1 files changed, 58 insertions, 0 deletions
diff --git a/src/devices/scratch.rs b/src/devices/scratch.rs
new file mode 100644
index 0000000..eea011b
--- /dev/null
+++ b/src/devices/scratch.rs
@@ -0,0 +1,58 @@
+pub struct ScratchDevice {
+    memory: Vec<u8>,
+    pub max_capacity: u32,
+    pub pointer_1: u32,
+    pub pointer_2: u32,
+}
+
+impl ScratchDevice {
+    pub fn new() -> Self {
+        Self {
+            memory: Vec::new(),
+            max_capacity: 16 * 65536,
+
+            pointer_1: 0,
+            pointer_2: 0,
+        }
+    }
+
+    pub fn read_head_1(&mut self) -> u8 {
+        let value = self.read_byte(self.pointer_1);
+        self.pointer_1 += 1;
+        return value;
+    }
+
+    pub fn read_head_2(&mut self) -> u8 {
+        let value = self.read_byte(self.pointer_2);
+        self.pointer_2 += 1;
+        return value;
+    }
+
+    pub fn write_head_1(&mut self, value: u8) {
+        self.write_byte(self.pointer_1, value);
+        self.pointer_1 += 1;
+    }
+
+    pub fn write_head_2(&mut self, value: u8) {
+        self.write_byte(self.pointer_2, value);
+        self.pointer_2 += 1;
+    }
+
+    fn read_byte(&self, pointer: u32) -> u8 {
+        let pointer = pointer as usize;
+        match self.memory.get(pointer) {
+            Some(value) => *value,
+            None => 0,
+        }
+    }
+
+    fn write_byte(&mut self, pointer: u32, value: u8) {
+        if pointer < self.max_capacity {
+            let pointer = pointer as usize;
+            if pointer >= self.memory.len() {
+                self.memory.resize(pointer + 1, 0);
+            }
+            self.memory[pointer] = value;
+        }
+    }
+}