X-Git-Url: https://git.saurik.com/apple/security.git/blobdiff_plain/72a12576750f52947eb043106ba5c12c0d07decf..b1ab9ed8d0e0f1c3b66d7daa8fd5564444c56195:/libsecurity_utilities/lib/threading_internal.h

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+/*
+ * Copyright (c) 2000-2001,2003-2004 Apple Computer, Inc. All Rights Reserved.
+ * 
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+//
+// threading_internal - internal support classes and functions for threading implementation
+//
+#ifndef _H_THREADING_INTERNAL
+#define _H_THREADING_INTERNAL
+
+#include <security_utilities/utilities.h>
+#include <libkern/OSAtomic.h>
+
+
+namespace Security {
+
+
+//
+// Do we have 64-bit atomic operations?
+//
+#define _HAVE_64BIT_ATOMIC (defined(__ppc64__) || defined(__i386__) || defined(__x86_64__))
+
+
+//
+// The AtomicTypes class is an implementation detail.
+// Do not use it.
+//
+template <unsigned wordsize>
+struct AtomicTypes {
+	// unsupported word size (this will cause compilation errors if used)
+};
+
+template <>
+struct AtomicTypes<32> {
+	typedef int32_t Integer;
+	
+	static Integer add(int delta, Integer &base)
+	{ return OSAtomicAdd32(delta, &base); }
+	static Integer addb(int delta, Integer &base) { return OSAtomicAdd32Barrier(delta, &base); }
+	
+	static bool cas(Integer oldValue, Integer newValue, Integer &base)
+	{ return OSAtomicCompareAndSwap32(oldValue, newValue, &base); }
+	static bool casb(Integer oldValue, Integer newValue, Integer &base)
+	{ return OSAtomicCompareAndSwap32Barrier(oldValue, newValue, &base); }
+};
+
+#if _HAVE_64BIT_ATOMIC
+
+template <>
+struct AtomicTypes<64> {
+	typedef int64_t Integer;
+	
+	static Integer add(int delta, Integer &base) { return OSAtomicAdd64(delta, &base); }
+	static Integer addb(int delta, Integer &base) { return OSAtomicAdd64Barrier(delta, &base); }
+	
+	static bool cas(Integer oldValue, Integer newValue, Integer &base)
+	{ return OSAtomicCompareAndSwap64(oldValue, newValue, &base); }
+	static bool casb(Integer oldValue, Integer newValue, Integer &base)
+	{ return OSAtomicCompareAndSwap64Barrier(oldValue, newValue, &base); }
+};
+
+#endif //_HAVE_64BIT_ATOMIC
+
+
+//
+// Atomic<Type> is a set of (static) operations that can atomically access memory.
+// This is not a wrapper object. Think of it as a generator class that produces
+// the proper atomic memory operations for arbitrary data types.
+// If the underlying system does not support atomicity for a particular type
+// (e.g. 64 bits on ppc, or 16 bits anywhere), you will get compilation errors.
+//
+template <class Type>
+class Atomic {
+	typedef AtomicTypes<sizeof(Type) * 8> _Ops;
+	typedef typename _Ops::Integer _Type;
+
+public:
+	static Type add(int delta, Type &store)
+	{ return Type(_Ops::add(delta, (_Type &)store)); }
+	static Type addb(int delta, Type &store)
+	{ return Type(_Ops::addb(delta, (_Type &)store)); }
+	
+	static bool cas(Type oldValue, Type newValue, Type &store)
+	{ return _Ops::cas(_Type(oldValue), _Type(newValue), (_Type &)store); }
+	static bool casb(Type oldValue, Type newValue, Type &store)
+	{ return _Ops::casb(_Type(oldValue), _Type(newValue), (_Type &)store); }
+	
+	static void barrier() { OSMemoryBarrier(); }
+	static void readBarrier() { OSMemoryBarrier(); }
+	static void writeBarrier() { OSMemoryBarrier(); }
+	
+	// convenience additions (expressed in terms above)
+	
+	static Type increment(Type &store) { return add(1, store); }
+	static Type decrement(Type &store) { return add(-1, store); }
+	
+	static Type load(const Type &store) { readBarrier(); return store; }
+	static Type store(Type value, Type &store)
+	{ while (!casb(store, value, store)) /* again */; return value; }
+};
+
+
+} // end namespace Security
+
+#endif //_H_THREADING_INTERNAL