diff options
author | The Android Open Source Project <initial-contribution@android.com> | 2009-03-05 14:34:32 -0800 |
---|---|---|
committer | The Android Open Source Project <initial-contribution@android.com> | 2009-03-05 14:34:32 -0800 |
commit | 635860845790a19bf50bbc51ba8fb66a96dde068 (patch) | |
tree | ef6ad9ff73a5b57f65249d4232a202fa77e6a140 /JavaScriptCore/wtf/RandomNumber.cpp | |
parent | 8e35f3cfc7fba1d1c829dc557ebad6409cbe16a2 (diff) | |
download | external_webkit-635860845790a19bf50bbc51ba8fb66a96dde068.zip external_webkit-635860845790a19bf50bbc51ba8fb66a96dde068.tar.gz external_webkit-635860845790a19bf50bbc51ba8fb66a96dde068.tar.bz2 |
auto import from //depot/cupcake/@136594
Diffstat (limited to 'JavaScriptCore/wtf/RandomNumber.cpp')
-rw-r--r-- | JavaScriptCore/wtf/RandomNumber.cpp | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/JavaScriptCore/wtf/RandomNumber.cpp b/JavaScriptCore/wtf/RandomNumber.cpp new file mode 100644 index 0000000..c94d5a4 --- /dev/null +++ b/JavaScriptCore/wtf/RandomNumber.cpp @@ -0,0 +1,94 @@ +/* + * 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 +} + +} |