From eb0f61aebd301b812fffb52d4c94901fff32ec65 Mon Sep 17 00:00:00 2001
From: Franco Colmenarez <info@francoacg.com>
Date: Sun, 26 Dec 2021 08:58:09 -0500
Subject: [PATCH] CPU Registers for CGB mode

---
 src/bus.rs      |  2 ++
 src/cpu.rs      | 22 ++++++++++++++++++++--
 src/emulator.rs |  6 ++++--
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/bus.rs b/src/bus.rs
index 241b9ad..ca4d23c 100644
--- a/src/bus.rs
+++ b/src/bus.rs
@@ -36,6 +36,7 @@ pub struct Bus {
     pub timer: Timer,
     pub sound: Sound,
     pub interrupts: Interrupts,
+    pub cgb_mode: bool,
 }
 
 impl Bus {
@@ -67,6 +68,7 @@ impl Bus {
             timer: Timer::new(),
             sound: Sound::new(),
             interrupts: Interrupts::new(),
+            cgb_mode,
         };
 
         // Hardware registers after the bootrom
diff --git a/src/cpu.rs b/src/cpu.rs
index 8eb594f..2db01a6 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -87,6 +87,21 @@ impl Registers {
         }
     }
 
+    pub fn new_cgb() -> Self {
+        Self {
+            a: 0x11,
+            f: 0x00,
+            b: 0x00,
+            c: 0x00,
+            d: 0xFF,
+            e: 0x56,
+            h: 0x00,
+            l: 0x0D,
+            sp: 0xFFFE,
+            pc: 0x0100,
+        }
+    }
+
     pub fn get(&self, register: Register) -> u16 {
         match register {
             Register::A => self.a as u16,
@@ -818,9 +833,12 @@ pub struct CPU {
 }
 
 impl CPU {
-    pub fn new() -> Self {
+    pub fn new(cgb_mode: bool) -> Self {
         Self {
-            registers: Registers::new(),
+            registers: match cgb_mode {
+                true => Registers::new_cgb(),
+                false => Registers::new(),
+            },
             cycles: Cycles(0),
             last_op_cycles: Cycles(0),
             exec_calls_count: 0,
diff --git a/src/emulator.rs b/src/emulator.rs
index 53f328c..d272e7f 100644
--- a/src/emulator.rs
+++ b/src/emulator.rs
@@ -16,9 +16,11 @@ pub struct Emulator {
 
 impl Emulator {
     pub fn new() -> Self {
+        let bus = Bus::new();
+        let cgb_mode = bus.cgb_mode;
         Self {
-            bus: Bus::new(),
-            cpu: CPU::new(),
+            bus,
+            cpu: CPU::new(cgb_mode),
         }
     }