1#include <stdlib.h> 2#include <stdint.h> 3#include "lock.h" 4#include "fork_impl.h" 5 6/* 7this code uses the same lagged fibonacci generator as the 8original bsd random implementation except for the seeding 9which was broken in the original 10*/ 11 12static uint32_t init[] = { 130x00000000,0x5851f42d,0xc0b18ccf,0xcbb5f646, 140xc7033129,0x30705b04,0x20fd5db4,0x9a8b7f78, 150x502959d8,0xab894868,0x6c0356a7,0x88cdb7ff, 160xb477d43f,0x70a3a52b,0xa8e4baf1,0xfd8341fc, 170x8ae16fd9,0x742d2f7a,0x0d1f0796,0x76035e09, 180x40f7702c,0x6fa72ca5,0xaaa84157,0x58a0df74, 190xc74a0364,0xae533cc4,0x04185faf,0x6de3b115, 200x0cab8628,0xf043bfa4,0x398150e9,0x37521657}; 21 22static int n = 31; 23static int i = 3; 24static int j = 0; 25static uint32_t *x = init+1; 26static volatile int lock[1]; 27volatile int *const __random_lockptr = lock; 28 29static uint32_t lcg31(uint32_t x) { 30 return (1103515245*x + 12345) & 0x7fffffff; 31} 32 33static uint64_t lcg64(uint64_t x) { 34 return 6364136223846793005ull*x + 1; 35} 36 37static void *savestate() { 38 x[-1] = (n<<16)|(i<<8)|j; 39 return x-1; 40} 41 42static void loadstate(uint32_t *state) { 43 x = state+1; 44 n = x[-1]>>16; 45 i = (x[-1]>>8)&0xff; 46 j = x[-1]&0xff; 47} 48 49static void __srandom(unsigned seed) { 50 int k; 51 uint64_t s = seed; 52 53 if (n == 0) { 54 x[0] = s; 55 return; 56 } 57 i = n == 31 || n == 7 ? 3 : 1; 58 j = 0; 59 for (k = 0; k < n; k++) { 60 s = lcg64(s); 61 x[k] = s>>32; 62 } 63 /* make sure x contains at least one odd number */ 64 x[0] |= 1; 65} 66 67void srandom(unsigned seed) { 68 LOCK(lock); 69 __srandom(seed); 70 UNLOCK(lock); 71} 72 73char *initstate(unsigned seed, char *state, size_t size) { 74 void *old; 75 76 if (size < 8) 77 return 0; 78 LOCK(lock); 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 UNLOCK(lock); 94 return old; 95} 96 97char *setstate(char *state) { 98 void *old; 99 100 LOCK(lock); 101 old = savestate(); 102 loadstate((uint32_t*)state); 103 UNLOCK(lock); 104 return old; 105} 106 107long random(void) { 108 long k; 109 110 LOCK(lock); 111 if (n == 0) { 112 k = x[0] = lcg31(x[0]); 113 goto end; 114 } 115 x[i] += x[j]; 116 k = x[i]>>1; 117 if (++i == n) 118 i = 0; 119 if (++j == n) 120 j = 0; 121end: 122 UNLOCK(lock); 123 return k; 124} 125