VLC_EXPORT( void, vlc_rand_bytes, (void *buf, size_t len) );
+/* Interlocked (but not reproducible) functions for the POSIX PRNG */
+VLC_EXPORT( double, vlc_drand48, (void) LIBVLC_USED );
+VLC_EXPORT( long, vlc_lrand48, (void) LIBVLC_USED );
+VLC_EXPORT( long, vlc_mrand48, (void) LIBVLC_USED );
+
#endif
}
}
#endif
+
+static struct
+{
+ bool init;
+ unsigned short subi[3];
+ vlc_mutex_t lock;
+} rand48 = { false, { 0, 0, 0, }, VLC_STATIC_MUTEX, };
+
+static void init_rand48 (void)
+{
+ if (!rand48.init)
+ {
+ vlc_rand_bytes (rand48.subi, sizeof (rand48.subi));
+#if 0 // short would be more than 16-bits ?
+ for (unsigned i = 0; i < 3; i++)
+ subi[i] &= 0xffff;
+#endif
+ }
+}
+
+/**
+ * PRNG uniformly distributed between 0.0 and 1.0 with 48-bits precision.
+ *
+ * @note Contrary to POSIX drand48(), this function is thread-safe.
+ * @warning Series generated by this function are not reproducible.
+ * Use erand48() if you need reproducible series.
+ *
+ * @return a double value within [0.0, 1.0] inclusive
+ */
+double vlc_drand48 (void)
+{
+ double ret;
+
+ vlc_mutex_lock (&rand48.lock);
+ init_rand48 ();
+ ret = erand48 (rand48.subi);
+ vlc_mutex_unlock (&rand48.lock);
+ return ret;
+}
+
+/**
+ * PRNG uniformly distributed between 0 and 2^32 - 1.
+ *
+ * @note Contrary to POSIX lrand48(), this function is thread-safe.
+ * @warning Series generated by this function are not reproducible.
+ * Use nrand48() if you need reproducible series.
+ *
+ * @return a double value within [0.0, 1.0] inclusive
+ */
+long vlc_lrand48 (void)
+{
+ long ret;
+
+ vlc_mutex_lock (&rand48.lock);
+ init_rand48 ();
+ ret = nrand48 (rand48.subi);
+ vlc_mutex_unlock (&rand48.lock);
+ return ret;
+}
+
+/**
+ * PRNG uniformly distributed between -2^32 and 2^32 - 1.
+ *
+ * @note Contrary to POSIX mrand48(), this function is thread-safe.
+ * @warning Series generated by this function are not reproducible.
+ * Use jrand48() if you need reproducible series.
+ *
+ * @return a double value within [0.0, 1.0] inclusive
+ */
+long vlc_mrand48 (void)
+{
+ long ret;
+
+ vlc_mutex_lock (&rand48.lock);
+ init_rand48 ();
+ ret = jrand48 (rand48.subi);
+ vlc_mutex_unlock (&rand48.lock);
+ return ret;
+}