| 1 | /*
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| 2 | * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
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| 3 | * (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | * 1. Redistributions of source code must retain the above copyright
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| 9 | * notice, this list of conditions and the following disclaimer.
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| 10 | * 2. Redistributions in binary form must reproduce the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer in the
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| 12 | * documentation and/or other materials provided with the distribution.
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| 13 | *
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| 14 | * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
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| 15 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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| 17 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
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| 18 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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| 19 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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| 20 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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| 21 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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| 22 | * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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| 24 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 25 | */
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| 26 |
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| 27 | #include "config.h"
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| 28 | #include "RandomNumber.h"
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| 29 |
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| 30 | #include "RandomNumberSeed.h"
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| 31 |
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| 32 | #include <limits>
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| 33 | #include <limits.h>
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| 34 | #include <stdint.h>
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| 35 | #include <stdlib.h>
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| 36 |
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| 37 | namespace WTF {
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| 38 |
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| 39 | double randomNumber()
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| 40 | {
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| 41 | #if !ENABLE(JSC_MULTIPLE_THREADS)
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| 42 | static bool s_initialized = false;
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| 43 | if (!s_initialized) {
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| 44 | initializeRandomNumberGenerator();
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| 45 | s_initialized = true;
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| 46 | }
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| 47 | #endif
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| 48 |
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| 49 | uint64_t fullRandom;
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| 50 | #if COMPILER(MSVC) && defined(_CRT_RAND_S)
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| 51 | uint32_t part1;
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| 52 | rand_s(&part1);
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| 53 | fullRandom = part1;
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| 54 | #elif PLATFORM(DARWIN)
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| 55 | fullRandom = arc4random();
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| 56 | #elif PLATFORM(UNIX)
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| 57 | uint32_t part1 = random() & (RAND_MAX - 1);
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| 58 | uint32_t part2 = random() & (RAND_MAX - 1);
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| 59 | // random only provides 31 bits
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| 60 | fullRandom = part1;
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| 61 | fullRandom <<= 31;
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| 62 | fullRandom |= part2;
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| 63 | #else
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| 64 | uint32_t part1 = rand() & (RAND_MAX - 1);
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| 65 | uint32_t part2 = rand() & (RAND_MAX - 1);
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| 66 | // rand only provides 31 bits, and the low order bits of that aren't very random
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| 67 | // so we take the high 26 bits of part 1, and the high 27 bits of part2.
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| 68 | part1 >>= 5; // drop the low 5 bits
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| 69 | part2 >>= 4; // drop the low 4 bits
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| 70 | fullRandom = part1;
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| 71 | fullRandom <<= 27;
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| 72 | fullRandom |= part2;
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| 73 | #endif
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| 74 | // Mask off the low 53bits
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| 75 | fullRandom &= (1LL << 53) - 1;
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| 76 | return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53);
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| 77 | }
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| 78 |
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| 79 | }
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