From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 11 Nov 2006 14:19:40 +0000 (+0000)
Subject: Make sure loops_per_tick doesn't overflow to zero.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?p=pintos-anon;a=commitdiff_plain;h=2ce1eb4d6c0adc209f56789920362d455cca443e

Make sure loops_per_tick doesn't overflow to zero.
---

diff --git a/src/devices/timer.c b/src/devices/timer.c
index 070c487..662e0c6 100644
--- a/src/devices/timer.c
+++ b/src/devices/timer.c
@@ -57,8 +57,11 @@ timer_calibrate (void)
   /* Approximate loops_per_tick as the largest power-of-two
      still less than one timer tick. */
   loops_per_tick = 1u << 10;
-  while (!too_many_loops (loops_per_tick << 1))
-    loops_per_tick <<= 1;
+  while (!too_many_loops (loops_per_tick << 1)) 
+    {
+      loops_per_tick <<= 1;
+      ASSERT (loops_per_tick != 0);
+    }
 
   /* Refine the next 8 bits of loops_per_tick. */
   high_bit = loops_per_tick;