Split code into modules, add font stuff

src/error.rs

@@ -0,0 +1,66 @@
+#[derive(Debug)]
+pub enum GeorgeErrorKind {
+    Memory(MemoryError),
+    Execution(ExecutionError),
+    AddrMode(AddressingModeError),
+}
+
+impl From<MemoryError> for GeorgeErrorKind {
+    fn from(value: MemoryError) -> Self {
+        Self::Memory(value)
+    }
+}
+impl From<AddressingModeError> for GeorgeErrorKind {
+    fn from(value: AddressingModeError) -> Self {
+        Self::AddrMode(value)
+    }
+}
+impl From<ExecutionError> for GeorgeErrorKind {
+    fn from(value: ExecutionError) -> Self {
+        Self::Execution(value)
+    }
+}
+
+#[derive(Debug)]
+pub enum ExecutionError {
+    InvalidInstruction,
+    InterruptsDisabled,
+    StackOverflow,
+    MemoryError(MemoryError),
+}
+
+#[derive(Debug)]
+pub enum AddressingModeError {
+    IncompatibleAddrMode,
+}
+
+impl From<ExecutionError> for AddressingModeError {
+    fn from(_value: ExecutionError) -> Self {
+        Self::IncompatibleAddrMode
+    }
+}
+
+impl From<MemoryError> for ExecutionError {
+    fn from(error: MemoryError) -> Self {
+        ExecutionError::MemoryError(error)
+    }
+}
+
+#[derive(Debug)]
+pub struct GeorgeError {
+    pub desc: String,
+    pub kind: GeorgeErrorKind,
+}
+
+#[derive(Debug)]
+pub enum MemoryError {
+    Unmapped,
+    NoDataAtAddress,
+    Unwritable,
+}
+
+#[derive(Debug)]
+pub enum MappingError {
+    RegionOccupied,
+    InvalidPage,
+}