--- /dev/null
+++ xnu/xnu-201.19/iokit/Kernel/IOPMchangeNoteList.cpp
@@ -0,0 +1,219 @@
+/*
+ * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * 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 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 OR NON-INFRINGEMENT.  Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+#include <IOKit/pwr_mgt/IOPM.h>
+#include <IOKit/pwr_mgt/IOPMchangeNoteList.h>
+
+#define super OSObject
+OSDefineMetaClassAndStructors(IOPMchangeNoteList,OSObject)
+
+//*********************************************************************************
+// init
+//
+//*********************************************************************************
+void IOPMchangeNoteList::initialize ( void )
+{
+    long i;
+
+    firstInList = 0;
+    firstUnused = 0;
+    for ( i = 0; i < IOPMMaxChangeNotes; i++ ) {
+        changeNote[i].flags = IOPMNotInUse;
+    }
+}
+
+//*********************************************************************************
+// createChangeNote
+//
+//*********************************************************************************
+
+long IOPMchangeNoteList::createChangeNote ( void )
+{
+    unsigned long i, j;
+
+    i = increment(firstUnused);
+    if ( firstInList == i ) {
+        return -1;
+    }
+    j = firstUnused;
+    firstUnused = i;
+
+    return j;
+}
+
+//*********************************************************************************
+// currentChange
+//
+// Return the ordinal of the first change note in the list.
+// If the list is empty, return -1.
+//*********************************************************************************
+
+long IOPMchangeNoteList::currentChange ( void )
+{
+    if ( firstUnused == firstInList ) {
+        return -1;
+    }
+    else {
+        return firstInList;
+    }
+}
+
+//*********************************************************************************
+// latestChange
+//
+// Return the ordinal of the last change note in the list.
+// If the list is empty, return -1.
+//*********************************************************************************
+
+long IOPMchangeNoteList::latestChange ( void )
+{
+    if ( firstUnused == firstInList ) {
+        return -1;
+    }
+    else {
+        return decrement(firstUnused);
+    }
+}
+
+//*********************************************************************************
+// releaseHeadChangeNote
+//
+// Mark the head node unused.
+// This happens when the first change in the list is completely processed.
+// That is, all interested parties have acknowledged it, and power is settled
+// at the new level.
+//*********************************************************************************
+
+IOReturn IOPMchangeNoteList::releaseHeadChangeNote ( void )
+{
+    changeNote[firstInList].flags = IOPMNotInUse;
+    firstInList = increment(firstInList);
+    return IOPMNoErr;
+}
+
+//*********************************************************************************
+// releaseTailChangeNote
+//
+// Mark the tail node unused.
+// This happens when a power change is queued up after another which has
+// not yet been started, and the second one supercedes the first.  The data in
+// the second is copied into the first and the the second is released.  This
+// collapses the first change out of the list.
+//*********************************************************************************
+
+IOReturn IOPMchangeNoteList::releaseTailChangeNote ( void )
+{
+    firstUnused = decrement(firstUnused);
+    changeNote[firstUnused].flags = IOPMNotInUse;
+    return IOPMNoErr;
+}
+
+//*********************************************************************************
+// changeNoteInUse
+//
+//*********************************************************************************
+
+bool IOPMchangeNoteList::changeNoteInUse ( unsigned long ordinal )
+{
+    if ( changeNote[ordinal].flags == IOPMNotInUse ) {
+        return false;
+    }
+    else {
+        return true;
+    }
+}
+
+//*********************************************************************************
+// nextChangeNote
+//
+// If the parameter corresponds to the most recent power change notification
+// passed to drivers and children, return -1.  Otherwise, return the array
+// position of the next notification in the circular list.
+//*********************************************************************************
+
+long IOPMchangeNoteList::nextChangeNote ( unsigned long ordinal )
+{
+    unsigned long i;
+
+    i = increment(ordinal);
+    if ( i == firstUnused)  {
+        return -1;
+    }
+    return ( i );
+}
+
+//*********************************************************************************
+// increment
+//
+// Increment the parameter mod the circular list size and return it.
+//*********************************************************************************
+
+unsigned long IOPMchangeNoteList::increment ( unsigned long ordinal )
+{
+    if ( ordinal == (IOPMMaxChangeNotes - 1) ) {
+        return 0;
+    }
+    else {
+        return ordinal + 1;
+    }
+}
+
+//*********************************************************************************
+// decrement
+//
+// Decrement the parameter mod the circular list size and return it.
+//*********************************************************************************
+
+unsigned long IOPMchangeNoteList::decrement ( unsigned long  ordinal )
+{
+    if ( ordinal == 0 ) {
+        return IOPMMaxChangeNotes - 1;
+    }
+    else {
+        return ordinal - 1;
+    }
+}
+
+//*********************************************************************************
+// previousChangeNote
+//
+// If the parameter corresponds to the oldest power change notification
+// passed to drivers and children, return -1.  Otherwise, return the array
+// position of the previous notification in the circular list.
+//*********************************************************************************
+
+long IOPMchangeNoteList::previousChangeNote ( unsigned long ordinal )
+{
+    if ( ordinal == firstInList )  {
+        return -1;
+    }
+    return decrement(ordinal);
+}
+
+//*********************************************************************************
+// listEmpty
+//
+//*********************************************************************************
+
+bool IOPMchangeNoteList::listEmpty ( void )
+{
+    return ( firstInList == firstUnused ) ;
+}