/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-â
âvi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :viâ
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â Copyright 2020 Justine Alexandra Roberts Tunney                              â
â                                                                              â
â Permission to use, copy, modify, and/or distribute this software for         â
â any purpose with or without fee is hereby granted, provided that the         â
â above copyright notice and this permission notice appear in all copies.      â
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â THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                â
â WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                â
â WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             â
â AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         â
â DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        â
â PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               â
â TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             â
â PERFORMANCE OF THIS SOFTWARE.                                                â
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#include "libc/stdio/rand.h"
#include "libc/stdio/internal.h"
#include "libc/stdio/lcg.internal.h"

/**
 * Returns 31-bit linear congruential pseudorandom number, e.g.
 *
 *     int x = rand();
 *     assert(x >= 0);
 *
 * This function always returns a positive number. If srand() isn't
 * called, then it'll return the same sequence each time your program
 * runs. Faster and more modern alternatives exist to this function.
 *
 * This function is not thread safe in the sense that multiple threads
 * might simultaneously generate the same random values.
 *
 * @note this function does well on bigcrush and practrand
 * @note this function is not intended for cryptography
 * @see lemur64(), _rand64(), rdrand()
 */
int rand(void) {
  return KnuthLinearCongruentialGenerator(&g_rando) >> 33;
}
