X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lib%2Frandom.c;h=a771c97ae624a2dd83bda57c95c062e316b77108;hb=231e128f91f6cc7f23f5d2392dffaa7857f1dcfa;hp=57516fd2f89bae94afa1d079e558c4f65987c685;hpb=5b53087fa5a07ff89d34cf3bf3bc1b28809f05c2;p=libucw.git

diff --git a/lib/random.c b/lib/random.c
index 57516fd2..a771c97a 100644
--- a/lib/random.c
+++ b/lib/random.c
@@ -1,22 +1,58 @@
 /*
- *	Sherlock Library -- Unbiased Range Correction for random()
+ *	UCW Library -- Unbiased Random Numbers
  *
- *	(c) 1998 Martin Mares, <mj@atrey.karlin.mff.cuni.cz>
+ *	(c) 1998--2006 Martin Mares <mj@ucw.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
  */
 
-#include <stdio.h>
+#include "lib/lib.h"
+
 #include <stdlib.h>
 
-#include "lib/lib.h"
+/* We expect the random generator in libc to give at least 30 bits of randomness */
+COMPILE_ASSERT(RAND_MAX_RANGE_TEST, RAND_MAX >= (1 << 30)-1);
+
+uns
+random_u32(void)
+{
+  return (random() & 0xffff) | ((random() & 0xffff) << 16);
+}
 
 uns
 random_max(uns max)
 {
   uns r, l;
 
+  ASSERT(max <= (1 << 30));
   l = (RAND_MAX + 1U) - ((RAND_MAX + 1U) % max);
   do
     r = random();
   while (r >= l);
   return r % max;
 }
+
+u64
+random_u64(void)
+{
+  return
+    ((u64)(random() & 0xffff) << 48) |
+    ((u64)(random() & 0xffffff) << 24) |
+    (random() & 0xffffff);
+}
+
+u64
+random_max_u64(u64 max)
+{
+  if (max < (1 << 30))
+    return random_max(max);
+
+  u64 r, l, m;
+  m = 0xffffffffffffffff;
+  l = m - (m % max);
+  do
+    r = random_u64();
+  while (r >= l);
+  return r % max;
+}