Implement VGA byte panning and cursor skew. Patch from Greatpsycho.

sarah-walker-pcem · Nov 14, 2020 · ed30e17 · ed30e17
1 parent 9bdbcc1
commit ed30e17
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Showing 3 changed files with 12 additions and 6 deletions.
diff --git a/src/vid_et4000.c b/src/vid_et4000.c
@@ -264,6 +264,11 @@ void et4000k_recalctimings(svga_t *svga)
 
         if (svga->render == svga_render_text_80 && ((svga->crtc[0x37] & 0x0A) == 0x0A))
         {
+                if(et4000->port_32cb_val & 0x80)
+                {
+                        svga->ma_latch -= 2;
+                        svga->ca_adj = -2;
+                }
                 if((et4000->port_32cb_val & 0xB4) == ((svga->crtc[0x37] & 3) == 2 ? 0xB4 : 0xB0))
                 {
                         svga->render = svga_render_text_80_ksc5601;

diff --git a/src/vid_svga.c b/src/vid_svga.c
@@ -322,7 +322,7 @@ void svga_recalctimings(svga_t *svga)
         if (svga->crtc[9] & 0x20) svga->vblankstart |= 0x200;
         svga->vblankstart++;
 
-        svga->hdisp = svga->crtc[1];
+        svga->hdisp = svga->crtc[1] - ((svga->crtc[5] & 0x60) >> 5);
         svga->hdisp++;
 
         svga->htotal = svga->crtc[0];
@@ -336,7 +336,8 @@ void svga_recalctimings(svga_t *svga)
 
         svga->interlace = 0;
 
-        svga->ma_latch = (svga->crtc[0xc] << 8) | svga->crtc[0xd];
+        svga->ma_latch = ((svga->crtc[0xc] << 8) | svga->crtc[0xd]) + ((svga->crtc[8] & 0x60) >> 5);
+        svga->ca_adj = 0;
 
         svga->hdisp_time = svga->hdisp;
         svga->render = svga_render_blank;
@@ -658,9 +659,9 @@ void svga_poll(void *p)
                         changeframecount = svga->interlace ? 3 : 2;
                         svga->vslines = 0;
 
-                        if (svga->interlace && svga->oddeven) svga->ma = svga->maback = svga->ma_latch + (svga->rowoffset << 1);
-                        else                                  svga->ma = svga->maback = svga->ma_latch;
-                        svga->ca = (svga->crtc[0xe] << 8) | svga->crtc[0xf];
+                        if (svga->interlace && svga->oddeven) svga->ma = svga->maback = svga->ma_latch + (svga->rowoffset << 1) + ((svga->crtc[5] & 0x60) >> 5);
+                        else                                  svga->ma = svga->maback = svga->ma_latch + ((svga->crtc[5] & 0x60) >> 5);
+                        svga->ca = ((svga->crtc[0xe] << 8) | svga->crtc[0xf]) + ((svga->crtc[0xb] & 0x60) >> 5) + svga->ca_adj;
 
                         svga->ma <<= 2;
                         svga->maback <<= 2;

diff --git a/src/vid_svga.h b/src/vid_svga.h
@@ -60,7 +60,7 @@ typedef struct svga_t
         int lowres, interlace;
         int linedbl, rowcount;
         double clock;
-        uint32_t ma_latch;
+        uint32_t ma_latch, ca_adj;
         int bpp;
 
         uint64_t dispontime, dispofftime;