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34 // This "Do It Yourself Floating Point" class implements a floating-point number
35 // with a uint64 significand and an int exponent. Normalized DiyFp numbers will
36 // have the most significant bit of the significand set.
37 // Multiplication and Subtraction do not normalize their results.
38 // DiyFp are not designed to contain special doubles (NaN and Infinity).
41 static const int kSignificandSize = 64;
43 DiyFp() : f_(0), e_(0) {}
44 DiyFp(uint64_t f, int e) : f_(f), e_(e) {}
46 // this = this - other.
47 // The exponents of both numbers must be the same and the significand of this
48 // must be bigger than the significand of other.
49 // The result will not be normalized.
50 void Subtract(const DiyFp& other) {
51 ASSERT(e_ == other.e_);
52 ASSERT(f_ >= other.f_);
57 // The exponents of both numbers must be the same and this must be bigger
58 // than other. The result will not be normalized.
59 static DiyFp Minus(const DiyFp& a, const DiyFp& b) {
66 // this = this * other.
67 void Multiply(const DiyFp& other);
70 static DiyFp Times(const DiyFp& a, const DiyFp& b) {
81 // This method is mainly called for normalizing boundaries. In general
82 // boundaries need to be shifted by 10 bits. We thus optimize for this case.
83 const uint64_t k10MSBits = static_cast<uint64_t>(0x3FF) << 54;
84 while ((f & k10MSBits) == 0) {
88 while ((f & kUint64MSB) == 0) {
96 static DiyFp Normalize(const DiyFp& a) {
102 uint64_t f() const { return f_; }
103 int e() const { return e_; }
105 void set_f(uint64_t new_value) { f_ = new_value; }
106 void set_e(int new_value) { e_ = new_value; }
109 static const uint64_t kUint64MSB = static_cast<uint64_t>(1) << 63;
115 } } // namespace v8::internal
117 #endif // V8_DIY_FP_H_