1 #include <stdlib.h>
2 #include <stdint.h>
3 #include "lock.h"
4 #include "fork_impl.h"
5
6 /*
7 this code uses the same lagged fibonacci generator as the
8 original bsd random implementation except for the seeding
9 which was broken in the original
10 */
11
12 static uint32_t init[] = {
13 0x00000000,0x5851f42d,0xc0b18ccf,0xcbb5f646,
14 0xc7033129,0x30705b04,0x20fd5db4,0x9a8b7f78,
15 0x502959d8,0xab894868,0x6c0356a7,0x88cdb7ff,
16 0xb477d43f,0x70a3a52b,0xa8e4baf1,0xfd8341fc,
17 0x8ae16fd9,0x742d2f7a,0x0d1f0796,0x76035e09,
18 0x40f7702c,0x6fa72ca5,0xaaa84157,0x58a0df74,
19 0xc74a0364,0xae533cc4,0x04185faf,0x6de3b115,
20 0x0cab8628,0xf043bfa4,0x398150e9,0x37521657};
21
22 static int n = 31;
23 static int i = 3;
24 static int j = 0;
25 static uint32_t *x = init+1;
26 #ifdef __wasilibc_unmodified_upstream
27 static volatile int lock[1];
28 volatile int *const __random_lockptr = lock;
29 #endif
30
lcg31(uint32_t x)31 static uint32_t lcg31(uint32_t x) {
32 return (1103515245*x + 12345) & 0x7fffffff;
33 }
34
lcg64(uint64_t x)35 static uint64_t lcg64(uint64_t x) {
36 return 6364136223846793005ull*x + 1;
37 }
38
savestate()39 static void *savestate() {
40 x[-1] = (n<<16)|(i<<8)|j;
41 return x-1;
42 }
43
loadstate(uint32_t * state)44 static void loadstate(uint32_t *state) {
45 x = state+1;
46 n = x[-1]>>16;
47 i = (x[-1]>>8)&0xff;
48 j = x[-1]&0xff;
49 }
50
__srandom(unsigned seed)51 static void __srandom(unsigned seed) {
52 int k;
53 uint64_t s = seed;
54
55 if (n == 0) {
56 x[0] = s;
57 return;
58 }
59 i = n == 31 || n == 7 ? 3 : 1;
60 j = 0;
61 for (k = 0; k < n; k++) {
62 s = lcg64(s);
63 x[k] = s>>32;
64 }
65 /* make sure x contains at least one odd number */
66 x[0] |= 1;
67 }
68
srandom(unsigned seed)69 void srandom(unsigned seed) {
70 LOCK(lock);
71 __srandom(seed);
72 UNLOCK(lock);
73 }
74
initstate(unsigned seed,char * state,size_t size)75 char *initstate(unsigned seed, char *state, size_t size) {
76 void *old;
77
78 if (size < 8)
79 return 0;
80 LOCK(lock);
81 old = savestate();
82 if (size < 32)
83 n = 0;
84 else if (size < 64)
85 n = 7;
86 else if (size < 128)
87 n = 15;
88 else if (size < 256)
89 n = 31;
90 else
91 n = 63;
92 x = (uint32_t*)state + 1;
93 __srandom(seed);
94 savestate();
95 UNLOCK(lock);
96 return old;
97 }
98
setstate(char * state)99 char *setstate(char *state) {
100 void *old;
101
102 LOCK(lock);
103 old = savestate();
104 loadstate((uint32_t*)state);
105 UNLOCK(lock);
106 return old;
107 }
108
random(void)109 long random(void) {
110 long k;
111
112 LOCK(lock);
113 if (n == 0) {
114 k = x[0] = lcg31(x[0]);
115 goto end;
116 }
117 x[i] += x[j];
118 k = x[i]>>1;
119 if (++i == n)
120 i = 0;
121 if (++j == n)
122 j = 0;
123 end:
124 UNLOCK(lock);
125 return k;
126 }
127