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+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+//
+// From the double-conversion library. Original license:
+//
+// 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.
+
+// ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
+#include "unicode/utypes.h"
+#if !UCONFIG_NO_FORMATTING
+
+#include <climits>
+#include <cstdarg>
+
+// ICU PATCH: Customize header file paths for ICU.
+
+#include "double-conversion-bignum.h"
+#include "double-conversion-cached-powers.h"
+#include "double-conversion-ieee.h"
+#include "double-conversion-strtod.h"
+
+// ICU PATCH: Wrap in ICU namespace
+U_NAMESPACE_BEGIN
+
+namespace double_conversion {
+
+#if defined(DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS)
+// 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;
+#endif // #if defined(DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS)
+// 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 = DOUBLE_CONVERSION_UINT64_2PART_C(0xFFFFFFFF, FFFFFFFF);
+
+
+#if defined(DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS)
+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 = DOUBLE_CONVERSION_ARRAY_SIZE(exact_powers_of_ten);
+#endif // #if defined(DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS)
+
+// 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 void CutToMaxSignificantDigits(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'.
+ DOUBLE_CONVERSION_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);
+}
+
+
+// Trims the buffer and cuts it to at most kMaxSignificantDecimalDigits.
+// If possible the input-buffer is reused, but if the buffer needs to be
+// modified (due to cutting), then the input needs to be copied into the
+// buffer_copy_space.
+static void TrimAndCut(Vector<const char> buffer, int exponent,
+ char* buffer_copy_space, int space_size,
+ Vector<const char>* trimmed, int* updated_exponent) {
+ Vector<const char> left_trimmed = TrimLeadingZeros(buffer);
+ Vector<const char> right_trimmed = TrimTrailingZeros(left_trimmed);
+ exponent += left_trimmed.length() - right_trimmed.length();
+ if (right_trimmed.length() > kMaxSignificantDecimalDigits) {
+ (void) space_size; // Mark variable as used.
+ DOUBLE_CONVERSION_ASSERT(space_size >= kMaxSignificantDecimalDigits);
+ CutToMaxSignificantDigits(right_trimmed, exponent,
+ buffer_copy_space, updated_exponent);
+ *trimmed = Vector<const char>(buffer_copy_space,
+ kMaxSignificantDecimalDigits);
+ } else {
+ *trimmed = right_trimmed;
+ *updated_exponent = exponent;
+ }
+}
+
+
+// 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';
+ DOUBLE_CONVERSION_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)
+ // Avoid "unused parameter" warnings
+ (void) trimmed;
+ (void) exponent;
+ (void) result;
+ // 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.
+ return false;
+#else
+ 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));
+ DOUBLE_CONVERSION_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));
+ DOUBLE_CONVERSION_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));
+ DOUBLE_CONVERSION_ASSERT(read_digits == trimmed.length());
+ *result *= exact_powers_of_ten[remaining_digits];
+ *result *= exact_powers_of_ten[exponent - remaining_digits];
+ return true;
+ }
+ }
+ return false;
+#endif
+}
+
+
+// Returns 10^exponent as an exact DiyFp.
+// The given exponent must be in the range [1; kDecimalExponentDistance[.
+static DiyFp AdjustmentPowerOfTen(int exponent) {
+ DOUBLE_CONVERSION_ASSERT(0 < exponent);
+ DOUBLE_CONVERSION_ASSERT(exponent < PowersOfTenCache::kDecimalExponentDistance);
+ // Simply hardcode the remaining powers for the given decimal exponent
+ // distance.
+ DOUBLE_CONVERSION_ASSERT(PowersOfTenCache::kDecimalExponentDistance == 8);
+ switch (exponent) {
+ case 1: return DiyFp(DOUBLE_CONVERSION_UINT64_2PART_C(0xa0000000, 00000000), -60);
+ case 2: return DiyFp(DOUBLE_CONVERSION_UINT64_2PART_C(0xc8000000, 00000000), -57);
+ case 3: return DiyFp(DOUBLE_CONVERSION_UINT64_2PART_C(0xfa000000, 00000000), -54);
+ case 4: return DiyFp(DOUBLE_CONVERSION_UINT64_2PART_C(0x9c400000, 00000000), -50);
+ case 5: return DiyFp(DOUBLE_CONVERSION_UINT64_2PART_C(0xc3500000, 00000000), -47);
+ case 6: return DiyFp(DOUBLE_CONVERSION_UINT64_2PART_C(0xf4240000, 00000000), -44);
+ case 7: return DiyFp(DOUBLE_CONVERSION_UINT64_2PART_C(0x98968000, 00000000), -40);
+ default:
+ DOUBLE_CONVERSION_UNREACHABLE();
+ }
+}
+
+
+// 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;
+ uint64_t error = (remaining_decimals == 0 ? 0 : kDenominator / 2);
+
+ int old_e = input.e();
+ input.Normalize();
+ error <<= old_e - input.e();
+
+ DOUBLE_CONVERSION_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.
