Complete day 10

day10/src/main.rs

@@ -1,3 +1,5 @@
+use std::cmp;
+
 #[derive(Debug)]
 enum Instruction {
     Addx(isize),
@@ -35,7 +37,7 @@ impl CPU {
         1
     }
 
-    fn addx(&mut self, i: isize) -> usize {
+    fn add_x(&mut self, i: isize) -> usize {
         self.x += i;
 
         2
@@ -47,7 +49,7 @@ impl CPU {
 
     pub fn run(&mut self, command: Instruction) -> usize {
         match command {
-            Addx(i) => self.addx(i),
+            Addx(i) => self.add_x(i),
             Noop => self.noop(),
         }
     }
@@ -55,20 +57,90 @@ impl CPU {
 
 // -----------------------------------------------------------------------------
 
+#[derive(Debug, Copy, Clone)]
+enum Pixel {
+    Lit,
+    Dark,
+}
+use Pixel::*;
+
+impl Default for Pixel {
+    fn default() -> Self {
+        Dark
+    }
+}
+
+// -----------------------------------------------------------------------------
+
+#[derive(Debug)]
+struct CRT {
+    pixels: [Pixel; 240],
+}
+
+impl CRT {
+    fn new() -> Self {
+        Self {
+            pixels: [Dark; 240],
+        }
+    }
+
+    fn get_lines(&self) -> Vec<String> {
+        self.pixels
+            .map(|p| match p {
+                Lit => '#',
+                Dark => '.',
+            })
+            .chunks(40)
+            .map(|c| String::from_iter(c))
+            .collect()
+    }
+
+    pub fn draw_pixel(&mut self, cycle: usize, x: isize) {
+        let line_x = x % 40;
+        let line_cycle = (cycle - 1) % 40;
+
+        let sprite_s = cmp::max(line_x - 1, 0);
+        let sprite_e = cmp::min(line_x + 1, 39);
+        let sprite: Vec<usize> = ((sprite_s as usize)..=(sprite_e as usize)).collect();
+
+        if cycle == 2 {
+            println!(
+                "Pixel {}, Sprite {:#?}, Line cycle: {}",
+                cycle - 1,
+                sprite,
+                line_cycle
+            );
+        }
+
+        if sprite.contains(&(line_cycle)) {
+            self.pixels[cycle - 1] = Lit;
+        }
+    }
+}
+
+// -----------------------------------------------------------------------------
+
 #[derive(Debug)]
 struct CycleCounter {
     cpu: CPU,
+    crt: CRT,
     log: Vec<isize>,
     cycle: usize,
 }
 
 impl CycleCounter {
     pub fn new() -> Self {
-        Self {
+        let mut cc = Self {
             cpu: CPU::new(),
+            crt: CRT::new(),
             log: vec![1, 1],
             cycle: 1,
-        }
+        };
+
+        // Do first cycle
+        cc.crt.draw_pixel(cc.cycle, cc.cpu.get_x());
+
+        cc
     }
 
     fn run_line(&mut self, line: &str) {
@@ -76,12 +148,22 @@ impl CycleCounter {
         let cycles = self.cpu.run(Instruction::from_line(line));
 
         for _ in 0..(cycles - 1) {
-            self.cycle += 1;
-            self.log.push(x);
+            self.add_cycle(x);
         }
 
+        self.add_cycle(self.cpu.get_x());
+    }
+
+    fn add_cycle(&mut self, x: isize) {
         self.cycle += 1;
-        self.log.push(self.cpu.get_x());
+        self.crt.draw_pixel(self.cycle, x);
+        self.log.push(x);
+    }
+
+    pub fn display(&self) {
+        for line in self.crt.get_lines() {
+            println!("{}", line);
+        }
     }
 
     pub fn get_signal_strength(&self, cycle: usize) -> usize {
@@ -105,18 +187,24 @@ fn main() {
         .sum();
 
     println!("Part 1: sum of signal strength: {}", sum);
+
+    println!("Part 2: display output");
+    cc.display();
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    fn get_test_data() -> &'static str {
+        include_str!("test-input.txt")
+    }
+
     #[test]
     fn test_get_signal_strength() {
-        let file_str = include_str!("test-input.txt");
         let mut cc = CycleCounter::new();
 
-        file_str.lines().for_each(|line| cc.run_line(line));
+        get_test_data().lines().for_each(|line| cc.run_line(line));
 
         assert_eq!(cc.get_signal_strength(20), 420);
         assert_eq!(cc.get_signal_strength(60), 1140);
@@ -125,4 +213,25 @@ mod tests {
         assert_eq!(cc.get_signal_strength(180), 2880);
         assert_eq!(cc.get_signal_strength(220), 3960);
     }
+
+    #[test]
+    fn test_crt_get_lines() {
+        let file_str = include_str!("test-input.txt");
+        let mut cc = CycleCounter::new();
+
+        file_str.lines().for_each(|line| cc.run_line(line));
+
+        let actual = cc.crt.get_lines();
+
+        let expected = vec![
+            "##..##..##..##..##..##..##..##..##..##..".to_string(),
+            "###...###...###...###...###...###...###.".to_string(),
+            "####....####....####....####....####....".to_string(),
+            "#####.....#####.....#####.....#####.....".to_string(),
+            "######......######......######......####".to_string(),
+            "#######.......#######.......#######.....".to_string(),
+        ];
+
+        assert_eq!(actual, expected);
+    }
 }