misc/winutils/include/libavutil/lfg.h
author Wuzzy <Wuzzy2@mail.ru>
Thu, 25 Apr 2019 23:01:05 +0200
changeset 14844 e239378a9400
parent 7813 7ac83d79b897
permissions -rw-r--r--
Prevent entering “/”, “\” and “:” in team and scheme names. The name of teams and schems is saved in the file name itself, so these characters would cause trouble as they are used in path names in Linux and Windows.
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/*
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 * Lagged Fibonacci PRNG
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 * Copyright (c) 2008 Michael Niedermayer
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#ifndef AVUTIL_LFG_H
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#define AVUTIL_LFG_H
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typedef struct AVLFG {
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    unsigned int state[64];
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    int index;
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} AVLFG;
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void av_lfg_init(AVLFG *c, unsigned int seed);
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/**
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 * Get the next random unsigned 32-bit number using an ALFG.
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 *
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 * Please also consider a simple LCG like state= state*1664525+1013904223,
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 * it may be good enough and faster for your specific use case.
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 */
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static inline unsigned int av_lfg_get(AVLFG *c){
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    c->state[c->index & 63] = c->state[(c->index-24) & 63] + c->state[(c->index-55) & 63];
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    return c->state[c->index++ & 63];
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}
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/**
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 * Get the next random unsigned 32-bit number using a MLFG.
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 *
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 * Please also consider av_lfg_get() above, it is faster.
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 */
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static inline unsigned int av_mlfg_get(AVLFG *c){
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    unsigned int a= c->state[(c->index-55) & 63];
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    unsigned int b= c->state[(c->index-24) & 63];
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    return c->state[c->index++ & 63] = 2*a*b+a+b;
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}
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/**
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 * Get the next two numbers generated by a Box-Muller Gaussian
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 * generator using the random numbers issued by lfg.
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 *
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 * @param out array where the two generated numbers are placed
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 */
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void av_bmg_get(AVLFG *lfg, double out[2]);
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#endif /* AVUTIL_LFG_H */