Code cleanup

src/stackframe.rs

@@ -0,0 +1,61 @@
+
+use crate::classfile::{ JavaClassFile, AttributeData };
+
+#[derive(Copy, Clone, Debug)]
+pub enum LocalVariable {
+    Boolean(bool),
+    Byte(u8),
+    Char(u16),
+    Short(u16),
+    Int(u32),
+    Float(u32),
+    Reference(u32),
+    ReturnAddress(u32),
+    Double0(u32),
+    Double1(u32),
+    Long0(u32),
+    Long1(u32),
+    Empty(),
+}
+
+#[derive(Debug)]
+pub struct OperandStack {
+    stack: Box<[LocalVariable]>,
+    depth: u16,
+}
+
+impl OperandStack {
+    fn new(size: u16) -> Self {
+        return OperandStack {
+            stack: vec![LocalVariable::Empty(); size.into()].into_boxed_slice(),
+            depth: 0,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct StackFrame {
+    locals: Box<[LocalVariable]>,
+    operand_stack: OperandStack,
+    class_id: usize,
+    method_index: u16,
+    instruction_pointer: u32,
+}
+
+impl StackFrame {
+    pub fn new(classfile: &JavaClassFile, class_id: usize, method_index: u16) -> Self {
+        let method_info = &classfile.methods[method_index as usize];
+        let code_data = match &method_info.attributes[method_info.code_attribute_index].data {
+            AttributeData::Code(data) => data,
+            _ => unreachable!(),
+        };
+
+        StackFrame {
+            locals: vec![LocalVariable::Empty(); code_data.max_locals.into()].into_boxed_slice(),
+            operand_stack: OperandStack::new(code_data.max_stack),
+            class_id,
+            method_index,
+            instruction_pointer: 0,
+        }
+    }
+}