From 9bb34aec209c547e56d90bdcfabf2e10c209f7d1 Mon Sep 17 00:00:00 2001
From: Olivier Galibert <galibert@pobox.com>
Date: Sun, 31 Jan 2021 19:13:31 +0100
Subject: [PATCH] flopimg: Fix wrapping on mac sector extraction

---
 src/lib/formats/flopimg.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/lib/formats/flopimg.cpp b/src/lib/formats/flopimg.cpp
index 0bdec18d201..9322551124b 100644
--- a/src/lib/formats/flopimg.cpp
+++ b/src/lib/formats/flopimg.cpp
@@ -2986,8 +2986,14 @@ std::vector<std::vector<uint8_t>> floppy_image_format_t::extract_sectors_from_tr
 		auto &sdata = sector_data[se];
 		uint8_t ca = 0, cb = 0, cc = 0;
 
-		uint32_t hstate = (nib[pos] << 8) | nib[pos + 1];
-		pos += 2;
+		uint32_t hstate = (nib[pos] << 8);
+		pos ++;
+		if(pos == nib.size())
+			pos = 0;
+		hstate |= nib[pos];
+		pos ++;
+		if(pos == nib.size())
+			pos = 0;
 		for(;;) {
 			hstate = ((hstate << 8) | nib[pos]) & 0xffffff;
 			pos ++;