Index: third_party/WebKit/Source/wtf/dtoa/strtod.cc |
diff --git a/third_party/WebKit/Source/wtf/dtoa/strtod.cc b/third_party/WebKit/Source/wtf/dtoa/strtod.cc |
deleted file mode 100644 |
index 998a0c4e912bcb9ab9bce844343c445685271378..0000000000000000000000000000000000000000 |
--- a/third_party/WebKit/Source/wtf/dtoa/strtod.cc |
+++ /dev/null |
@@ -1,445 +0,0 @@ |
-// Copyright 2010 the V8 project authors. All rights reserved. |
-// Redistribution and use in source and binary forms, with or without |
-// modification, are permitted provided that the following conditions are |
-// met: |
-// |
-// * Redistributions of source code must retain the above copyright |
-// notice, this list of conditions and the following disclaimer. |
-// * Redistributions in binary form must reproduce the above |
-// copyright notice, this list of conditions and the following |
-// disclaimer in the documentation and/or other materials provided |
-// with the distribution. |
-// * Neither the name of Google Inc. nor the names of its |
-// contributors may be used to endorse or promote products derived |
-// from this software without specific prior written permission. |
-// |
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
- |
-#include "strtod.h" |
- |
-#include "bignum.h" |
-#include "cached-powers.h" |
-#include "double.h" |
-#include <stdarg.h> |
-#include <limits.h> |
- |
-namespace WTF { |
- |
-namespace double_conversion { |
- |
- // 2^53 = 9007199254740992. |
- // Any integer with at most 15 decimal digits will hence fit into a double |
- // (which has a 53bit significand) without loss of precision. |
- static const int kMaxExactDoubleIntegerDecimalDigits = 15; |
- // 2^64 = 18446744073709551616 > 10^19 |
- static const int kMaxUint64DecimalDigits = 19; |
- |
- // Max double: 1.7976931348623157 x 10^308 |
- // Min non-zero double: 4.9406564584124654 x 10^-324 |
- // Any x >= 10^309 is interpreted as +infinity. |
- // Any x <= 10^-324 is interpreted as 0. |
- // Note that 2.5e-324 (despite being smaller than the min double) will be read |
- // as non-zero (equal to the min non-zero double). |
- static const int kMaxDecimalPower = 309; |
- static const int kMinDecimalPower = -324; |
- |
- // 2^64 = 18446744073709551616 |
- static const uint64_t kMaxUint64 = UINT64_2PART_C(0xFFFFFFFF, FFFFFFFF); |
- |
- |
- static const double exact_powers_of_ten[] = { |
- 1.0, // 10^0 |
- 10.0, |
- 100.0, |
- 1000.0, |
- 10000.0, |
- 100000.0, |
- 1000000.0, |
- 10000000.0, |
- 100000000.0, |
- 1000000000.0, |
- 10000000000.0, // 10^10 |
- 100000000000.0, |
- 1000000000000.0, |
- 10000000000000.0, |
- 100000000000000.0, |
- 1000000000000000.0, |
- 10000000000000000.0, |
- 100000000000000000.0, |
- 1000000000000000000.0, |
- 10000000000000000000.0, |
- 100000000000000000000.0, // 10^20 |
- 1000000000000000000000.0, |
- // 10^22 = 0x21e19e0c9bab2400000 = 0x878678326eac9 * 2^22 |
- 10000000000000000000000.0 |
- }; |
- static const int kExactPowersOfTenSize = ARRAY_SIZE(exact_powers_of_ten); |
- |
- // Maximum number of significant digits in the decimal representation. |
- // In fact the value is 772 (see conversions.cc), but to give us some margin |
- // we round up to 780. |
- static const int kMaxSignificantDecimalDigits = 780; |
- |
- static Vector<const char> TrimLeadingZeros(Vector<const char> buffer) { |
- for (int i = 0; i < buffer.length(); i++) { |
- if (buffer[i] != '0') { |
