X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmisc%2Frand.c;h=28546271b3d13f6f95b52b0a0653f8a1b04210a3;hb=e3c350269cf1b482d2f6842e5b31a83be27a1c40;hp=081ece3ff8234463d25c6efac66b3525beaaeddc;hpb=7e45ab1b284217f191c35c5c2916742b4fbe39ee;p=vlc

diff --git a/src/misc/rand.c b/src/misc/rand.c
index 081ece3ff8..28546271b3 100644
--- a/src/misc/rand.c
+++ b/src/misc/rand.c
@@ -92,19 +92,21 @@ void vlc_rand_bytes (void *buf, size_t len)
         uint64_t val;
         struct md5_s mdi, mdo;
 
+        InitMD5 (&mdi);
+        InitMD5 (&mdo);
+
         pthread_mutex_lock (&lock);
         if (counter == 0)
             vlc_rand_init ();
         val = counter++;
-        pthread_mutex_unlock (&lock);
 
-        InitMD5 (&mdi);
         AddMD5 (&mdi, ikey, sizeof (ikey));
+        AddMD5 (&mdo, okey, sizeof (okey));
+        pthread_mutex_unlock (&lock);
+
         AddMD5 (&mdi, &stamp, sizeof (stamp));
         AddMD5 (&mdi, &val, sizeof (val));
         EndMD5 (&mdi);
-        InitMD5 (&mdo);
-        AddMD5 (&mdo, okey, sizeof (okey));
         AddMD5 (&mdo, mdi.p_digest, sizeof (mdi.p_digest));
         EndMD5 (&mdo);
 
@@ -161,3 +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 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;
+}