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Diffstat (limited to 'deps/node/deps/icu-small/source/i18n/double-conversion-bignum-dtoa.cpp')
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diff --git a/deps/node/deps/icu-small/source/i18n/double-conversion-bignum-dtoa.cpp b/deps/node/deps/icu-small/source/i18n/double-conversion-bignum-dtoa.cpp deleted file mode 100644 index 07d0b0eb..00000000 --- a/deps/node/deps/icu-small/source/i18n/double-conversion-bignum-dtoa.cpp +++ /dev/null @@ -1,659 +0,0 @@ -// © 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 <math.h> - -// ICU PATCH: Customize header file paths for ICU. - -#include "double-conversion-bignum-dtoa.h" - -#include "double-conversion-bignum.h" -#include "double-conversion-ieee.h" - -// ICU PATCH: Wrap in ICU namespace -U_NAMESPACE_BEGIN - -namespace double_conversion { - -static int NormalizedExponent(uint64_t significand, int exponent) { - ASSERT(significand != 0); - while ((significand & Double::kHiddenBit) == 0) { - significand = significand << 1; - exponent = exponent - 1; - } - return exponent; -} - - -// Forward declarations: -// Returns an estimation of k such that 10^(k-1) <= v < 10^k. -static int EstimatePower(int exponent); -// Computes v / 10^estimated_power exactly, as a ratio of two bignums, numerator -// and denominator. -static void InitialScaledStartValues(uint64_t significand, - int exponent, - bool lower_boundary_is_closer, - int estimated_power, - bool need_boundary_deltas, - Bignum* numerator, - Bignum* denominator, - Bignum* delta_minus, - Bignum* delta_plus); -// Multiplies numerator/denominator so that its values lies in the range 1-10. -// Returns decimal_point s.t. -// v = numerator'/denominator' * 10^(decimal_point-1) -// where numerator' and denominator' are the values of numerator and -// denominator after the call to this function. -static void FixupMultiply10(int estimated_power, bool is_even, - int* decimal_point, - Bignum* numerator, Bignum* denominator, - Bignum* delta_minus, Bignum* delta_plus); -// Generates digits from the left to the right and stops when the generated -// digits yield the shortest decimal representation of v. -static void GenerateShortestDigits(Bignum* numerator, Bignum* denominator, - Bignum* delta_minus, Bignum* delta_plus, - bool is_even, - Vector<char> buffer, int* length); -// Generates 'requested_digits' after the decimal point. -static void BignumToFixed(int requested_digits, int* decimal_point, - Bignum* numerator, Bignum* denominator, - Vector<char>(buffer), int* length); -// Generates 'count' digits of numerator/denominator. -// Once 'count' digits have been produced rounds the result depending on the -// remainder (remainders of exactly .5 round upwards). Might update the -// decimal_point when rounding up (for example for 0.9999). -static void GenerateCountedDigits(int count, int* decimal_point, - Bignum* numerator, Bignum* denominator, - Vector<char>(buffer), int* length); - - -void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits, - Vector<char> buffer, int* length, int* decimal_point) { - ASSERT(v > 0); - ASSERT(!Double(v).IsSpecial()); - uint64_t significand; - int exponent; - bool lower_boundary_is_closer; - if (mode == BIGNUM_DTOA_SHORTEST_SINGLE) { - float f = static_cast<float>(v); - ASSERT(f == v); - significand = Single(f).Significand(); - exponent = Single(f).Exponent(); - lower_boundary_is_closer = Single(f).LowerBoundaryIsCloser(); - } else { - significand = Double(v).Significand(); - exponent = Double(v).Exponent(); - lower_boundary_is_closer = Double(v).LowerBoundaryIsCloser(); - } - bool need_boundary_deltas = - (mode == BIGNUM_DTOA_SHORTEST || mode == BIGNUM_DTOA_SHORTEST_SINGLE); - - bool is_even = (significand & 1) == 0; - int normalized_exponent = NormalizedExponent(significand, exponent); - // estimated_power might be too low by 1. - int estimated_power = EstimatePower(normalized_exponent); - - // Shortcut for Fixed. - // The requested digits correspond to the digits after the point. If the - // number is much too small, then there is no need