Security-55163.44.tar.gz

[apple/security.git] / libsecurity_utilities / lib / memutils.h

diff --git a/libsecurity_utilities/lib/memutils.h b/libsecurity_utilities/lib/memutils.h
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+/*
+ * Copyright (c) 2000-2004 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@
+ */
+
+
+//
+// memutils - memory-related low-level utilities for easier living
+//
+#ifndef _H_MEMUTILS
+#define _H_MEMUTILS
+
+#include <security_utilities/utilities.h>
+#include <sys/types.h>
+#include <stdlib.h>
+#include <algorithm>
+
+
+//
+// Encapsulate these very sharp tools in a separate (ugly-named) namespace
+//
+namespace Security {
+namespace LowLevelMemoryUtilities {
+
+
+//
+// The default system alignment.
+//
+static const size_t systemAlignment = 4;
+
+
+//
+// Get the local alignment for a type, as used by the acting compiler.
+//
+template <class T>
+inline size_t alignof() { struct { char c; T t; } s; return sizeof(s) - sizeof(T); }
+
+
+//
+// Get the local offset of a field in a (struct or class) type, as layed out
+// by the acting compiler.
+// NB: "offsetof" is a standard-defined macro. Don't use that.
+//
+template <class Type, class Field>
+inline size_t fieldOffsetOf(Field (Type::*field))
+{
+       Type *object = 0;       // we don't REALLY need this, but it's easier to read
+       return uintptr_t(&(object->*field)) - uintptr_t(object);
+}
+
+
+//
+// Round up a size or pointer to an alignment boundary.
+// Alignment must be a power of two; default is default alignment.
+//
+inline size_t alignUp(size_t size, size_t alignment = systemAlignment)
+{
+       return ((size - 1) & ~(alignment - 1)) + alignment;
+}
+
+inline void *alignUp(void *p, size_t alignment = systemAlignment)
+{
+       return reinterpret_cast<void *>(alignUp(uintptr_t(p), alignment));
+}
+
+inline const void *alignUp(const void *p, size_t alignment = systemAlignment)
+{
+       return reinterpret_cast<const void *>(alignUp(uintptr_t(p), alignment));
+}
+
+template <class T>
+inline const T *increment(const void *p, ptrdiff_t offset)
+{ return reinterpret_cast<const T *>(uintptr_t(p) + offset); }
+
+template <class T>
+inline T *increment(void *p, ptrdiff_t offset)
+{ return reinterpret_cast<T *>(uintptr_t(p) + offset); }
+
+inline const void *increment(const void *p, ptrdiff_t offset)
+{ return increment<const void>(p, offset); }
+
+inline void *increment(void *p, ptrdiff_t offset)
+{ return increment<void>(p, offset); }
+
+template <class T>
+inline const T *increment(const void *p, ptrdiff_t offset, size_t alignment)
+{ return increment<const T>(alignUp(p, alignment), offset); }
+
+template <class T>
+inline T *increment(void *p, ptrdiff_t offset, size_t alignment)
+{ return increment<T>(alignUp(p, alignment), offset); }
+
+inline const void *increment(const void *p, ptrdiff_t offset, size_t alignment)
+{ return increment<const void>(p, offset, alignment); }
+
+inline void *increment(void *p, ptrdiff_t offset, size_t alignment)
+{ return increment<void>(p, offset, alignment); }
+
+inline ptrdiff_t difference(const void *p1, const void *p2)
+{ return uintptr_t(p1) - uintptr_t(p2); }
+
+
+} // end namespace LowLevelMemoryUtilities
+} // end namespace Security
+
+#endif //_H_MEMUTILS