Protection against weird VPOSW writes incorrectly causing continuous vblanks.

diff --git a/custom.cpp b/custom.cpp
index 6a3cbacd62fb37c30b3d6027662810325040d536..4c3456d8ebc62ff7d1a983ad26450e11e377fc67 100644 (file)
--- a/custom.cpp
+++ b/custom.cpp
@@ -314,6 +314,7 @@ int maxvpos_display = MAXVPOS_PAL; // value used for display size
 int maxhpos_display = AMIGA_WIDTH_MAX;
 int maxvsize_display = AMIGA_HEIGHT_MAX;
 int maxvpos_display_vsync; // extra lines from top visible in bottom
+static bool maxvpos_display_vsync_next;
 static int vblank_extraline;
 static int maxhposm1;
 int maxhposm0 = MAXHPOS_PAL;
@@ -7266,7 +7267,6 @@ static void init_beamcon0(bool fakehz)
                        minfirstline--;
                        hsstop_detect -= 1;
                }
-
        }
 
        if (currprefs.gfx_extrawidth > 0) {
@@ -14259,7 +14259,7 @@ static void hsync_handler(void)
                events_schedule();
 
        }
-       if (vpos == maxvpos_display_vsync) {
+       if (vpos == maxvpos_display_vsync && !maxvpos_display_vsync_next) {
                hsync_record_line_state_last(next_lineno, nextline_how, 0);
                inputdevice_read_msg(true);
                vsync_display_render();
@@ -14269,6 +14269,10 @@ static void hsync_handler(void)
                minfirstline_linear = minfirstline;
                reset_autoscale();
                display_vsync_counter++;
+               maxvpos_display_vsync_next = true;
+       } else if (vpos != maxvpos_display_vsync && maxvpos_display_vsync_next) {
+               // protect against weird VPOSW writes causing continuous vblanks
+               maxvpos_display_vsync_next = false;
        }
        vsync_line = vs;
        hsync_handler_post(vs);
@@ -14391,6 +14395,7 @@ void custom_reset(bool hardreset, bool keyboardreset)
        vt_old = 0;
        ht_old = 0;
        hdiwstate_blank = diw_states::DIW_waiting_start;
+       maxvpos_display_vsync_next = false;
 
        irq_forced_delay = 0;
        irq_forced = 0;