in trying to get any - // digits. - if (mode == BIGNUM_DTOA_FIXED && -estimated_power - 1 > requested_digits) { - buffer[0] = '\0'; - *length = 0; - // Set decimal-point to -requested_digits. This is what Gay does. - // Note that it should not have any effect anyways since the string is - // empty. - *decimal_point = -requested_digits; - return; - } - - Bignum numerator; - Bignum denominator; - Bignum delta_minus; - Bignum delta_plus; - // Make sure the bignum can grow large enough. The smallest double equals - // 4e-324. In this case the denominator needs fewer than 324*4 binary digits. - // The maximum double is 1.7976931348623157e308 which needs fewer than - // 308*4 binary digits. - ASSERT(Bignum::kMaxSignificantBits >= 324*4); - InitialScaledStartValues(significand, exponent, lower_boundary_is_closer, - estimated_power, need_boundary_deltas, - &numerator, &denominator, - &delta_minus, &delta_plus); - // We now have v = (numerator / denominator) * 10^estimated_power. - FixupMultiply10(estimated_power, is_even, decimal_point, - &numerator, &denominator, - &delta_minus, &delta_plus); - // We now have v = (numerator / denominator) * 10^(decimal_point-1), and - // 1 <= (numerator + delta_plus) / denominator < 10 - switch (mode) { - case BIGNUM_DTOA_SHORTEST: - case BIGNUM_DTOA_SHORTEST_SINGLE: - GenerateShortestDigits(&numerator, &denominator, - &delta_minus, &delta_plus, - is_even, buffer, length); - break; - case BIGNUM_DTOA_FIXED: - BignumToFixed(requested_digits, decimal_point, - &numerator, &denominator, - buffer, length); - break; - case BIGNUM_DTOA_PRECISION: - GenerateCountedDigits(requested_digits, decimal_point, - &numerator, &denominator, - buffer, length); - break; - default: - UNREACHABLE(); - } - buffer[*length] = '\0'; -} - - -// The procedure starts generating digits from the left to the right and stops -// when the generated digits yield the shortest decimal representation of v. A -// decimal representation of v is a number lying closer to v than to any other -// double, so it converts to v when read. -// -// This is true if d, the decimal representation, is between m- and m+, the -// upper and lower boundaries. d must be strictly between them if !is_even. -// m- := (numerator - delta_minus) / denominator -// m+ := (numerator + delta_plus) / denominator -// -// Precondition: 0 <= (numerator+delta_plus) / denominator < 10. -// If 1 <= (numerator+delta_plus) / denominator < 10 then no leading 0 digit -// will be produced. This should be the standard precondition. -static void GenerateShortestDigits(Bignum* numerator, Bignum* denominator, - Bignum* delta_minus, Bignum* delta_plus, - bool is_even, - Vector<char> buffer, int* length) { - // Small optimization: if delta_minus and delta_plus are the same just reuse - // one of the two bignums. - if (Bignum::Equal(*delta_minus, *delta_plus)) { - delta_plus = delta_minus; - } - *length = 0; - for (;;) { - uint16_t digit; - digit = numerator->DivideModuloIntBignum(*denominator); - ASSERT(digit <= 9); // digit is a uint16_t and therefore always positive. - // digit = numerator / denominator (integer division). - // numerator = numerator % denominator. - buffer[(*length)++] = static_cast<char>(digit + '0'); - - // Can we stop already? - // If the remainder of the division is less than the distance to the lower - // boundary we can stop. In this case we simply round down (discarding the - // remainder). - // Similarly we test if we can round up (using the upper boundary). - bool in_delta_room_minus; - bool in_delta_room_plus; - if (is_even) { - in_delta_room_minus = Bignum::LessEqual(*numerator, *delta_minus); - } else { - in_delta_room_minus = Bignum::Less(*numerator, *delta_minus); - } - if (is_even) { - in_delta_room_plus = - Bignum::PlusCompare(*numerator, *delta_plus, *denominator) >= 0; - } else { - in_delta_room_plus = - Bignum::PlusCompare(*numerator, *delta_plus, *denominator) > 0; - } - if (!in_delta_room_minus && !in_delta_room_plus) { - // Prepare for next iteration. - numerator->Times10(); - delta_minus->Times10(); - // We optimized delta_plus