8_2PART_UINT64_C(0xa0000000, 00000000), -60); 239303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org case 2: return DiyFp(V8_2PART_UINT64_C(0xc8000000, 00000000), -57); 240303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org case 3: return DiyFp(V8_2PART_UINT64_C(0xfa000000, 00000000), -54); 241303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org case 4: return DiyFp(V8_2PART_UINT64_C(0x9c400000, 00000000), -50); 242303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org case 5: return DiyFp(V8_2PART_UINT64_C(0xc3500000, 00000000), -47); 243303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org case 6: return DiyFp(V8_2PART_UINT64_C(0xf4240000, 00000000), -44); 244303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org case 7: return DiyFp(V8_2PART_UINT64_C(0x98968000, 00000000), -40); 245303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org default: 246303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org UNREACHABLE(); 247303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org return DiyFp(0, 0); 248303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 249303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org} 250303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 251303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 252303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// If the function returns true then the result is the correct double. 253303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// Otherwise it is either the correct double or the double that is just below 254303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org// the correct double. 255303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.orgstatic bool DiyFpStrtod(Vector<const char> buffer, 256303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int exponent, 257303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org double* result) { 258303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org DiyFp input; 259303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int remaining_decimals; 260303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ReadDiyFp(buffer, &input, &remaining_decimals); 261303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Since we may have dropped some digits the input is not accurate. 262303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // If remaining_decimals is different than 0 than the error is at most 263303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // .5 ulp (unit in the last place). 264303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // We don't want to deal with fractions and therefore keep a common 265303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // denominator. 266303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org const int kDenominatorLog = 3; 267303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org const int kDenominator = 1 << kDenominatorLog; 268303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Move the remaining decimals into the exponent. 269303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org exponent += remaining_decimals; 270303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int error = (remaining_decimals == 0 ? 0 : kDenominator / 2); 271303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 272303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int old_e = input.e(); 273303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org input.Normalize(); 274303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org error <<= old_e - input.e(); 275303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 276303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(exponent <= PowersOfTenCache::kMaxDecimalExponent); 277303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (exponent < PowersOfTenCache::kMinDecimalExponent) { 278303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *result = 0.0; 279303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org return true; 280303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 281303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org DiyFp cached_power; 282303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int cached_decimal_exponent; 283303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org PowersOfTenCache::GetCachedPowerForDecimalExponent(exponent, 284303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org &cached_power, 285303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org &cached_decimal_exponent); 286303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 287303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (cached_decimal_exponent != exponent) { 288303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int adjustment_exponent = exponent - cached_decimal_exponent; 289303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org DiyFp adjustment_power = AdjustmentPowerOfTen(adjustment_exponent); 290303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org input.Multiply(adjustment_power); 291303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (kMaxUint64DecimalDigits - buffer.length() >= adjustment_exponent) { 292303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // The product of input with the adjustment power fits into a 64 bit 293303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // integer. 294303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(DiyFp::kSignificandSize == 64); 295303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } else { 296303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // The adjustment power is exact. There is hence only an error of 0.5. 297303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org error += kDenominator / 2; 298303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 299303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 300303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 301303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org input.Multiply(cached_power); 302303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // The error introduced by a multiplication of a*b equals 303303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // error_a + error_b + error_a*error_b/2^64 + 0.5 304303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Substituting a with 'input' and b with 'cached_power' we have 305303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // error_b = 0.5 (all cached powers have an error of less than 0.5 ulp), 306303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // error_ab = 0 or 1 / kDenominator > error_a*error_b/ 2^64 307303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int error_b = kDenominator / 2; 308303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int error_ab = (error == 0 ? 0 : 1); // We round up to 1. 309303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int fixed_error = kDenominator / 2; 310303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org error += error_b + error_ab + fixed_error; 311303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 312303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org old_e = input.e(); 313303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org input.Normalize(); 314303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org error <<= old_e - input.e(); 315303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 316303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // See if the double's significand changes if we add/subtract the error. 317303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int order_of_magnitude = DiyFp::kSignificandSize + input.e(); 318303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int effective_significand_size = 319303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org Double::SignificandSizeForOrderOfMagnitude(order_of_magnitude); 320303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int precision_digits_count = 321303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org DiyFp::kSignificandSize - effective_significand_size; 322303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (precision_digits_count + kDenominatorLog >= DiyFp::kSignificandSize) { 323303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // This can only happen for very small denormals. In this case the 324303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // half-way multiplied by the denominator exceeds the range of an uint64. 325303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Simply shift everything to the right. 326303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org int shift_amount = (precision_digits_count + kDenominatorLog) - 327303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org DiyFp::kSignificandSize + 1; 328303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org input.set_f(input.f() >> shift_amount); 329303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org input.set_e(input.e() + shift_amount); 330303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // We add 1 for the lost precision of error, and kDenominator for 331303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // the lost precision of input.f(). 