- return buffer.SubVector(i, buffer.length()); |
- } |
- } |
- return Vector<const char>(buffer.start(), 0); |
- } |
- |
- |
- static Vector<const char> TrimTrailingZeros(Vector<const char> buffer) { |
- for (int i = buffer.length() - 1; i >= 0; --i) { |
- if (buffer[i] != '0') { |
- return buffer.SubVector(0, i + 1); |
- } |
- } |
- return Vector<const char>(buffer.start(), 0); |
- } |
- |
- |
- static void TrimToMaxSignificantDigits(Vector<const char> buffer, |
- int exponent, |
- char* significant_buffer, |
- int* significant_exponent) { |
- for (int i = 0; i < kMaxSignificantDecimalDigits - 1; ++i) { |
- significant_buffer[i] = buffer[i]; |
- } |
- // The input buffer has been trimmed. Therefore the last digit must be |
- // different from '0'. |
- ASSERT(buffer[buffer.length() - 1] != '0'); |
- // Set the last digit to be non-zero. This is sufficient to guarantee |
- // correct rounding. |
- significant_buffer[kMaxSignificantDecimalDigits - 1] = '1'; |
- *significant_exponent = |
- exponent + (buffer.length() - kMaxSignificantDecimalDigits); |
- } |
- |
- // Reads digits from the buffer and converts them to a uint64. |
- // Reads in as many digits as fit into a uint64. |
- // When the string starts with "1844674407370955161" no further digit is read. |
- // Since 2^64 = 18446744073709551616 it would still be possible read another |
- // digit if it was less or equal than 6, but this would complicate the code. |
- static uint64_t ReadUint64(Vector<const char> buffer, |
- int* number_of_read_digits) { |
- uint64_t result = 0; |
- int i = 0; |
- while (i < buffer.length() && result <= (kMaxUint64 / 10 - 1)) { |
- int digit = buffer[i++] - '0'; |
- ASSERT(0 <= digit && digit <= 9); |
- result = 10 * result + digit; |
- } |
- *number_of_read_digits = i; |
- return result; |
- } |
- |
- |
- // Reads a DiyFp from the buffer. |
- // The returned DiyFp is not necessarily normalized. |
- // If remaining_decimals is zero then the returned DiyFp is accurate. |
- // Otherwise it has been rounded and has error of at most 1/2 ulp. |
- static void ReadDiyFp(Vector<const char> buffer, |
- DiyFp* result, |
- int* remaining_decimals) { |
- int read_digits; |
- uint64_t significand = ReadUint64(buffer, &read_digits); |
- if (buffer.length() == read_digits) { |
- *result = DiyFp(significand, 0); |
- *remaining_decimals = 0; |
- } else { |
- // Round the significand. |
- if (buffer[read_digits] >= '5') { |
- significand++; |
- } |
- // Compute the binary exponent. |
- int exponent = 0; |
- *result = DiyFp(significand, exponent); |
- *remaining_decimals = buffer.length() - read_digits; |
- } |
- } |
- |
- |
- static bool DoubleStrtod(Vector<const char> trimmed, |
- int exponent, |
- double* result) { |
-#if !defined(DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS) |
- // On x86 the floating-point stack can be 64 or 80 bits wide. If it is |
- // 80 bits wide (as is the case on Linux) then double-rounding occurs and the |
- // result is not accurate. |
- // We know that Windows32 uses 64 bits and is therefore accurate. |
- // Note that the ARM simulator is compiled for 32bits. It therefore exhibits |
- // the same problem. |
- return false; |
-#endif |
- if (trimmed.length() <= kMaxExactDoubleIntegerDecimalDigits) { |
- int read_digits; |
- // The trimmed input fits into a double. |
- // If the 10^exponent (resp. 10^-exponent) fits into a double too then we |
