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29 #include <wtf/MathExtras.h>
33 // This is used in converting the integer part of a number to a string.
36 BigInteger(double number)
38 ASSERT(isfinite(number) && !signbit(number));
39 ASSERT(number == floor(number));
44 decomposeDouble(number, sign, exponent, mantissa);
45 ASSERT(!sign && exponent >= 0);
47 int32_t zeroBits = exponent - 52;
50 mantissa >>= -zeroBits;
54 while (zeroBits >= 32) {
59 // Left align the 53 bits of the mantissa within 96 bits.
61 values[0] = static_cast<uint32_t>(mantissa);
62 values[1] = static_cast<uint32_t>(mantissa >> 32);
64 // Shift based on the remainder of the exponent.
66 values[2] = values[1] >> (32 - zeroBits);
67 values[1] = (values[1] << zeroBits) | (values[0] >> (32 - zeroBits));
68 values[0] = (values[0] << zeroBits);
70 m_values.append(values[0]);
71 m_values.append(values[1]);
72 m_values.append(values[2]);
74 // Canonicalize; remove all trailing zeros.
75 while (m_values.size() && !m_values.last())
76 m_values.removeLast();
79 uint32_t divide(uint32_t divisor)
83 for (size_t i = m_values.size(); i; ) {
85 uint64_t dividend = (static_cast<uint64_t>(carry) << 32) + static_cast<uint64_t>(m_values[i]);
87 uint64_t result = dividend / static_cast<uint64_t>(divisor);
88 ASSERT(result == static_cast<uint32_t>(result));
89 uint64_t remainder = dividend % static_cast<uint64_t>(divisor);
90 ASSERT(remainder == static_cast<uint32_t>(remainder));
92 m_values[i] = static_cast<uint32_t>(result);
93 carry = static_cast<uint32_t>(remainder);
96 // Canonicalize; remove all trailing zeros.
97 while (m_values.size() && !m_values.last())
98 m_values.removeLast();
103 bool operator!() { return !m_values.size(); }
106 Vector<uint32_t, 36> m_values;