xnu-792.2.4.tar.gz

[apple/xnu.git] / iokit / Kernel / IOMemoryCursor.cpp

diff --git a/iokit/Kernel/IOMemoryCursor.cpp b/iokit/Kernel/IOMemoryCursor.cpp
index 2125a5f675422f1c3036e4e6f08b70223a752427..ccc9539571a2d2369e34fcbcfe374d52d341892e 100644 (file)
--- a/iokit/Kernel/IOMemoryCursor.cpp
+++ b/iokit/Kernel/IOMemoryCursor.cpp
@@ -3,22 +3,19 @@
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
- * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
+ * The contents of this file constitute Original Code as defined in and
+ * are subject to the Apple Public Source License Version 1.1 (the
+ * "License").  You may not use this file except in compliance with the
+ * License.  Please obtain a copy of the License at
+ * http://www.apple.com/publicsource and read it before using this file.
  * 
- * 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
+ * This 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.
+ * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
  * 
  * @APPLE_LICENSE_HEADER_END@
  */
@@ -119,22 +116,66 @@ IOMemoryCursor::genPhysicalSegments(IOMemoryDescriptor *inDescriptor,
      * If we finished cleanly return number of segments found
      * and update the position in the descriptor.
      */
+    PhysicalSegment curSeg = { 0, 0 };
     UInt curSegIndex = 0;
     UInt curTransferSize = 0;
-    PhysicalSegment seg;
+    IOByteCount inDescriptorLength = inDescriptor->getLength();
+    PhysicalSegment seg = { 0, 0 };
 
-    while ((curSegIndex < inMaxSegments)
-    &&  (curTransferSize < inMaxTransferSize)
-    &&  (seg.location = inDescriptor->getPhysicalSegment(
-                            fromPosition + curTransferSize, &seg.length)))
+    while ((seg.location) || (fromPosition < inDescriptorLength)) 
     {
-        assert(seg.length);
-        seg.length = min(inMaxTransferSize-curTransferSize,
-                         (min(seg.length, maxSegmentSize)));
-        (*outSeg)(seg, inSegments, curSegIndex++);
-        curTransferSize += seg.length;
+        if (!seg.location)
+        {
+            seg.location = inDescriptor->getPhysicalSegment(
+                               fromPosition, &seg.length);
+            assert(seg.location);
+            assert(seg.length);
+            fromPosition += seg.length;
+        }
+
+        if (!curSeg.location)
+        {
+            curTransferSize += seg.length;
+            curSeg = seg;
+            seg.location = 0;
+        }
+        else if ((curSeg.location + curSeg.length == seg.location))
+        {
+            curTransferSize += seg.length;
+            curSeg.length += seg.length;
+            seg.location = 0;
+        }
+
+        if (!seg.location)
+        {
+            if ((curSeg.length > maxSegmentSize))
+            {
+                seg.location = curSeg.location + maxSegmentSize;
+                seg.length = curSeg.length - maxSegmentSize;
+                curTransferSize -= seg.length;
+                curSeg.length -= seg.length;
+            }
+
+            if ((curTransferSize >= inMaxTransferSize))
+            {
+                curSeg.length -= curTransferSize - inMaxTransferSize;
+                curTransferSize = inMaxTransferSize;
+                break;
+            }
+        }
+
+        if (seg.location)
+        {
+            if ((curSegIndex + 1 == inMaxSegments))
+                break;
+            (*outSeg)(curSeg, inSegments, curSegIndex++);
+            curSeg.location = 0;
+        }
     }
 
+    if (curSeg.location)
+        (*outSeg)(curSeg, inSegments, curSegIndex++);
+
     if (outTransferSize)
         *outTransferSize = curTransferSize;