+ DOUBLE_CONVERSION_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.
+ DOUBLE_CONVERSION_ASSERT(DiyFp::kSignificandSize == 64);
+ DOUBLE_CONVERSION_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
+// - -1 if buffer*10^exponent < diy_fp.
+// - 0 if buffer*10^exponent == diy_fp.
+// - +1 if buffer*10^exponent > diy_fp.
+// Preconditions:
+// buffer.length() + exponent <= kMaxDecimalPower + 1
+// buffer.length() + exponent > kMinDecimalPower
+// buffer.length() <= kMaxDecimalSignificantDigits
+static int CompareBufferWithDiyFp(Vector<const char> buffer,
+ int exponent,
+ DiyFp diy_fp) {
+ DOUBLE_CONVERSION_ASSERT(buffer.length() + exponent <= kMaxDecimalPower + 1);
+ DOUBLE_CONVERSION_ASSERT(buffer.length() + exponent > kMinDecimalPower);
+ DOUBLE_CONVERSION_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...
+ DOUBLE_CONVERSION_ASSERT(((kMaxDecimalPower + 1) * 333 / 100) < Bignum::kMaxSignificantBits);
+ Bignum buffer_bignum;
+ Bignum diy_fp_bignum;
+ buffer_bignum.AssignDecimalString(buffer);
+ diy_fp_bignum.AssignUInt64(diy_fp.f());
+ if (exponent >= 0) {
+ buffer_bignum.MultiplyByPowerOfTen(exponent);
+ } else {
+ diy_fp_bignum.MultiplyByPowerOfTen(-exponent);
+ }
+ if (diy_fp.e() > 0) {
+ diy_fp_bignum.ShiftLeft(diy_fp.e());
+ } else {
+ buffer_bignum.ShiftLeft(-diy_fp.e());
+ }
+ return Bignum::Compare(buffer_bignum, diy_fp_bignum);
+}
+
+
+// Returns true if the guess is the correct double.
+// Returns false, when guess is either correct or the next-lower double.
+static bool ComputeGuess(Vector<const char> trimmed, int exponent,
+ double* guess) {
+ if (trimmed.length() == 0) {
+ *guess = 0.0;
+ return true;
+ }
+ if (exponent + trimmed.length() - 1 >= kMaxDecimalPower) {
+ *guess = Double::Infinity();
+ return true;
+ }
+ if (exponent + trimmed.length() <= kMinDecimalPower) {
+ *guess = 0.0;
+ return true;
+ }
+
+ if (DoubleStrtod(trimmed, exponent, guess) ||
+ DiyFpStrtod(trimmed, exponent, guess)) {
+ return true;
+ }
+ if (*guess == Double::Infinity()) {
+ return true;
+ }
+ return false;
+}
+
+#if U_DEBUG // needed for ICU only in debug mode
+static bool IsDigit(const char d) {
+ return ('0' <= d) && (d <= '9');
+}
+
+static bool IsNonZeroDigit(const char d) {
+ return ('1' <= d) && (d <= '9');
+}
+
+#ifdef __has_cpp_attribute
+#if __has_cpp_attribute(maybe_unused)
+[[maybe_unused]]
+#endif
+#endif
+static bool AssertTrimmedDigits(const Vector<const char>& buffer) {
+ for(int i = 0; i < buffer.length(); ++i) {
+ if(!IsDigit(buffer[i])) {
+ return false;
+ }
+ }
+ return (buffer.length() == 0) || (IsNonZeroDigit(buffer[0]) && IsNonZeroDigit(buffer[buffer.length()-1]));
+}
+#endif // needed for ICU only in debug mode
+
+double StrtodTrimmed(Vector<const char> trimmed, int exponent) {
+ DOUBLE_CONVERSION_ASSERT(trimmed.length() <= kMaxSignificantDecimalDigits);
+ DOUBLE_CONVERSION_ASSERT(AssertTrimmedDigits(trimmed));
+ double guess;
+ const bool is_correct = ComputeGuess(trimmed, exponent, &guess);
+ if (is_correct) {
+ return guess;
+ }
+ DiyFp upper_boundary = Double(guess).UpperBoundary();
+ int comparison = CompareBufferWithDiyFp(trimmed, exponent, upper_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) {
+ char copy_buffer[kMaxSignificantDecimalDigits];
+ Vector<const char> trimmed;
+ int updated_exponent;
+ TrimAndCut(buffer, exponent, copy_buffer, kMaxSignificantDecimalDigits,
+ &trimmed, &updated_exponent);
+ return StrtodTrimmed(trimmed, updated_exponent);
+}
+
+static float SanitizedDoubletof(double d) {
+ DOUBLE_CONVERSION_ASSERT(d >= 0.0);
+ // ASAN has a sanitize check that disallows casting doubles to floats if
+ // they are too big.
