[tthompson] 75425: [NTFS] - Add GetAllocationOffsetFromVCN() function, which was mistakenly left out of the last commit.

Author: tthompson
Date: Thu Jul 27 18:34:23 2017
New Revision: 75425

URL: http://svn.reactos.org/svn/reactos?rev=75425&view=rev
Log:
[NTFS] - Add GetAllocationOffsetFromVCN() function, which was mistakenly left out of the
last commit.

Modified:
    branches/GSoC_2016/NTFS/drivers/filesystems/ntfs/btree.c

Modified: branches/GSoC_2016/NTFS/drivers/filesystems/ntfs/btree.c
URL:
http://svn.reactos.org/svn/reactos/branches/GSoC_2016/NTFS/drivers/filesyst…
==============================================================================
--- branches/GSoC_2016/NTFS/drivers/filesystems/ntfs/btree.c	[iso-8859-1] (original)
+++ branches/GSoC_2016/NTFS/drivers/filesystems/ntfs/btree.c	[iso-8859-1] Thu Jul 27
18:34:23 2017
@@ -511,6 +511,18 @@
     DumpBTreeNode(Tree->RootNode, 0, 0);
 }
 
+// Calculates start of Index Buffer relative to the index allocation, given the
node's VCN
+ULONGLONG
+GetAllocationOffsetFromVCN(PDEVICE_EXTENSION DeviceExt,
+                           ULONG IndexBufferSize,
+                           ULONGLONG Vcn)
+{
+    if (IndexBufferSize < DeviceExt->NtfsInfo.BytesPerCluster)
+        return Vcn * DeviceExt->NtfsInfo.BytesPerSector;
+
+    return Vcn * DeviceExt->NtfsInfo.BytesPerCluster;
+}
+
 /**
 * @name NtfsInsertKey
 * @implemented