/*
  * Lagged Fibonacci PRNG
  * Copyright (c) 2008 Michael Niedermayer
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 #ifndef AVUTIL_LFG_H
 #define AVUTIL_LFG_H

 typedef struct AVLFG {

     unsigned int state[64];
     int index;
 } AVLFG;
 
 void av_lfg_init(AVLFG *c, unsigned int seed);
 

 /**

  * Get the next random unsigned 32-bit number using an ALFG.

  *
  * Please also consider a simple LCG like state= state*1664525+1013904223,
  * it may be good enough and faster for your specific use case.
  */

 static inline unsigned int av_lfg_get(AVLFG *c){
     c->state[c->index & 63] = c->state[(c->index-24) & 63] + c->state[(c->index-55) & 63];
     return c->state[c->index++ & 63];
 }
 

 /**

  * Get the next random unsigned 32-bit number using a MLFG.

  *

  * Please also consider av_lfg_get() above, it is faster.

  */
 static inline unsigned int av_mlfg_get(AVLFG *c){
     unsigned int a= c->state[(c->index-55) & 63];
     unsigned int b= c->state[(c->index-24) & 63];

     return c->state[c->index++ & 63] = 2*a*b+a+b;

 }
 

 /**

  * Get the next two numbers generated by a Box-Muller Gaussian

  * generator using the random numbers issued by lfg.
  *

  * @param out array where the two generated numbers are placed

  */
 void av_bmg_get(AVLFG *lfg, double out[2]);
 

 #endif /* AVUTIL_LFG_H */