skia / external / github.com / libsdl-org / SDL / refs/tags/prerelease-3.1.2 / . / src / test / SDL_test_random.c

/* | |

Simple DirectMedia Layer | |

Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org> | |

This software is provided 'as-is', without any express or implied | |

warranty. In no event will the authors be held liable for any damages | |

arising from the use of this software. | |

Permission is granted to anyone to use this software for any purpose, | |

including commercial applications, and to alter it and redistribute it | |

freely, subject to the following restrictions: | |

1. The origin of this software must not be misrepresented; you must not | |

claim that you wrote the original software. If you use this software | |

in a product, an acknowledgment in the product documentation would be | |

appreciated but is not required. | |

2. Altered source versions must be plainly marked as such, and must not be | |

misrepresented as being the original software. | |

3. This notice may not be removed or altered from any source distribution. | |

*/ | |

/* | |

A portable "32-bit Multiply with carry" random number generator. | |

Used by the fuzzer component. | |

Original source code contributed by A. Schiffler for GSOC project. | |

*/ | |

#include <SDL3/SDL_test.h> | |

#include <stdlib.h> /* Needed for srand() and rand() */ | |

#include <time.h> /* Needed for time() */ | |

/* Initialize random number generator with two integer variables */ | |

void SDLTest_RandomInit(SDLTest_RandomContext *rndContext, unsigned int xi, unsigned int ci) | |

{ | |

if (!rndContext) { | |

return; | |

} | |

/* | |

* Choose a value for 'a' from this list | |

* 1791398085 1929682203 1683268614 1965537969 1675393560 | |

* 1967773755 1517746329 1447497129 1655692410 1606218150 | |

* 2051013963 1075433238 1557985959 1781943330 1893513180 | |

* 1631296680 2131995753 2083801278 1873196400 1554115554 | |

*/ | |

rndContext->a = 1655692410; | |

rndContext->x = 30903; | |

rndContext->c = 0; | |

if (xi != 0) { | |

rndContext->x = xi; | |

} | |

rndContext->c = ci; | |

rndContext->ah = rndContext->a >> 16; | |

rndContext->al = rndContext->a & 65535; | |

} | |

/* Initialize random number generator from system time */ | |

void SDLTest_RandomInitTime(SDLTest_RandomContext *rndContext) | |

{ | |

int a, b; | |

if (!rndContext) { | |

return; | |

} | |

srand((unsigned int)time(NULL)); | |

a = rand(); | |

srand((unsigned int)SDL_GetPerformanceCounter()); | |

b = rand(); | |

SDLTest_RandomInit(rndContext, a, b); | |

} | |

/* Returns random numbers */ | |

unsigned int SDLTest_Random(SDLTest_RandomContext *rndContext) | |

{ | |

unsigned int xh, xl; | |

if (!rndContext) { | |

return 0; | |

} | |

xh = rndContext->x >> 16; | |

xl = rndContext->x & 65535; | |

rndContext->x = rndContext->x * rndContext->a + rndContext->c; | |

rndContext->c = | |

xh * rndContext->ah + ((xh * rndContext->al) >> 16) + | |

((xl * rndContext->ah) >> 16); | |

if (xl * rndContext->al >= (~rndContext->c + 1)) { | |

rndContext->c++; | |

} | |

return rndContext->x; | |

} |