mirror of
https://github.com/darlinghq/darling-JavaScriptCore.git
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109 lines
3.7 KiB
C++
109 lines
3.7 KiB
C++
/*
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* Copyright (C) 2011 Apple Inc. All rights reserved.
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*
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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
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* are met:
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* 1. 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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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* 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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*/
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#pragma once
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#include <wtf/MathExtras.h>
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namespace JSC {
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// This is used in converting the integer part of a number to a string.
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class BigInteger {
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public:
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BigInteger(double number)
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{
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ASSERT(std::isfinite(number) && !std::signbit(number));
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ASSERT(number == floor(number));
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bool sign;
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int32_t exponent;
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uint64_t mantissa;
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decomposeDouble(number, sign, exponent, mantissa);
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ASSERT(!sign && exponent >= 0);
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int32_t zeroBits = exponent - 52;
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if (zeroBits < 0) {
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mantissa >>= -zeroBits;
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zeroBits = 0;
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}
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while (zeroBits >= 32) {
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m_values.append(0);
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zeroBits -= 32;
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}
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// Left align the 53 bits of the mantissa within 96 bits.
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uint32_t values[3];
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values[0] = static_cast<uint32_t>(mantissa);
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values[1] = static_cast<uint32_t>(mantissa >> 32);
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values[2] = 0;
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// Shift based on the remainder of the exponent.
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if (zeroBits) {
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values[2] = values[1] >> (32 - zeroBits);
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values[1] = (values[1] << zeroBits) | (values[0] >> (32 - zeroBits));
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values[0] = (values[0] << zeroBits);
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}
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m_values.append(values[0]);
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m_values.append(values[1]);
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m_values.append(values[2]);
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// Canonicalize; remove all trailing zeros.
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while (m_values.size() && !m_values.last())
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m_values.removeLast();
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}
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uint32_t divide(uint32_t divisor)
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{
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uint32_t carry = 0;
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for (size_t i = m_values.size(); i; ) {
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--i;
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uint64_t dividend = (static_cast<uint64_t>(carry) << 32) + static_cast<uint64_t>(m_values[i]);
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uint64_t result = dividend / static_cast<uint64_t>(divisor);
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ASSERT(result == static_cast<uint32_t>(result));
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uint64_t remainder = dividend % static_cast<uint64_t>(divisor);
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ASSERT(remainder == static_cast<uint32_t>(remainder));
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m_values[i] = static_cast<uint32_t>(result);
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carry = static_cast<uint32_t>(remainder);
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}
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// Canonicalize; remove all trailing zeros.
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while (m_values.size() && !m_values.last())
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m_values.removeLast();
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return carry;
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}
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bool operator!() { return !m_values.size(); }
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private:
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Vector<uint32_t, 36> m_values;
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};
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} // namespace JSC
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