Fix genlock buffer overflow

diff --git a/drawing.cpp b/drawing.cpp
index e6729997263fa977fc4adf4ab80af3b31981ef81..4759627383152c3ec5ee05e11ee9a08519934201 100644 (file)
--- a/drawing.cpp
+++ b/drawing.cpp
@@ -7074,8 +7074,7 @@ void draw_denise_border_line_fast(int gfx_ypos, bool blank, enum nln_how how, st
                        draw_blank_end();
                }
 
-               total = end - start;
-               if (need_genlock_data && gbuf && total) {
+               if (need_genlock_data && gbuf && total > 0) {
                        int max = addrdiff(xlinebuffer_genlock_end, gbufp);
                        total += GENLOCK_EXTRA_CLEAR;
                        if (total > max) {