From 2969a8567ffd1e0fd1096199ec32b78beaf779fc Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@ipxe.org>
Date: Mon, 7 Mar 2011 17:40:12 +0000
Subject: [PATCH] [console] Avoid timer wraparound problems in
 getchar_timeout()

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/core/getkey.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/core/getkey.c b/src/core/getkey.c
index d93ba1e6..5710f190 100644
--- a/src/core/getkey.c
+++ b/src/core/getkey.c
@@ -39,9 +39,9 @@ FILE_LICENCE ( GPL2_OR_LATER );
  * @ret character	Character read from console
  */
 int getchar_timeout ( unsigned long timeout ) {
-	unsigned long expiry = ( currticks() + timeout );
+	unsigned long start = currticks();
 
-	while ( currticks() < expiry ) {
+	while ( ( currticks() - start ) < timeout ) {
 		step();
 		if ( iskey() )
 			return getchar();