xnu-792.12.6.tar.gz

[apple/xnu.git] / libkern / gen / OSAtomicOperations.c

diff --git a/libkern/gen/OSAtomicOperations.c b/libkern/gen/OSAtomicOperations.c
index 222db2a333e870bb4a259b867978684131c7ace9..1eedf229133d1a28040ea20b142ee2cab18c4d8b 100644 (file)
--- a/libkern/gen/OSAtomicOperations.c
+++ b/libkern/gen/OSAtomicOperations.c
@@ -1,26 +1,31 @@
 /*
  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
  *
- * @APPLE_LICENSE_HEADER_START@
+ * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
  * 
- * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
- * 
- * 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
+ * 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.  The rights granted to you under the 
+ * License may not be used to create, or enable the creation or 
+ * redistribution of, unlawful or unlicensed copies of an Apple operating 
+ * system, or to circumvent, violate, or enable the circumvention or 
+ * violation of, any terms of an Apple operating system software license 
+ * agreement.
+ *
+ * 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
+ *
+ * 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@
+ *
+ * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  */
 
 #include <libkern/OSAtomic.h>
@@ -42,6 +47,11 @@ enum {
  *     which I wrote for NuKernel in a previous life with a different last name...)
  *
  * native Boolean      CompareAndSwap(UInt32 oldValue, UInt32 newValue, UInt32 * oldValuePtr);
+ *
+ * We've since implemented a few more of these -- OSAddAtomic, OSDequeueAtomic,
+ * OSEnqueueAtomic etc -- in assembler, either for speed or correctness.  See also the
+ * commpage atomic operations, and the platform specific versions.
+ * Like standards, there are a lot of atomic ops to choose from!
  */
 
 #ifndef __ppc__
@@ -69,6 +79,37 @@ SInt32       OSDecrementAtomic(SInt32 * value)
        return OSAddAtomic(-1, value);
 }
 
+void * OSDequeueAtomic(void ** inList, SInt32 inOffset)
+{
+       void *  oldListHead;
+       void *  newListHead;
+       
+       do {
+               oldListHead = *inList;
+               if (oldListHead == NULL) {
+                       break;
+               }
+               
+               newListHead = *(void **) (((char *) oldListHead) + inOffset);
+       } while (! OSCompareAndSwap((UInt32)oldListHead,
+                                       (UInt32)newListHead, (UInt32 *)inList));
+       
+       return oldListHead;
+}
+
+void   OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
+{
+       void *  oldListHead;
+       void *  newListHead = inNewLink;
+       void ** newLinkNextPtr = (void **) (((char *) inNewLink) + inOffset);
+       
+       do {
+               oldListHead = *inList;
+               *newLinkNextPtr = oldListHead;
+       } while (! OSCompareAndSwap((UInt32)oldListHead, (UInt32)newListHead,
+                                       (UInt32 *)inList));
+}
+
 #endif /* !__ppc__ */
 
 static UInt32  OSBitwiseAtomic(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt32 * value)
@@ -148,37 +189,6 @@ Boolean    OSTestAndClear(UInt32 bit, UInt8 * startAddress)
        return OSTestAndSetClear(bit, false, startAddress);
 }
 
-void * OSDequeueAtomic(void ** inList, SInt32 inOffset)
-{
-       void *  oldListHead;
-       void *  newListHead;
-       
-       do {
-               oldListHead = *inList;
-               if (oldListHead == NULL) {
-                       break;
-               }
-               
-               newListHead = *(void **) (((char *) oldListHead) + inOffset);
-       } while (! OSCompareAndSwap((UInt32)oldListHead,
-                                       (UInt32)newListHead, (UInt32 *)inList));
-       
-       return oldListHead;
-}
-
-void   OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
-{
-       void *  oldListHead;
-       void *  newListHead = inNewLink;
-       void ** newLinkNextPtr = (void **) (((char *) inNewLink) + inOffset);
-       
-       do {
-               oldListHead = *inList;
-               *newLinkNextPtr = oldListHead;
-       } while (! OSCompareAndSwap((UInt32)oldListHead, (UInt32)newListHead,
-                                       (UInt32 *)inList));
-}
-
 /*
  * silly unaligned versions
  */