From b7b527edfa9ec0f0672379f7ee8bc8475b73967f Mon Sep 17 00:00:00 2001
From: Marcel Moolenaar <marcel@FreeBSD.org>
Date: Sat, 4 Jun 2005 21:50:44 +0000
Subject: [PATCH] Fix delay(). The processor cycle counter is a 32-bit wrapping
 counter. Hence, mask off the upper 32 bits and deal with wrap-arounds.

MFC after: 1 week
---
 sys/boot/alpha/libalpha/delay.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/sys/boot/alpha/libalpha/delay.c b/sys/boot/alpha/libalpha/delay.c
index 6e437a7f0ba9..5a81c78531d5 100644
--- a/sys/boot/alpha/libalpha/delay.c
+++ b/sys/boot/alpha/libalpha/delay.c
@@ -33,9 +33,12 @@ __FBSDID("$FreeBSD$");
 void
 delay(int usecs)
 {
-    struct rpb *hwrpb = (struct rpb *)HWRPB_ADDR;
-    unsigned long start = alpha_rpcc();
-    unsigned long end = start + (hwrpb->rpb_cc_freq * usecs) / 1000000;
-    while (alpha_rpcc() < end)
-	;
+	struct rpb *hwrpb = (struct rpb *)HWRPB_ADDR;
+	unsigned long end, now, start;
+
+	start = alpha_rpcc() & 0xfffffffful;
+	end = start + (hwrpb->rpb_cc_freq * usecs) / 1000000;
+	do {
+		now = alpha_rpcc() & 0xfffffffful;
+	} while (now < end || (now > start && end < start));
 }