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Diffstat (limited to 'deps/node/deps/icu-small/source/i18n/double-conversion-bignum.cpp')
| -rw-r--r-- | deps/node/deps/icu-small/source/i18n/double-conversion-bignum.cpp | 784 |
1 files changed, 0 insertions, 784 deletions
diff --git a/deps/node/deps/icu-small/source/i18n/double-conversion-bignum.cpp b/deps/node/deps/icu-small/source/i18n/double-conversion-bignum.cpp deleted file mode 100644 index d5682af3..00000000 --- a/deps/node/deps/icu-small/source/i18n/double-conversion-bignum.cpp +++ /dev/null @@ -1,784 +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 - -// 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::Bignum() - : bigits_(bigits_buffer_, kBigitCapacity), used_digits_(0), exponent_(0) { - for (int i = 0; i < kBigitCapacity; ++i) { - bigits_[i] = 0; - } -} - - -template<typename S> -static int BitSize(S value) { - (void) value; // Mark variable as used. - return 8 * sizeof(value); -} - -// Guaranteed to lie in one Bigit. -void Bignum::AssignUInt16(uint16_t value) { - ASSERT(kBigitSize >= BitSize(value)); - Zero(); - if (value == 0) return; - - EnsureCapacity(1); - bigits_[0] = value; - used_digits_ = 1; -} - - -void Bignum::AssignUInt64(uint64_t value) { - const int kUInt64Size = 64; - - Zero(); - if (value == 0) return; - - int needed_bigits = kUInt64Size / kBigitSize + 1; - EnsureCapacity(needed_bigits); - for (int i = 0; i < needed_bigits; ++i) { - bigits_[i] = value & kBigitMask; - value = value >> kBigitSize; - } - used_digits_ = needed_bigits; - Clamp(); -} - - -void Bignum::AssignBignum(const Bignum& other) { - exponent_ = other.exponent_; - for (int i = 0; i < other.used_digits_; ++i) { - bigits_[i] = other.bigits_[i]; - } - // Clear the excess digits (if there were any). - for (int i = other.used_digits_; i < used_digits_; ++i) { - bigits_[i] = 0; - } - used_digits_ = other.used_digits_; -} - - -static uint64_t ReadUInt64(Vector<const char> buffer, - int from, - int digits_to_read) { - uint64_t result = 0; - for (int i = from; i < from + digits_to_read; ++i) { - int digit = buffer[i] - '0'; - ASSERT(0 <= digit && digit <= 9); - result = result * 10 + digit; - } - return result; -} - - -void Bignum::AssignDecimalString(Vector<const char> value) { - // 2^64 = 18446744073709551616 > 10^19 - const int kMaxUint64DecimalDigits = 19; - Zero(); - int length = value.length(); - unsigned int pos = 0; - // Let's just say that each digit needs 4 bits. - while (length >= kMaxUint64DecimalDigits) { - uint64_t digits = ReadUInt64(value, pos, kMaxUint64DecimalDigits); - pos += kMaxUint64DecimalDigits; - length -= kMaxUint64DecimalDigits; - MultiplyByPowerOfTen(kMaxUint64DecimalDigits); - AddUInt64(digits); - } - uint64_t digits = ReadUInt64(value, pos, length); - MultiplyByPowerOfTen(length); - AddUInt64(digits); - Clamp(); -} - - -static int HexCharValue(char c) { - if ('0' <= c && c <= '9') return c - '0'; - if ('a' <= c && c <= 'f') return 10 + c - 'a'; - ASSERT('A' <= c && c <= 'F'); - return 10 + c - 'A'; -} - - -void Bignum::AssignHexString(Vector<const char> value) { - Zero(); - int length = value.length(); - - int needed_bigits = length * 4 / kBigitSize + 1; - EnsureCapacity(needed_bigits); - int string_index = length - 1; - for (int i = 0; i < needed_bigits - 1; ++i) { - // These bigits are guaranteed to be "full". - Chunk current_bigit = 0; - for (int j = 0; j < kBigitSize / 4; j++) { - current_bigit += HexCharValue(value[string_index--]) << (j * 4); - } - bigits_[i] = current_bigit; - } - used_digits_ = needed_bigits - 1; - - Chunk most_significant_bigit = 0; // Could be = 0; - for (int j = 0; j <= string_index; ++j) { - most_significant_bigit <<= 4; - most_significant_bigit += HexCharValue(value[j]); - } - if (most_significant_bigit != 0) { - bigits_[used_digits_] = most_significant_bigit; - used_digits_++; - } - Clamp(); -} - - -void Bignum::AddUInt64(uint64_t