these interfaces are required to be thread-safe even though they are
not state-free. the random number sequence is shared across all
threads.
#include <stdlib.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdint.h>
/*
this code uses the same lagged fibonacci generator as the
/*
this code uses the same lagged fibonacci generator as the
static int i = 3;
static int j = 0;
static uint32_t *x = init+1;
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 uint32_t lcg31(uint32_t x) {
return (1103515245*x + 12345) & 0x7fffffff;
-void srandom(unsigned seed) {
+static void __srandom(unsigned seed) {
int k;
uint64_t s = seed;
int k;
uint64_t s = seed;
+void srandom(unsigned seed) {
+ LOCK(&lock);
+ __srandom(seed);
+ UNLOCK(&lock);
+}
+
char *initstate(unsigned seed, char *state, size_t size) {
char *initstate(unsigned seed, char *state, size_t size) {
- void *old = savestate();
+ LOCK(&lock);
+ old = savestate();
+ if (size < 32)
n = 0;
else if (size < 64)
n = 7;
n = 0;
else if (size < 64)
n = 7;
else
n = 63;
x = (uint32_t*)state + 1;
else
n = 63;
x = (uint32_t*)state + 1;
+ __srandom(seed);
+ UNLOCK(&lock);
return old;
}
char *setstate(char *state) {
return old;
}
char *setstate(char *state) {
- void *old = savestate();
+ void *old;
+
+ LOCK(&lock);
+ old = savestate();
loadstate((uint32_t*)state);
loadstate((uint32_t*)state);
return old;
}
long random(void) {
long k;
return old;
}
long random(void) {
long k;
- if (n == 0)
- return x[0] = lcg31(x[0]);
+ 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;
x[i] += x[j];
k = x[i]>>1;
if (++i == n)
i = 0;
if (++j == n)
j = 0;