From 7afb3ea904f9cb3d787526f0b73fa13b76e5f9f6 Mon Sep 17 00:00:00 2001
From: ReactOS Portable Systems Group <ros-arm-bringup@svn.reactos.org>
Date: Sun, 21 Jun 2009 04:28:31 +0000
Subject: [PATCH] - Add another helper: MiGetPfnEntryIndex. This returns the
 page frame number (PFN) for a given MMPFN entry. - Also add MiPteToAddress to
 complement MiAddressToPte. This returns the VA for a given PTE. Bonus points
 if you can figure out the bit magic.

svn path=/trunk/; revision=41507
---
 reactos/ntoskrnl/include/internal/i386/mm.h |  5 +++++
 reactos/ntoskrnl/include/internal/mm.h      | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/reactos/ntoskrnl/include/internal/i386/mm.h b/reactos/ntoskrnl/include/internal/i386/mm.h
index 67a4ddff817..2846b6993d5 100644
--- a/reactos/ntoskrnl/include/internal/i386/mm.h
+++ b/reactos/ntoskrnl/include/internal/i386/mm.h
@@ -23,6 +23,11 @@ PULONG MmGetPageDirectory(VOID);
 #define MiAddressToPteOffset(x) \
     ((((ULONG)(x)) << 10) >> 22)
 
+//
+// Convert a PTE into a corresponding address
+//
+#define MiPteToAddress(PTE) ((PVOID)((ULONG)(PTE) << 10))
+
 #define ADDR_TO_PAGE_TABLE(v) (((ULONG)(v)) / (1024 * PAGE_SIZE))
 #define ADDR_TO_PDE_OFFSET(v) ((((ULONG)(v)) / (1024 * PAGE_SIZE)))
 #define ADDR_TO_PTE_OFFSET(v)  ((((ULONG)(v)) % (1024 * PAGE_SIZE)) / PAGE_SIZE)
diff --git a/reactos/ntoskrnl/include/internal/mm.h b/reactos/ntoskrnl/include/internal/mm.h
index c74624c76ea..ac776199304 100644
--- a/reactos/ntoskrnl/include/internal/mm.h
+++ b/reactos/ntoskrnl/include/internal/mm.h
@@ -1050,6 +1050,16 @@ MiGetPfnEntry(IN PFN_TYPE Pfn)
     return Page;
 };
 
+FORCEINLINE
+PFN_NUMBER
+MiGetPfnEntryIndex(IN PMMPFN Pfn1)
+{
+    //
+    // This will return the Page Frame Number (PFN) from the MMPFN
+    //
+    return Pfn1 - MmPfnDatabase;
+}
+
 PFN_TYPE
 NTAPI
 MmGetLRUNextUserPage(PFN_TYPE PreviousPage);