From: Toni Wilen <twilen@winuae.net>
Date: Sat, 22 May 2021 12:20:27 +0000 (+0300)
Subject: Return zero when executing code in ROM and CPU accesses non-existing address space.
X-Git-Tag: 4900~131
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=bd181f518bb185af86ef958eefbb7a4a7286155f;p=francis%2Fwinuae.git

Return zero when executing code in ROM and CPU accesses non-existing address space.
---

diff --git a/memory.cpp b/memory.cpp
index 3a4c26ac..4948f183 100644
--- a/memory.cpp
+++ b/memory.cpp
@@ -334,6 +334,12 @@ uae_u32 dummy_get_safe(uaecptr addr, int size, bool inst, uae_u32 defvalue)
 	if (currprefs.cs_unmapped_space == 2)
 		return 0xffffffff & mask;
 	if ((currprefs.cpu_model <= 68010) || (currprefs.cpu_model == 68020 && (currprefs.chipset_mask & CSMASK_AGA) && currprefs.address_space_24)) {
+		// if executed from ROM: always return zero
+		uaecptr pc = m68k_getpc();
+		addrbank *ab = &get_mem_bank(pc);
+		if (ab->flags & ABFLAG_ROM) {
+			return 0;
+		}
 		if (size == sz_long) {
 			v = regs.irc & 0xffff;
 			if (addr & 1)