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      1 /*
      2   Simple DirectMedia Layer
      3   Copyright (C) 1997-2014 Sam Lantinga <slouken (at) libsdl.org>
      4 
      5   This software is provided 'as-is', without any express or implied
      6   warranty.  In no event will the authors be held liable for any damages
      7   arising from the use of this software.
      8 
      9   Permission is granted to anyone to use this software for any purpose,
     10   including commercial applications, and to alter it and redistribute it
     11   freely, subject to the following restrictions:
     12 
     13   1. The origin of this software must not be misrepresented; you must not
     14      claim that you wrote the original software. If you use this software
     15      in a product, an acknowledgment in the product documentation would be
     16      appreciated but is not required.
     17   2. Altered source versions must be plainly marked as such, and must not be
     18      misrepresented as being the original software.
     19   3. This notice may not be removed or altered from any source distribution.
     20 */
     21 
     22 /**
     23  *  \file SDL_test_random.h
     24  *
     25  *  Include file for SDL test framework.
     26  *
     27  *  This code is a part of the SDL2_test library, not the main SDL library.
     28  */
     29 
     30 /*
     31 
     32  A "32-bit Multiply with carry random number generator. Very fast.
     33  Includes a list of recommended multipliers.
     34 
     35  multiply-with-carry generator: x(n) = a*x(n-1) + carry mod 2^32.
     36  period: (a*2^31)-1
     37 
     38 */
     39 
     40 #ifndef _SDL_test_random_h
     41 #define _SDL_test_random_h
     42 
     43 #include "begin_code.h"
     44 /* Set up for C function definitions, even when using C++ */
     45 #ifdef __cplusplus
     46 extern "C" {
     47 #endif
     48 
     49 /* --- Definitions */
     50 
     51 /*
     52  * Macros that return a random number in a specific format.
     53  */
     54 #define SDLTest_RandomInt(c)        ((int)SDLTest_Random(c))
     55 
     56 /*
     57  * Context structure for the random number generator state.
     58  */
     59   typedef struct {
     60     unsigned int a;
     61     unsigned int x;
     62     unsigned int c;
     63     unsigned int ah;
     64     unsigned int al;
     65   } SDLTest_RandomContext;
     66 
     67 
     68 /* --- Function prototypes */
     69 
     70 /**
     71  *  \brief Initialize random number generator with two integers.
     72  *
     73  *  Note: The random sequence of numbers returned by ...Random() is the
     74  *  same for the same two integers and has a period of 2^31.
     75  *
     76  *  \param rndContext     pointer to context structure
     77  *  \param xi         integer that defines the random sequence
     78  *  \param ci         integer that defines the random sequence
     79  *
     80  */
     81  void SDLTest_RandomInit(SDLTest_RandomContext * rndContext, unsigned int xi,
     82                   unsigned int ci);
     83 
     84 /**
     85  *  \brief Initialize random number generator based on current system time.
     86  *
     87  *  \param rndContext     pointer to context structure
     88  *
     89  */
     90  void SDLTest_RandomInitTime(SDLTest_RandomContext *rndContext);
     91 
     92 
     93 /**
     94  *  \brief Initialize random number generator based on current system time.
     95  *
     96  *  Note: ...RandomInit() or ...RandomInitTime() must have been called
     97  *  before using this function.
     98  *
     99  *  \param rndContext     pointer to context structure
    100  *
    101  *  \returns A random number (32bit unsigned integer)
    102  *
    103  */
    104  unsigned int SDLTest_Random(SDLTest_RandomContext *rndContext);
    105 
    106 
    107 /* Ends C function definitions when using C++ */
    108 #ifdef __cplusplus
    109 }
    110 #endif
    111 #include "close_code.h"
    112 
    113 #endif /* _SDL_test_random_h */
    114 
    115 /* vi: set ts=4 sw=4 expandtab: */
    116