operand) { - if (operand == 0) return; - Bignum other; - other.AssignUInt64(operand); - AddBignum(other); -} - - -void Bignum::AddBignum(const Bignum& other) { - ASSERT(IsClamped()); - 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 + Max(BigitLength(), other.BigitLength()) - exponent_); - Chunk carry = 0; - int bigit_pos = other.exponent_ - exponent_; - ASSERT(bigit_pos >= 0); - for (int i = 0; i < other.used_digits_; ++i) { - Chunk sum = bigits_[bigit_pos] + other.bigits_[i] + carry; - bigits_[bigit_pos] = sum & kBigitMask; - carry = sum >> kBigitSize; - bigit_pos++; - } - - while (carry != 0) { - Chunk sum = bigits_[bigit_pos] + carry; - bigits_[bigit_pos] = sum & kBigitMask; - carry = sum >> kBigitSize; - bigit_pos++; - } - used_digits_ = Max(bigit_pos, used_digits_); - ASSERT(IsClamped()); -} - - -void Bignum::SubtractBignum(const Bignum& other) { - ASSERT(IsClamped()); - ASSERT(other.IsClamped()); - // We require this to be bigger than other. - ASSERT(LessEqual(other, *this)); - - Align(other); - - int offset = other.exponent_ - exponent_; - Chunk borrow = 0; - int i; - for (i = 0; i < other.used_digits_; ++i) { - ASSERT((borrow == 0) || (borrow == 1)); - Chunk difference = bigits_[i + offset] - other.bigits_[i] - borrow; - bigits_[i + offset] = difference & kBigitMask; - borrow = difference >> (kChunkSize - 1); - } - while (borrow != 0) { - Chunk difference = bigits_[i + offset] - borrow; - bigits_[i + offset] = difference & kBigitMask; - borrow = difference >> (kChunkSize - 1); - ++i; - } - Clamp(); -} - - -void Bignum::ShiftLeft(int shift_amount) { - if (used_digits_ == 0) return; - exponent_ += shift_amount / kBigitSize; - int local_shift = shift_amount % kBigitSize; - EnsureCapacity(used_digits_ + 1); - BigitsShiftLeft(local_shift); -} - - -void Bignum::MultiplyByUInt32(uint32_t factor) { - if (factor == 1) return; - if (factor == 0) { - Zero(); - return; - } - if (used_digits_ == 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. - ASSERT(kDoubleChunkSize >= kBigitSize + 32 + 1); - DoubleChunk carry = 0; - for (int i = 0; i < used_digits_; ++i) { - DoubleChunk product = static_cast<DoubleChunk>(factor) * bigits_[i] + carry; - bigits_[i] = static_cast<Chunk>(product & kBigitMask); - carry = (product >> kBigitSize); - } - while (carry != 0) { - EnsureCapacity(used_digits_ + 1); - bigits_[used_digits_] = carry & kBigitMask; - used_digits_++; - carry >>= kBigitSize; - } -} - - -void Bignum::MultiplyByUInt64(uint64_t factor) { - if (factor == 1) return; - if (factor == 0) { - Zero(); - return; - } - ASSERT(kBigitSize < 32); - uint64_t carry = 0; - uint64_t low = factor & 0xFFFFFFFF; - uint64_t high = factor >> 32; - for (int i = 0; i < used_digits_; ++i) { - uint64_t product_low = low * bigits_[i]; - uint64_t product_high = high * bigits_[i]; - uint64_t tmp = (carry & kBigitMask) + product_low; - bigits_[i] = tmp & kBigitMask; - carry = (carry >> kBigitSize) + (tmp >> kBigitSize) + - (product_high << (32 - kBigitSize)); - } - while (carry != 0) { - EnsureCapacity(used_digits_ + 1); - bigits_[used_digits_] = carry & kBigitMask; - used_digits_++; - carry >>= kBigitSize; - } -} - - -void Bignum::MultiplyByPowerOfTen(int exponent) { - const uint64_t kFive27 = UINT64_2PART_C(0x6765c793, fa10079d); - const uint16_t kFive1 = 5; - const uint16_t kFive2 = kFive1 * 5; - const uint16_t kFive3 = kFive2 * 5; - const uint16_t kFive4 = kFive3 * 5; - const uint16_t kFive5 = kFive4 * 5; - const uint16_t kFive6 = kFive5 * 5; - const uint32_t kFive7 = kFive6 * 5; - const uint32_t kFive8 = kFive7 * 5; - const uint32_t kFive9 = kFive8 * 5; - const uint32_t kFive10 = kFive9 * 5; - const uint32_t kFive11 = kFive10 * 5; - const uint32_t kFive12 = kFive11 * 5; - const uint32_t kFive13 = kFive12 * 5; - const uint32_t kFive1_to_12[] = - { kFive1, kFive2, kFive3, kFive4, kFive5, kFive6, - kFive7, kFive8, kFive9, kFive10, kFive11, kFive12 }; - - ASSERT(exponent >= 0); - if (exponent == 0) return; - if (used_digits_ == 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() { - ASSERT(IsClamped()); - int product_length = 2 * used_digits_; - 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_digits_) { - UNIMPLEMENTED(); - } - DoubleChunk accumulator = 0; - // First shift the digits so we don't overwrite them. - int copy_offset = used_digits_; - for (int i = 0; i < used_digits_; ++i) { - bigits_[copy_offset + i] = bigits_[i]; - } - // We have two loops to avoid some 'if's in the loop. - for (int i = 0; i < used_digits_; ++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) { - Chunk chunk1 = bigits_[copy_offset + bigit_index1]; - Chunk chunk2 = bigits_[copy_offset + bigit_index2]; - accumulator += static_cast<DoubleChunk>(chunk1) * chunk2; - bigit_index1--; - bigit_index2++; - } - bigits_[i] = static_cast<Chunk>(accumulator) & kBigitMask; - accumulator >>= kBigitSize; - } - for (int i = used_digits_; i < product_length; ++i) { - int bigit_index1 = used_digits_ - 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_digits_) { - Chunk chunk1 = bigits_[copy_offset + bigit_index1]; - Chunk chunk2 = bigits_[copy_offset + bigit_index2]; - accumulator += static_cast<DoubleChunk>(chunk1) * chunk2; - bigit_index1--; - bigit_index2++; - } - // The overwritten bigits_[i] will never be read in further loop iterations, - // because bigit_index1 and bigit_index2 are always greater - // than i - used_digits_. - bigits_[i] = static_cast<Chunk>(accumulator) & kBigitMask; - accumulator >>= kBigitSize; - } - // Since the result was guaranteed to lie inside the number the - // accumulator must be 0 now. - ASSERT(accumulator == 0); - - // Don't forget to update the used_digits and the exponent. - used_digits_ = product_length; - exponent_ *= 2; - Clamp(); -} - - -void Bignum::AssignPowerUInt16(uint16_t base, int power_exponent) { - ASSERT(base != 0); - 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++; - } - 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_multipliciation = 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) { - uint64_t base_bits_mask = - ~((static_cast<uint64_t>(1) << (64 - bit_size)) - 1); - bool high_bits_zero = (this_value & base_bits_mask) == 0; - if (high_bits_zero) { - this_value *= base; - } else { - delayed_multipliciation = true; - } - } - mask >>= 1; - } - AssignUInt64(this_value); - if (delayed_multipliciation) { - 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) { - ASSERT(IsClamped()); - ASSERT(other.IsClamped()); - ASSERT(other.used_digits_ > 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). - ASSERT(other.bigits_[other.used_digits_ - 1] >= ((1 << kBigitSize) / 16)); - ASSERT(bigits_[used_digits_ - 1] < 0x10000); - // Remove the multiples of the first digit. - // Example this = 23 and other equals 9. -> Remove 2 multiples. - result += static_cast<uint16_t>(bigits_[used_digits_ - 1]); - SubtractTimes(other, bigits_[used_digits_ - 1]); - } - - 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 - // bigits_[used_digits_ - 1] is safe. - Chunk this_bigit = bigits_[used_digits_ - 1]; - Chunk other_bigit = other.bigits_[other.used_digits_ - 1]; - - if (other.used_digits_ == 1) { - // Shortcut for easy (and common) case. - int quotient = this_bigit / other_bigit; - bigits_[used_digits_ - 1] = this_bigit - other_bigit * quotient; - ASSERT(quotient < 0x10000); - result += static_cast<uint16_t>(quotient); - Clamp(); - return result; - } - - int division_estimate = this_bigit / (other_bigit + 1); - 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) { - ASSERT(number > 0); - int result = 0; - while (number != 0) { - number >>= 4; - result++; - } - return result; -} - - -static char HexCharOfValue(int value) { - 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, int buffer_size) const { - ASSERT(IsClamped()); - // Each