[aandrejevic] 72514: [NTVDM:SVGA] Chain-4 addressing isn't really the same as packed-pixel addressing. Also, fix a bug in the optimized odd/even mode reading code.

Author: aandrejevic
Date: Tue Aug 30 21:07:26 2016
New Revision: 72514

URL: http://svn.reactos.org/svn/reactos?rev=72514&view=rev
Log:
[NTVDM:SVGA]
Chain-4 addressing isn't really the same as packed-pixel addressing.
Also, fix a bug in the optimized odd/even mode reading code.

Modified:
    trunk/reactos/subsystems/mvdm/ntvdm/hardware/video/svga.c

Modified: trunk/reactos/subsystems/mvdm/ntvdm/hardware/video/svga.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/mvdm/ntvdm/hardw...
==============================================================================
--- trunk/reactos/subsystems/mvdm/ntvdm/hardware/video/svga.c	[iso-8859-1] (original)
+++ trunk/reactos/subsystems/mvdm/ntvdm/hardware/video/svga.c	[iso-8859-1] Tue Aug 30 21:07:26 2016
@@ -1797,8 +1797,9 @@
     {
         VideoAddress = VgaTranslateAddress(Address);

-        /* Check for chain-4 and odd-even mode */
-        if (VgaSeqRegisters[VGA_SEQ_MEM_REG] & VGA_SEQ_MEM_C4)
+#if 0
+        /* Packed pixel mode - not used yet */
+        if (VgaSeqRegisters[SVGA_SEQ_EXT_MODE_REG] & SVGA_SEQ_EXT_MODE_HIGH_RES)
         {
             /* Just copy from the video memory */
             PVOID VideoMemory = &VgaMemory[VideoAddress * VGA_NUM_BANKS + (Address & 3)];
@@ -1829,12 +1830,65 @@
 #endif
             }
         }
+#endif
+
+        /* Check for chain-4 and odd-even mode */
+        if (VgaSeqRegisters[VGA_SEQ_MEM_REG] & VGA_SEQ_MEM_C4)
+        {
+            i = 0;
+
+            /* Write the unaligned part first */
+            if (Address & 3)
+            {
+                switch (Address & 3)
+                {
+                    case 1:
+                        BufPtr[i++] = VgaMemory[VideoAddress * VGA_NUM_BANKS + 1];
+                    case 2:
+                        BufPtr[i++] = VgaMemory[VideoAddress * VGA_NUM_BANKS + 2];
+                    case 3:
+                        BufPtr[i++] = VgaMemory[VideoAddress * VGA_NUM_BANKS + 3];
+                }
+
+                VideoAddress += 4;
+            }
+
+            /* Copy the aligned dwords */
+            while ((i + 3) < Size)
+            {
+                *(PULONG)&BufPtr[i] = *(PULONG)&VgaMemory[VideoAddress * VGA_NUM_BANKS];
+
+                i += 4;
+                VideoAddress += 4;
+            }
+
+            /* Write the remaining part */
+            if (i < Size)
+            {
+                switch (Size - i - 3)
+                {
+                    case 3:
+                        BufPtr[i] = VgaMemory[VideoAddress * VGA_NUM_BANKS + ((Address + i) & 3)];
+                        i++;
+                    case 2:
+                        BufPtr[i] = VgaMemory[VideoAddress * VGA_NUM_BANKS + ((Address + i) & 3)];
+                        i++;
+                    case 1:
+                        BufPtr[i] = VgaMemory[VideoAddress * VGA_NUM_BANKS + ((Address + i) & 3)];
+                        i++;
+                }
+            }
+        }
         else if (VgaGcRegisters[VGA_GC_MODE_REG] & VGA_GC_MODE_OE)
         {
             i = 0;

/* Check if the starting address is odd */
-            if (Address & 1) BufPtr[i++] = VgaMemory[(VideoAddress++) * VGA_NUM_BANKS + 1];
+            if (Address & 1)
+            {
+                BufPtr[i++] = VgaMemory[VideoAddress * VGA_NUM_BANKS + 1];
+                VideoAddress += 2;
+            }

while (i < (Size - 1))
             {