From 632eab5e344383bab2a054c42c2b2933ae559952 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <musukarekai@gmail.com>
Date: Mon, 15 Jun 2020 00:45:49 -0500
Subject: [PATCH] Create Chip8 Struct and implement opcode parsing

---
 Cargo.lock  |   5 +++
 src/main.rs | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 118 insertions(+), 2 deletions(-)
 create mode 100644 Cargo.lock

diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..60fb3b2
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "chip8"
+version = "0.1.0"
diff --git a/src/main.rs b/src/main.rs
index e7a11a9..ad3dcd0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,114 @@
-fn main() {
-    println!("Hello, world!");
+
+const SCREEN_SIZE: usize = 64 * 32;
+
+struct Chip8 {
+    opcode: u16,
+    i: u16,
+    pc: u16,
+    sp: u16,
+    key: Option<u8>,
+    v: [u8; 16],
+    stack: [u16; 16],
+    memory: [u8; 4096],
+    delay: Timer,
+    sound: Timer,
+    display: Display,
 }
+
+
+impl Default for Chip8 {
+    fn default() -> Self {
+        Chip8 {
+            opcode: 0,
+            i: 0,
+            pc: 0,
+            sp: 0,
+            key: None,
+            v: [0; 16],
+            stack: [0; 16],
+            memory: [0; 4096],
+            delay: Default::default(),
+            sound: Default::default(),
+            display: Display::default(),
+        }
+    }
+}
+
+
+impl Chip8 {
+    fn new() -> Self {
+        Default::default()
+    }
+
+    pub fn execute_cycle(&self) {
+        
+    }
+
+    fn get_opcode(&self) -> u16 {
+        let pc = self.pc as usize;     
+        ((self.memory[pc] as u16) << 8) | self.memory[pc + 1] as u16
+    }
+
+    fn handle_opcode(&mut self) {
+        // Given: 0xA2F0
+        let nib_1 = (self.opcode & 0xF000) >> 12; //0xA
+        let nib_2 = (self.opcode & 0x0F00) >> 8; // 0x2
+        let nib_3 = (self.opcode & 0x00F0) >> 4; // 0xF
+        let nib_4 =  self.opcode & 0x000F; // 0x0
+
+        // nib_ns are u16s so we waste 4 bytes here. 
+
+        match (nib_1, nib_2, nib_3, nib_4) {
+            // CLS
+            (0x0, 0x0, 0xE, 0x0) => self.clear_display(),
+            // 00EE
+            (0x0, 0x0, 0xE, 0xE) => {}
+            // 1NNN
+            (0x1, _, _, _) => {}
+            // 2NNN
+            (0x2, _, _, _) => {}
+            // 3XKK
+            (0x3, _, _, _) => {}
+            _ => unimplemented!("UNIMPLEMENTED OPCODE: {:#x}", self.opcode)
+        }
+    }
+
+    fn clear_display(&mut self) {
+        self.display.clear();
+    }
+    
+}
+
+struct Display {
+    buf: [u8; SCREEN_SIZE],
+}
+
+impl Display {
+    pub fn clear(&mut self) {
+        self.buf = [0; SCREEN_SIZE]
+    }
+}
+
+impl Default for Display {
+    fn default() -> Self {
+        Display {
+            buf: [0; SCREEN_SIZE],
+        }
+    }
+}
+
+struct Timer {
+    value: u8,
+}
+
+impl Default for Timer {
+    fn default() -> Self {
+        Timer {
+            value: 0,
+        }
+    }
+}
+
+fn main() {
+    println!("Chip8 Emulator");
+}
\ No newline at end of file