- // can compute the result-double simply by multiplying (resp. dividing) the |
- // two numbers. |
- // This is possible because IEEE guarantees that floating-point operations |
- // return the best possible approximation. |
- if (exponent < 0 && -exponent < kExactPowersOfTenSize) { |
- // 10^-exponent fits into a double. |
- *result = static_cast<double>(ReadUint64(trimmed, &read_digits)); |
- ASSERT(read_digits == trimmed.length()); |
- *result /= exact_powers_of_ten[-exponent]; |
- return true; |
- } |
- if (0 <= exponent && exponent < kExactPowersOfTenSize) { |
- // 10^exponent fits into a double. |
- *result = static_cast<double>(ReadUint64(trimmed, &read_digits)); |
- ASSERT(read_digits == trimmed.length()); |
- *result *= exact_powers_of_ten[exponent]; |
- return true; |
- } |
- int remaining_digits = |
- kMaxExactDoubleIntegerDecimalDigits - trimmed.length(); |
- if ((0 <= exponent) && |
- (exponent - remaining_digits < kExactPowersOfTenSize)) { |
- // The trimmed string was short and we can multiply it with |
- // 10^remaining_digits. As a result the remaining exponent now fits |
- // into a double too. |
- *result = static_cast<double>(ReadUint64(trimmed, &read_digits)); |
- ASSERT(read_digits == trimmed.length()); |
- *result *= exact_powers_of_ten[remaining_digits]; |
- *result *= exact_powers_of_ten[exponent - remaining_digits]; |
- return true; |
- } |
- } |
- return false; |
- } |
- |
- |
- // Returns 10^exponent as an exact DiyFp. |
- // The given exponent must be in the range [1; kDecimalExponentDistance[. |
- static DiyFp AdjustmentPowerOfTen(int exponent) { |
- ASSERT(0 < exponent); |
- ASSERT(exponent < PowersOfTenCache::kDecimalExponentDistance); |
- // Simply hardcode the remaining powers for the given decimal exponent |
- // distance. |
- ASSERT(PowersOfTenCache::kDecimalExponentDistance == 8); |
- switch (exponent) { |
- case 1: return DiyFp(UINT64_2PART_C(0xa0000000, 00000000), -60); |
- case 2: return DiyFp(UINT64_2PART_C(0xc8000000, 00000000), -57); |
- case 3: return DiyFp(UINT64_2PART_C(0xfa000000, 00000000), -54); |
- case 4: return DiyFp(UINT64_2PART_C(0x9c400000, 00000000), -50); |
- case 5: return DiyFp(UINT64_2PART_C(0xc3500000, 00000000), -47); |
- case 6: return DiyFp(UINT64_2PART_C(0xf4240000, 00000000), -44); |
- case 7: return DiyFp(UINT64_2PART_C(0x98968000, 00000000), -40); |
- default: |
- UNREACHABLE(); |
- return DiyFp(0, 0); |
- } |
- } |
- |
- |
- // If the function returns true then the result is the correct double. |
- // Otherwise it is either the correct double or the double that is just below |
- // the correct double. |
- static bool DiyFpStrtod(Vector<const char> buffer, |
- int exponent, |
- double* result) { |
- DiyFp input; |
- int remaining_decimals; |
- ReadDiyFp(buffer, &input, &remaining_decimals); |
- // Since we may have dropped some digits the input is not accurate. |
- // If remaining_decimals is different than 0 than the error is at most |
- // .5 ulp (unit in the last place). |
- // We don't want to deal with fractions and therefore keep a common |
- // denominator. |
- const int kDenominatorLog = 3; |
- const int kDenominator = 1 << kDenominatorLog; |
- // Move the remaining decimals into the exponent. |
- exponent += remaining_decimals; |
- int64_t error = (remaining_decimals == 0 ? 0 : kDenominator / 2); |
- |
- int old_e = input.e(); |
- input.Normalize(); |
