ager@chromium.org | 9258b6b | 2008-09-11 09:11:10 +0000 | [diff] [blame] | 1 | // Copyright 2006-2008 the V8 project authors. All rights reserved. |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 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 | |
| 34 | // ---------------------------------------------------------------------------- |
| 35 | // Extra POSIX/ANSI functions for Win32/MSVC. |
| 36 | |
| 37 | #include "conversions.h" |
| 38 | #include "platform.h" |
| 39 | |
| 40 | namespace v8 { namespace internal { |
| 41 | |
| 42 | // The fast double-to-int conversion routine does not guarantee |
| 43 | // rounding towards zero. |
| 44 | static inline int FastD2I(double x) { |
| 45 | #ifdef __USE_ISOC99 |
| 46 | // The ISO C99 standard defines the lrint() function which rounds a |
| 47 | // double to an integer according to the current rounding direction. |
| 48 | return lrint(x); |
| 49 | #else |
| 50 | // This is incredibly slow on Intel x86. The reason is that rounding |
| 51 | // towards zero is implied by the C standard. This means that the |
| 52 | // status register of the FPU has to be changed with the 'fldcw' |
| 53 | // instruction. This completely stalls the pipeline and takes many |
| 54 | // hundreds of clock cycles. |
| 55 | return static_cast<int>(x); |
| 56 | #endif |
| 57 | } |
| 58 | |
| 59 | |
| 60 | static inline double DoubleToInteger(double x) { |
| 61 | if (isnan(x)) return 0; |
| 62 | if (!isfinite(x) || x == 0) return x; |
| 63 | return (x >= 0) ? floor(x) : ceil(x); |
| 64 | } |
| 65 | |
| 66 | |
| 67 | int32_t NumberToInt32(Object* number) { |
| 68 | if (number->IsSmi()) return Smi::cast(number)->value(); |
| 69 | return DoubleToInt32(number->Number()); |
| 70 | } |
| 71 | |
| 72 | |
| 73 | uint32_t NumberToUint32(Object* number) { |
| 74 | if (number->IsSmi()) return Smi::cast(number)->value(); |
| 75 | return DoubleToUint32(number->Number()); |
| 76 | } |
| 77 | |
| 78 | |
| 79 | int32_t DoubleToInt32(double x) { |
| 80 | int32_t i = FastD2I(x); |
| 81 | if (FastI2D(i) == x) return i; |
| 82 | static const double two32 = 4294967296.0; |
| 83 | static const double two31 = 2147483648.0; |
| 84 | if (!isfinite(x) || x == 0) return 0; |
| 85 | if (x < 0 || x >= two32) x = fmod(x, two32); |
| 86 | x = (x >= 0) ? floor(x) : ceil(x) + two32; |
| 87 | return (int32_t) ((x >= two31) ? x - two32 : x); |
| 88 | } |
| 89 | |
| 90 | |
| 91 | } } // namespace v8::internal |
| 92 | |
| 93 | #endif // V8_CONVERSIONS_INL_H_ |