From 89303ab04652fe147559772ed2b54016e08f1655 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Thu, 27 Feb 2020 00:12:42 +0200
Subject: [PATCH] WX access conflicts

---
 Core/display.c  |  2 +-
 Core/gb.h       |  3 +++
 Core/sm83_cpu.c | 14 ++++++++++++--
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Core/display.c b/Core/display.c
index 908c551..256d981 100644
--- a/Core/display.c
+++ b/Core/display.c
@@ -1042,7 +1042,7 @@ abort_fetching_object:
                         // Too late to enable the window
                     }
                     else if (gb->io_registers[GB_IO_WX] == (uint8_t) (gb->position_in_line + 7) ||
-                               gb->io_registers[GB_IO_WX] == (uint8_t) (gb->position_in_line + 6)) {
+                               (gb->io_registers[GB_IO_WX] == (uint8_t) (gb->position_in_line + 6) && !gb->wx_just_changed)) {
                         gb->window_y++;
                         if (gb->io_registers[GB_IO_WX] != 166) {
                             gb->wx_triggered = true;
diff --git a/Core/gb.h b/Core/gb.h
index e02c7ad..b8cbd97 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -651,6 +651,9 @@ struct GB_gameboy_internal_s {
         bool vblank_just_occured; // For slow operations involving syscalls; these should only run once per vblank
         uint8_t cycles_since_run; // How many cycles have passed since the last call to GB_run(), in 8MHz units
         double clock_multiplier;
+               
+        /* Temporary state */
+        bool wx_just_changed;
    );
 };
     
diff --git a/Core/sm83_cpu.c b/Core/sm83_cpu.c
index b0e28f4..f25e14b 100644
--- a/Core/sm83_cpu.c
+++ b/Core/sm83_cpu.c
@@ -20,6 +20,7 @@ typedef enum {
     GB_CONFLICT_PALETTE_CGB,
     GB_CONFLICT_DMG_LCDC,
     GB_CONFLICT_SGB_LCDC,
+    GB_CONFLICT_WX,
 } GB_conflict_t;
 
 /* Todo: How does double speed mode affect these? */
@@ -46,9 +47,9 @@ static const GB_conflict_t dmg_conflict_map[0x80] = {
     [GB_IO_OBP0] = GB_CONFLICT_PALETTE_DMG,
     [GB_IO_OBP1] = GB_CONFLICT_PALETTE_DMG,
     [GB_IO_WY] = GB_CONFLICT_READ_OLD,
+    [GB_IO_WX] = GB_CONFLICT_WX,
 
     /* Todo: these were not verified at all */
-    [GB_IO_WX] = GB_CONFLICT_READ_NEW,
     [GB_IO_SCX] = GB_CONFLICT_READ_NEW,
 };
 
@@ -64,9 +65,9 @@ static const GB_conflict_t sgb_conflict_map[0x80] = {
     [GB_IO_OBP0] = GB_CONFLICT_READ_NEW,
     [GB_IO_OBP1] = GB_CONFLICT_READ_NEW,
     [GB_IO_WY] = GB_CONFLICT_READ_OLD,
+    [GB_IO_WX] = GB_CONFLICT_WX,
 
     /* Todo: these were not verified at all */
-    [GB_IO_WX] = GB_CONFLICT_READ_NEW,
     [GB_IO_SCX] = GB_CONFLICT_READ_NEW,
 };
 
@@ -261,6 +262,15 @@ static void cycle_write(GB_gameboy_t *gb, uint16_t addr, uint8_t value)
             gb->pending_cycles = 5;
             return;
         }
+            
+        case GB_CONFLICT_WX:
+            GB_advance_cycles(gb, gb->pending_cycles);
+            GB_write_memory(gb, addr, value);
+            gb->wx_just_changed = true;
+            GB_advance_cycles(gb, 1);
+            gb->wx_just_changed = false;
+            gb->pending_cycles = 3;
+            return;
     }
 }