to be equal to delta_minus (if they share the - // same value). So don't multiply delta_plus if they point to the same - // object. - if (delta_minus != delta_plus) { - delta_plus->Times10(); - } - } else if (in_delta_room_minus && in_delta_room_plus) { - // Let's see if 2*numerator < denominator. - // If yes, then the next digit would be < 5 and we can round down. - int compare = Bignum::PlusCompare(*numerator, *numerator, *denominator); - if (compare < 0) { - // Remaining digits are less than .5. -> Round down (== do nothing). - } else if (compare > 0) { - // Remaining digits are more than .5 of denominator. -> Round up. - // Note that the last digit could not be a '9' as otherwise the whole - // loop would have stopped earlier. - // We still have an assert here in case the preconditions were not - // satisfied. - ASSERT(buffer[(*length) - 1] != '9'); - buffer[(*length) - 1]++; - } else { - // Halfway case. - // TODO(floitsch): need a way to solve half-way cases. - // For now let's round towards even (since this is what Gay seems to - // do). - - if ((buffer[(*length) - 1] - '0') % 2 == 0) { - // Round down => Do nothing. - } else { - ASSERT(buffer[(*length) - 1] != '9'); - buffer[(*length) - 1]++; - } - } - return; - } else if (in_delta_room_minus) { - // Round down (== do nothing). - return; - } else { // in_delta_room_plus - // Round up. - // Note again that the last digit could not be '9' since this would have - // stopped the loop earlier. - // We still have an ASSERT here, in case the preconditions were not - // satisfied. - ASSERT(buffer[(*length) -1] != '9'); - buffer[(*length) - 1]++; - return; - } - } -} - - -// Let v = numerator / denominator < 10. -// Then we generate 'count' digits of d = x.xxxxx... (without the decimal point) -// from left to right. Once 'count' digits have been produced we decide wether -// to round up or down. Remainders of exactly .5 round upwards. Numbers such -// as 9.999999 propagate a carry all the way, and change the -// exponent (decimal_point), when rounding upwards. -static void GenerateCountedDigits(int count, int* decimal_point, - Bignum* numerator, Bignum* denominator, - Vector<char> buffer, int* length) { - ASSERT(count >= 0); - for (int i = 0; i < count - 1; ++i) { - uint16_t digit; - digit = numerator->DivideModuloIntBignum(*denominator); - ASSERT(digit <= 9); // digit is a uint16_t and therefore always positive. - // digit = numerator / denominator (integer division). - // numerator = numerator % denominator. - buffer[i] = static_cast<char>(digit + '0'); - // Prepare for next iteration. - numerator->Times10(); - } - // Generate the last digit. - uint16_t digit; - digit = numerator->DivideModuloIntBignum(*denominator); - if (Bignum::PlusCompare(*numerator, *numerator, *denominator) >= 0) { - digit++; - } - ASSERT(digit <= 10); - buffer[count - 1] = static_cast<char>(digit + '0'); - // Correct bad digits (in case we had a sequence of '9's). Propagate the - // carry until we hat a non-'9' or til we reach the first digit. - for (int i = count - 1; i > 0; --i) { - if (buffer[i] != '0' + 10) break; - buffer[i] = '0'; - buffer[i - 1]++; - } - if (buffer[0] == '0' + 10) { - // Propagate a carry past the top place. - buffer[0] = '1'; - (*decimal_point)++; - } - *length = count; -} - - -// Generates 'requested_digits' after the decimal point. It might omit -// trailing '0's. If the input number is too small then no digits at all are -// generated (ex.: 2 fixed digits for 0.00001). -// -// Input verifies: 1 <= (numerator + delta) / denominator < 10. -static void BignumToFixed(int requested_digits, int* decimal_point, - Bignum* numerator, Bignum* denominator, - Vector<char>(buffer), int* length) { - // Note that we have to look at more than just the requested_digits, since - // a number could be rounded up. Example: v=0.5 with requested_digits=0. - // Even though the power of v equals 0 we can't just stop here. - if (-(*decimal_point) > requested_digits) { - // The number is definitively too small. - // Ex: 0.001 with requested_digits == 1. - // Set decimal-point to -requested_digits. This is what Gay does. - // Note that it should not have any effect anyways since the string is - // empty. - *decimal_point = -requested_digits; - *length = 0; - return; - } else if (-(*decimal_point) == requested_digits) { - // We only need to verify if the number rounds down or up. - // Ex: 0.04 and 0.06 with requested_digits == 1. - ASSERT(*decimal_point == -requested_digits); - // Initially the fraction lies in range (1, 10]. Multiply the denominator - // by 10 so that we can compare more easily. - denominator->Times10(); - if (Bignum::PlusCompare(*numerator, *numerator, *denominator) >= 0) { - // If the fraction is >= 0.5 then we have to include the rounded - // digit. - buffer[0] = '1'; - *length = 1; - (*decimal_point)++; - } else { - // Note that we caught most of similar cases earlier. - *length = 0; - } - return; - } else { - // The requested digits correspond to the digits after the point. - // The variable 'needed_digits' includes the digits before the point. - int needed_digits = (*decimal_point) + requested_digits; - GenerateCountedDigits(needed_digits, decimal_point, - numerator, denominator, - buffer, length); - } -} - - -// Returns an estimation of k such that 10^(k-1) <= v < 10^k where -// v = f * 2^exponent and 2^52 <= f < 2^53. -// v is hence a normalized double with the given exponent. The output is an -// approximation for the exponent of the decimal approimation .digits * 10^k. -// -// The result might undershoot by 1 in which case 10^k <= v < 10^k+1. -// Note: this property holds for v's upper boundary m+ too. -// 10^k <= m+ < 10^k+1. -// (see explanation below). -// -// Examples: -// EstimatePower(0) => 16 -// EstimatePower(-52) => 0 -// -// Note: e >= 0 => EstimatedPower(e) > 0. No similar claim can be made for e<0. -static int EstimatePower(int exponent) { - // This function estimates log10 of v where v = f*2^e (with e == exponent). - // Note that 10^floor(log10(v)) <= v, but v <= 10^ceil(log10(v)). - // Note that f is bounded by its container size. Let p = 53 (the double's - // significand size). Then 2^(p-1) <= f < 2^p. - // - // Given that log10(v) == log2(v)/log2(10) and e+(len(f)-1) is quite close - // to log2(v) the function is simplified to (e+(len(f)-1)/log2(10)). - // The computed number undershoots by less than 0.631 (when we compute log3 - // and not log10). - // - // Optimization: since we only need an approximated result this computation - // can be performed on 64 bit integers. On x86/x64 architecture the speedup is - // not really measurable, though. - // - // Since we want to avoid overshooting we decrement by 1e10 so that - // floating-point imprecisions don't affect us. - // - // Explanation for v's boundary m+: the computation takes advantage of - // the fact that 2^(p-1) <= f < 2^p. Boundaries still satisfy this requirement - // (even for denormals where the delta can be much more important). - - const double k1Log10 = 0.30102999566398114; // 1/lg(10) - - // For doubles len(f) == 53 (don't forget the hidden bit). - const int kSignificandSize = Double::kSignificandSize; - double estimate = ceil((exponent + kSignificandSize - 1) * k1Log10 - 1e-10); - return static_cast<int>(estimate); -} - - -// See comments for InitialScaledStartValues. -static void InitialScaledStartValuesPositiveExponent( - uint64_t significand, int exponent, - int estimated_power, bool need_boundary_deltas, - Bignum* numerator, Bignum* denominator, - Bignum* delta_minus, Bignum* delta_plus) { - // A positive exponent implies a positive power. - ASSERT(estimated_power >= 0); - // Since the estimated_power is positive we simply multiply the denominator - // by 10^estimated_power. - - // numerator = v. - numerator->AssignUInt64(significand); - numerator->ShiftLeft(exponent); - // denominator = 10^estimated_power. - denominator->AssignPowerUInt16(10, estimated_power); - - if (need_boundary_deltas) { - // Introduce a common denominator so that the deltas to the boundaries are - // integers. - denominator->ShiftLeft(1); - numerator->ShiftLeft(1); - // Let v = f * 2^e, then m+ - v = 