include/SDL_test_random.h
author David Ludwig <dludwig@pobox.com>
Mon, 01 Apr 2013 21:33:06 -0400
changeset 8453 499aa167ea79
parent 6885 700f1b25f77f
child 7191 75360622e65f
permissions -rw-r--r--
WinRT: made WinRT path retrieval be available in both UCS-2 and UTF-8 flavors
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2013 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 /* *INDENT-OFF* */
    47 extern "C" {
    48 /* *INDENT-ON* */
    49 #endif
    50 
    51 /* --- Definitions */
    52 
    53 /*
    54  * Macros that return a random number in a specific format.
    55  */
    56 #define SDLTest_RandomInt(c)		((int)SDLTest_Random(c))
    57 
    58 /*
    59  * Context structure for the random number generator state.
    60  */
    61   typedef struct {
    62     unsigned int a;
    63     unsigned int x;
    64     unsigned int c;
    65     unsigned int ah;
    66     unsigned int al;
    67   } SDLTest_RandomContext;
    68 
    69 
    70 /* --- Function prototypes */
    71 
    72 /**
    73  *  \brief Initialize random number generator with two integers. 
    74  *
    75  *  Note: The random sequence of numbers returned by ...Random() is the
    76  *  same for the same two integers and has a period of 2^31.
    77  *
    78  *  \param rndContext     pointer to context structure
    79  *  \param xi         integer that defines the random sequence
    80  *  \param ci         integer that defines the random sequence
    81  *
    82  */
    83  void SDLTest_RandomInit(SDLTest_RandomContext * rndContext, unsigned int xi,
    84 				  unsigned int ci);
    85 
    86 /**
    87  *  \brief Initialize random number generator based on current system time. 
    88  *
    89  *  \param rndContext     pointer to context structure
    90  *
    91  */
    92  void SDLTest_RandomInitTime(SDLTest_RandomContext *rndContext);
    93 
    94 
    95 /**
    96  *  \brief Initialize random number generator based on current system time. 
    97  *
    98  *  Note: ...RandomInit() or ...RandomInitTime() must have been called
    99  *  before using this function.
   100  *
   101  *  \param rndContext     pointer to context structure
   102  *
   103  *  \returns A random number (32bit unsigned integer)
   104  *
   105  */
   106  unsigned int SDLTest_Random(SDLTest_RandomContext *rndContext);
   107 
   108 
   109 /* Ends C function definitions when using C++ */
   110 #ifdef __cplusplus
   111 /* *INDENT-OFF* */
   112 }
   113 /* *INDENT-ON* */
   114 #endif
   115 #include "close_code.h"
   116 
   117 #endif /* _SDL_test_random_h */
   118 
   119 /* vi: set ts=4 sw=4 expandtab: */