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