From 83b85051c299979d2980b7558a7a0bb3df5c80d2 Mon Sep 17 00:00:00 2001
From: Aaditya Dhruv <aadityadhruv@mailbox.org>
Date: Sun, 1 Jan 2023 19:02:38 +0530
Subject: docs, init chip8 mem, basic read rom

---
 pinkan      |  1 +
 src/lib.rs  | 58 ++++++++++++++++++++++++++++++++++++++++++++--------------
 src/main.rs | 20 ++++++++++++++++++--
 3 files changed, 63 insertions(+), 16 deletions(-)
 create mode 100644 pinkan

diff --git a/pinkan b/pinkan
new file mode 100644
index 0000000..119927e
--- /dev/null
+++ b/pinkan
@@ -0,0 +1 @@
+Pooki
diff --git a/src/lib.rs b/src/lib.rs
index 6089af3..61615bf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,28 +1,34 @@
-//Basic struct to represent the Chip-8 interpreter structure
 use sdl2::keyboard::Keycode;
 use sdl2::rect::Rect;
+use std::io;
+use std::io::prelude::*;
+use std::fs::File;
+
 pub const WIDTH : u32 = 32;
 pub const HEIGHT : u32 = 64;
 pub const SCALE : u32 = 20;
 
+//length for the array of display "pixels" where pixels are the rectangles being rendered
 const DISPLAY_LENGTH : usize = (WIDTH * HEIGHT) as usize;
 
 
+//Basic struct to represent the Chip-8 interpreter structure
 pub struct Chip {
-    mem : [u8; 4096],
-    registers: [u8; 16],
-    index: u16,
-    pc: u16, 
-    stack: [u16; 16],
-    sp: u8,
-    delay_timer: u8,
-    sound_timer: u8,
-    keys : [Keycode; 16],
-    fonts : [u32; 80],
-    display:  [Rect; DISPLAY_LENGTH as usize]
+    mem : [u8; 4096], //4kb of memory
+    registers: [u8; 16], //16 8-bit registers
+    index: u16, //16-bit index pointer
+    pc: u16, //Program counter
+    stack: [u16; 16], //16 level stack
+    sp: u8, //stack pointer
+    delay_timer: u8, //delay timer 
+    sound_timer: u8, //sound timer
+    keys : [Keycode; 16], //mapping keys to chip-8 input keys
+    fonts : [u8; 80], //all the 16 chars that can be rendered 16 * 5
+    display:  [Rect; DISPLAY_LENGTH as usize] //the display array 
 }
 
 impl Chip {
+    //return a new Chip, with memory 0-initialized
     pub fn new() -> Self {
         Chip {
             mem : [0; 4096],
@@ -55,11 +61,35 @@ impl Chip {
             display: [Rect::new(0, 0, SCALE - 1, SCALE - 1); DISPLAY_LENGTH],
         }
     }
-    pub fn init(mut self) {
+    //initialize memory with all the starting values
+    pub fn init(&mut self) {
+        for i in 0..80 {
+            self.mem[0x50 + i] = self.fonts[i];
+        }
+    }
+
+    pub fn read_rom(&mut self, rom : &str) {
+        let mut buf = Vec::new();
+        let mut rom = File::open(rom).unwrap_or_else(|_err| panic!("Valid ROM needed"));
+
+        rom.read_to_end(&mut buf).unwrap_or_else(|_err| panic!("Error reading ROM"));
+
+        let mut start = 0x200;
+        for i in buf {
+            self.mem[start] = i;
+            start += 1;
+        }
+
+        println!("{:?}", self.mem);
+    }
 
+    pub fn fetch(&mut self) {
+        let instr = (self.mem[self.pc as usize] << 8) | self.mem[self.pc + 1 as usize];
+        self.pc += 2;
     }
 
-    pub fn render(& mut self) -> &[Rect] {
+    //render the current grid of pixels accounting for scale
+    pub fn render(&mut self) -> &[Rect] {
         for idx in 0..DISPLAY_LENGTH {
             let (mut x_coord, mut y_coord) : (i32, i32) =((idx as i32 % WIDTH as i32), (idx as i32 / WIDTH as i32));
             x_coord *= SCALE as i32;
diff --git a/src/main.rs b/src/main.rs
index 4c47172..a49fa6f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -4,12 +4,20 @@ use sdl2::pixels::Color;
 use sdl2::event::Event;
 use sdl2::keyboard::Keycode;
 use std::time::Duration;
-use sdl2::rect::Rect;
 use chip8::Chip;
+use std::env;
 
 
 pub fn main() {
+    //new chip struct
+    let args: Vec<String> = env::args().collect();
+    if args.len() != 2 { panic!("Incorrect format; please pass a single rom file as a parameter"); }
     let mut chip = Chip::new();
+    chip.init();
+    chip.read_rom(args[1].as_str());
+
+
+    //SDL initalizationa and window creation
     let sdl_context = sdl2::init().unwrap();
     let video_subsystem = sdl_context.video().unwrap();
     let window = video_subsystem.window("CHIP-8", chip8::WIDTH * chip8::SCALE, chip8::HEIGHT * chip8::SCALE)
@@ -17,9 +25,12 @@ pub fn main() {
         .build()
         .unwrap();
 
+    //Canvas to interact with
     let mut canvas = window.into_canvas().build().unwrap();
 
+    //Keyboard input handler
     let mut event_pump = sdl_context.event_pump().unwrap();
+    //Main loop called 'running', checks for keyboard input and renders the display grid
     'running: loop {
         for event in event_pump.poll_iter() {
             match event {
@@ -31,10 +42,15 @@ pub fn main() {
             }
         }
         // The rest of the game loop goes here...
+        //Draw black bg
         canvas.set_draw_color(Color::RGB(0, 0, 0));
+        //clear the screen with black bg
         canvas.clear();
+        //choose white color 
         canvas.set_draw_color(Color::RGB(255, 255, 255));
-        canvas.fill_rects(chip.render());
+        //render all the rectangles as white pixels on the canvas
+        canvas.fill_rects(chip.render()).unwrap();
+        //display canvas
         canvas.present();
 
         std::thread::sleep(Duration::new(0, 1_000_000_000u32 / 60));
-- 
cgit