VARVBEN without VARBEAMEN + programmed HBLANK: calculate position using HBLANK values

diff --git a/custom.cpp b/custom.cpp
index 93414e35e0e161b237d21c018a2ad7e2b0b42864..47fef384bd7893e607828ef37cda772d344f0bdd 100644 (file)
--- a/custom.cpp
+++ b/custom.cpp
@@ -1780,10 +1780,50 @@ static void init_beamcon0(void)
        vblank_hz_lace = clk / ((display_maxvpos + 0.5f) * (display_maxhpos + halfhpos));
 
        display_hstart_cyclewait_end = 4;
-       if (beamcon0 & bemcon0_hsync_mask) {
+       if (beamcon0_has_hsync) {
                display_hstart_cyclewait = 4;
                if (currprefs.gfx_overscanmode >= OVERSCANMODE_ULTRA) {
                        display_hstart_cyclewait_end = 0;
+               } else {
+                       if (exthblanken && !(beamcon0 & BEAMCON0_VARBEAMEN)) {
+                               int hp2 = maxhpos * 2;
+                               int hbstrtx, hbstopx;
+                               int hb = 1;
+                               hbstrtx = (hbstrt & 0xff) * 2;
+                               hbstopx = (hbstop & 0xff) * 2;
+                               if (aga_mode) {
+                                       hbstrtx |= (hbstrt & 0x400) ? 1 : 0;
+                                       hbstopx |= (hbstop & 0x400) ? 1 : 0;
+                               }
+                               if (hbstrtx > hp2) {
+                                       hbstrtx = hp2;
+                               }
+                               if (hbstopx > hp2) {
+                                       hbstopx = hp2;
+                               }
+                               if (hbstrtx > hp2 / 2 && hbstopx < hp2 / 2) {
+                                       hb = (hp2 - hbstrtx) + hbstopx;
+                               } else if (hbstopx < hp2 / 2 && hbstrtx < hbstopx) {
+                                       hb = hbstopx - hbstrtx;
+                               }
+                               if (hbstopx > hp2 / 2) {
+                                       hbstopx = 0;
+                               }
+                               if (hb < 1) {
+                                       hb = 1;
+                               }
+
+                               display_hstart_cyclewait = 4;
+                               if (hbstopx / 2 > hsstrt && (hbstopx / 2 - hsstrt < maxhpos / 2)) {
+                                       display_hstart_cyclewait = hbstopx / 2 - hsstrt;
+                               } else if (hsstrt - hbstopx / 2 < maxhpos / 2) {
+                                       display_hstart_cyclewait = hsstrt - hbstopx / 2;
+                               }
+                               if (hb) {
+                                       display_hstart_cyclewait_end = hb / 2 - display_hstart_cyclewait;
+                                       display_hstart_cyclewait += 1;
+                               }
+                       }
                }
        } else {
                display_hstart_cyclewait = 0;