# HG changeset patch
# User Michael Pavone <pavone@retrodev.com>
# Date 1644648901 28800
# Node ID 522d04e2adcd940db9be1e86ef678e61196092a6
# Parent  f3fb7e2c727a4ab303017b71c5c59fde64ff8b29
Fix regression in booting games with Japanese Mega CD BIOS

diff -r f3fb7e2c727a -r 522d04e2adcd m68k_core_x86.c
--- a/m68k_core_x86.c	Fri Feb 11 22:31:40 2022 -0800
+++ b/m68k_core_x86.c	Fri Feb 11 22:55:01 2022 -0800
@@ -2507,7 +2507,11 @@
 {
 	m68k_options *opts = context->options;
 	native_map_slot *native_code_map = opts->gen.native_code_map;
-	start -= M68K_MAX_INST_SIZE - 2;
+	if (start > M68K_MAX_INST_SIZE - 2) {
+		start -= M68K_MAX_INST_SIZE - 2;
+	} else {
+		start = 0;
+	}
 	memmap_chunk const *mem_chunk = find_map_chunk(start, &opts->gen, 0, NULL);
 	if (mem_chunk) {
 		//calculate the lowest alias for this address