[aandrejevic] 59688: [NTVDM] Clear the screen when switching video modes.

Author: aandrejevic
Date: Sat Aug 10 19:24:00 2013
New Revision: 59688

URL: http://svn.reactos.org/svn/reactos?rev=59688&view=rev
Log:
[NTVDM]
Clear the screen when switching video modes.

Modified:
    branches/ntvdm/subsystems/ntvdm/bios.c

Modified: branches/ntvdm/subsystems/ntvdm/bios.c
URL: http://svn.reactos.org/svn/reactos/branches/ntvdm/subsystems/ntvdm/bios.c?re...
==============================================================================
--- branches/ntvdm/subsystems/ntvdm/bios.c	[iso-8859-1] (original)
+++ branches/ntvdm/subsystems/ntvdm/bios.c	[iso-8859-1] Sat Aug 10 19:24:00 2013
@@ -255,6 +255,31 @@
     }
 }

+static VOID BiosClearScreen(VOID)
+{
+    INT i;
+    BYTE PlaneMask;
+
+    /* Save the plane write register */
+    VgaWritePort(VGA_SEQ_INDEX, VGA_SEQ_MASK_REG);
+    PlaneMask = VgaReadPort(VGA_SEQ_DATA);
+
+    /* Write to all planes */
+    VgaWritePort(VGA_SEQ_DATA, 0x0F);
+
+    /* Clear the screen */
+    for (i = VgaGetVideoBaseAddress();
+         i < VgaGetVideoLimitAddress();
+         i += sizeof(DWORD))
+    {
+        DWORD Zero = 0;
+        VgaWriteMemory(i, (LPVOID)&Zero, sizeof(DWORD));
+    }
+
+    /* Restore the plane write register */
+    VgaWritePort(VGA_SEQ_DATA, PlaneMask);
+}
+
 /* PUBLIC FUNCTIONS ***********************************************************/

BYTE BiosGetVideoMode(VOID)
@@ -304,7 +329,7 @@
     /* Update the values in the BDA */
     Bda->VideoMode = ModeNumber;
     Bda->VideoPage = 0;
-    Bda->VideoPageSize   = BIOS_PAGE_SIZE;
+    Bda->VideoPageSize = BIOS_PAGE_SIZE;
     Bda->VideoPageOffset = 0;

/* Get the character height */
@@ -629,6 +654,8 @@
         case 0x00:
         {
             BiosSetVideoMode(LOBYTE(Eax));
+            BiosClearScreen();
+
             break;
         }