171 lines
6.3 KiB
C++
171 lines
6.3 KiB
C++
// © 2018 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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//
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// From the double-conversion library. Original license:
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//
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// Copyright 2010 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_FORMATTING
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#ifndef DOUBLE_CONVERSION_BIGNUM_H_
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#define DOUBLE_CONVERSION_BIGNUM_H_
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// ICU PATCH: Customize header file paths for ICU.
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#include "double-conversion-utils.h"
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// ICU PATCH: Wrap in ICU namespace
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U_NAMESPACE_BEGIN
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namespace double_conversion {
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class Bignum {
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public:
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// 3584 = 128 * 28. We can represent 2^3584 > 10^1000 accurately.
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// This bignum can encode much bigger numbers, since it contains an
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// exponent.
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static const int kMaxSignificantBits = 3584;
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Bignum() : used_bigits_(0), exponent_(0) {}
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void AssignUInt16(const uint16_t value);
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void AssignUInt64(uint64_t value);
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void AssignBignum(const Bignum& other);
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void AssignDecimalString(const Vector<const char> value);
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void AssignHexString(const Vector<const char> value);
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void AssignPowerUInt16(uint16_t base, const int exponent);
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void AddUInt64(const uint64_t operand);
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void AddBignum(const Bignum& other);
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// Precondition: this >= other.
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void SubtractBignum(const Bignum& other);
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void Square();
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void ShiftLeft(const int shift_amount);
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void MultiplyByUInt32(const uint32_t factor);
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void MultiplyByUInt64(const uint64_t factor);
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void MultiplyByPowerOfTen(const int exponent);
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void Times10() { return MultiplyByUInt32(10); }
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// Pseudocode:
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// int result = this / other;
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// this = this % other;
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// In the worst case this function is in O(this/other).
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uint16_t DivideModuloIntBignum(const Bignum& other);
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bool ToHexString(char* buffer, const int buffer_size) const;
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// Returns
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// -1 if a < b,
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// 0 if a == b, and
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// +1 if a > b.
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static int Compare(const Bignum& a, const Bignum& b);
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static bool Equal(const Bignum& a, const Bignum& b) {
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return Compare(a, b) == 0;
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}
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static bool LessEqual(const Bignum& a, const Bignum& b) {
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return Compare(a, b) <= 0;
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}
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static bool Less(const Bignum& a, const Bignum& b) {
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return Compare(a, b) < 0;
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}
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// Returns Compare(a + b, c);
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static int PlusCompare(const Bignum& a, const Bignum& b, const Bignum& c);
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// Returns a + b == c
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static bool PlusEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
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return PlusCompare(a, b, c) == 0;
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}
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// Returns a + b <= c
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static bool PlusLessEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
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return PlusCompare(a, b, c) <= 0;
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}
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// Returns a + b < c
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static bool PlusLess(const Bignum& a, const Bignum& b, const Bignum& c) {
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return PlusCompare(a, b, c) < 0;
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}
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private:
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typedef uint32_t Chunk;
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typedef uint64_t DoubleChunk;
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static const int kChunkSize = sizeof(Chunk) * 8;
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static const int kDoubleChunkSize = sizeof(DoubleChunk) * 8;
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// With bigit size of 28 we loose some bits, but a double still fits easily
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// into two chunks, and more importantly we can use the Comba multiplication.
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static const int kBigitSize = 28;
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static const Chunk kBigitMask = (1 << kBigitSize) - 1;
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// Every instance allocates kBigitLength chunks on the stack. Bignums cannot
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// grow. There are no checks if the stack-allocated space is sufficient.
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static const int kBigitCapacity = kMaxSignificantBits / kBigitSize;
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static void EnsureCapacity(const int size) {
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if (size > kBigitCapacity) {
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DOUBLE_CONVERSION_UNREACHABLE();
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}
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}
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void Align(const Bignum& other);
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void Clamp();
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bool IsClamped() const {
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return used_bigits_ == 0 || RawBigit(used_bigits_ - 1) != 0;
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}
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void Zero() {
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used_bigits_ = 0;
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exponent_ = 0;
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}
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// Requires this to have enough capacity (no tests done).
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// Updates used_bigits_ if necessary.
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// shift_amount must be < kBigitSize.
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void BigitsShiftLeft(const int shift_amount);
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// BigitLength includes the "hidden" bigits encoded in the exponent.
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int BigitLength() const { return used_bigits_ + exponent_; }
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Chunk& RawBigit(const int index);
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const Chunk& RawBigit(const int index) const;
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Chunk BigitOrZero(const int index) const;
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void SubtractTimes(const Bignum& other, const int factor);
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// The Bignum's value is value(bigits_buffer_) * 2^(exponent_ * kBigitSize),
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// where the value of the buffer consists of the lower kBigitSize bits of
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// the first used_bigits_ Chunks in bigits_buffer_, first chunk has lowest
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// significant bits.
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int16_t used_bigits_;
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int16_t exponent_;
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Chunk bigits_buffer_[kBigitCapacity];
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DOUBLE_CONVERSION_DISALLOW_COPY_AND_ASSIGN(Bignum);
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};
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} // namespace double_conversion
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// ICU PATCH: Close ICU namespace
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U_NAMESPACE_END
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#endif // DOUBLE_CONVERSION_BIGNUM_H_
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#endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING
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