From b0c5426a7cecfc12c1148d25d7b0645d7678c2ed Mon Sep 17 00:00:00 2001
From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Sat, 6 Jun 2015 02:22:36 +0000
Subject: [PATCH] [NTVDM] Programs don't expect the XMS function AH = 07h to
 access the keyboard controller, since the specification says it's done in a
 hardware-independent way. So, reimplement this function by calling
 EmulatorGetA20() instead. Also, for the sake of simplicity, use
 EmulatorSetA20 instead of PCAT_A20Control to change the A20 state.

svn path=/trunk/; revision=68029
---
 .../mvdm/ntvdm/dos/dos32krnl/himem.c          | 67 ++-----------------
 1 file changed, 4 insertions(+), 63 deletions(-)

diff --git a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c
index 1d57efba72f..259f90e58b3 100644
--- a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c
+++ b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c
@@ -76,47 +76,13 @@ static LONG A20EnableCount = 0;
 
 /* HELPERS FOR A20 LINE *******************************************************/
 
-static BOOLEAN PCAT_A20Control(BYTE Control, PBOOLEAN A20Status)
-{
-    BYTE ControllerOutput;
-
-    /* Retrieve PS/2 controller output byte */
-    IOWriteB(PS2_CONTROL_PORT, 0xD0);
-    ControllerOutput = IOReadB(PS2_DATA_PORT);
-
-    switch (Control)
-    {
-        case 0: /* Disable A20 line */
-            ControllerOutput &= ~0x02;
-            IOWriteB(PS2_CONTROL_PORT, 0xD1);
-            IOWriteB(PS2_DATA_PORT, ControllerOutput);
-            break;
-
-        case 1: /* Enable A20 line */
-            ControllerOutput |= 0x02;
-            IOWriteB(PS2_CONTROL_PORT, 0xD1);
-            IOWriteB(PS2_DATA_PORT, ControllerOutput);
-            break;
-
-        default: /* Get A20 status */
-            break;
-    }
-
-    if (A20Status)
-        *A20Status = (ControllerOutput & 0x02) != 0;
-
-    /* Return success */
-    return TRUE;
-}
-
 static VOID XmsLocalEnableA20(VOID)
 {
     /* Enable A20 only if we can do so, otherwise make the caller believe we enabled it */
     if (!CanChangeA20) goto Quit;
 
     /* The count is zero so enable A20 */
-    if (A20EnableCount == 0 && !PCAT_A20Control(1, NULL))
-        goto Fail;
+    if (A20EnableCount == 0) EmulatorSetA20(TRUE);
 
     ++A20EnableCount;
 
@@ -124,11 +90,6 @@ Quit:
     setAX(0x0001); /* Line successfully enabled */
     setBL(XMS_STATUS_SUCCESS);
     return;
-
-Fail:
-    setAX(0x0000); /* Line failed to be enabled */
-    setBL(XMS_STATUS_A20_ERROR);
-    return;
 }
 
 static VOID XmsLocalDisableA20(VOID)
@@ -142,8 +103,7 @@ static VOID XmsLocalDisableA20(VOID)
     --A20EnableCount;
 
     /* The count is zero so disable A20 */
-    if (A20EnableCount == 0 && !PCAT_A20Control(0, NULL))
-        goto Fail;
+    if (A20EnableCount == 0) EmulatorSetA20(FALSE);
 
 Quit:
     setAX(0x0001); /* Line successfully disabled */
@@ -156,25 +116,6 @@ Fail:
     return;
 }
 
-static VOID XmsGetA20State(VOID)
-{
-    BOOLEAN A20Status = FALSE;
-
-    /*
-     * NOTE: The XMS specification explicitely says that this check is done
-     * in a hardware-independent manner, by checking whether high memory wraps.
-     * For our purposes we just call the emulator API.
-     */
-
-    /* Get A20 status */
-    if (PCAT_A20Control(2, &A20Status))
-        setBL(XMS_STATUS_SUCCESS);
-    else
-        setBL(XMS_STATUS_A20_ERROR);
-
-    setAX(A20Status);
-}
-
 /* PRIVATE FUNCTIONS **********************************************************/
 
 static inline PXMS_HANDLE GetHandleRecord(WORD Handle)
@@ -395,8 +336,8 @@ static VOID WINAPI XmsBopProcedure(LPWORD Stack)
         /* Query A20 State */
         case 0x07:
         {
-            /* This call sets AX and BL to their correct values */
-            XmsGetA20State();
+            setAX(EmulatorGetA20());
+            setBL(XMS_STATUS_SUCCESS);
             break;
         }