Move Source/WTF/wtf to Source/wtf

Source/WTF/wtf/dtoa/bignum.h

-// 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.
-
-#ifndef DOUBLE_CONVERSION_BIGNUM_H_
-#define DOUBLE_CONVERSION_BIGNUM_H_
-
-#include "utils.h"
-
-namespace WTF {
-
-namespace double_conversion {
-    
-    class Bignum {
-    public:
-        // 3584 = 128 * 28. We can represent 2^3584 > 10^1000 accurately.
-        // This bignum can encode much bigger numbers, since it contains an
-        // exponent.
-        static const int kMaxSignificantBits = 3584;
-        
-        Bignum();
-        void AssignUInt16(uint16_t value);
-        void AssignUInt64(uint64_t value);
-        void AssignBignum(const Bignum& other);
-        
-        void AssignDecimalString(Vector<const char> value);
-        void AssignHexString(Vector<const char> value);
-        
-        void AssignPowerUInt16(uint16_t base, int exponent);
-        
-        void AddUInt16(uint16_t operand);
-        void AddUInt64(uint64_t operand);
-        void AddBignum(const Bignum& other);
-        // Precondition: this >= other.
-        void SubtractBignum(const Bignum& other);
-        
-        void Square();
-        void ShiftLeft(int shift_amount);
-        void MultiplyByUInt32(uint32_t factor);
-        void MultiplyByUInt64(uint64_t factor);
-        void MultiplyByPowerOfTen(int exponent);
-        void Times10() { return MultiplyByUInt32(10); }
-        // Pseudocode:
-        //  int result = this / other;
-        //  this = this % other;
-        // In the worst case this function is in O(this/other).
-        uint16_t DivideModuloIntBignum(const Bignum& other);
-        
-        bool ToHexString(char* buffer, int buffer_size) const;
-        
-        static int Compare(const Bignum& a, const Bignum& b);
-        static bool Equal(const Bignum& a, const Bignum& b) {
-            return Compare(a, b) == 0;
-        }
-        static bool LessEqual(const Bignum& a, const Bignum& b) {
-            return Compare(a, b) <= 0;
-        }
-        static bool Less(const Bignum& a, const Bignum& b) {
-            return Compare(a, b) < 0;
-        }
-        // Returns Compare(a + b, c);
-        static int PlusCompare(const Bignum& a, const Bignum& b, const Bignum& c);
-        // Returns a + b == c
-        static bool PlusEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
-            return PlusCompare(a, b, c) == 0;
-        }
-        // Returns a + b <= c
-        static bool PlusLessEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
-            return PlusCompare(a, b, c) <= 0;
-        }
-        // Returns a + b < c
-        static bool PlusLess(const Bignum& a, const Bignum& b, const Bignum& c) {
-            return PlusCompare(a, b, c) < 0;
-        }
-    private:
-        typedef uint32_t Chunk;
-        typedef uint64_t DoubleChunk;
-        
-        static const int kChunkSize = sizeof(Chunk) * 8;
-        static const int kDoubleChunkSize = sizeof(DoubleChunk) * 8;
-        // With bigit size of 28 we loose some bits, but a double still fits easily
-        // into two chunks, and more importantly we can use the Comba multiplication.
-        static const int kBigitSize = 28;
-        static const Chunk kBigitMask = (1 << kBigitSize) - 1;
-        // Every instance allocates kBigitLength chunks on the stack. Bignums cannot
-        // grow. There are no checks if the stack-allocated space is sufficient.
-        static const int kBigitCapacity = kMaxSignificantBits / kBigitSize;
-        
-        void EnsureCapacity(int size) {
-            if (size > kBigitCapacity) {
-                UNREACHABLE();
-            }
-        }
-        void Align(const Bignum& other);
-        void Clamp();
-        bool IsClamped() const;
-        void Zero();
-        // Requires this to have enough capacity (no tests done).
-        // Updates used_digits_ if necessary.
-        // shift_amount must be < kBigitSize.
-        void BigitsShiftLeft(int shift_amount);
-        // BigitLength includes the "hidden" digits encoded in the exponent.
-        int BigitLength() const { return used_digits_ + exponent_; }
-        Chunk BigitAt(int index) const;
-        void SubtractTimes(const Bignum& other, int factor);
-        
-        Chunk bigits_buffer_[kBigitCapacity];
-        // A vector backed by bigits_buffer_. This way accesses to the array are
-        // checked for out-of-bounds errors.
-        Vector<Chunk> bigits_;
-        int used_digits_;
-        // The Bignum's value equals value(bigits_) * 2^(exponent_ * kBigitSize).
-        int exponent_;
-        
-        DISALLOW_COPY_AND_ASSIGN(Bignum);
-    };
-    
-}  // namespace double_conversion
-
-} // namespace WTF
-
-#endif  // DOUBLE_CONVERSION_BIGNUM_H_