Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
tree: c581b6d981
Fetching contributors…

Cannot retrieve contributors at this time

95 lines (84 sloc) 3.413 kb
/*
* Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
* (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``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 APPLE COMPUTER, INC. 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.
*/
#include "config.h"
#include "RandomNumber.h"
#include "RandomNumberSeed.h"
#include <limits>
#include <limits.h>
#include <stdint.h>
#include <stdlib.h>
namespace WTF {
double weakRandomNumber()
{
#if COMPILER(MSVC) && defined(_CRT_RAND_S)
// rand_s is incredibly slow on windows so we fall back on rand for Math.random
return (rand() + (rand() / (RAND_MAX + 1.0))) / (RAND_MAX + 1.0);
#else
return randomNumber();
#endif
}
double randomNumber()
{
#if !ENABLE(JSC_MULTIPLE_THREADS)
static bool s_initialized = false;
if (!s_initialized) {
initializeRandomNumberGenerator();
s_initialized = true;
}
#endif
#if COMPILER(MSVC) && defined(_CRT_RAND_S)
uint32_t bits;
rand_s(&bits);
return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);
#elif PLATFORM(DARWIN)
uint32_t bits = arc4random();
return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);
#elif PLATFORM(UNIX)
uint32_t part1 = random() & (RAND_MAX - 1);
uint32_t part2 = random() & (RAND_MAX - 1);
// random only provides 31 bits
uint64_t fullRandom = part1;
fullRandom <<= 31;
fullRandom |= part2;
// Mask off the low 53bits
fullRandom &= (1LL << 53) - 1;
return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53);
#else
uint32_t part1 = rand() & (RAND_MAX - 1);
uint32_t part2 = rand() & (RAND_MAX - 1);
// rand only provides 31 bits, and the low order bits of that aren't very random
// so we take the high 26 bits of part 1, and the high 27 bits of part2.
part1 >>= 5; // drop the low 5 bits
part2 >>= 4; // drop the low 4 bits
uint64_t fullRandom = part1;
fullRandom <<= 27;
fullRandom |= part2;
// Mask off the low 53bits
fullRandom &= (1LL << 53) - 1;
return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53);
#endif
}
}
Jump to Line
Something went wrong with that request. Please try again.