reformat code

src/display.rs

@@ -8,8 +8,8 @@ const DISPLAY_HEIGHT: usize = 32;
 pub trait Display {
     /// Re-draws the display.
     fn clear(&self);
-    /// Draws the display.
+    /// Renders the display data on screen.
-    fn draw(&mut self);
+    fn render(&mut self);
 }
 
 /// Display models the Chip8's display.
@@ -33,8 +33,8 @@ impl Display for TerminalDisplay {
         // See https://stackoverflow.com/a/4062051
         print!("{esc}[2J{esc}[1;1H", esc = 27 as char);
     }
-    /// Draws the display.
+    /// Renders the display data on screen.
-    fn draw(&mut self) {
+    fn render(&mut self) {
         for row in 0..32 {
             for column in 0..64 {
                 if self.display_data[row * DISPLAY_WIDTH + column] {

src/emulator.rs

@@ -109,7 +109,6 @@ where
             }
             last_program_counter = self.program_counter;
 
-
             // decode & execute
             self.execute_instruction(instruction)?;
         }
@@ -128,11 +127,14 @@ where
             }
             ProcessorInstruction::SetRegister(register, data) => {
                 trace!("Set register {} to data {:04x}", register, data);
-                self.registers[register] = data
+                self.registers[register as usize] = data
             }
             ProcessorInstruction::AddValueToRegister(register, data) => {
                 trace!("Add to register {} data {:04x}", register, data);
-                self.registers[register] += data
+                self.registers[register as usize] += data
+            }
+            ProcessorInstruction::Draw(vx_register, vy_register, pixels) => {
+                trace!("Draw vx_register={vx_register} vy_register={vy_register} pixels={pixels}")
             }
             ProcessorInstruction::UnknownInstruction => {
                 warn!("Unknown instruction: {:04x}, skipping.", instruction);

src/instruction.rs

@@ -1,6 +1,6 @@
+use log::info;
 use std::fmt;
 use std::fmt::{Display, Formatter, LowerHex};
-use log::info;
 /*
 Although every instruction will have a first nibble that tells you what kind of instruction it is,
 the rest of the nibbles will have different meanings. To differentiate these meanings,
@@ -20,16 +20,18 @@ pub enum ProcessorInstruction {
     /// Jumps to a given address
     Jump(u16),
     /// Sets the register in the first argument to the given value
-    SetRegister(usize, u8),
+    SetRegister(u8, u8),
     /// Adds the value to the register
-    AddValueToRegister(usize, u8),
+    AddValueToRegister(u8, u8),
-    UnknownInstruction
+    /// Draws to the screen.
+    Draw(u8, u8, u8),
+    UnknownInstruction,
 }
 
 #[derive(Debug)]
 pub struct Instruction {
     data: u16,
-    processor_instruction: ProcessorInstruction
+    processor_instruction: ProcessorInstruction,
 }
 
 impl Instruction {
@@ -55,9 +57,7 @@ impl Instruction {
     fn decode_instruction(data: u16) -> ProcessorInstruction {
         match data {
             // Clear Display
-            0x00E0 => {
+            0x00E0 => ProcessorInstruction::ClearScreen,
-                ProcessorInstruction::ClearScreen
-            }
             // Jump
             0x1000..=0x1FFF => {
                 // 1NNN
@@ -66,16 +66,24 @@ impl Instruction {
             // Set Register
             0x6000..=0x6FFF => {
                 // 6XNN
-                ProcessorInstruction::SetRegister(Self::grab_first_nibble(data), Self::grab_last_byte(data))
+                ProcessorInstruction::SetRegister(
+                    Self::grab_first_nibble(data),
+                    Self::grab_last_byte(data),
+                )
             }
-            0x7000..0x7FFF => {
+            0x7000..=0x7FFF => {
                 // 7XNN
-                ProcessorInstruction::AddValueToRegister(Self::grab_first_nibble(data), Self::grab_last_byte(data))
+                ProcessorInstruction::AddValueToRegister(
+                    Self::grab_first_nibble(data),
+                    Self::grab_last_byte(data),
+                )
+            }
+            0xD000..=0xDFFF => {
+                // DXYN
+                ProcessorInstruction::Draw(Self::grab_first_nibble(data), Self::grab_middle_nibble(data), Self::grab_last_nibble(data))
             }
             // Unknown instruction
-            _ => {
+            _ => ProcessorInstruction::UnknownInstruction,
-                ProcessorInstruction::UnknownInstruction
-            }
         }
     }
 
@@ -90,8 +98,18 @@ impl Instruction {
     }
 
     /// Grabs the first nibble from the data.
-    fn grab_first_nibble(data: u16) -> usize {
+    fn grab_first_nibble(data: u16) -> u8 {
-        ((data & 0x0F00) >> 8) as usize
+        ((data & 0x0F00) >> 8) as u8
+    }
+
+    /// Grabs the middle nibble from the data.
+    fn grab_middle_nibble(data: u16) -> u8 {
+        ((data & 0x00F0) >> 4) as u8
+    }
+
+    /// Grabs the last nibble from the data.
+    fn grab_last_nibble(data: u16) -> u8 {
+        (data & 0x000F) as u8
     }
 }