From 73dc3560a5e62f40718367d91709fcd7e1c5eb85 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Sat, 31 Mar 2018 13:18:02 +0300
Subject: [PATCH] Mode 0 interrupts do not occur in the glitched mode 0 of the
 first line 0. The extra OAM interrupt bug also affects DMG.

---
 Core/display.c | 6 ++++--
 Core/gb.h      | 1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/Core/display.c b/Core/display.c
index cb3c090..7d0be76 100644
--- a/Core/display.c
+++ b/Core/display.c
@@ -245,7 +245,7 @@ void GB_STAT_update(GB_gameboy_t *gb)
     }
     
     switch (gb->io_registers[GB_IO_STAT] & 3) {
-        case 0: gb->stat_interrupt_line = (gb->io_registers[GB_IO_STAT] & 8); break;
+        case 0: gb->stat_interrupt_line = (gb->io_registers[GB_IO_STAT] & 8) && !gb->is_first_line_mode2; break;
         case 1: gb->stat_interrupt_line = gb->io_registers[GB_IO_STAT] & 0x10; break;
         case 2: gb->stat_interrupt_line = gb->io_registers[GB_IO_STAT] & 0x20; break;
     }
@@ -431,6 +431,7 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
     }
 
     /* Handle the very first line 0 */
+    gb->is_first_line_mode2 = true;
     gb->current_line = 0;
     gb->ly_for_comparison = 0;
     gb->io_registers[GB_IO_STAT] &= ~3;
@@ -448,6 +449,7 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
     gb->vram_read_blocked = !gb->is_cgb;
     gb->oam_write_blocked = true;
     gb->vram_write_blocked = !gb->is_cgb;
+    gb->is_first_line_mode2 = false;
     GB_STAT_update(gb);
     
     gb->cycles_for_line += 2;
@@ -727,7 +729,7 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
             if (!gb->is_cgb) {
                 gb->ly_for_comparison = -1;
             }
-            if (gb->is_cgb && gb->current_line == LINES) {
+            if (gb->current_line == LINES) {
                 gb->io_registers[GB_IO_STAT] &= ~3;
                 gb->io_registers[GB_IO_STAT] |= 2;
                 GB_STAT_update(gb);
diff --git a/Core/gb.h b/Core/gb.h
index 897dfb9..599b6b9 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -429,6 +429,7 @@ struct GB_gameboy_internal_s {
         uint8_t oam_search_index;
         uint8_t accessed_oam_row;
         uint8_t extra_penalty_for_sprite_at_0;
+        bool is_first_line_mode2;
     );
 
     /* Unsaved data. This includes all pointers, as well as everything that shouldn't be on a save state */