1 // Copyright 2006-2008 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #ifndef V8_CONVERSIONS_INL_H_ 29 #define V8_CONVERSIONS_INL_H_ 30 31 #include <math.h> 32 #include <float.h> // required for DBL_MAX and on Win32 for finite() 33 #include <stdarg.h> 34 35 // ---------------------------------------------------------------------------- 36 // Extra POSIX/ANSI functions for Win32/MSVC. 37 38 #include "conversions.h" 39 #include "platform.h" 40 41 namespace v8 { 42 namespace internal { 43 44 // The fast double-to-int conversion routine does not guarantee 45 // rounding towards zero. 46 static inline int FastD2I(double x) { 47 #ifdef __USE_ISOC99 48 // The ISO C99 standard defines the lrint() function which rounds a 49 // double to an integer according to the current rounding direction. 50 return lrint(x); 51 #else 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 54 // status register of the FPU has to be changed with the 'fldcw' 55 // instruction. This completely stalls the pipeline and takes many 56 // hundreds of clock cycles. 57 return static_cast<int>(x); 58 #endif 59 } 60 61 62 static inline double DoubleToInteger(double x) { 63 if (isnan(x)) return 0; 64 if (!isfinite(x) || x == 0) return x; 65 return (x >= 0) ? floor(x) : ceil(x); 66 } 67 68 69 int32_t NumberToInt32(Object* number) { 70 if (number->IsSmi()) return Smi::cast(number)->value(); 71 return DoubleToInt32(number->Number()); 72 } 73 74 75 uint32_t NumberToUint32(Object* number) { 76 if (number->IsSmi()) return Smi::cast(number)->value(); 77 return DoubleToUint32(number->Number()); 78 } 79 80 81 int32_t DoubleToInt32(double x) { 82 int32_t i = FastD2I(x); 83 if (FastI2D(i) == x) return i; 84 static const double two32 = 4294967296.0; 85 static const double two31 = 2147483648.0; 86 if (!isfinite(x) || x == 0) return 0; 87 if (x < 0 || x >= two32) x = modulo(x, two32); 88 x = (x >= 0) ? floor(x) : ceil(x) + two32; 89 return (int32_t) ((x >= two31) ? x - two32 : x); 90 } 91 92 93 } } // namespace v8::internal 94 95 #endif // V8_CONVERSIONS_INL_H_ 96
