From 0ba148b6bbfc1ecf0af1942f8a08ac4fae94e7ce Mon Sep 17 00:00:00 2001
From: drmortalwombat <90205530+drmortalwombat@users.noreply.github.com>
Date: Tue, 20 May 2025 18:26:42 +0200
Subject: [PATCH] Make raster interrupt start more deterministic

---
 include/c64/rasterirq.c | 1 +
 include/crt.c           | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/include/c64/rasterirq.c b/include/c64/rasterirq.c
index 43067c9..6e8de1b 100644
--- a/include/c64/rasterirq.c
+++ b/include/c64/rasterirq.c
@@ -662,6 +662,7 @@ void rirq_start(void)
         lda #100
         sta $d012
 
+        asl $d019
         cli
     }
 }
diff --git a/include/crt.c b/include/crt.c
index 203262d..974ebef 100644
--- a/include/crt.c
+++ b/include/crt.c
@@ -756,6 +756,11 @@ __asm mul32
 		sta	tmp + 6
 		sta	tmp + 7
 
+		lda tmp + 3
+		ora tmp + 2
+		ora tmp + 1
+		beq WB
+
 		lda	tmp + 0
 		jsr WM
 		lda	tmp + 1
@@ -773,6 +778,7 @@ WM:
 		stx accu + 1
 		sta accu
 		rts
+WB:		lda tmp + 0
 W0:
 		sec
 		ror