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      1 /*
      2  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef WTF_RandomNumberSeed_h
     27 #define WTF_RandomNumberSeed_h
     28 
     29 #include <stdlib.h>
     30 #include <time.h>
     31 
     32 #if HAVE(SYS_TIME_H)
     33 #include <sys/time.h>
     34 #endif
     35 
     36 #if OS(UNIX)
     37 #include <sys/types.h>
     38 #include <unistd.h>
     39 #endif
     40 
     41 #if USE(MERSENNE_TWISTER_19937)
     42 extern "C" {
     43 void init_by_array(unsigned long init_key[],int key_length);
     44 }
     45 #endif
     46 
     47 // Internal JavaScriptCore usage only
     48 namespace WTF {
     49 
     50 inline void initializeRandomNumberGenerator()
     51 {
     52 #if OS(DARWIN)
     53     // On Darwin we use arc4random which initialises itself.
     54 #elif OS(WINCE)
     55     // initialize rand()
     56     srand(GetTickCount());
     57 #elif COMPILER(MSVC) && defined(_CRT_RAND_S)
     58     // On Windows we use rand_s which initialises itself
     59 #elif PLATFORM(BREWMP)
     60     // On Brew MP we use AEECLSID_RANDOM which initialises itself
     61 #elif OS(UNIX)
     62     // srandomdev is not guaranteed to exist on linux so we use this poor seed, this should be improved
     63     timeval time;
     64     gettimeofday(&time, 0);
     65     srandom(static_cast<unsigned>(time.tv_usec * getpid()));
     66 #else
     67     srand(static_cast<unsigned>(time(0)));
     68 #endif
     69 
     70 #if USE(MERSENNE_TWISTER_19937)
     71     // use rand() to initialize the Mersenne Twister random number generator.
     72     unsigned long initializationBuffer[4];
     73     initializationBuffer[0] = (rand() << 16) | rand();
     74     initializationBuffer[1] = (rand() << 16) | rand();
     75     initializationBuffer[2] = (rand() << 16) | rand();
     76     initializationBuffer[3] = (rand() << 16) | rand();
     77     init_by_array(initializationBuffer, 4);
     78 #endif
     79 }
     80 
     81 }
     82 
     83 #endif
     84