bigit must be printable as separate hex-character. - ASSERT(kBigitSize % 4 == 0); - const int kHexCharsPerBigit = kBigitSize / 4; - - if (used_digits_ == 0) { - if (buffer_size < 2) return false; - buffer[0] = '0'; - buffer[1] = '\0'; - return true; - } - // We add 1 for the terminating '\0' character. - int needed_chars = (BigitLength() - 1) * kHexCharsPerBigit + - SizeInHexChars(bigits_[used_digits_ - 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_digits_ - 1; ++i) { - Chunk current_bigit = bigits_[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 = bigits_[used_digits_ - 1]; - while (most_significant_bigit != 0) { - buffer[string_index--] = HexCharOfValue(most_significant_bigit & 0xF); - most_significant_bigit >>= 4; - } - return true; -} - - -Bignum::Chunk Bignum::BigitAt(int index) const { - if (index >= BigitLength()) return 0; - if (index < exponent_) return 0; - return bigits_[index - exponent_]; -} - - -int Bignum::Compare(const Bignum& a, const Bignum& b) { - ASSERT(a.IsClamped()); - ASSERT(b.IsClamped()); - int bigit_length_a = a.BigitLength(); - 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 >= Min(a.exponent_, b.exponent_); --i) { - Chunk bigit_a = a.BigitAt(i); - Chunk bigit_b = b.BigitAt(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) { - ASSERT(a.IsClamped()); - ASSERT(b.IsClamped()); - 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. - int min_exponent = Min(Min(a.exponent_, b.exponent_), c.exponent_); - for (int i = c.BigitLength() - 1; i >= min_exponent; --i) { - Chunk chunk_a = a.BigitAt(i); - Chunk chunk_b = b.BigitAt(i); - Chunk chunk_c = c.BigitAt(i); - 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_digits_ > 0 && bigits_[used_digits_ - 1] == 0) { - used_digits_--; - } - if (used_digits_ == 0) { - // Zero. - exponent_ = 0; - } -} - - -bool Bignum::IsClamped() const { - return used_digits_ == 0 || bigits_[used_digits_ - 1] != 0; -} - - -void Bignum::Zero() { - for (int i = 0; i < used_digits_; ++i) { - bigits_[i] = 0; - } - used_digits_ = 0; - exponent_ = 0; -} - - -void Bignum::Align(const Bignum& other) { - if (exponent_ > other.exponent_) { - // If "X" represents a "hidden" digit (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 - int zero_digits = exponent_ - other.exponent_; - EnsureCapacity(used_digits_ + zero_digits); - for (int i = used_digits_ - 1; i >= 0; --i) { - bigits_[i + zero_digits] = bigits_[i]; - } - for (int i = 0; i < zero_digits; ++i) { - bigits_[i] = 0; - } - used_digits_ += zero_digits; - exponent_ -= zero_digits; - ASSERT(used_digits_ >= 0); - ASSERT(exponent_ >= 0); - } -} - - -void Bignum::BigitsShiftLeft(int shift_amount) { - ASSERT(shift_amount < kBigitSize); - ASSERT(shift_amount >= 0); - Chunk carry = 0; - for (int i = 0; i < used_digits_; ++i) { - Chunk new_carry = bigits_[i] >> (kBigitSize - shift_amount); - bigits_[i] = ((bigits_[i] << shift_amount) + carry) & kBigitMask; - carry = new_carry; - } - if (carry != 0) { - bigits_[used_digits_] = carry; - used_digits_++; - } -} - - -void Bignum::SubtractTimes(const Bignum& other, int factor) { - ASSERT(exponent_ <= other.exponent_); - if (factor < 3) { - for (int i = 0; i < factor; ++i) { - SubtractBignum(other); - } - return; - } - Chunk borrow = 0; - int exponent_diff = other.exponent_ - exponent_; - for (int i = 0; i < other.used_digits_; ++i) { - DoubleChunk product = static_cast<DoubleChunk>(factor) * other.bigits_[i]; - DoubleChunk remove = borrow + product; - Chunk difference = bigits_[i + exponent_diff] - (remove & kBigitMask); - bigits_[i + exponent_diff] = difference & kBigitMask; - borrow = static_cast<Chunk>((difference >> (kChunkSize - 1)) + - (remove >> kBigitSize)); - } - for (int i = other.used_digits_ + exponent_diff; i < used_digits_; ++i) { - if (borrow == 0) return; - Chunk difference = bigits_[i] - borrow; - bigits_[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 |