+ // https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html#available-checks
+ // The behavior should be covered by IEEE 754, but some projects use this
+ // flag, so work around it.
+ float max_finite = 3.4028234663852885981170418348451692544e+38;
+ // The half-way point between the max-finite and infinity value.
+ // Since infinity has an even significand everything equal or greater than
+ // this value should become infinity.
+ double half_max_finite_infinity =
+ 3.40282356779733661637539395458142568448e+38;
+ if (d >= max_finite) {
+ if (d >= half_max_finite_infinity) {
+ return Single::Infinity();
+ } else {
+ return max_finite;
+ }
+ } else {
+ return static_cast<float>(d);
+ }
+}
+
+float Strtof(Vector<const char> buffer, int exponent) {
+ char copy_buffer[kMaxSignificantDecimalDigits];
+ Vector<const char> trimmed;
+ int updated_exponent;
+ TrimAndCut(buffer, exponent, copy_buffer, kMaxSignificantDecimalDigits,
+ &trimmed, &updated_exponent);
+ exponent = updated_exponent;
+ return StrtofTrimmed(trimmed, exponent);
+}
+
+float StrtofTrimmed(Vector<const char> trimmed, int exponent) {
+ DOUBLE_CONVERSION_ASSERT(trimmed.length() <= kMaxSignificantDecimalDigits);
+ DOUBLE_CONVERSION_ASSERT(AssertTrimmedDigits(trimmed));
+
+ double double_guess;
+ bool is_correct = ComputeGuess(trimmed, exponent, &double_guess);
+
+ float float_guess = SanitizedDoubletof(double_guess);
+ if (float_guess == double_guess) {
+ // This shortcut triggers for integer values.
+ return float_guess;
+ }
+
+ // We must catch double-rounding. Say the double has been rounded up, and is
+ // now a boundary of a float, and rounds up again. This is why we have to
+ // look at previous too.
+ // Example (in decimal numbers):
+ // input: 12349
+ // high-precision (4 digits): 1235
+ // low-precision (3 digits):
+ // when read from input: 123
+ // when rounded from high precision: 124.
+ // To do this we simply look at the neighbors of the correct result and see
+ // if they would round to the same float. If the guess is not correct we have
+ // to look at four values (since two different doubles could be the correct
+ // double).
+
+ double double_next = Double(double_guess).NextDouble();
+ double double_previous = Double(double_guess).PreviousDouble();
+
+ float f1 = SanitizedDoubletof(double_previous);
+ float f2 = float_guess;
+ float f3 = SanitizedDoubletof(double_next);
+ float f4;
+ if (is_correct) {
+ f4 = f3;
+ } else {
+ double double_next2 = Double(double_next).NextDouble();
+ f4 = SanitizedDoubletof(double_next2);
+ }
+ (void) f2; // Mark variable as used.
+ DOUBLE_CONVERSION_ASSERT(f1 <= f2 && f2 <= f3 && f3 <= f4);
+
+ // If the guess doesn't lie near a single-precision boundary we can simply
+ // return its float-value.
+ if (f1 == f4) {
+ return float_guess;
+ }
+
+ DOUBLE_CONVERSION_ASSERT((f1 != f2 && f2 == f3 && f3 == f4) ||
+ (f1 == f2 && f2 != f3 && f3 == f4) ||
+ (f1 == f2 && f2 == f3 && f3 != f4));
+
+ // guess and next are the two possible candidates (in the same way that
+ // double_guess was the lower candidate for a double-precision guess).
+ float guess = f1;
+ float next = f4;
+ DiyFp upper_boundary;
+ if (guess == 0.0f) {
+ float min_float = 1e-45f;
+ upper_boundary = Double(static_cast<double>(min_float) / 2).AsDiyFp();
+ } else {
+ upper_boundary = Single(guess).UpperBoundary();
+ }
+ int comparison = CompareBufferWithDiyFp(trimmed, exponent, upper_boundary);
+ if (comparison < 0) {
+ return guess;
+ } else if (comparison > 0) {
+ return next;
+ } else if ((Single(guess).Significand() & 1) == 0) {
+ // Round towards even.
+ return guess;
+ } else {
+ return next;
+ }
+}
+
+} // namespace double_conversion
+
+// ICU PATCH: Close ICU namespace
+U_NAMESPACE_END
+#endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING
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