From 97eb3fe209ac2539b8a8ea2547018615801c01d9 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Tue, 20 Sep 2016 22:59:00 +0300
Subject: [PATCH] Detect games stuck on blank screens

---
 Tester/main.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/Tester/main.c b/Tester/main.c
index 52d797cb..94450a4d 100755
--- a/Tester/main.c
+++ b/Tester/main.c
@@ -89,15 +89,29 @@ static void vblank(GB_gameboy_t *gb)
         }
     }
 
-    if (frames == test_length) {
-        FILE *f = fopen(bmp_filename, "wb");
-        fwrite(&bmp_header, 1, sizeof(bmp_header), f);
-        fwrite(&bitmap, 1, sizeof(bitmap), f);
-        fclose(f);
-        if (!gb->boot_rom_finished) {
-            GB_log(gb, "Boot ROM did not finish.\n");
+    if (frames >= test_length ) {
+        bool is_screen_blank = false;
+        if (!(gb->io_registers[GB_IO_LCDC] & 0x80)) { /* LCD is off */
+            is_screen_blank = true;
+        }
+        else if(!gb->cgb_mode) { /* BG can't be disabled in CGB mode */
+            is_screen_blank =!(gb->io_registers[GB_IO_LCDC] & (gb->is_cgb? 3 : 0x23));
+        }
+        
+        /* Let the test run for an extra 8 frames if the screen is off/disabled */
+        if (!is_screen_blank || frames >= test_length + 8) {
+            FILE *f = fopen(bmp_filename, "wb");
+            fwrite(&bmp_header, 1, sizeof(bmp_header), f);
+            fwrite(&bitmap, 1, sizeof(bitmap), f);
+            fclose(f);
+            if (!gb->boot_rom_finished) {
+                GB_log(gb, "Boot ROM did not finish.\n");
+            }
+            if (is_screen_blank) {
+                GB_log(gb, "Game probably stuck with blank screen. \n");
+            }
+            running = false;
         }
-        running = false;
     }
     else if (frames == test_length - 1) {
         gb->disable_rendering = false;