From edbbfb0d5f4473854643ad3575d76b48f11ef75d Mon Sep 17 00:00:00 2001
From: velllu <91963404+velllu@users.noreply.github.com>
Date: Wed, 6 Sep 2023 23:08:43 +0200
Subject: [PATCH] Added `LD (a8), A` opcode (`0xE0`)

---
 src/consts.rs | 1 +
 src/cpu.rs    | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/src/consts.rs b/src/consts.rs
index e026584..511b7c3 100644
--- a/src/consts.rs
+++ b/src/consts.rs
@@ -2,6 +2,7 @@ pub(crate) mod bus {
     pub(crate) const EOM_SIZE: usize = 160;
     pub(crate) const HIGH_RAM_SIZE: usize = 127;
     pub(crate) const IO_SIZE: usize = 128;
+    pub(crate) const IO_START: usize = 0xFF00;
     pub(crate) const ROM_SIZE: usize = 32768;
     pub(crate) const VIDEO_RAM_SIZE: usize = 8192;
     pub(crate) const WORK_RAM_SIZE: usize = 8192;
diff --git a/src/cpu.rs b/src/cpu.rs
index a097744..c80d135 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -1,4 +1,5 @@
 use crate::common::{merge_two_u8s_into_u16, Operator};
+use crate::consts::bus::IO_START;
 use crate::registers::OneByteRegister;
 use crate::GameBoy;
 
@@ -63,6 +64,11 @@ impl GameBoy {
         let register = self.registers.get_r(register);
         *register = i;
     }
+
+    pub(crate) fn load_i_into_io(&mut self, register: OneByteRegister) {
+        let register = *self.registers.get_r(register);
+        self.bus.write_byte((IO_START + self.next(1) as usize) as u16, register);
+    }
 }
 
 // Bitwise operation functions (not all of them as of now)
@@ -221,6 +227,9 @@ impl GameBoy {
                 (1, 2)
             },
 
+            // Load R into IO (yes, only one of this)
+            0xE0 => { self.load_i_into_io(OneByteRegister::A); (2, 3) },
+
             // Jump
             // When we jump, we set 0 bytes, because if we returned the "correct" amount
             // of bytes, the program will add them to PC after the jump