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Side by Side Diff: src/conversions-inl.h

Issue 661275: Added implementation if Uint32::Value. (Closed)
Patch Set: Added IsUint32 Created 10 years, 9 months ago
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1 // Copyright 2006-2008 the V8 project authors. All rights reserved. 1 // Copyright 2006-2008 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without 2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are 3 // modification, are permitted provided that the following conditions are
4 // met: 4 // met:
5 // 5 //
6 // * Redistributions of source code must retain the above copyright 6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer. 7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above 8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following 9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided 10 // disclaimer in the documentation and/or other materials provided
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52 // This is incredibly slow on Intel x86. The reason is that rounding 52 // This is incredibly slow on Intel x86. The reason is that rounding
53 // towards zero is implied by the C standard. This means that the 53 // towards zero is implied by the C standard. This means that the
54 // status register of the FPU has to be changed with the 'fldcw' 54 // status register of the FPU has to be changed with the 'fldcw'
55 // instruction. This completely stalls the pipeline and takes many 55 // instruction. This completely stalls the pipeline and takes many
56 // hundreds of clock cycles. 56 // hundreds of clock cycles.
57 return static_cast<int>(x); 57 return static_cast<int>(x);
58 #endif 58 #endif
59 } 59 }
60 60
61 61
62 // The fast double-to-unsigned-int conversion routine does not guarantee
63 // rounding towards zero.
64 static inline unsigned int FastD2UI(double x) {
65 // There is no unsigned version of lrint, so there is no fast path
66 // in this function as there is in FastD2I. Using lrint doesn't work
67 // for values of 2^31 and above.
68
69 // Convert "small enough" doubles to uint32_t by fixing the 32
70 // least significant non-fractional bits in the low 32 bits of the
71 // double, and reading them from there.
72 const double k2Pow52 = 4503599627370496.0;
73 bool negative = x < 0;
74 if (negative) { x = -x; }
Mads Ager (chromium) 2010/03/03 13:16:50 Remove the braces or split on multiple lines.
75 if (x < k2Pow52) {
76 x += k2Pow52;
77 uint32_t result;
78 memcpy(&result, &x, sizeof(result)); // Copy low 32 bits.
79 return negative ? ~result + 1 : result;
80 }
81 // Large number (outside uint32 range), Infinity or NaN.
82 return 0x80000000u; // Return integer indefinite.
83 }
84
85
62 static inline double DoubleToInteger(double x) { 86 static inline double DoubleToInteger(double x) {
63 if (isnan(x)) return 0; 87 if (isnan(x)) return 0;
64 if (!isfinite(x) || x == 0) return x; 88 if (!isfinite(x) || x == 0) return x;
65 return (x >= 0) ? floor(x) : ceil(x); 89 return (x >= 0) ? floor(x) : ceil(x);
66 } 90 }
67 91
68 92
69 int32_t NumberToInt32(Object* number) { 93 int32_t NumberToInt32(Object* number) {
70 if (number->IsSmi()) return Smi::cast(number)->value(); 94 if (number->IsSmi()) return Smi::cast(number)->value();
71 return DoubleToInt32(number->Number()); 95 return DoubleToInt32(number->Number());
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86 if (!isfinite(x) || x == 0) return 0; 110 if (!isfinite(x) || x == 0) return 0;
87 if (x < 0 || x >= two32) x = modulo(x, two32); 111 if (x < 0 || x >= two32) x = modulo(x, two32);
88 x = (x >= 0) ? floor(x) : ceil(x) + two32; 112 x = (x >= 0) ? floor(x) : ceil(x) + two32;
89 return (int32_t) ((x >= two31) ? x - two32 : x); 113 return (int32_t) ((x >= two31) ? x - two32 : x);
90 } 114 }
91 115
92 116
93 } } // namespace v8::internal 117 } } // namespace v8::internal
94 118
95 #endif // V8_CONVERSIONS_INL_H_ 119 #endif // V8_CONVERSIONS_INL_H_
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