feat: implement span interface

src/forestry.rs

@@ -66,7 +66,8 @@ pub fn op_plant(instruction: &u16, tree: &mut Tree, next_tree_id: &mut u16, tree
         trunk: Vec::with_capacity((new_stack_size / 2) as usize),
         asleep: false,
         resume_from: 0,
-        position: ((tree.position.0 + relative_x) % land.width, (tree.position.1 + relative_y) % land.height)
+        position: ((tree.position.0 + relative_x) % land.width, (tree.position.1 + relative_y) % land.height),
+        span: [[0u16; 8]; 8], // TODO: should take from current state of land!
     });
     
     *next_tree_id += 1;

src/main.rs

@@ -103,7 +103,8 @@ fn parse_rom(path: &String) -> io::Result<(state::Land, Vec<state::Rule>, HashMa
         asleep: false,
         resume_from: 0,
         stack_size: original_stack_size,
-        position: (seed_cell_x % land.width, seed_cell_y % land.height)
+        position: (seed_cell_x % land.width, seed_cell_y % land.height),
+        span: [[0u16; 8]; 8],
     });
 
     Ok((land, rules, trees))

src/state.rs

@@ -42,7 +42,12 @@ pub struct Tree {
     pub asleep: bool,
     pub resume_from: u16,
     pub stack_size: usize,
-    pub position: (u16, u16)
+    pub position: (u16, u16),
+    pub span: [[u16; 8]; 8],
+}
+
+fn derelativize_span_coordinates(x: i16, y: i16) -> (usize, usize) {
+    return ((x + 4) as usize, (y + 4) as usize);
 }
 
 impl Tree {
@@ -91,4 +96,16 @@ impl Tree {
             self.pull_trunk()
         }
     }
+
+    pub fn sow(&mut self, relative_x: i16, relative_y: i16, value: u16) {
+        let (x, y) = derelativize_span_coordinates(relative_x, relative_y);
+        self.span[x][y] = value;
+    }
+
+    pub fn reap(&mut self, relative_x: i16, relative_y: i16) -> u16 {
+        let (x, y) = derelativize_span_coordinates(relative_x, relative_y);
+        let value = self.span[x][y];
+        self.sow(relative_x, relative_y, 0);
+        return value;
+    }
 }