332303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org error = (error >> shift_amount) + 1 + kDenominator; 333303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org precision_digits_count -= shift_amount; 334303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 335303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // We use uint64_ts now. This only works if the DiyFp uses uint64_ts too. 336303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(DiyFp::kSignificandSize == 64); 337303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org ASSERT(precision_digits_count < 64); 338303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org uint64_t one64 = 1; 339303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org uint64_t precision_bits_mask = (one64 << precision_digits_count) - 1; 340303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org uint64_t precision_bits = input.f() & precision_bits_mask; 341303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org uint64_t half_way = one64 << (precision_digits_count - 1); 342303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org precision_bits *= kDenominator; 343303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org half_way *= kDenominator; 344303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org DiyFp rounded_input(input.f() >> precision_digits_count, 345303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org input.e() + precision_digits_count); 346303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (precision_bits >= half_way + error) { 347303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org rounded_input.set_f(rounded_input.f() + 1); 348303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 349303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // If the last_bits are too close to the half-way case than we are too 350303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // inaccurate and round down. In this case we return false so that we can 351303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // fall back to a more precise algorithm. 352303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 353303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org *result = Double(rounded_input).value(); 354303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org if (half_way - error < precision_bits && precision_bits < half_way + error) { 355303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // Too imprecise. The caller will have to fall back to a slower version. 356303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // However the returned number is guaranteed to be either the correct 357303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org // double, or the next-lower double. 358303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org return false; 359303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } else { 360303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org return true; 361303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org } 362303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org} 363303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 364303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 36501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// Returns the correct double for the buffer*10^exponent. 36601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// The variable guess should be a close guess that is either the correct double 36701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// or its lower neighbor (the nearest double less than the correct one). 36801fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// Preconditions: 36901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// buffer.length() + exponent <= kMaxDecimalPower + 1 37001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// buffer.length() + exponent > kMinDecimalPower 37101fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org// buffer.length() <= kMaxDecimalSignificantDigits 37201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.orgstatic double BignumStrtod(Vector<const char> buffer, 37301fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org int exponent, 37401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org double guess) { 37501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org if (guess == V8_INFINITY) { 37601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org return guess; 37701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } 37801fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org 37901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org DiyFp upper_boundary = Double(guess).UpperBoundary(); 38001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org 38101fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org ASSERT(buffer.length() + exponent <= kMaxDecimalPower + 1); 38201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org ASSERT(buffer.length() + exponent > kMinDecimalPower); 38301fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org ASSERT(buffer.length() <= kMaxSignificantDecimalDigits); 38401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // Make sure that the Bignum will be able to hold all our numbers. 38501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // Our Bignum implementation has a separate field for exponents. Shifts will 38601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // consume at most one bigit (< 64 bits). 38701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // ln(10) == 3.3219... 38801fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org ASSERT(((kMaxDecimalPower + 1) * 333 / 100) < Bignum::kMaxSignificantBits); 38901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org Bignum input; 39001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org Bignum boundary; 39101fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org input.AssignDecimalString(buffer); 39201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org boundary.AssignUInt64(upper_boundary.f()); 39301fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org if (exponent >= 0) { 39401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org input.MultiplyByPowerOfTen(exponent); 39501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } else { 39601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org boundary.MultiplyByPowerOfTen(-exponent); 39701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } 39801fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org if (upper_boundary.e() > 0) { 39901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org boundary.ShiftLeft(upper_boundary.e()); 40001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } else { 40101fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org input.ShiftLeft(-upper_boundary.e()); 40201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } 40301fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org int comparison = Bignum::Compare(input, boundary); 40401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org if (comparison < 0) { 40501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org return guess; 40601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } else if (comparison > 0) { 40701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org return Double(guess).NextDouble(); 40801fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } else if ((Double(guess).Significand() & 1) == 0) { 40901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org // Round towards even. 41001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org return guess; 41101fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } else { 41201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org return Double(guess).NextDouble(); 41301fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } 41401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org} 41501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org 41601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org 4174a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.orgdouble Strtod(Vector<const char> buffer, int exponent) { 4184a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org Vector<const char> left_trimmed = TrimLeadingZeros(buffer); 4194a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org Vector<const char> trimmed = TrimTrailingZeros(left_trimmed); 4204a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org exponent += left_trimmed.length() - trimmed.length(); 4214a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org if (trimmed.length() == 0) return 0.0; 42201fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org if (trimmed.length() > kMaxSignificantDecimalDigits) { 42301fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org char significant_buffer[kMaxSignificantDecimalDigits]; 42401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org int significant_exponent; 42501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org TrimToMaxSignificantDigits(trimmed, exponent, 42601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org significant_buffer, &significant_exponent); 4274a6c3279070e8f133607a74c08d8c08ac394ab98erik.corry@gmail.com return Strtod(Vector<const char>(significant_buffer, 4284a6c3279070e8f133607a74c08d8c08ac394ab98erik.corry@gmail.com kMaxSignificantDecimalDigits), 4294a6c3279070e8f133607a74c08d8c08ac394ab98erik.corry@gmail.com significant_exponent); 43001fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org } 4314a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org if (exponent + trimmed.length() - 1 >= kMaxDecimalPower) return V8_INFINITY; 4324a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org if (exponent + trimmed.length() <= kMinDecimalPower) return 0.0; 433303ada708275d2d425b846fb237f1ba7598ee239lrn@chromium.org 43401fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org double guess; 43501fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org if (DoubleStrtod(trimmed, exponent, &guess) || 43601fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org DiyFpStrtod(trimmed, exponent, &guess)) { 43701fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org return guess; 4384a5224e84636d192e82f288bfab0d308bdae5c37whesse@chromium.org } 43901fe7df37ce9858e3d0069ec6a2d7c667256b95aager@chromium.org return BignumStrtod(trimmed, exponent, guess); 440b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org} 441b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org 442b61a0d13e9690ef4c2de424bbe82a38884d981a6ager@chromium.org} } // namespace v8::internal 443