include/SDL_test_random.h
author Sam Lantinga <slouken@libsdl.org>
Wed, 12 Jun 2019 10:38:49 -0700
changeset 12848 a9a7c1e48f0b
parent 12503 806492103856
permissions -rw-r--r--
Better patch to make it more clear what's going on
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2019 Sam Lantinga <slouken@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: */