sndh: Fix unordered substring offsets

Author: mywave82

include/psgplay/sndh.h

@@ -292,6 +292,7 @@ struct sndh_cursor {
 		bool (*read)(struct sndh_cursor *cursor);
 		size_t start;
 		size_t bound;
+		size_t end;
 	} subtag;
 
 	bool hdns;

lib/psgplay/sndh.c

@@ -168,12 +168,15 @@ static bool sndh_substrings_subtag(struct sndh_cursor  *cursor)
 	if (!e)
 		return false;
 
+	if (e > cursor->subtag.end)
+		cursor->subtag.end = e;	/* Keep end of last substring */
+
 	tag_update(&c[o], 0, cursor);
 
 	cursor->offset += 2;
 
 	if (cursor->offset == cursor->subtag.bound)
-		cursor->offset = cursor->subtag.bound = e;
+		cursor->offset = cursor->subtag.bound = cursor->subtag.end;
 
 	return true;
 }
@@ -189,6 +192,7 @@ static bool sndh_substrings(struct sndh_cursor  *cursor)
 
 	cursor->subtag.start = cursor->offset - strlen(cursor->tag->name);
 	cursor->subtag.bound = cursor->offset + cursor->subtunes * 2;
+	cursor->subtag.end = 0;
 
 	if (cursor->bound < cursor->subtag.bound) {
 		diag_error(cursor, "tag %s too short", cursor->tag->name);