handle ADD instruction

2 files changed, 152 insertions, 145 deletions

diff --git a/Readme.md b/Readme.md
index d4e7470..947e122 100644
--- a/Readme.md
+++ b/Readme.md
@@ -1 +1 @@
-Following along on https://multigesture.net/articles/how-to-write-an-emulator-chip-8-interpreter/

+Following along on https://multigesture.net/articles/how-to-write-an-emulator-chip-8-interpreter/
diff --git a/src/chip8.rs b/src/chip8.rs
index 50b5c12..e372367 100644
--- a/src/chip8.rs
+++ b/src/chip8.rs
@@ -1,144 +1,151 @@
-use std::io::Read;

-use std::io::Write;

-

-const WIDTH: u16 = 64;

-const HEIGHT: u16 = 32;

-const PIXELS: usize = (WIDTH * HEIGHT) as usize;

-

-fn unknown_opcode(opcode: u16) {

-    eprintln!("Unknwown opcode {:#06x}", opcode);

-    std::process::exit(1);

-}

-

-pub struct Chip8 {

-    v: [u8; 4096],

-    i: u16,

-    pc: u16,

-    stack: [u16; 16],

-    sp: u16,

-    memory: [u8; 4096],

-    screen: [u8; PIXELS],

-    delay_timer: u8,

-    sound_timer: u8,

-    key: [u8; 16],

-    draw: bool,

-}

-

-impl Chip8 {

-    pub fn new() -> Self {

-        return Self {

-            v: [0; 4096],

-            i: 0,

-            pc: 0x200,

-            stack: [0; 16],

-            sp: 0,

-            memory: [0; 4096],

-            screen: [0; PIXELS],

-            delay_timer: 0,

-            sound_timer: 0,

-            key: [0; 16],

-            draw: false,

-        };

-    }

-

-    pub fn load_rom<R: Read>(&mut self, mut reader: R) -> std::io::Result<()> {

-        reader.read(&mut self.memory[0x200..])?;

-        Ok(())

-    }

-

-    pub fn cycle(&mut self) {

-        let pc = self.pc as usize;

-        let opcode = (self.memory[pc] as u16) << 8 | self.memory[pc + 1] as u16;

-        match opcode & 0xF000 {

-            0x0000 => match opcode & 0x000F {

-                0x0000 => {

-                    eprintln!("CLS");

-                    self.screen = [0; PIXELS];

-                    self.draw = true;

-                    self.pc += 2;

-                }

-                0x000E => {

-                    eprintln!("RET");

-                    self.pc += 2;

-                }

-                _ => unknown_opcode(opcode),

-            },

-            0x6000 => {

-                let x = (opcode & 0x0F00) >> 8;

-                let value = opcode & 0x00FF;

-                eprintln!("LD V{}, {}", x, value);

-                self.v[x as usize] = value as u8;

-                self.pc += 2;

-            }

-            0xA000 => {

-                self.i = opcode & 0x0FFF;

-                self.pc += 2;

-                eprintln!("LD I, {}", self.i);

-            }

-            0xD000 => {

-                let x = (opcode & 0x0F00) >> 8;

-                let y = (opcode & 0x00F0) >> 4;

-                let nibble = opcode & 0x000F;

-                eprintln!("DRW V{}, V{}, {}", x, y, nibble);

-                self.v[0xF] = 0;

-                for yy in 0..nibble {

-                    let pixel = self.memory[(self.i + yy) as usize];

-                    for xx in 0..8 {

-                        if (pixel & (0x80 >> xx)) != 0 {

-                            let si = x + xx + ((y + yy) * WIDTH);

-                            if self.screen[si as usize] == 1 {

-                                self.v[0xF] = 1;

-                            }

-                            self.screen[si as usize] ^= 1;

-                        }

-                    }

-                }

-                self.draw = true;

-                self.pc += 2;

-            }

-            _ => unknown_opcode(opcode),

-        };

-

-        if self.delay_timer > 0 {

-            self.delay_timer -= 1;

-        }

-

-        if self.sound_timer > 0 {

-            if self.sound_timer == 1 {

-                eprintln!("BEEP");

-            }

-            self.sound_timer -= 1;

-        }

-    }

-

-    pub fn display(&mut self) -> std::io::Result<()> {

-        if self.draw {

-            self.draw = false;

-            self.draw()

-        } else {

-            Ok(())

-        }

-    }

-

-    fn draw(&self) -> std::io::Result<()> {

-        let lines: String = std::iter::once("\x1B[2J\n")

-            .chain((0..HEIGHT).flat_map(|y| {

-                (0..WIDTH)

-                    .map(move |x| {

-                        let si = x + y * WIDTH;

-                        if self.screen[si as usize] == 0 {

-                            "░"

-                        } else {

-                            "█"

-                        }

-                    })

-                    .chain(std::iter::once("\n"))

-            }))

