add growing benchmark

Cargo.toml

@@ -9,7 +9,7 @@ edition = "2021"
 rand = "0.8.5"
 
 [[bench]]
-name = "large_grid"
+name = "main"
 harness = false
 
 [dev-dependencies]

benches/large_grid.rs

@@ -1,17 +0,0 @@
-use criterion::{black_box, criterion_group, criterion_main, Criterion};
-use gol_bitwise::region::Region;
-
-fn large_grid(c: &mut Criterion) {
-	const SIZE: usize = 2048 / gol_bitwise::tile::WIDTH; // same number of cells regardless of tile size
-	let mut region = black_box(Region::new(SIZE, SIZE));
-	region.randomise();
-
-	c.bench_function("large grid", |b| {
-		b.iter(|| {
-			region.step();
-		})
-	});
-}
-
-criterion_group!(benches, large_grid);
-criterion_main!(benches);

benches/main.rs

@@ -0,0 +1,33 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use gol_bitwise::{
+	region::Region,
+	tile::{self, Tile},
+};
+
+fn large_grid(c: &mut Criterion) {
+	const SIZE: usize = 2048 / tile::WIDTH; // same number of cells regardless of tile size
+	let mut region = black_box(Region::new(SIZE, SIZE));
+	region.randomise();
+
+	c.bench_function("large grid", |b| {
+		b.iter(|| {
+			region.step();
+		})
+	});
+}
+
+fn growing(c: &mut Criterion) {
+	c.bench_function("growing", |b| {
+		b.iter(|| {
+			let mut region = black_box(Region::new(1, 1));
+			region.set_tile(Tile::gliders(), 0, 0);
+			for _ in 0..1024 {
+				region.step();
+				region.auto_grow();
+			}
+		})
+	});
+}
+
+criterion_group!(benches, large_grid, growing);
+criterion_main!(benches);

src/region.rs

@@ -19,6 +19,10 @@ impl Region {
 		}
 	}
 
+	pub fn set_tile(&mut self, tile: Tile, x: usize, y: usize) {
+		self.tiles[y][x] = tile;
+	}
+
 	pub fn height(&self) -> usize {
 		self.tiles.len()
 	}

src/tile.rs

@@ -27,6 +27,17 @@ impl Tile {
 		Self::EMPTY
 	}
 
+	pub fn gliders() -> Self {
+		let mut t = Self::EMPTY;
+		t.rows[1] = 0b1110000;
+		t.rows[2] = 0b1000000;
+		t.rows[3] = 0b0100000;
+		t.rows[WIDTH - 4] = 0b0100;
+		t.rows[WIDTH - 3] = 0b0010;
+		t.rows[WIDTH - 2] = 0b1110;
+		t
+	}
+
 	pub fn edge_east(&self) -> Row {
 		let mut edge = 0;
 		for n in 0..WIDTH {