1/2 * 2^e; With the common - // denominator (of 2) delta_plus equals 2^e. - delta_plus->AssignUInt16(1); - delta_plus->ShiftLeft(exponent); - // Same for delta_minus. The adjustments if f == 2^p-1 are done later. - delta_minus->AssignUInt16(1); - delta_minus->ShiftLeft(exponent); - } -} - - -// See comments for InitialScaledStartValues -static void InitialScaledStartValuesNegativeExponentPositivePower( - uint64_t significand, int exponent, - int estimated_power, bool need_boundary_deltas, - Bignum* numerator, Bignum* denominator, - Bignum* delta_minus, Bignum* delta_plus) { - // v = f * 2^e with e < 0, and with estimated_power >= 0. - // This means that e is close to 0 (have a look at how estimated_power is - // computed). - - // numerator = significand - // since v = significand * 2^exponent this is equivalent to - // numerator = v * / 2^-exponent - numerator->AssignUInt64(significand); - // denominator = 10^estimated_power * 2^-exponent (with exponent < 0) - denominator->AssignPowerUInt16(10, estimated_power); - denominator->ShiftLeft(-exponent); - - if (need_boundary_deltas) { - // Introduce a common denominator so that the deltas to the boundaries are - // integers. - denominator->ShiftLeft(1); - numerator->ShiftLeft(1); - // Let v = f * 2^e, then m+ - v = 1/2 * 2^e; With the common - // denominator (of 2) delta_plus equals 2^e. - // Given that the denominator already includes v's exponent the distance - // to the boundaries is simply 1. - delta_plus->AssignUInt16(1); - // Same for delta_minus. The adjustments if f == 2^p-1 are done later. - delta_minus->AssignUInt16(1); - } -} - - -// See comments for InitialScaledStartValues -static void InitialScaledStartValuesNegativeExponentNegativePower( - uint64_t significand, int exponent, - int estimated_power, bool need_boundary_deltas, - Bignum* numerator, Bignum* denominator, - Bignum* delta_minus, Bignum* delta_plus) { - // Instead of multiplying the denominator with 10^estimated_power we - // multiply all values (numerator and deltas) by 10^-estimated_power. - - // Use numerator as temporary container for power_ten. - Bignum* power_ten = numerator; - power_ten->AssignPowerUInt16(10, -estimated_power); - - if (need_boundary_deltas) { - // Since power_ten == numerator we must make a copy of 10^estimated_power - // before we complete the computation of the numerator. - // delta_plus = delta_minus = 10^estimated_power - delta_plus->AssignBignum(*power_ten); - delta_minus->AssignBignum(*power_ten); - } - - // numerator = significand * 2 * 10^-estimated_power - // since v = significand * 2^exponent this is equivalent to - // numerator = v * 10^-estimated_power * 2 * 2^-exponent. - // Remember: numerator has been abused as power_ten. So no need to assign it - // to itself. - ASSERT(numerator == power_ten); - numerator->MultiplyByUInt64(significand); - - // denominator = 2 * 2^-exponent with exponent < 0. - denominator->AssignUInt16(1); - denominator->ShiftLeft(-exponent); - - if (need_boundary_deltas) { - // Introduce a common denominator so that the deltas to the boundaries are - // integers. - numerator->ShiftLeft(1); - denominator->ShiftLeft(1); - // With this shift the boundaries have their correct value, since - // delta_plus = 10^-estimated_power, and - // delta_minus = 10^-estimated_power. - // These assignments have been done earlier. - // The adjustments if f == 2^p-1 (lower boundary is closer) are done later. - } -} - - -// Let v = significand * 2^exponent. -// Computes v / 10^estimated_power exactly, as a ratio of two bignums, numerator -// and denominator. The functions GenerateShortestDigits and -// GenerateCountedDigits will then convert this ratio to its decimal -// representation d, with the required accuracy. -// Then d * 10^estimated_power is the representation of v. -// (Note: the fraction and the estimated_power might get adjusted before -// generating the decimal representation.) -// -// The initial start values consist of: -// - a scaled numerator: s.t. numerator/denominator == v / 10^estimated_power. -// - a scaled (common) denominator. -// optionally (used by GenerateShortestDigits to decide if it has the shortest -// decimal converting back to v): -// - v - m-: the distance to the lower boundary. -// - m+ - v: the distance to the upper boundary. -// -// v, m+, m-, and therefore v - m- and m+ - v all share the same denominator. -// -// Let ep == estimated_power, then the returned values will satisfy: -// v / 10^ep = numerator / denominator. -// v's boundarys m- and m+: -// m- / 10^ep == v / 10^ep - delta_minus / denominator -// m+ / 10^ep == v / 10^ep + delta_plus / denominator -// Or in other words: -// m- == v - delta_minus * 10^ep / denominator; -// m+ == v + delta_plus * 10^ep / denominator; -// -// Since 10^(k-1) <= v < 10^k (with k == estimated_power) -// or 10^k <= v < 10^(k+1) -// we then have 0.1 <= numerator/denominator < 1 -// or 1 <= numerator/denominator < 10 -// -// It is then easy to kickstart the digit-generation routine. -// -// The boundary-deltas are only filled if the mode equals BIGNUM_DTOA_SHORTEST -// or BIGNUM_DTOA_SHORTEST_SINGLE. - -static void InitialScaledStartValues(uint64_t significand, - int exponent, - bool lower_boundary_is_closer, - int estimated_power, - bool need_boundary_deltas, - Bignum* numerator, - Bignum* denominator, - Bignum* delta_minus, - Bignum* delta_plus) { - if (exponent >= 0) { - InitialScaledStartValuesPositiveExponent( - significand, exponent, estimated_power, need_boundary_deltas, - numerator, denominator, delta_minus, delta_plus); - } else if (estimated_power >= 0) { - InitialScaledStartValuesNegativeExponentPositivePower( - significand, exponent, estimated_power, need_boundary_deltas, - numerator, denominator, delta_minus, delta_plus); - } else { - InitialScaledStartValuesNegativeExponentNegativePower( - significand, exponent, estimated_power, need_boundary_deltas, - numerator, denominator, delta_minus, delta_plus); - } - - if (need_boundary_deltas && lower_boundary_is_closer) { - // The lower boundary is closer at half the distance of "normal" numbers. - // Increase the common denominator and adapt all but the delta_minus. - denominator->ShiftLeft(1); // *2 - numerator->ShiftLeft(1); // *2 - delta_plus->ShiftLeft(1); // *2 - } -} - - -// This routine multiplies numerator/denominator so that its values lies in the -// range 1-10. That is after a call to this function we have: -// 1 <= (numerator + delta_plus) /denominator < 10. -// Let numerator the input before modification and numerator' the argument -// after modification, then the output-parameter decimal_point is such that -// numerator / denominator * 10^estimated_power == -// numerator' / denominator' * 10^(decimal_point - 1) -// In some cases estimated_power was too low, and this is already the case. We -// then simply adjust the power so that 10^(k-1) <= v < 10^k (with k == -// estimated_power) but do not touch the numerator or denominator. -// Otherwise the routine multiplies the numerator and the deltas by 10. -static void FixupMultiply10(int estimated_power, bool is_even, - int* decimal_point, - Bignum* numerator, Bignum* denominator, - Bignum* delta_minus, Bignum* delta_plus) { - bool in_range; - if (is_even) { - // For IEEE doubles half-way cases (in decimal system numbers ending with 5) - // are rounded to the closest floating-point number with even significand. - in_range = Bignum::PlusCompare(*numerator, *delta_plus, *denominator) >= 0; - } else { - in_range = Bignum::PlusCompare(*numerator, *delta_plus, *denominator) > 0; - } - if (in_range) { - // Since numerator + delta_plus >= denominator we already have - // 1 <= numerator/denominator < 10. Simply update the estimated_power. - *decimal_point = estimated_power + 1; - } else { - *decimal_point = estimated_power; - numerator->Times10(); - if (Bignum::Equal(*delta_minus, *delta_plus)) { - delta_minus->Times10(); - delta_plus->AssignBignum(*delta_minus); - } else { - delta_minus->Times10(); - delta_plus->Times10(); - } - } -} - -} // namespace double_conversion - -// ICU PATCH: Close ICU namespace -U_NAMESPACE_END -#endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING |