// © 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 <algorithm> #include <cstring> // ICU PATCH: Customize header file paths for ICU. #include "double-conversion-bignum.h" #include "double-conversion-utils.h" // ICU PATCH: Wrap in ICU namespace U_NAMESPACE_BEGIN namespace double_conversion { Bignum::Chunk& Bignum::RawBigit(const int index) { DOUBLE_CONVERSION_ASSERT(static_cast<unsigned>(index) < kBigitCapacity); return bigits_buffer_[index]; } const Bignum::Chunk& Bignum::RawBigit(const int index) const { DOUBLE_CONVERSION_ASSERT(static_cast<unsigned>(index) < kBigitCapacity); return bigits_buffer_[index]; } template<typename S> static int BitSize(const S value) { (void) value; // Mark variable as used. return 8 * sizeof(value); } // Guaranteed to lie in one Bigit. void Bignum::AssignUInt16(const uint16_t value) { DOUBLE_CONVERSION_ASSERT(kBigitSize >= BitSize(value)); Zero(); if (value > 0) { RawBigit(0) = value; used_bigits_ = 1; } } void Bignum::AssignUInt64(uint64_t value) { Zero(); for(int i = 0; value > 0; ++i) { RawBigit(i) = value & kBigitMask; value >>= kBigitSize; ++used_bigits_; } } void Bignum::AssignBignum(const Bignum& other) { exponent_ = other.exponent_; for (int i = 0; i < other.used_bigits_; ++i) { RawBigit(i) = other.RawBigit(i); } used_bigits_ = other.used_bigits_; } static uint64_t ReadUInt64(const Vector<const char> buffer, const int from, const int digits_to_read) { uint64_t result = 0; for (int i = from; i < from + digits_to_read; ++i) { const int digit = buffer[i] - '0'; DOUBLE_CONVERSION_ASSERT(0 <= digit && digit <= 9); result = result * 10 + digit; } return result; } void Bignum::AssignDecimalString(const Vector<const char> value) { // 2^64 = 18446744073709551616 > 10^19 static const int kMaxUint64DecimalDigits = 19; Zero(); int length = value.length(); unsigned pos = 0; // Let's just say that each digit needs 4 bits. while (length >= kMaxUint64DecimalDigits) { const uint64_t digits = ReadUInt64(value, pos, kMaxUint64DecimalDigits); pos += kMaxUint64DecimalDigits; length -= kMaxUint64DecimalDigits; MultiplyByPowerOfTen(kMaxUint64DecimalDigits); AddUInt64(digits); } const uint64_t digits = ReadUInt64(value, pos, length); MultiplyByPowerOfTen(length); AddUInt64(digits); Clamp(); } static uint64_t HexCharValue(const int c) { if ('0' <= c && c <= '9') { return c - '0'; } if ('a' <= c && c <= 'f') { return 10 + c - 'a'; } DOUBLE_CONVERSION_ASSERT('A' <= c && c <= 'F'); return 10 + c - 'A'; } // Unlike AssignDecimalString(), this function is "only" used // for unit-tests and therefore not performance critical. void Bignum::AssignHexString(Vector<const char> value) { Zero(); // Required capacity could be reduced by ignoring leading zeros. EnsureCapacity(((value.length() * 4) + kBigitSize - 1) / kBigitSize); DOUBLE_CONVERSION_ASSERT(sizeof(uint64_t) * 8 >= kBigitSize + 4); // TODO: static_assert // Accumulates converted hex digits until at least kBigitSize bits. // Works with non-factor-of-four kBigitSizes. uint64_t tmp = 0; for (int cnt = 0; !value.is_empty(); value.pop_back()) { tmp |= (HexCharValue(value.last()) << cnt); if ((cnt += 4) >= kBigitSize) { RawBigit(used_bigits_++) = (tmp & kBigitMask); cnt -= kBigitSize; tmp >>= kBigitSize; } } if (tmp > 0) { DOUBLE_CONVERSION_ASSERT(tmp <= kBigitMask); RawBigit(used_bigits_++) = static_cast<Bignum::Chunk>(tmp & kBigitMask); } Clamp(); } void Bignum::AddUInt64(const uint64_t operand) { if (operand == 0) { return; } Bignum other; other.AssignUInt64(operand); AddBignum(other); } void Bignum::AddBignum(const Bignum& other) { DOUBLE_CONVERSION_ASSERT(IsClamped()); DOUBLE_CONVERSION_ASSERT(other.IsClamped()); // If this has a greater exponent than other append zero-bigits to this. // After this call exponent_ <= other.exponent_. Align(other); // There are two possibilities: // aaaaaaaaaaa 0000 (where the 0s represent a's exponent) // bbbbb 00000000 // ---------------- // ccccccccccc 0000 // or // aaaaaaaaaa 0000 // bbbbbbbbb 0000000 // ----------------- // cccccccccccc 0000 // In both cases we might need a carry bigit. EnsureCapacity(1 + (std::max)(BigitLength(), other.BigitLength()) - exponent_); Chunk carry = 0; int bigit_pos = other.exponent_ - exponent_; DOUBLE_CONVERSION_ASSERT(bigit_pos >= 0); for (int i = used_bigits_; i < bigit_pos; ++i) { RawBigit(i) = 0; } for (int i = 0; i < other.used_bigits_; ++i) { const Chunk my = (bigit_pos < used_bigits_) ? RawBigit(bigit_pos) : 0; const Chunk sum = my + other.RawBigit(i) + carry; RawBigit(bigit_pos) = sum & kBigitMask; carry = sum >> kBigitSize; ++bigit_pos; } while (carry != 0) { const Chunk my = (bigit_pos < used_bigits_) ? RawBigit(bigit_pos) : 0; const Chunk sum = my + carry; RawBigit(bigit_pos) = sum & kBigitMask; carry = sum >> kBigitSize; ++bigit_pos; } used_bigits_ = static_cast<int16_t>(std::max(bigit_pos, static_cast<int>(used_bigits_))); DOUBLE_CONVERSION_ASSERT(IsClamped()); } void Bignum::SubtractBignum(const Bignum& other) { DOUBLE_CONVERSION_ASSERT(IsClamped()); DOUBLE_CONVERSION_ASSERT(other.IsClamped()); // We require this to be bigger than other. DOUBLE_CONVERSION_ASSERT(LessEqual(other, *this)); Align(other); const int offset = other.exponent_ - exponent_; Chunk borrow = 0; int i; for (i = 0; i < other.used_bigits_; ++i) { DOUBLE_CONVERSION_ASSERT((borrow == 0) || (borrow == 1)); const Chunk difference = RawBigit(i + offset) - other.RawBigit(i) - borrow; RawBigit(i + offset) = difference & kBigitMask; borrow = difference >> (kChunkSize - 1); } while (borrow != 0) { const Chunk difference = RawBigit(i + offset) - borrow; RawBigit(i + offset) = difference & kBigitMask; borrow = difference >> (kChunkSize - 1); ++i; } Clamp(); } void Bignum::ShiftLeft(const int shift_amount) { if (used_bigits_ == 0) { return; } exponent_ += static_cast<int16_t>(shift_amount / kBigitSize); const int local_shift = shift_amount % kBigitSize; EnsureCapacity(used_bigits_ + 1); BigitsShiftLeft(local_shift); } void Bignum::MultiplyByUInt32(const uint32_t factor) { if (factor == 1) { return; } if (factor == 0) { Zero(); return; } if (used_bigits_ == 0) { return; } // The product of a bigit with the factor is of size kBigitSize + 32. // Assert that this number + 1 (for the carry) fits into double chunk. DOUBLE_CONVERSION_ASSERT(kDoubleChunkSize >= kBigitSize + 32 + 1); DoubleChunk carry = 0; for (int i = 0; i < used_bigits_; ++i) { const DoubleChunk product = static_cast<DoubleChunk>(factor) * RawBigit(i) + carry; RawBigit(i) = static_cast<Chunk>(product & kBigitMask); carry = (product >> kBigitSize); } while (carry != 0) { EnsureCapacity(used_bigits_ + 1); RawBigit(used_bigits_) = carry & kBigitMask; used_bigits_++; carry >>= kBigitSize; } } void Bignum::MultiplyByUInt64(const uint64_t factor) { if (factor == 1) { return; } if (factor == 0) { Zero(); return; } if (used_bigits_ == 0) { return; } DOUBLE_CONVERSION_ASSERT(kBigitSize < 32); uint64_t carry = 0; const uint64_t low = factor & 0xFFFFFFFF; const uint64_t high = factor >> 32; for (int i = 0; i < used_bigits_; ++i) { const uint64_t product_low = low * RawBigit(i); const uint64_t product_high = high * RawBigit(i); const uint64_t tmp = (carry & kBigitMask) + product_low; RawBigit(i) = tmp & kBigitMask; carry = (carry >> kBigitSize) + (tmp >> kBigitSize) + (product_high << (32 - kBigitSize)); } while (carry != 0) { EnsureCapacity(used_bigits_ + 1); RawBigit(used_bigits_) = carry & kBigitMask; used_bigits_++; carry >>= kBigitSize; } } void Bignum::MultiplyByPowerOfTen(const int exponent) { static const uint64_t kFive27 = DOUBLE_CONVERSION_UINT64_2PART_C(0x6765c793, fa10079d); static const uint16_t kFive1 = 5; static const uint16_t kFive2 = kFive1 * 5; static const uint16_t kFive3 = kFive2 * 5; static const uint16_t kFive4 = kFive3 * 5; static const uint16_t kFive5 = kFive4 * 5; static const uint16_t kFive6 = kFive5 * 5; static const uint32_t kFive7 = kFive6 * 5; static const uint32_t kFive8 = kFive7 * 5; static const uint32_t kFive9 = kFive8 * 5; static const uint32_t kFive10 = kFive9 * 5; static const uint32_t kFive11 = kFive10 * 5; static const uint32_t kFive12 = kFive11 * 5; static const uint32_t kFive13 = kFive12 * 5; static const uint32_t kFive1_to_12[] = { kFive1, kFive2, kFive3, kFive4, kFive5, kFive6, kFive7, kFive8, kFive9, kFive10, kFive11, kFive12 }; DOUBLE_CONVERSION_ASSERT(exponent >= 0); if (exponent == 0) { return; } if (used_bigits_ == 0) { return; } // We shift by exponent at the end just before returning. int remaining_exponent = exponent; while (remaining_exponent >= 27) { MultiplyByUInt64(kFive27); remaining_exponent -= 27; } while (remaining_exponent >= 13) { MultiplyByUInt32(kFive13); remaining_exponent -= 13; } if (remaining_exponent > 0) { MultiplyByUInt32(kFive1_to_12[remaining_exponent - 1]); } ShiftLeft(exponent); } void Bignum::Square() { DOUBLE_CONVERSION_ASSERT(IsClamped()); const int product_length = 2 * used_bigits_; EnsureCapacity(product_length); // Comba multiplication: compute each column separately. // Example: r = a2a1a0 * b2b1b0. // r = 1 * a0b0 + // 10 * (a1b0 + a0b1) + // 100 * (a2b0 + a1b1 + a0b2) + // 1000 * (a2b1 + a1b2) + // 10000 * a2b2 // // In the worst case we have to accumulate nb-digits products of digit*digit. // // Assert that the additional number of bits in a DoubleChunk are enough to // sum up used_digits of Bigit*Bigit. if ((1 << (2 * (kChunkSize - kBigitSize))) <= used_bigits_) { DOUBLE_CONVERSION_UNIMPLEMENTED(); } DoubleChunk accumulator = 0; // First shift the digits so we don't overwrite them. const int copy_offset = used_bigits_; for (int i = 0; i < used_bigits_; ++i) { RawBigit(copy_offset + i) = RawBigit(i); } // We have two loops to avoid some 'if's in the loop. for (int i = 0; i < used_bigits_; ++i) { // Process temporary digit i with power i. // The sum of the two indices must be equal to i. int bigit_index1 = i; int bigit_index2 = 0; // Sum all of the sub-products. while (bigit_index1 >= 0) { const Chunk chunk1 = RawBigit(copy_offset + bigit_index1); const Chunk chunk2 = RawBigit(copy_offset + bigit_index2); accumulator += static_cast<DoubleChunk>(chunk1) * chunk2; bigit_index1--; bigit_index2++; } RawBigit(i) = static_cast<Chunk>(accumulator) & kBigitMask; accumulator >>= kBigitSize; } for (int i = used_bigits_; i < product_length; ++i) { int bigit_index1 = used_bigits_ - 1; int bigit_index2 = i - bigit_index1; // Invariant: sum of both indices is again equal to i. // Inner loop runs 0 times on last iteration, emptying accumulator. while (bigit_index2 < used_bigits_) { const Chunk chunk1 = RawBigit(copy_offset + bigit_index1); const Chunk chunk2 = RawBigit(copy_offset + bigit_index2); accumulator += static_cast<DoubleChunk>(chunk1) * chunk2; bigit_index1--; bigit_index2++; } // The overwritten RawBigit(i) will never be read in further loop iterations, // because bigit_index1 and bigit_index2 are always greater // than i - used_bigits_. RawBigit(i) = static_cast<Chunk>(accumulator) & kBigitMask; accumulator >>= kBigitSize; } // Since the result was guaranteed to lie inside the number the // accumulator must be 0 now. DOUBLE_CONVERSION_ASSERT(accumulator == 0); // Don't forget to update the used_digits and the exponent. used_bigits_ = static_cast<int16_t>(product_length); exponent_ *= 2; Clamp(); } void Bignum::AssignPowerUInt16(uint16_t base, const int power_exponent) { DOUBLE_CONVERSION_ASSERT(base != 0); DOUBLE_CONVERSION_ASSERT(power_exponent >= 0); if (power_exponent == 0) { AssignUInt16(1); return; } Zero(); int shifts = 0; // We expect base to be in range 2-32, and most often to be 10. // It does not make much sense to implement different algorithms for counting // the bits. while ((base & 1) == 0) { base >>= 1; shifts++; } int bit_size = 0; int tmp_base = base; while (tmp_base != 0) { tmp_base >>= 1; bit_size++; } const int final_size = bit_size * power_exponent; // 1 extra bigit for the shifting, and one for rounded final_size. EnsureCapacity(final_size / kBigitSize + 2); // Left to Right exponentiation. int mask = 1; while (power_exponent >= mask) mask <<= 1; // The mask is now pointing to the bit above the most significant 1-bit of // power_exponent. // Get rid of first 1-bit; mask >>= 2; uint64_t this_value = base; bool delayed_multiplication = false; const uint64_t max_32bits = 0xFFFFFFFF; while (mask != 0 && this_value <= max_32bits) { this_value = this_value * this_value; // Verify that there is enough space in this_value to perform the // multiplication. The first bit_size bits must be 0. if ((power_exponent & mask) != 0) { DOUBLE_CONVERSION_ASSERT(bit_size > 0); const uint64_t base_bits_mask = ~((static_cast<uint64_t>(1) << (64 - bit_size)) - 1); const bool high_bits_zero = (this_value & base_bits_mask) == 0; if (high_bits_zero) { this_value *= base; } else { delayed_multiplication = true; } } mask >>= 1; } AssignUInt64(this_value); if (delayed_multiplication) { MultiplyByUInt32(base); } // Now do the same thing as a bignum. while (mask != 0) { Square(); if ((power_exponent & mask) != 0) { MultiplyByUInt32(base); } mask >>= 1; } // And finally add the saved shifts. ShiftLeft(shifts * power_exponent); } // Precondition: this/other < 16bit. uint16_t Bignum::DivideModuloIntBignum(const Bignum& other) { DOUBLE_CONVERSION_ASSERT(IsClamped()); DOUBLE_CONVERSION_ASSERT(other.IsClamped()); DOUBLE_CONVERSION_ASSERT(other.used_bigits_ > 0); // Easy case: if we have less digits than the divisor than the result is 0. // Note: this handles the case where this == 0, too. if (BigitLength() < other.BigitLength()) { return 0; } Align(other); uint16_t result = 0; // Start by removing multiples of 'other' until both numbers have the same // number of digits. while (BigitLength() > other.BigitLength()) { // This naive approach is extremely inefficient if `this` divided by other // is big. This function is implemented for doubleToString where // the result should be small (less than 10). DOUBLE_CONVERSION_ASSERT(other.RawBigit(other.used_bigits_ - 1) >= ((1 << kBigitSize) / 16)); DOUBLE_CONVERSION_ASSERT(RawBigit(used_bigits_ - 1) < 0x10000); // Remove the multiples of the first digit. // Example this = 23 and other equals 9. -> Remove 2 multiples. result += static_cast<uint16_t>(RawBigit(used_bigits_ - 1)); SubtractTimes(other, RawBigit(used_bigits_ - 1)); } DOUBLE_CONVERSION_ASSERT(BigitLength() == other.BigitLength()); // Both