Index: fusl/src/prng/random.c |
diff --git a/fusl/src/prng/random.c b/fusl/src/prng/random.c |
new file mode 100644 |
index 0000000000000000000000000000000000000000..7d557d700de027291017046230a0506f8af7842e |
--- /dev/null |
+++ b/fusl/src/prng/random.c |
@@ -0,0 +1,122 @@ |
+#include <stdlib.h> |
+#include <stdint.h> |
+#include "libc.h" |
+ |
+/* |
+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 volatile int lock[2]; |
+ |
+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() { |
+ 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; |
+} |
+ |
+static void __srandom(unsigned seed) { |
+ int k; |
+ uint64_t s = seed; |
+ |
+ if (n == 0) { |
+ 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; |
+} |
+ |
+void srandom(unsigned seed) { |
+ LOCK(lock); |
+ __srandom(seed); |
+ UNLOCK(lock); |
+} |
+ |
+char *initstate(unsigned seed, char *state, size_t size) { |
+ void *old; |
+ |
+ if (size < 8) |
+ return 0; |
+ LOCK(lock); |
+ 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(); |
+ UNLOCK(lock); |
+ return old; |
+} |
+ |
+char *setstate(char *state) { |
+ void *old; |
+ |
+ LOCK(lock); |
+ old = savestate(); |
+ loadstate((uint32_t*)state); |
+ UNLOCK(lock); |
+ return old; |
+} |
+ |
+long random(void) { |
+ long k; |
+ |
+ LOCK(lock); |
+ if (n == 0) { |
+ k = x[0] = lcg31(x[0]); |
+ goto end; |
+ } |
+ x[i] += x[j]; |
+ k = x[i]>>1; |
+ if (++i == n) |
+ i = 0; |
+ if (++j == n) |
+ j = 0; |
+end: |
+ UNLOCK(lock); |
+ return k; |
+} |