X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/0b4e3aa066abc0728aacb4bbeb86f53f9737156e..cc9f6e38162d3c1bf6ca97536c2477f476c8e01b:/libkern/gen/OSAtomicOperations.c

diff --git a/libkern/gen/OSAtomicOperations.c b/libkern/gen/OSAtomicOperations.c
index c6e86aaca..4a1e7beb0 100644
--- a/libkern/gen/OSAtomicOperations.c
+++ b/libkern/gen/OSAtomicOperations.c
@@ -39,6 +39,11 @@ 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__
@@ -66,6 +71,37 @@ 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)
@@ -145,37 +181,6 @@ 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
  */