bignums are at the same length now. // Since other has more than 0 digits we know that the access to // RawBigit(used_bigits_ - 1) is safe. const Chunk this_bigit = RawBigit(used_bigits_ - 1); const Chunk other_bigit = other.RawBigit(other.used_bigits_ - 1); if (other.used_bigits_ == 1) { // Shortcut for easy (and common) case. int quotient = this_bigit / other_bigit; RawBigit(used_bigits_ - 1) = this_bigit - other_bigit * quotient; DOUBLE_CONVERSION_ASSERT(quotient < 0x10000); result += static_cast<uint16_t>(quotient); Clamp(); return result; } const int division_estimate = this_bigit / (other_bigit + 1); DOUBLE_CONVERSION_ASSERT(division_estimate < 0x10000); result += static_cast<uint16_t>(division_estimate); SubtractTimes(other, division_estimate); if (other_bigit * (division_estimate + 1) > this_bigit) { // No need to even try to subtract. Even if other's remaining digits were 0 // another subtraction would be too much. return result; } while (LessEqual(other, *this)) { SubtractBignum(other); result++; } return result; } template<typename S> static int SizeInHexChars(S number) { DOUBLE_CONVERSION_ASSERT(number > 0); int result = 0; while (number != 0) { number >>= 4; result++; } return result; } static char HexCharOfValue(const int value) { DOUBLE_CONVERSION_ASSERT(0 <= value && value <= 16); if (value < 10) { return static_cast<char>(value + '0'); } return static_cast<char>(value - 10 + 'A'); } bool Bignum::ToHexString(char* buffer, const int buffer_size) const { DOUBLE_CONVERSION_ASSERT(IsClamped()); // Each bigit must be printable as separate hex-character. DOUBLE_CONVERSION_ASSERT(kBigitSize % 4 == 0); static const int kHexCharsPerBigit = kBigitSize / 4; if (used_bigits_ == 0) { if (buffer_size < 2) { return false; } buffer[0] = '0'; buffer[1] = '\0'; return true; } // We add 1 for the terminating '\0' character. const int needed_chars = (BigitLength() - 1) * kHexCharsPerBigit + SizeInHexChars(RawBigit(used_bigits_ - 1)) + 1; if (needed_chars > buffer_size) { return false; } int string_index = needed_chars - 1; buffer[string_index--] = '\0'; for (int i = 0; i < exponent_; ++i) { for (int j = 0; j < kHexCharsPerBigit; ++j) { buffer[string_index--] = '0'; } } for (int i = 0; i < used_bigits_ - 1; ++i) { Chunk current_bigit = RawBigit(i); for (int j = 0; j < kHexCharsPerBigit; ++j) { buffer[string_index--] = HexCharOfValue(current_bigit & 0xF); current_bigit >>= 4; } } // And finally the last bigit. Chunk most_significant_bigit = RawBigit(used_bigits_ - 1); while (most_significant_bigit != 0) { buffer[string_index--] = HexCharOfValue(most_significant_bigit & 0xF); most_significant_bigit >>= 4; } return true; } Bignum::Chunk Bignum::BigitOrZero(const int index) const { if (index >= BigitLength()) { return 0; } if (index < exponent_) { return 0; } return RawBigit(index - exponent_); } int Bignum::Compare(const Bignum& a, const Bignum& b) { DOUBLE_CONVERSION_ASSERT(a.IsClamped()); DOUBLE_CONVERSION_ASSERT(b.IsClamped()); const int bigit_length_a = a.BigitLength(); const int bigit_length_b = b.BigitLength(); if (bigit_length_a < bigit_length_b) { return -1; } if (bigit_length_a > bigit_length_b) { return +1; } for (int i = bigit_length_a - 1; i >= (std::min)(a.exponent_, b.exponent_); --i) { const Chunk bigit_a = a.BigitOrZero(i); const Chunk bigit_b = b.BigitOrZero(i); if (bigit_a < bigit_b) { return -1; } if (bigit_a > bigit_b) { return +1; } // Otherwise they are equal up to this digit. Try the next digit. } return 0; } int Bignum::PlusCompare(const Bignum& a, const Bignum& b, const