- error <<= old_e - input.e(); |
- |
- ASSERT(exponent <= PowersOfTenCache::kMaxDecimalExponent); |
- if (exponent < PowersOfTenCache::kMinDecimalExponent) { |
- *result = 0.0; |
- return true; |
- } |
- DiyFp cached_power; |
- int cached_decimal_exponent; |
- PowersOfTenCache::GetCachedPowerForDecimalExponent(exponent, |
- &cached_power, |
- &cached_decimal_exponent); |
- |
- if (cached_decimal_exponent != exponent) { |
- int adjustment_exponent = exponent - cached_decimal_exponent; |
- DiyFp adjustment_power = AdjustmentPowerOfTen(adjustment_exponent); |
- input.Multiply(adjustment_power); |
- if (kMaxUint64DecimalDigits - buffer.length() >= adjustment_exponent) { |
- // The product of input with the adjustment power fits into a 64 bit |
- // integer. |
- ASSERT(DiyFp::kSignificandSize == 64); |
- } else { |
- // The adjustment power is exact. There is hence only an error of 0.5. |
- error += kDenominator / 2; |
- } |
- } |
- |
- input.Multiply(cached_power); |
- // The error introduced by a multiplication of a*b equals |
- // error_a + error_b + error_a*error_b/2^64 + 0.5 |
- // Substituting a with 'input' and b with 'cached_power' we have |
- // error_b = 0.5 (all cached powers have an error of less than 0.5 ulp), |
- // error_ab = 0 or 1 / kDenominator > error_a*error_b/ 2^64 |
- int error_b = kDenominator / 2; |
- int error_ab = (error == 0 ? 0 : 1); // We round up to 1. |
- int fixed_error = kDenominator / 2; |
- error += error_b + error_ab + fixed_error; |
- |
- old_e = input.e(); |
- input.Normalize(); |
- error <<= old_e - input.e(); |
- |
- // See if the double's significand changes if we add/subtract the error. |
- int order_of_magnitude = DiyFp::kSignificandSize + input.e(); |
- int effective_significand_size = |
- Double::SignificandSizeForOrderOfMagnitude(order_of_magnitude); |
- int precision_digits_count = |
- DiyFp::kSignificandSize - effective_significand_size; |
- if (precision_digits_count + kDenominatorLog >= DiyFp::kSignificandSize) { |
- // This can only happen for very small denormals. In this case the |
- // half-way multiplied by the denominator exceeds the range of an uint64. |
- // Simply shift everything to the right. |
- int shift_amount = (precision_digits_count + kDenominatorLog) - |
- DiyFp::kSignificandSize + 1; |
- input.set_f(input.f() >> shift_amount); |
- input.set_e(input.e() + shift_amount); |
- // We add 1 for the lost precision of error, and kDenominator for |
- // the lost precision of input.f(). |
- error = (error >> shift_amount) + 1 + kDenominator; |
- precision_digits_count -= shift_amount; |
- } |
- // We use uint64_ts now. This only works if the DiyFp uses uint64_ts too. |
- ASSERT(DiyFp::kSignificandSize == 64); |
- ASSERT(precision_digits_count < 64); |
- uint64_t one64 = 1; |
- uint64_t precision_bits_mask = (one64 << precision_digits_count) - 1; |
- uint64_t precision_bits = input.f() & precision_bits_mask; |
- uint64_t half_way = one64 << (precision_digits_count - 1); |
- precision_bits *= kDenominator; |
- half_way *= kDenominator; |
- DiyFp rounded_input(input.f() >> precision_digits_count, |
- input.e() + precision_digits_count); |
- if (precision_bits >= half_way + error) { |
- rounded_input.set_f(rounded_input.f() + 1); |
- } |
- // If the last_bits are too close to the half-way case than we are too |
- // inaccurate and round down. In this case we return false so that we can |
