d51f2c96cb
Review URL: http://codereview.chromium.org/661275 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4008 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
122 lines
4.3 KiB
C++
122 lines
4.3 KiB
C++
// Copyright 2006-2008 the V8 project authors. All rights reserved.
|
|
// Redistribution and use in source and binary forms, with or without
|
|
// modification, are permitted provided that the following conditions are
|
|
// met:
|
|
//
|
|
// * Redistributions of source code must retain the above copyright
|
|
// notice, this list of conditions and the following disclaimer.
|
|
// * Redistributions in binary form must reproduce the above
|
|
// copyright notice, this list of conditions and the following
|
|
// disclaimer in the documentation and/or other materials provided
|
|
// with the distribution.
|
|
// * Neither the name of Google Inc. nor the names of its
|
|
// contributors may be used to endorse or promote products derived
|
|
// from this software without specific prior written permission.
|
|
//
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
#ifndef V8_CONVERSIONS_INL_H_
|
|
#define V8_CONVERSIONS_INL_H_
|
|
|
|
#include <math.h>
|
|
#include <float.h> // required for DBL_MAX and on Win32 for finite()
|
|
#include <stdarg.h>
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// Extra POSIX/ANSI functions for Win32/MSVC.
|
|
|
|
#include "conversions.h"
|
|
#include "platform.h"
|
|
|
|
namespace v8 {
|
|
namespace internal {
|
|
|
|
// The fast double-to-int conversion routine does not guarantee
|
|
// rounding towards zero.
|
|
static inline int FastD2I(double x) {
|
|
#ifdef __USE_ISOC99
|
|
// The ISO C99 standard defines the lrint() function which rounds a
|
|
// double to an integer according to the current rounding direction.
|
|
return lrint(x);
|
|
#else
|
|
// This is incredibly slow on Intel x86. The reason is that rounding
|
|
// towards zero is implied by the C standard. This means that the
|
|
// status register of the FPU has to be changed with the 'fldcw'
|
|
// instruction. This completely stalls the pipeline and takes many
|
|
// hundreds of clock cycles.
|
|
return static_cast<int>(x);
|
|
#endif
|
|
}
|
|
|
|
|
|
// The fast double-to-unsigned-int conversion routine does not guarantee
|
|
// rounding towards zero.
|
|
static inline unsigned int FastD2UI(double x) {
|
|
// There is no unsigned version of lrint, so there is no fast path
|
|
// in this function as there is in FastD2I. Using lrint doesn't work
|
|
// for values of 2^31 and above.
|
|
|
|
// Convert "small enough" doubles to uint32_t by fixing the 32
|
|
// least significant non-fractional bits in the low 32 bits of the
|
|
// double, and reading them from there.
|
|
const double k2Pow52 = 4503599627370496.0;
|
|
bool negative = x < 0;
|
|
if (negative) {
|
|
x = -x;
|
|
}
|
|
if (x < k2Pow52) {
|
|
x += k2Pow52;
|
|
uint32_t result;
|
|
memcpy(&result, &x, sizeof(result)); // Copy low 32 bits.
|
|
return negative ? ~result + 1 : result;
|
|
}
|
|
// Large number (outside uint32 range), Infinity or NaN.
|
|
return 0x80000000u; // Return integer indefinite.
|
|
}
|
|
|
|
|
|
static inline double DoubleToInteger(double x) {
|
|
if (isnan(x)) return 0;
|
|
if (!isfinite(x) || x == 0) return x;
|
|
return (x >= 0) ? floor(x) : ceil(x);
|
|
}
|
|
|
|
|
|
int32_t NumberToInt32(Object* number) {
|
|
if (number->IsSmi()) return Smi::cast(number)->value();
|
|
return DoubleToInt32(number->Number());
|
|
}
|
|
|
|
|
|
uint32_t NumberToUint32(Object* number) {
|
|
if (number->IsSmi()) return Smi::cast(number)->value();
|
|
return DoubleToUint32(number->Number());
|
|
}
|
|
|
|
|
|
int32_t DoubleToInt32(double x) {
|
|
int32_t i = FastD2I(x);
|
|
if (FastI2D(i) == x) return i;
|
|
static const double two32 = 4294967296.0;
|
|
static const double two31 = 2147483648.0;
|
|
if (!isfinite(x) || x == 0) return 0;
|
|
if (x < 0 || x >= two32) x = modulo(x, two32);
|
|
x = (x >= 0) ? floor(x) : ceil(x) + two32;
|
|
return (int32_t) ((x >= two31) ? x - two32 : x);
|
|
}
|
|
|
|
|
|
} } // namespace v8::internal
|
|
|
|
#endif // V8_CONVERSIONS_INL_H_
|