random: Fix behavior of kernel option "-rs".

[pintos-anon] / src / lib / random.c

diff --git a/src/lib/random.c b/src/lib/random.c
index 63d798d6bf6394dcb017f096c5980cf4722c4fb9..6a963e21b42ccce71551e66e8dad806edd542d9a 100644 (file)
--- a/src/lib/random.c
+++ b/src/lib/random.c
@@ -29,8 +29,7 @@ swap_byte (uint8_t *a, uint8_t *b)
   *b = t;
 }
 
-/* Initializes the PRNG with the given SEED.
-   Does nothing if the PRNG has already been initialized. */
+/* Initializes or reinitializes the PRNG with the given SEED. */
 void
 random_init (unsigned seed)
 {
@@ -40,7 +39,7 @@ random_init (unsigned seed)
 
   if (inited)
     return;
-  
+
   for (i = 0; i < 256; i++) 
     s[i] = i;
   for (i = j = 0; i < 256; i++) 
@@ -59,7 +58,9 @@ random_bytes (void *buf_, size_t size)
 {
   uint8_t *buf;
 
-  ASSERT (inited);
+  if (!inited)
+    random_init (0);
+
   for (buf = buf_; size-- > 0; buf++)
     {
       uint8_t s_k;
@@ -73,7 +74,9 @@ random_bytes (void *buf_, size_t size)
     }
 }
 
-/* Returns a pseudo-random unsigned long. */
+/* Returns a pseudo-random unsigned long.
+   Use random_ulong() % n to obtain a random number in the range
+   0...n (exclusive). */
 unsigned long
 random_ulong (void) 
 {