-            .collect();

-

-        let stdout = std::io::stdout();

-        let mut handle = stdout.lock();

-        handle.write_all(lines.as_bytes())?;

-        handle.flush()

-    }

-}

+use std::io::Read;
+use std::io::Write;
+
+const WIDTH: u16 = 64;
+const HEIGHT: u16 = 32;
+const PIXELS: usize = (WIDTH * HEIGHT) as usize;
+
+fn unknown_opcode(opcode: u16) {
+    eprintln!("Unknwown opcode {:#06x}", opcode);
+    std::process::exit(1);
+}
+
+pub struct Chip8 {
+    v: [u8; 4096],
+    i: u16,
+    pc: u16,
+    stack: [u16; 16],
+    sp: u16,
+    memory: [u8; 4096],
+    screen: [u8; PIXELS],
+    delay_timer: u8,
+    sound_timer: u8,
+    key: [u8; 16],
+    draw: bool,
+}
+
+impl Chip8 {
+    pub fn new() -> Self {
+        return Self {
+            v: [0; 4096],
+            i: 0,
+            pc: 0x200,
+            stack: [0; 16],
+            sp: 0,
+            memory: [0; 4096],
+            screen: [0; PIXELS],
+            delay_timer: 0,
+            sound_timer: 0,
+            key: [0; 16],
+            draw: false,
+        };
+    }
+
+    pub fn load_rom<R: Read>(&mut self, mut reader: R) -> std::io::Result<()> {
+        reader.read(&mut self.memory[0x200..])?;
+        Ok(())
+    }
+
+    pub fn cycle(&mut self) {
+        let pc = self.pc as usize;
+        let opcode = (self.memory[pc] as u16) << 8 | self.memory[pc + 1] as u16;
+        match opcode & 0xF000 {
+            0x0000 => match opcode & 0x000F {
+                0x0000 => {
+                    eprintln!("CLS");
+                    self.screen = [0; PIXELS];
+                    self.draw = true;
+                    self.pc += 2;
+                }
+                0x000E => {
+                    eprintln!("RET");
+                    self.pc += 2;
+                }
+                _ => unknown_opcode(opcode),
+            },
+            0x6000 => {
+                let x = (opcode & 0x0F00) >> 8;
+                let value = opcode & 0x00FF;
+                eprintln!("LD V{}, {}", x, value);
+                self.v[x as usize] = value as u8;
+                self.pc += 2;
+            }
+            0x7000 => {
+                let x = (opcode & 0x0F00) >> 8;
+                let value = opcode & 0x00FF;
+                eprintln!("ADD V{}, {}", x, value);
+                self.v[x as usize] += value as u8;
+                self.pc += 2;
+            }
+            0xA000 => {
+                self.i = opcode & 0x0FFF;
+                self.pc += 2;
+                eprintln!("LD I, {}", self.i);
+            }
+            0xD000 => {
+                let x = (opcode & 0x0F00) >> 8;
+                let y = (opcode & 0x00F0) >> 4;
+                let nibble = opcode & 0x000F;
+                eprintln!("DRW V{}, V{}, {}", x, y, nibble);
+                self.v[0xF] = 0;
+                for yy in 0..nibble {
+                    let pixel = self.memory[(self.i + yy) as usize];
+                    for xx in 0..8 {
+                        if (pixel & (0x80 >> xx)) != 0 {
+                            let si = x + xx + ((y + yy) * WIDTH);
+                            if self.screen[si as usize] == 1 {
+                                self.v[0xF] = 1;
+                            }
+                            self.screen[si as usize] ^= 1;
+                        }
+                    }
+                }
+                self.draw = true;
+                self.pc += 2;
+            }
+            _ => unknown_opcode(opcode),
+        };
+
+        if self.delay_timer > 0 {
+            self.delay_timer -= 1;
+        }
+
+        if self.sound_timer > 0 {
+            if self.sound_timer == 1 {
+                eprintln!("BEEP");
+            }
+            self.sound_timer -= 1;
+        }
+    }
+
+    pub fn display(&mut self) -> std::io::Result<()> {
+        if self.draw {
+            self.draw = false;
+            self.draw()
+        } else {
+            Ok(())
+        }
+    }
+
+    fn draw(&self) -> std::io::Result<()> {
+        let lines: String = std::iter::once("\x1B[2J\n")
+            .chain((0..HEIGHT).flat_map(|y| {
+                (0..WIDTH)
+                    .map(move |x| {
+                        let si = x + y * WIDTH;
+                        if self.screen[si as usize] == 0 {
+                            "░"
+                        } else {
+                            "█"
+                        }
+                    })
+                    .chain(std::iter::once("\n"))
+            }))
+            .collect();
+
+        let stdout = std::io::stdout();
+        let mut handle = stdout.lock();
+        handle.write_all(lines.as_bytes())?;
+        handle.flush()
+    }
+}