From 8e9d50c603a1a9c1c96445c79bd152f0f5462ff8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Herm=C3=A8s=20B=C3=A9lusca-Ma=C3=AFto?=
 <hermes.belusca-maito@reactos.org>
Date: Mon, 23 Dec 2013 18:09:18 +0000
Subject: [PATCH] [NTVDM] - Simplify EmulatorReadMemory (first MMIO-mapped
 devices copy their memory image back to the VM' memory area, then data is
 read via RtlCopyMemory), and EmulatorWriteMemory (simplify VgaBuffer
 computation and rename this variable accordingly, for readability purposes).
 - Fix Sim32pGetVDMPointer and MGetVdmPointer prototypes.

svn path=/branches/ntvdm/; revision=61356
---
 subsystems/ntvdm/emulator.c | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/subsystems/ntvdm/emulator.c b/subsystems/ntvdm/emulator.c
index 32b0af5fb69..71e2741310a 100644
--- a/subsystems/ntvdm/emulator.c
+++ b/subsystems/ntvdm/emulator.c
@@ -43,21 +43,24 @@ VOID WINAPI EmulatorReadMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer
     /* Make sure the requested address is valid */
     if ((Address + Size) >= MAX_ADDRESS) return;
 
-    /* Read the data from the virtual address space and store it in the buffer */
-    RtlCopyMemory(Buffer, (LPVOID)((ULONG_PTR)BaseAddress + Address), Size);
-
-    /* Check if we modified the console video memory */
+    /*
+     * Check if we are going to read the VGA memory and
+     * copy it into the virtual address space if needed.
+     */
     if (((Address + Size) >= VgaGetVideoBaseAddress())
         && (Address < VgaGetVideoLimitAddress()))
     {
         DWORD VgaAddress = max(Address, VgaGetVideoBaseAddress());
         DWORD ActualSize = min(Address + Size - 1, VgaGetVideoLimitAddress())
                            - VgaAddress + 1;
-        LPBYTE VgaBuffer = (LPBYTE)((ULONG_PTR)Buffer + VgaAddress - Address);
+        LPBYTE DestBuffer = (LPBYTE)((ULONG_PTR)BaseAddress + VgaAddress);
 
         /* Read from the VGA memory */
-        VgaReadMemory(VgaAddress, VgaBuffer, ActualSize);
+        VgaReadMemory(VgaAddress, DestBuffer, ActualSize);
     }
+
+    /* Read the data from the virtual address space and store it in the buffer */
+    RtlCopyMemory(Buffer, (LPVOID)((ULONG_PTR)BaseAddress + Address), Size);
 }
 
 VOID WINAPI EmulatorWriteMemory(PFAST486_STATE State, ULONG Address, PVOID Buffer, ULONG Size)
@@ -76,17 +79,19 @@ VOID WINAPI EmulatorWriteMemory(PFAST486_STATE State, ULONG Address, PVOID Buffe
     /* Read the data from the buffer and store it in the virtual address space */
     RtlCopyMemory((LPVOID)((ULONG_PTR)BaseAddress + Address), Buffer, Size);
 
-    /* Check if we modified the console video memory */
+    /*
+     * Check if we modified the VGA memory.
+     */
     if (((Address + Size) >= VgaGetVideoBaseAddress())
         && (Address < VgaGetVideoLimitAddress()))
     {
         DWORD VgaAddress = max(Address, VgaGetVideoBaseAddress());
         DWORD ActualSize = min(Address + Size - 1, VgaGetVideoLimitAddress())
                            - VgaAddress + 1;
-        LPBYTE VgaBuffer = (LPBYTE)((ULONG_PTR)Buffer + VgaAddress - Address);
+        LPBYTE SrcBuffer = (LPBYTE)((ULONG_PTR)BaseAddress + VgaAddress);
 
         /* Write to the VGA memory */
-        VgaWriteMemory(VgaAddress, VgaBuffer, ActualSize);
+        VgaWriteMemory(VgaAddress, SrcBuffer, ActualSize);
     }
 }
 
@@ -178,8 +183,8 @@ VOID EmulatorSetA20(BOOLEAN Enabled)
 
 PBYTE
 WINAPI
-Sim32pGetVDMPointer(IN ULONG Address,
-                    IN BOOL  ProtectedMode)
+Sim32pGetVDMPointer(IN ULONG   Address,
+                    IN BOOLEAN ProtectedMode)
 {
     // FIXME
     UNREFERENCED_PARAMETER(ProtectedMode);
@@ -189,14 +194,14 @@ Sim32pGetVDMPointer(IN ULONG Address,
      *                 or Selector (if ProtectedMode == TRUE )
      * LOWORD(Address) == Offset
      */
-    return SEG_OFF_TO_PTR(HIWORD(Address), LOWORD(Address));
+    return (PBYTE)FAR_POINTER(Address);
 }
 
 PBYTE
 WINAPI
-MGetVdmPointer(IN ULONG Address,
-               IN ULONG Size,
-               IN BOOL ProtectedMode)
+MGetVdmPointer(IN ULONG   Address,
+               IN ULONG   Size,
+               IN BOOLEAN ProtectedMode)
 {
     UNREFERENCED_PARAMETER(Size);
     return Sim32pGetVDMPointer(Address, ProtectedMode);