X-Git-Url: https://git.reactos.org/?p=reactos.git;a=blobdiff_plain;f=subsystems%2Fntvdm%2Fvga.c;h=d4616a789b25dab55464c94a34ea5c0ee41d99be;hp=eae4f113c3cbb53cdd461d306de31609767c588a;hb=0043c2f37785f45d909d5e64cc9a02fa1b6342ef;hpb=0c3e20ab8971781531a430238f387982f8c1a2b3

diff --git a/subsystems/ntvdm/vga.c b/subsystems/ntvdm/vga.c
index eae4f113c3c..d4616a789b2 100644
--- a/subsystems/ntvdm/vga.c
+++ b/subsystems/ntvdm/vga.c
@@ -488,12 +488,22 @@ static VOID VgaChangeMode(VOID)
     if (!(VgaGcRegisters[VGA_GC_MISC_REG] & VGA_GC_MISC_NOALPHA))
     {
         /* Enter new text mode */
-        if (!VgaEnterTextMode(&Resolution)) return;
+        if (!VgaEnterTextMode(&Resolution))
+        {
+            DisplayMessage(L"An unexpected VGA error occurred while switching into text mode.");
+            VdmRunning = FALSE;
+            return;
+        }
     }
     else
     {
         /* Enter 8-bit graphics mode */
-        if (!VgaEnterGraphicsMode(&Resolution)) return;
+        if (!VgaEnterGraphicsMode(&Resolution))
+        {
+            DisplayMessage(L"An unexpected VGA error occurred while switching into graphics mode.");
+            VdmRunning = FALSE;
+            return;
+        }
     }
 
     /* Trigger a full update of the screen */
@@ -516,6 +526,12 @@ static VOID VgaUpdateFramebuffer(VOID)
                     + VgaCrtcRegisters[VGA_CRTC_START_ADDR_LOW_REG];
     DWORD ScanlineSize = (DWORD)VgaCrtcRegisters[VGA_CRTC_OFFSET_REG] * 2;
 
+    /*
+     * If console framebuffer is NULL, that means something went wrong
+     * earlier and this is the final display refresh.
+     */
+    if (ConsoleFramebuffer == NULL) return;
+
     /* Check if this is text mode or graphics mode */
     if (VgaGcRegisters[VGA_GC_MISC_REG] & VGA_GC_MISC_NOALPHA)
     {
@@ -572,13 +588,30 @@ static VOID VgaUpdateFramebuffer(VOID)
                 }
                 else if (VgaGcRegisters[VGA_GC_MODE_REG] & VGA_GC_MODE_SHIFTREG)
                 {
-                    /*
-                     * 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
-                     */
+                    /* Check if this is 16 or 256 color mode */
+                    if (VgaAcRegisters[VGA_AC_CONTROL_REG] & VGA_AC_CONTROL_8BIT)
+                    {
+                        // TODO: NOT IMPLEMENTED
+                        DPRINT1("8-bit interleaved mode is not implemented!\n");
+                    }
+                    else
+                    {
+                        /*
+                         * 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 / 4)) * AddressSize];
+                        BYTE HighPlaneData = VgaMemory[(((j / 4) % 2) + 2) * VGA_BANK_SIZE
+                                                       + (Address + (j / 4)) * AddressSize];
+
+                        /* Extract the two bits from each plane */
+                        LowPlaneData = (LowPlaneData >> (6 - ((j % 4) * 2))) & 3;
+                        HighPlaneData = (HighPlaneData >> (6 - ((j % 4) * 2))) & 3;
 
-                    // TODO: NOT IMPLEMENTED!
-                    DPRINT1("Interleaved shift mode is not implemented!\n");
+                        /* Combine them into the pixel */
+                        PixelData = LowPlaneData | (HighPlaneData << 2);
+                    }
                 }
                 else
                 {
@@ -620,6 +653,12 @@ static VOID VgaUpdateFramebuffer(VOID)
                     }
                 }
 
+                if (!(VgaAcRegisters[VGA_AC_CONTROL_REG] & VGA_AC_CONTROL_8BIT))
+                {
+                    /* In 16 color mode, the value is an index to the AC registers */
+                    PixelData = VgaAcRegisters[PixelData];
+                }
+
                 /* Now check if the resulting pixel data has changed */
                 if (GraphicsBuffer[i * Resolution.X + j] != PixelData)
                 {