From 86b0ea6447c40be506cd71c2fdeb98255f08b23d Mon Sep 17 00:00:00 2001
From: Dean Prichard <dean.prichard@gmail.com>
Date: Thu, 18 Feb 2010 15:37:16 -0800
Subject: [PATCH] sync: allow to work on armv5

asm_arm.s was using ldrex which does not work
on armv5. Tested on Sheevaplug.

R=rsc, kaib
CC=golang-dev
https://golang.org/cl/214049
---
 src/pkg/sync/Makefile                  | 16 ++++++++++-
 src/pkg/sync/asm_arm5.s                | 40 ++++++++++++++++++++++++++
 src/pkg/sync/{asm_arm.s => asm_arm6.s} |  0
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 src/pkg/sync/asm_arm5.s
 rename src/pkg/sync/{asm_arm.s => asm_arm6.s} (100%)

diff --git a/src/pkg/sync/Makefile b/src/pkg/sync/Makefile
index 25d11d03db..4b9a05816d 100644
--- a/src/pkg/sync/Makefile
+++ b/src/pkg/sync/Makefile
@@ -9,7 +9,21 @@ GOFILES=\
 	mutex.go\
 	rwmutex.go\
 
+# 386-specific object files
+OFILES_386=\
+	asm_386.$O\
+
+# amd64-specific object files
+OFILES_amd64=\
+	asm_amd64.$O\
+
+GOARM?=6
+
+# arm-specific object files
+OFILES_arm=\
+	asm_arm$(GOARM).$O\
+
 OFILES=\
-	asm_$(GOARCH).$O\
+	$(OFILES_$(GOARCH))\
 
 include ../../Make.pkg
diff --git a/src/pkg/sync/asm_arm5.s b/src/pkg/sync/asm_arm5.s
new file mode 100644
index 0000000000..3cdca0b870
--- /dev/null
+++ b/src/pkg/sync/asm_arm5.s
@@ -0,0 +1,40 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This version works on pre v6 architectures
+// func cas(val *int32, old, new int32) bool
+// Atomically:
+//	if *val == old {
+//		*val = new;
+//		return true;
+//	}else
+//		return false;
+
+TEXT    ·cas(SB),7,$0
+	MOVW	0(FP), R0	// *val
+	MOVW	4(FP), R1	// old
+	MOVW	8(FP), R2	// new
+	MOVW	$1, R3
+	MOVW	$cas_mutex(SB), R4
+l:
+	SWPW	(R4), R3	// acquire mutex
+	CMP		$0, R3
+	BNE		fail0
+	
+	MOVW	(R0), R5
+	CMP		R1, R5
+	BNE		fail1
+	
+	MOVW	R2, (R0)	
+	MOVW	R3, (R4)	// release mutex
+	MOVW	$1, R0
+	MOVW	R0, 16(SP)	
+	RET
+fail1:	
+	MOVW	R3, (R4)	// release mutex
+fail0:
+	MOVW	$0, R0
+	MOVW	R0, 16(SP)	
+	RET
+ 
diff --git a/src/pkg/sync/asm_arm.s b/src/pkg/sync/asm_arm6.s
similarity index 100%
rename from src/pkg/sync/asm_arm.s
rename to src/pkg/sync/asm_arm6.s
-- 
2.50.0