[src/trunk]: src/sys/arch/hpcarm/sa11x0 Fix bugs in delay().

[toshii <toshii%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/0af2e63c50ea
branches:  trunk
changeset: 506953:0af2e63c50ea
user:      toshii <toshii%NetBSD.org@localhost>
date:      Fri Mar 09 18:55:29 2001 +0000

description:
Fix bugs in delay().
 - it could wait infinitely.
 - large roundoff error.

diffstat:

 sys/arch/hpcarm/sa11x0/sa11x0_ost.c |  27 ++++++++++++++++-----------
 1 files changed, 16 insertions(+), 11 deletions(-)

diffs (61 lines):

diff -r 53488668f186 -r 0af2e63c50ea sys/arch/hpcarm/sa11x0/sa11x0_ost.c
--- a/sys/arch/hpcarm/sa11x0/sa11x0_ost.c       Fri Mar 09 16:24:51 2001 +0000
+++ b/sys/arch/hpcarm/sa11x0/sa11x0_ost.c       Fri Mar 09 18:55:29 2001 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sa11x0_ost.c,v 1.2 2001/02/23 04:31:19 ichiro Exp $    */
+/*     $NetBSD: sa11x0_ost.c,v 1.3 2001/03/09 18:55:29 toshii Exp $    */
 
 /*
  * Copyright (c) 1997 Mark Brinicombe.
@@ -73,7 +73,7 @@
 
 static struct saost_softc *saost_sc = NULL;
 
-#define TIMER_FREQUENCY         3686400         /* 3.6468MHz */
+#define TIMER_FREQUENCY         3686400         /* 3.6864MHz */
 #define TICKS_PER_MICROSECOND   (TIMER_FREQUENCY/1000000)
 
 
@@ -235,13 +235,17 @@
 delay(usecs)
        u_int usecs;
 {
-       int limit, tick, otick;
+       u_int32_t tick, otick, delta;
+       int j, csec, usec;
 
-       usecs *= TICKS_PER_MICROSECOND;
+       csec = usecs / 10000;
+       usec = usecs % 10000;
+       
+       usecs = (TIMER_FREQUENCY / 100) * csec
+           + (TIMER_FREQUENCY / 100) * usec / 10000;
 
        if (! saost_sc) {
                /* clock isn't initialized yet */
-               int j;
                for(; usecs > 0; usecs--)
                        for(j = 100; j > 0; j--)
                                ;
@@ -249,14 +253,15 @@
        }
 
        otick = gettick();
-       limit = 0xffffffff;
 
-       while (usecs > 0) {
+       while (1) {
+               for(j = 100; j > 0; j--)
+                       ;
                tick = gettick();
-               if (tick < otick)
-                       usecs -= limit - (otick - tick);
-               else
-                       usecs -= tick - otick;
+               delta = tick - otick;
+               if (delta > usecs)
+                       break;
+               usecs -= delta;
                otick = tick;
        }
 }