[aandrejevic] 63199: [NTVDM] Fix CGA emulation in shift interleave mode. CORE-8177 #comment Possibly fixed. Can you redo your tests with r63199?

Author: aandrejevic
Date: Fri May  9 00:15:40 2014
New Revision: 63199
URL: http://svn.reactos.org/svn/reactos?rev=63199&view=rev
Log:
[NTVDM]
Fix CGA emulation in shift interleave mode.
CORE-8177 #comment Possibly fixed. Can you redo your tests with r63199?
Modified:
    trunk/reactos/subsystems/ntvdm/hardware/vga.c
    trunk/reactos/subsystems/ntvdm/hardware/vga.h
Modified: trunk/reactos/subsystems/ntvdm/hardware/vga.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/ntvdm/hardware/…
==============================================================================
--- trunk/reactos/subsystems/ntvdm/hardware/vga.c       [iso-8859-1] (original)
+++ trunk/reactos/subsystems/ntvdm/hardware/vga.c       [iso-8859-1] Fri May  9 00:15:40
2014
@@ -1146,6 +1146,8 @@
         /* Loop through the scanlines */
         for (i = 0; i < Resolution.Y; i++)
         {
+            BOOL RepeatScanline = FALSE;
+
             /* Loop through the pixels */
             for (j = 0; j < Resolution.X; j++)
             {
@@ -1199,10 +1201,23 @@
                          * 2 bits shifted from plane 0 and 2 for the first 4 pixels,
                          * then 2 bits shifted from plane 1 and 3 for the next 4
                          */
-                        BYTE LowPlaneData = VgaMemory[((j / 4) % 2) * VGA_BANK_SIZE
-                                                      + (Address + (j / 8)) *
AddressSize];
-                        BYTE HighPlaneData = VgaMemory[(((j / 4) % 2) + 2) *
VGA_BANK_SIZE
-                                                       + (Address + (j / 8)) *
AddressSize];
+                        DWORD BankNumber = (j / 4) % 2;
+                        DWORD Offset = Address + (j / 8);
+                        BYTE LowPlaneData, HighPlaneData;
+
+                        if (i % 2 == 0)
+                        {
+                            /* Odd-numbered line - add the CGA emulation offset */
+                            Offset += VGA_CGA_ODD_LINE_OFFSET;
+                        }
+                        else
+                        {
+                            /* Even-numbered line - use the same scanline */
+                            RepeatScanline = TRUE;
+                        }
+
+                        LowPlaneData = VgaMemory[BankNumber * VGA_BANK_SIZE + Offset *
AddressSize];
+                        HighPlaneData = VgaMemory[(BankNumber + 2) * VGA_BANK_SIZE +
Offset * AddressSize];
                         /* Extract the two bits from each plane */
                         LowPlaneData = (LowPlaneData >> (6 - ((j % 4) * 2))) &
3;
@@ -1296,7 +1311,7 @@
             }
             /* Move to the next scanline */
-            Address += ScanlineSize;
+            if (!RepeatScanline) Address += ScanlineSize;
         }
         /*
Modified: trunk/reactos/subsystems/ntvdm/hardware/vga.h
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/ntvdm/hardware/…
==============================================================================
--- trunk/reactos/subsystems/ntvdm/hardware/vga.h       [iso-8859-1] (original)
+++ trunk/reactos/subsystems/ntvdm/hardware/vga.h       [iso-8859-1] Fri May  9 00:15:40
2014
@@ -24,7 +24,7 @@
 #define VGA_MINIMUM_HEIGHT 300
 #define VGA_DAC_TO_COLOR(x) (((x) << 2) | ((x) >> 4))
 #define VGA_COLOR_TO_DAC(x) ((x) >> 2)
-
+#define VGA_CGA_ODD_LINE_OFFSET 0x1000
 /* Register I/O ports */