From 09f8891e170e591bc89718cff635510d1ce839f4 Mon Sep 17 00:00:00 2001
From: frief <frief@4a8a32a2-be11-0410-ad9d-d568d2c75423>
Date: Sat, 13 Dec 2003 13:16:08 +0000
Subject: [PATCH] using the atomic test and clear instruction jbc. Allows
 non-interrupt and interrupt code to safely compete for a resource without the
 non-interrupt code having to disable interrupts.

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@3051 4a8a32a2-be11-0410-ad9d-d568d2c75423
---
 src/ds390/peeph.def | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/src/ds390/peeph.def b/src/ds390/peeph.def
index 7ffbf710..38d81982 100644
--- a/src/ds390/peeph.def
+++ b/src/ds390/peeph.def
@@ -2707,3 +2707,35 @@ replace {
 } by {
         ;       Peephole 243b    jump optimization
 } if labelRefCount %1 1
+
+
+// This allows non-interrupt and interrupt code to safely compete
+// for a resource without the non-interrupt code having to disable
+// interrupts:
+// volatile bit resource_is_free;
+// if( resource_is_free ) {
+//     resource_is_free=0; do_something; resource_is_free=1;
+// }
+replace {
+        jnb     %1,%2
+%3:
+        clr     %1
+} by {
+        ;       Peephole 244.a  using atomic test and clear
+        jbc     %1,%3
+        sjmp    %2
+%3:
+} if labelRefCount %3 0
+
+replace {
+        jb      %1,%2
+        ljmp    %3
+%2:
+        clr     %1
+} by {
+        ;       Peephole 244.b  using atomic test and clear
+        jbc     %1,%2
+        ljmp    %3
+%2:
+} if labelRefCount %2 1
+
-- 
2.30.2