Use var_Inherit* instead of var_CreateGet*.

[vlc] / src / misc / rand.c

diff --git a/src/misc/rand.c b/src/misc/rand.c
index 8932e407ad1343eb23d2dc04b7cefa323290f925..82c67c3d7f4626ce10b8495d7dc6c83f51b65705 100644 (file)
--- a/src/misc/rand.c
+++ b/src/misc/rand.c
@@ -163,3 +163,82 @@ void vlc_rand_bytes (void *buf, size_t len)
     }
 }
 #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 an integral value within [0.0, 2^32-1] 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 an integral value within [-2^32, 2^32-1] 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;
+}