From: Toni Wilen <twilen@winuae.net>
Date: Wed, 3 Apr 2024 15:55:10 +0000 (+0300)
Subject: Keep vblank active as long as last seen strobe is STRVBL.
X-Git-Tag: 5300~52
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=f02a9a9547552eb1d90df02dd3ca80ccbd2b2119;p=francis%2Fwinuae.git

Keep vblank active as long as last seen strobe is STRVBL.
---

diff --git a/custom.cpp b/custom.cpp
index 4c4732f3..45fa372b 100644
--- a/custom.cpp
+++ b/custom.cpp
@@ -382,6 +382,7 @@ static uae_u32 refmask;
 static int refresh_handled_slot;
 static bool refptr_preupdated;
 static bool hstrobe_conflict;
+static uae_u16 last_hstrobe;
 static bool vhposw_modified;
 static int line_disabled;
 static bool custom_disabled;
@@ -6291,6 +6292,9 @@ static void reset_decisions_hsync_start(void)
 	} else if (ecs_agnus) {
 		// Visible vblank end is delayed by 1 line
 		thisline_decision.vb = vb_start_line >= 2 + vblank_extraline || vb_end_next_line ? 0 : VB_NOVB;
+		if (hstrobe_conflict && last_hstrobe == 0x3a && thisline_decision.vb) {
+			thisline_decision.vb = VB_XBLANK;
+		}
 	} else {
 		thisline_decision.vb = vb_start_line >= 2 + vblank_extraline || vb_end_next_line ? 0 : VB_NOVB;
 	}
@@ -14140,6 +14144,11 @@ static void hsync_handler_post(bool onvsync)
 	refptr_p = refptr;
 	for (int i = 0; i < 4; i++) {
 		uae_u16 strobe = get_strobe_reg(i);
+		if (i == 0) {
+			if (!hstrobe_conflict) {
+				last_hstrobe = strobe;
+			}
+		}
 		alloc_cycle(hp, strobe != 0x1fe ? CYCLE_STROBE : CYCLE_REFRESH);
 		// assume refresh pointer not changed or conflicted
 #ifdef DEBUGGER
@@ -14520,6 +14529,8 @@ void custom_reset(bool hardreset, bool keyboardreset)
 	ht_old = 0;
 	hdiwstate_blank = diw_states::DIW_waiting_start;
 	maxvpos_display_vsync_next = false;
+	hstrobe_conflict = false;
+	last_hstrobe = 0;
 
 	irq_forced_delay = 0;
 	irq_forced = 0;
@@ -15156,6 +15167,10 @@ static int REGPARAM2 custom_wput_1 (int hpos, uaecptr addr, uae_u32 value, int n
 #endif
 	case 0x034: POTGO(value); break;
 
+	case 0x038: last_hstrobe = 0x38; break;
+	case 0x03a: last_hstrobe = 0x3a; break;
+	case 0x03c: last_hstrobe = 0x3c; break;
+
 	case 0x040: BLTCON0(hpos, value); break;
 	case 0x042: BLTCON1(hpos, value); break;