From 009efda1e9489a8fbcb939a697474885db674e46 Mon Sep 17 00:00:00 2001
From: Miod Vallat <miod@cvs.openbsd.org>
Date: Fri, 23 Dec 2005 18:50:24 +0000
Subject: m68k support code for librthread; atomic lock routine borrowed from
 the existing libpthread code.

---
 lib/librthread/arch/m68k/_atomic_lock.c | 36 +++++++++++++++++
 lib/librthread/arch/m68k/rfork_thread.S | 70 +++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 lib/librthread/arch/m68k/_atomic_lock.c
 create mode 100644 lib/librthread/arch/m68k/rfork_thread.S

diff --git a/lib/librthread/arch/m68k/_atomic_lock.c b/lib/librthread/arch/m68k/_atomic_lock.c
new file mode 100644
index 00000000000..30f079c6204
--- /dev/null
+++ b/lib/librthread/arch/m68k/_atomic_lock.c
@@ -0,0 +1,36 @@
+/*	$OpenBSD: _atomic_lock.c,v 1.1 2005/12/23 18:50:23 miod Exp $	*/
+/*
+ * Atomic lock for m68k
+ */
+
+#include "spinlock.h"
+
+int
+_atomic_lock(volatile _spinlock_lock_t *lock)
+{
+	_spinlock_lock_t old;
+
+	/*
+	 * The Compare And Swap instruction (mc68020 and above)
+	 * compares its first operand with the memory addressed by
+	 * the third. If they are the same value, the second operand
+	 * is stored at the address. Otherwise the 1st operand (register)
+	 * is loaded with the contents of the 3rd operand.
+	 *
+	 *      old = 0;
+	 *	CAS(old, 1, *lock);
+	 *	if (old == 1) { lock was acquired }
+	 *
+	 * From the MC68030 User's Manual (Motorola), page `3-13':
+	 *    CAS Dc,Du,<ea>:
+	 *	(<ea> - Dc) -> cc;
+	 *	if Z then Du -> <ea>
+	 *	else      <ea> -> Dc;
+	 */
+	old = _SPINLOCK_UNLOCKED;
+	__asm__("casl %0, %2, %1" : "=d" (old), "=m" (*lock)
+				  : "d" (_SPINLOCK_LOCKED),
+				    "0" (old),  "1" (*lock)
+				  : "cc");
+	return (old != _SPINLOCK_UNLOCKED);
+}
diff --git a/lib/librthread/arch/m68k/rfork_thread.S b/lib/librthread/arch/m68k/rfork_thread.S
new file mode 100644
index 00000000000..e9b37eb2f8f
--- /dev/null
+++ b/lib/librthread/arch/m68k/rfork_thread.S
@@ -0,0 +1,70 @@
+/*	$OpenBSD: rfork_thread.S,v 1.1 2005/12/23 18:50:23 miod Exp $	*/
+
+/*
+ * Copyright (c) 2005, Miodrag Vallat
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "../../../libc/arch/m68k/SYS.h"
+
+/*
+ * int rfork_thread(int flags, void *stack, void (*func)(void *), void *arg);
+ */
+ENTRY(rfork_thread)
+	/*
+	 * Set up the new thread's stack.
+	 */
+	movl	sp@(8), a0	/* stack */
+	movl	sp@(16), a0@-	/* arg */
+	movl	sp@(12), a1	/* func */
+
+	/*
+	 * We did not create a frame, so the stack is ready for an immediate
+	 * system call invocation.
+	 */
+	__DO_SYSCALL(rfork)
+	jcs	9f
+
+	tstl	d0
+	jeq	1f
+
+	/*
+	 * parent process: just return.
+	 */
+	rts
+
+1:
+	/*
+	 * child process: switch stacks, invoke function, then exit.
+	 */
+	movl	a0, sp		/* stack with arg pushed on it */
+	jsr	a1@		/* func */
+	addq	#4, sp
+
+	__DO_SYSCALL(threxit)
+
+9:
+	/*
+	 * system call failure.
+	 */
+	jra	__cerror
-- 
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