[aandrejevic] 68029: [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...

Author: aandrejevic
Date: Sat Jun  6 02:22:36 2015
New Revision: 68029

URL: http://svn.reactos.org/svn/reactos?rev=68029&view=rev
Log:
[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.

Modified:
    trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c

Modified: trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/mvdm/ntvdm/dos/d...
==============================================================================
--- trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c	[iso-8859-1] (original)
+++ trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/himem.c	[iso-8859-1] Sat Jun  6 02:22:36 2015
@@ -76,47 +76,13 @@

/* 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;

@@ -124,55 +90,30 @@
     setAX(0x0001); /* Line successfully enabled */
     setBL(XMS_STATUS_SUCCESS);
     return;
+}
+
+static VOID XmsLocalDisableA20(VOID)
+{
+    /* Disable A20 only if we can do so, otherwise make the caller believe we disabled it */
+    if (!CanChangeA20) goto Quit;
+
+    /* If the count is already zero, fail */
+    if (A20EnableCount == 0) goto Fail;
+
+    --A20EnableCount;
+
+    /* The count is zero so disable A20 */
+    if (A20EnableCount == 0) EmulatorSetA20(FALSE);
+
+Quit:
+    setAX(0x0001); /* Line successfully disabled */
+    setBL(XMS_STATUS_SUCCESS);
+    return;

Fail:
     setAX(0x0000); /* Line failed to be enabled */
     setBL(XMS_STATUS_A20_ERROR);
     return;
-}
-
-static VOID XmsLocalDisableA20(VOID)
-{
-    /* Disable A20 only if we can do so, otherwise make the caller believe we disabled it */
-    if (!CanChangeA20) goto Quit;
-
-    /* If the count is already zero, fail */
-    if (A20EnableCount == 0) goto Fail;
-
-    --A20EnableCount;
-
-    /* The count is zero so disable A20 */
-    if (A20EnableCount == 0 && !PCAT_A20Control(0, NULL))
-        goto Fail;
-
-Quit:
-    setAX(0x0001); /* Line successfully disabled */
-    setBL(XMS_STATUS_SUCCESS);
-    return;
-
-Fail:
-    setAX(0x0000); /* Line failed to be enabled */
-    setBL(XMS_STATUS_A20_ERROR);
-    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 **********************************************************/
@@ -395,8 +336,8 @@
         /* Query A20 State */
         case 0x07:
         {
-            /* This call sets AX and BL to their correct values */
-            XmsGetA20State();
+            setAX(EmulatorGetA20());
+            setBL(XMS_STATUS_SUCCESS);
             break;
         }