implement non-working draw instruction

src/display.rs

@@ -10,6 +10,8 @@ pub trait Display {
     fn clear(&self);
     /// Renders the display data on screen.
     fn render(&mut self);
+    /// Draws the pixels at x and y coordinates
+    fn draw(&mut self, x: u8, y: u8, pixels: u8) -> bool;
 }
 
 /// Display models the Chip8's display.
@@ -46,4 +48,15 @@ impl Display for TerminalDisplay {
             print!("\n")
         }
     }
+
+    /// Draws the pixels at x and y coordinates
+    fn draw(&mut self, x: u8, y: u8, pixels: u8) -> bool {
+        let row = y as usize;
+        let column = x as usize;
+        for pixel in 0..=pixels {
+            self.display_data[row * DISPLAY_WIDTH + column + pixel as usize] = true;
+        }
+        self.render();
+        true
+    }
 }

src/emulator.rs

@@ -6,6 +6,7 @@ use log::{debug, info, trace, warn};
 use std::fs::File;
 use std::io::Read;
 use std::path::Path;
+use std::{thread, time};
 
 const MEMORY_SIZE: usize = 4096;
 const NUMBER_OF_REGISTERS: usize = 16;
@@ -111,8 +112,10 @@ where
 
             // decode & execute
             self.execute_instruction(instruction)?;
+
+            // insert some delay
+            thread::sleep(time::Duration::from_millis(50));
         }
-        Ok(())
     }
 
     fn execute_instruction(&mut self, instruction: Instruction) -> Result<(), anyhow::Error> {
@@ -134,7 +137,11 @@ where
                 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}")
+                trace!("Draw vx_register={vx_register} vy_register={vy_register} pixels={pixels}");
+                let x_coordinate = self.registers[vx_register as usize] & 63;
+                let y_coordinate = self.registers[vy_register as usize] & 31;
+                self.registers[0xF] = 0;
+                self.display.draw(x_coordinate, y_coordinate, pixels);
             }
             ProcessorInstruction::UnknownInstruction => {
                 warn!("Unknown instruction: {:04x}, skipping.", instruction);

src/instruction.rs

@@ -1,4 +1,3 @@
-use log::info;
 use std::fmt;
 use std::fmt::{Display, Formatter, LowerHex};
 /*
@@ -80,7 +79,11 @@ impl Instruction {
             }
             0xD000..=0xDFFF => {
                 // DXYN
-                ProcessorInstruction::Draw(Self::grab_first_nibble(data), Self::grab_middle_nibble(data), Self::grab_last_nibble(data))
+                ProcessorInstruction::Draw(
+                    Self::grab_first_nibble(data),
+                    Self::grab_middle_nibble(data),
+                    Self::grab_last_nibble(data),
+                )
             }
             // Unknown instruction
             _ => ProcessorInstruction::UnknownInstruction,