[aandrejevic] 71990: [NTVDM] Always reset the AC latch before writing to the AC index register. CORE-11669 #resolve #comment Should be fixed in revision r71990.

Author: aandrejevic
Date: Sun Jul 24 15:45:50 2016
New Revision: 71990

URL: http://svn.reactos.org/svn/reactos?rev=71990&view=rev
Log:
[NTVDM]
Always reset the AC latch before writing to the AC index register.
CORE-11669 #resolve #comment Should be fixed in revision r71990.


Modified:
    trunk/reactos/subsystems/mvdm/ntvdm/bios/vidbios.c

Modified: trunk/reactos/subsystems/mvdm/ntvdm/bios/vidbios.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/mvdm/ntvdm/bios…
==============================================================================
--- trunk/reactos/subsystems/mvdm/ntvdm/bios/vidbios.c	[iso-8859-1] (original)
+++ trunk/reactos/subsystems/mvdm/ntvdm/bios/vidbios.c	[iso-8859-1] Sun Jul 24 15:45:50
2016
@@ -3241,6 +3241,7 @@
 
                     /* Set the overscan register */
                     // VgaSetSinglePaletteRegister(VGA_AC_OVERSCAN_REG,
Buffer[VGA_AC_PAL_F_REG + 1]);
+                    IOReadB(VGA_INSTAT1_READ);
                     IOWriteB(VGA_AC_INDEX, VGA_AC_OVERSCAN_REG);
                     IOWriteB(VGA_AC_WRITE, Buffer[VGA_AC_PAL_F_REG + 1]);
 
@@ -3255,6 +3256,8 @@
                 {
                     /* Read the old AC mode control register value */
                     BYTE VgaAcControlReg;
+
+                    IOReadB(VGA_INSTAT1_READ);
                     IOWriteB(VGA_AC_INDEX, VGA_AC_CONTROL_REG);
                     VgaAcControlReg = IOReadB(VGA_AC_READ);
 
@@ -3270,6 +3273,7 @@
                         Bda->CrtModeControl &= ~(1 << 5);
                     }
 
+                    IOReadB(VGA_INSTAT1_READ);
                     IOWriteB(VGA_AC_INDEX, VGA_AC_CONTROL_REG);
                     IOWriteB(VGA_AC_WRITE, VgaAcControlReg);
 
@@ -3329,6 +3333,7 @@
                     }
 
                     /* Get the overscan register */
+                    IOReadB(VGA_INSTAT1_READ);
                     IOWriteB(VGA_AC_INDEX, VGA_AC_OVERSCAN_REG);
                     Buffer[VGA_AC_PAL_F_REG + 1] = IOReadB(VGA_AC_READ);