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  1. /*
  2.   Simple DirectMedia Layer
  3.   Copyright (C) 1997-2023 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: */
  116.