From dbc338a887a14c5a206b53708f44189dd43a3502 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Sat, 15 Sep 2018 00:47:26 +0300
Subject: [PATCH] =?UTF-8?q?Compensate=20for=20prefetch=20in=20DIV=E2=80=99?=
 =?UTF-8?q?s=20initial=20value?=
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---
 Core/gb.c     |  3 +++
 Core/timing.c | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/Core/gb.c b/Core/gb.c
index ff5851e..73edb11 100644
--- a/Core/gb.c
+++ b/Core/gb.c
@@ -553,6 +553,9 @@ void GB_reset(GB_gameboy_t *gb)
     gb->io_registers[GB_IO_DMA] = gb->io_registers[GB_IO_OBP0] = gb->io_registers[GB_IO_OBP1] = GB_is_cgb(gb)? 0x00 : 0xFF;
     
     gb->accessed_oam_row = -1;
+    
+    /* Todo: Ugly, fixme, see comment in the timer state machine */
+    gb->div_state = 3;
 
     gb->magic = (uintptr_t)'SAME';
 }
diff --git a/Core/timing.c b/Core/timing.c
index 58177d5..65382e4 100644
--- a/Core/timing.c
+++ b/Core/timing.c
@@ -144,9 +144,11 @@ static void GB_timers_run(GB_gameboy_t *gb, uint8_t cycles)
     GB_STATE_MACHINE(gb, div, cycles, 1) {
         GB_STATE(gb, div, 1);
         GB_STATE(gb, div, 2);
+        GB_STATE(gb, div, 3);
     }
     
     GB_set_internal_div_counter(gb, 0);
+main:
     GB_SLEEP(gb, div, 1, 3);
     while (true) {
         advance_tima_state_machine(gb);
@@ -154,6 +156,14 @@ static void GB_timers_run(GB_gameboy_t *gb, uint8_t cycles)
         gb->apu.apu_cycles += 4 << !gb->cgb_double_speed;
         GB_SLEEP(gb, div, 2, 4);
     }
+    
+    /* Todo: This is ugly to allow compatibility with 0.11 save states. Fix me when breaking save compatibility */
+    {
+        div3:
+        /* Compensate for lack of prefetch emulation, as well as DIV's internal initial value */
+        GB_set_internal_div_counter(gb, 8);
+        goto main;
+    }
 }
 
 void GB_advance_cycles(GB_gameboy_t *gb, uint8_t cycles)