mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 19:43:32 +00:00
128 lines
4.7 KiB
C
128 lines
4.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
|
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
|
|
╚──────────────────────────────────────────────────────────────────────────────╝
|
|
│ │
|
|
│ Musl Libc │
|
|
│ Copyright © 2005-2014 Rich Felker, et al. │
|
|
│ │
|
|
│ Permission is hereby granted, free of charge, to any person obtaining │
|
|
│ a copy of this software and associated documentation files (the │
|
|
│ "Software"), to deal in the Software without restriction, including │
|
|
│ without limitation the rights to use, copy, modify, merge, publish, │
|
|
│ distribute, sublicense, and/or sell copies of the Software, and to │
|
|
│ permit persons to whom the Software is furnished to do so, subject to │
|
|
│ the following conditions: │
|
|
│ │
|
|
│ The above copyright notice and this permission notice shall be │
|
|
│ included in all copies or substantial portions of the Software. │
|
|
│ │
|
|
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
|
|
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
|
|
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
|
|
│ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY │
|
|
│ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, │
|
|
│ TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE │
|
|
│ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. │
|
|
│ │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include "libc/rand/rand.h"
|
|
|
|
asm(".ident\t\"\\n\\n\
|
|
Musl libc (MIT License)\\n\
|
|
Copyright 2005-2014 Rich Felker, et. al.\"");
|
|
asm(".include \"libc/disclaimer.inc\"");
|
|
|
|
/*
|
|
* this code uses the same lagged fibonacci generator as the
|
|
* original bsd random implementation except for the seeding
|
|
* which was broken in the original
|
|
*/
|
|
|
|
static uint32_t init[] = {
|
|
0x00000000, 0x5851f42d, 0xc0b18ccf, 0xcbb5f646, 0xc7033129, 0x30705b04,
|
|
0x20fd5db4, 0x9a8b7f78, 0x502959d8, 0xab894868, 0x6c0356a7, 0x88cdb7ff,
|
|
0xb477d43f, 0x70a3a52b, 0xa8e4baf1, 0xfd8341fc, 0x8ae16fd9, 0x742d2f7a,
|
|
0x0d1f0796, 0x76035e09, 0x40f7702c, 0x6fa72ca5, 0xaaa84157, 0x58a0df74,
|
|
0xc74a0364, 0xae533cc4, 0x04185faf, 0x6de3b115, 0x0cab8628, 0xf043bfa4,
|
|
0x398150e9, 0x37521657,
|
|
};
|
|
|
|
static int n = 31;
|
|
static int i = 3;
|
|
static int j = 0;
|
|
static uint32_t *x = init + 1;
|
|
|
|
static uint32_t lcg31(uint32_t x) {
|
|
return (1103515245 * x + 12345) & 0x7fffffff;
|
|
}
|
|
|
|
static uint64_t lcg64(uint64_t x) {
|
|
return 6364136223846793005ull * x + 1;
|
|
}
|
|
|
|
static void *savestate(void) {
|
|
x[-1] = (n << 16) | (i << 8) | j;
|
|
return x - 1;
|
|
}
|
|
|
|
static void loadstate(uint32_t *state) {
|
|
x = state + 1;
|
|
n = x[-1] >> 16;
|
|
i = (x[-1] >> 8) & 0xff;
|
|
j = x[-1] & 0xff;
|
|
}
|
|
|
|
void srandom(unsigned seed) {
|
|
int k;
|
|
uint64_t s = seed;
|
|
if (!n) {
|
|
x[0] = s;
|
|
return;
|
|
}
|
|
i = n == 31 || n == 7 ? 3 : 1;
|
|
j = 0;
|
|
for (k = 0; k < n; k++) {
|
|
s = lcg64(s);
|
|
x[k] = s >> 32;
|
|
}
|
|
/* make sure x contains at least one odd number */
|
|
x[0] |= 1;
|
|
}
|
|
|
|
char *initstate(unsigned seed, char *state, size_t size) {
|
|
void *old;
|
|
if (size < 8) return 0;
|
|
old = savestate();
|
|
if (size < 32) {
|
|
n = 0;
|
|
} else if (size < 64) {
|
|
n = 7;
|
|
} else if (size < 128) {
|
|
n = 15;
|
|
} else if (size < 256) {
|
|
n = 31;
|
|
} else {
|
|
n = 63;
|
|
}
|
|
x = (uint32_t *)state + 1;
|
|
srandom(seed);
|
|
savestate();
|
|
return old;
|
|
}
|
|
|
|
char *setstate(char *state) {
|
|
void *old;
|
|
old = savestate();
|
|
loadstate((uint32_t *)state);
|
|
return old;
|
|
}
|
|
|
|
long random(void) {
|
|
long k;
|
|
if (!n) return (x[0] = lcg31(x[0]));
|
|
x[i] += x[j];
|
|
k = x[i] >> 1;
|
|
if (++i == n) i = 0;
|
|
if (++j == n) j = 0;
|
|
return k;
|
|
}
|