Bignum& c) { DOUBLE_CONVERSION_ASSERT(a.IsClamped()); DOUBLE_CONVERSION_ASSERT(b.IsClamped()); DOUBLE_CONVERSION_ASSERT(c.IsClamped()); if (a.BigitLength() < b.BigitLength()) { return PlusCompare(b, a, c); } if (a.BigitLength() + 1 < c.BigitLength()) { return -1; } if (a.BigitLength() > c.BigitLength()) { return +1; } // The exponent encodes 0-bigits. So if there are more 0-digits in 'a' than // 'b' has digits, then the bigit-length of 'a'+'b' must be equal to the one // of 'a'. if (a.exponent_ >= b.BigitLength() && a.BigitLength() < c.BigitLength()) { return -1; } Chunk borrow = 0; // Starting at min_exponent all digits are == 0. So no need to compare them. const int min_exponent = (std::min)((std::min)(a.exponent_, b.exponent_), c.exponent_); for (int i = c.BigitLength() - 1; i >= min_exponent; --i) { const Chunk chunk_a = a.BigitOrZero(i); const Chunk chunk_b = b.BigitOrZero(i); const Chunk chunk_c = c.BigitOrZero(i); const Chunk sum = chunk_a + chunk_b; if (sum > chunk_c + borrow) { return +1; } else { borrow = chunk_c + borrow - sum; if (borrow > 1) { return -1; } borrow <<= kBigitSize; } } if (borrow == 0) { return 0; } return -1; } void Bignum::Clamp() { while (used_bigits_ > 0 && RawBigit(used_bigits_ - 1) == 0) { used_bigits_--; } if (used_bigits_ == 0) { // Zero. exponent_ = 0; } } void Bignum::Align(const Bignum& other) { if (exponent_ > other.exponent_) { // If "X" represents a "hidden" bigit (by the exponent) then we are in the // following case (a == this, b == other): // a: aaaaaaXXXX or a: aaaaaXXX // b: bbbbbbX b: bbbbbbbbXX // We replace some of the hidden digits (X) of a with 0 digits. // a: aaaaaa000X or a: aaaaa0XX const int zero_bigits = exponent_ - other.exponent_; EnsureCapacity(used_bigits_ + zero_bigits); for (int i = used_bigits_ - 1; i >= 0; --i) { RawBigit(i + zero_bigits) = RawBigit(i); } for (int i = 0; i < zero_bigits; ++i) { RawBigit(i) = 0; } used_bigits_ += static_cast<int16_t>(zero_bigits); exponent_ -= static_cast<int16_t>(zero_bigits); DOUBLE_CONVERSION_ASSERT(used_bigits_ >= 0); DOUBLE_CONVERSION_ASSERT(exponent_ >= 0); } } void Bignum::BigitsShiftLeft(const int shift_amount) { DOUBLE_CONVERSION_ASSERT(shift_amount < kBigitSize); DOUBLE_CONVERSION_ASSERT(shift_amount >= 0); Chunk carry = 0; for (int i = 0; i < used_bigits_; ++i) { const Chunk new_carry = RawBigit(i) >> (kBigitSize - shift_amount); RawBigit(i) = ((RawBigit(i) << shift_amount) + carry) & kBigitMask; carry = new_carry; } if (carry != 0) { RawBigit(used_bigits_) = carry; used_bigits_++; } } void Bignum::SubtractTimes(const Bignum& other, const int factor) { DOUBLE_CONVERSION_ASSERT(exponent_ <= other.exponent_); if (factor < 3) { for (int i = 0; i < factor; ++i) { SubtractBignum(other); } return; } Chunk borrow = 0; const int exponent_diff = other.exponent_ - exponent_; for (int i = 0; i < other.used_bigits_; ++i) { const DoubleChunk product = static_cast<DoubleChunk>(factor) * other.RawBigit(i); const DoubleChunk remove = borrow + product; const Chunk difference = RawBigit(i + exponent_diff) - (remove & kBigitMask); RawBigit(i + exponent_diff) = difference & kBigitMask; borrow = static_cast<Chunk>((difference >> (kChunkSize - 1)) + (remove >> kBigitSize)); } for (int i = other.used_bigits_ + exponent_diff; i < used_bigits_; ++i) { if (borrow == 0) { return; } const Chunk difference = RawBigit(i) - borrow; RawBigit(i) = difference & kBigitMask; borrow = difference >> (kChunkSize - 1); } Clamp(); } } // namespace double_conversion // ICU PATCH: Close ICU namespace U_NAMESPACE_END #endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING