use a more compact memory rep

Cargo.toml

@@ -11,6 +11,7 @@ crate-type = ["cdylib", "rlib"]
 default = ["console_error_panic_hook"]
 
 [dependencies]
+fixedbitset = "0.4.0"
 js-sys = "0.3"
 wasm-bindgen = "0.2.63"
 

src/lib.rs

@@ -1,9 +1,12 @@
 mod utils;
 
+extern crate js_sys;
+extern crate fixedbitset;
+
 use std::fmt;
 use wasm_bindgen::prelude::*;
+use fixedbitset::FixedBitSet;
 
-extern crate js_sys;
 
 // When the `wee_alloc` feature is enabled, use `wee_alloc` as the global
 // allocator.
@@ -21,19 +24,11 @@ pub fn greet(name: &str) {
     alert(&format!("Hello, {name}!", name=name))
 }
 
-#[wasm_bindgen]
-#[repr(u8)]
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum Cell {
-    Dead = 0,
-    Alive = 1,
-}
-
 #[wasm_bindgen]
 pub struct Universe {
     width: u32,
     height: u32,
-    cells: Vec<Cell>,
+    cells: FixedBitSet,
 }
 
 impl Universe{
@@ -69,14 +64,13 @@ impl Universe {
                 let i = self.get_index(row, col);
                 let cell = self.cells[i];
                 let live_neighbor = self.live_neighbor_count(row, col);
-                let next_cell = match (cell, live_neighbor){
-                    (Cell::Alive, x) if x < 2 => Cell::Dead,
-                    (Cell::Alive, 2) | (Cell::Alive, 3) => Cell::Alive,
-                    (Cell::Alive, x) if x > 3 => Cell::Dead,
-                    (Cell::Dead, 3) => Cell::Alive,
+                next.set(i, match (cell, live_neighbor){
+                    (true, x) if x < 2 => false,
+                    (true, 2) | (true, 3) => true,
+                    (true, x) if x > 3 => false,
+                    (false, 3) => true,
                     (other, _) => other,
-                };
-                next[i] = next_cell;
+                });
             }
         }
         self.cells = next;
@@ -85,16 +79,13 @@ impl Universe {
     pub fn new() -> Universe {
         let width = 64;
         let height = 64;
+        let size = (width * height) as usize;
 
-        let cells = (0..width * height)
-            .map(|i| {
-                if i % 2 == 0 || i % 7 == 0 {
-                    Cell::Alive
-                } else {
-                    Cell::Dead
-                }
-            })
-            .collect();
+        let mut cells = FixedBitSet::with_capacity(size);
+
+        for i in 0..size {
+            cells.set(i, i % 2 == 0 || i % 7 == 0);
+        }
 
         Universe {
             width,
@@ -106,16 +97,13 @@ impl Universe {
     pub fn new_random() -> Universe {
         let width = 64;
         let height = 64;
+        let size = (width * height) as usize;
 
-        let cells = (0..width * height)
-            .map(|_i| {
-                if js_sys::Math::random() < 0.5 {
-                    Cell::Alive
-                } else {
-                    Cell::Dead
-                }
-            })
-            .collect();
+        let mut cells = FixedBitSet::with_capacity(size);
+
+        for i in 0..size {
+            cells.set(i, js_sys::Math::random() < 0.5);
+        }
 
         Universe {
             width,
@@ -127,16 +115,19 @@ impl Universe {
     pub fn new_space_ship() -> Universe {
         let width : u32 = 64;
         let height : u32 = 64;
+        let size = (width * height) as usize;
 
-        let mut cells : Vec<Cell> = (0..width * height)
-            .map(|_i| { Cell::Dead })
-            .collect();
+        let mut cells = FixedBitSet::with_capacity(size);
+
+        for i in 0..size {
+            cells.set(i, false);
+        }
 
         let x0 = 32;
         let y0 = 32;
         for (x, y) in [(0, 2), (1, 0), (1, 2), (2, 1), (2, 2)].iter().cloned() {
             let i = ((y0 + y) * width + x0 + x) as usize;
-            cells[i] = Cell::Alive;
+            cells.set(i, true);
         }
 
         Universe {
@@ -158,16 +149,17 @@ impl Universe {
         self.height
     }
 
-    pub fn cells(&self) -> *const Cell {
-        self.cells.as_ptr()
+    pub fn cells(&self) -> *const u32 {
+        self.cells.as_slice().as_ptr()
     }
 }
 
 impl fmt::Display for Universe {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        for line in self.cells.as_slice().chunks(self.width as usize) {
-            for &cell in line {
-                let symbole = if cell == Cell::Dead { '◻' } else { '◼' };
+        for row in 0..self.height {
+            for col in 0..self.width {
+                let i = self.get_index(row, col);
+                let symbole = if self.cells[i] { '◻' } else { '◼' };
                 write!(f, "{}", symbole)?;
             }
             write!(f, "\n")?;

www

@@ -1 +1 @@
-Subproject commit b0799ea316d590cd432fee5f53914287e2a328d6
+Subproject commit f6fa2759a6dce5379554d7294f00487bb1565004