- // fall back to a more precise algorithm. |
- |
- *result = Double(rounded_input).value(); |
- if (half_way - error < precision_bits && precision_bits < half_way + error) { |
- // Too imprecise. The caller will have to fall back to a slower version. |
- // However the returned number is guaranteed to be either the correct |
- // double, or the next-lower double. |
- return false; |
- } else { |
- return true; |
- } |
- } |
- |
- |
- // Returns the correct double for the buffer*10^exponent. |
- // The variable guess should be a close guess that is either the correct double |
- // or its lower neighbor (the nearest double less than the correct one). |
- // Preconditions: |
- // buffer.length() + exponent <= kMaxDecimalPower + 1 |
- // buffer.length() + exponent > kMinDecimalPower |
- // buffer.length() <= kMaxDecimalSignificantDigits |
- static double BignumStrtod(Vector<const char> buffer, |
- int exponent, |
- double guess) { |
- if (guess == Double::Infinity()) { |
- return guess; |
- } |
- |
- DiyFp upper_boundary = Double(guess).UpperBoundary(); |
- |
- ASSERT(buffer.length() + exponent <= kMaxDecimalPower + 1); |
- ASSERT(buffer.length() + exponent > kMinDecimalPower); |
- ASSERT(buffer.length() <= kMaxSignificantDecimalDigits); |
- // Make sure that the Bignum will be able to hold all our numbers. |
- // Our Bignum implementation has a separate field for exponents. Shifts will |
- // consume at most one bigit (< 64 bits). |
- // ln(10) == 3.3219... |
- ASSERT(((kMaxDecimalPower + 1) * 333 / 100) < Bignum::kMaxSignificantBits); |
- Bignum input; |
- Bignum boundary; |
- input.AssignDecimalString(buffer); |
- boundary.AssignUInt64(upper_boundary.f()); |
- if (exponent >= 0) { |
- input.MultiplyByPowerOfTen(exponent); |
- } else { |
- boundary.MultiplyByPowerOfTen(-exponent); |
- } |
- if (upper_boundary.e() > 0) { |
- boundary.ShiftLeft(upper_boundary.e()); |
- } else { |
- input.ShiftLeft(-upper_boundary.e()); |
- } |
- int comparison = Bignum::Compare(input, boundary); |
- if (comparison < 0) { |
- return guess; |
- } else if (comparison > 0) { |
- return Double(guess).NextDouble(); |
- } else if ((Double(guess).Significand() & 1) == 0) { |
- // Round towards even. |
- return guess; |
- } else { |
- return Double(guess).NextDouble(); |
- } |
- } |
- |
- |
- double Strtod(Vector<const char> buffer, int exponent) { |
- Vector<const char> left_trimmed = TrimLeadingZeros(buffer); |
- Vector<const char> trimmed = TrimTrailingZeros(left_trimmed); |
- exponent += left_trimmed.length() - trimmed.length(); |
- if (trimmed.length() == 0) return 0.0; |
- if (trimmed.length() > kMaxSignificantDecimalDigits) { |
- char significant_buffer[kMaxSignificantDecimalDigits]; |
- int significant_exponent; |
- TrimToMaxSignificantDigits(trimmed, exponent, |
- significant_buffer, &significant_exponent); |
- return Strtod(Vector<const char>(significant_buffer, |
- kMaxSignificantDecimalDigits), |
- significant_exponent); |
- } |
- if (exponent + trimmed.length() - 1 >= kMaxDecimalPower) { |
- return Double::Infinity(); |
- } |
- if (exponent + trimmed.length() <= kMinDecimalPower) { |
- return 0.0; |
- } |
- |
- double guess; |
- if (DoubleStrtod(trimmed, exponent, &guess) || |
- DiyFpStrtod(trimmed, exponent, &guess)) { |
- return guess; |
- } |
- return BignumStrtod(trimmed, exponent, guess); |
- } |
- |
-} // namespace double_conversion |
- |
-} // namespace WTF |