v8/src/conversions-inl.h

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// 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-unsigned-int conversion routine does not guarantee
// rounding towards zero, or any reasonable value if the argument is larger
// than what fits in an unsigned 32-bit integer.
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;
#ifdef BIG_ENDIAN_FLOATING_POINT
Address mantissa_ptr = reinterpret_cast<Address>(&x) + kIntSize;
#else
Address mantissa_ptr = reinterpret_cast<Address>(&x);
#endif
// Copy least significant 32 bits of mantissa.
memcpy(&result, mantissa_ptr, sizeof(result));
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_