From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001
From: Erlang/OTP <otp@erlang.org>
Date: Fri, 20 Nov 2009 14:54:40 +0000
Subject: The R13B03 release.

---
 erts/include/internal/ppc32/spinlock.h | 93 ++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 erts/include/internal/ppc32/spinlock.h

(limited to 'erts/include/internal/ppc32/spinlock.h')

diff --git a/erts/include/internal/ppc32/spinlock.h b/erts/include/internal/ppc32/spinlock.h
new file mode 100644
index 0000000000..034c20c143
--- /dev/null
+++ b/erts/include/internal/ppc32/spinlock.h
@@ -0,0 +1,93 @@
+/*
+ * %CopyrightBegin%
+ * 
+ * Copyright Ericsson AB 2005-2009. All Rights Reserved.
+ * 
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ * 
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ * 
+ * %CopyrightEnd%
+ */
+
+/*
+ * Native ethread spinlocks on PowerPC.
+ * Author: Mikael Pettersson.
+ *
+ * Based on the examples in Appendix E of Motorola's
+ * "Programming Environments Manual For 32-Bit Implementations
+ * of the PowerPC Architecture". Uses eieio instead of sync
+ * in the unlock sequence, as suggested in the manual.
+ */
+#ifndef ETHREAD_PPC_SPINLOCK_H
+#define ETHREAD_PPC_SPINLOCK_H
+
+/* Unlocked if zero, locked if non-zero. */
+typedef struct {
+    volatile unsigned int lock;
+} ethr_native_spinlock_t;
+
+#ifdef ETHR_TRY_INLINE_FUNCS
+
+static ETHR_INLINE void
+ethr_native_spinlock_init(ethr_native_spinlock_t *lock)
+{
+    lock->lock = 0;
+}
+
+static ETHR_INLINE void
+ethr_native_spin_unlock(ethr_native_spinlock_t *lock)
+{
+    __asm__ __volatile__("eieio" : : : "memory");
+    lock->lock = 0;
+}
+
+static ETHR_INLINE int
+ethr_native_spin_trylock(ethr_native_spinlock_t *lock)
+{
+    unsigned int prev;
+
+    __asm__ __volatile__(
+	"1:\t"
+	"lwarx	%0,0,%1\n\t"	/* read lock to prev */
+	"cmpwi	0,%0,0\n\t"
+	"bne-	2f\n\t"		/* bail if non-zero/locked */
+	"stwcx.	%2,0,%1\n\t"	/* try to make the lock non-zero */
+	"bne-	1b\n\t"		/* loop if lost reservation */
+	"isync\n\t"		/* wait for previous insns to complete */
+	"2:"
+	: "=&r"(prev)
+	: "r"(&lock->lock), "r"(1)
+	: "cr0", "memory");
+    return prev == 0;
+}
+
+static ETHR_INLINE int
+ethr_native_spin_is_locked(ethr_native_spinlock_t *lock)
+{
+
+    return lock->lock != 0;
+}
+
+static ETHR_INLINE void
+ethr_native_spin_lock(ethr_native_spinlock_t *lock)
+{
+    for(;;) {
+	if (__builtin_expect(ethr_native_spin_trylock(lock) != 0, 1))
+	    break;
+	do {
+	    __asm__ __volatile__("":::"memory");
+	} while (ethr_native_spin_is_locked(lock));
+    }
+}
+
+#endif /* ETHR_TRY_INLINE_FUNCS */
+
+#endif /* ETHREAD_PPC_SPINLOCK_H */
-- 
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