/*

 * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.

 *           (C) 2008, 2009 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>

#if OS(WINCE)

extern "C" {

#include "wince/mt19937ar.c"

}

#endif

#if PLATFORM(BREWMP)

#include <AEEAppGen.h>

#include <AEESource.h>

#include <AEEStdLib.h>

#endif

namespace WTF {

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 OS(DARWIN)

    uint32_t bits = arc4random();

    return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);

#elif OS(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);

#elif OS(WINCE)

    return genrand_res53();

#elif OS(WINDOWS)

    uint32_t part1 = rand() & (RAND_MAX - 1);

    uint32_t part2 = rand() & (RAND_MAX - 1);

    uint32_t part3 = rand() & (RAND_MAX - 1);

    uint32_t part4 = rand() & (RAND_MAX - 1);

    // rand only provides 15 bits on Win32

    uint64_t fullRandom = part1;

    fullRandom <<= 15;

    fullRandom |= part2;

    fullRandom <<= 15;

    fullRandom |= part3;

    fullRandom <<= 15;

    fullRandom |= part4;

    // Mask off the low 53bits

    fullRandom &= (1LL << 53) - 1;

    return static_cast<double>(fullRandom)/static_cast<double>(1LL << 53);

#elif PLATFORM(BREWMP)

    uint32_t bits;

    ISource* randomSource;

    IShell* shell = reinterpret_cast<AEEApplet*>(GETAPPINSTANCE())->m_pIShell;

    ISHELL_CreateInstance(shell, AEECLSID_RANDOM, reinterpret_cast<void**>(&randomSource));

    ISOURCE_Read(randomSource, reinterpret_cast<char*>(&bits), 4);

    ISOURCE_Release(randomSource);

    return static_cast<double>(bits) / (static_cast<double>(std::numeric_limits<uint32_t>::max()) + 1.0);

#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

}

}