From a07cf92aed58a1fbf03d9010e6a81258300be642 Mon Sep 17 00:00:00 2001
From: bellard <bellard@c046a42c-6fe2-441c-8c8c-71466251a162>
Date: Tue, 30 Sep 2003 21:29:03 +0000
Subject: [PATCH] multiscan/doublescan fix (malc)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@396 c046a42c-6fe2-441c-8c8c-71466251a162
---
 hw/vga.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/hw/vga.c b/hw/vga.c
index 1176502e4c..b16118b88e 100644
--- a/hw/vga.c
+++ b/hw/vga.c
@@ -1109,7 +1109,7 @@ static void vga_draw_graphic(VGAState *s, int full_update)
 {
     int y1, y, update, page_min, page_max, linesize, y_start, double_scan, mask;
     int width, height, shift_control, line_offset, page0, page1, bwidth;
-    int disp_width;
+    int disp_width, multi_scan, multi_run;
     uint8_t *d;
     uint32_t v, addr1, addr;
     vga_draw_line_func *vga_draw_line;
@@ -1124,10 +1124,13 @@ static void vga_draw_graphic(VGAState *s, int full_update)
     disp_width = width;
     
     shift_control = (s->gr[0x05] >> 5) & 3;
-    if (shift_control > 1)
-        double_scan = ((s->cr[0x09] & 0x1f) != 0);
-    else
-        double_scan = (s->cr[0x09] & 0x80);
+    double_scan = (s->cr[0x09] & 0x80);
+    if (shift_control > 1) {
+        multi_scan = (s->cr[0x09] & 0x1f);
+    } else {
+        multi_scan = 0;
+    }
+    multi_run = multi_scan;
     if (shift_control != s->shift_control ||
         double_scan != s->double_scan) {
         full_update = 1;
@@ -1212,14 +1215,20 @@ static void vga_draw_graphic(VGAState *s, int full_update)
                 y_start = -1;
             }
         }
-        if (!double_scan || (y & 1) != 0) {
-            if (y1 == s->line_compare) {
-                addr1 = 0;
-            } else {
-                mask = (s->cr[0x17] & 3) ^ 3;
-                if ((y1 & mask) == mask)
-                    addr1 += line_offset; 
+        if (!multi_run) {
+            if (!double_scan || (y & 1) != 0) {
+                if (y1 == s->line_compare) {
+                    addr1 = 0;
+                } else {
+                    mask = (s->cr[0x17] & 3) ^ 3;
+                    if ((y1 & mask) == mask)
+                        addr1 += line_offset;
+                }
+                y1++;
             }
+            multi_run = multi_scan;
+        } else {
+            multi_run--;
             y1++;
         }
         d += linesize;