1 files changed, 140 insertions, 0 deletions
diff --git a/crates/sloth_vm/src/vm.rs b/crates/sloth_vm/src/vm.rs
new file mode 100644
index 0000000..22b769b
--- /dev/null
+++ b/crates/sloth_vm/src/vm.rs
@@ -0,0 +1,140 @@
+use sloth_bytecode::Instruction;
+
+use crate::{Chunk, Data, Stack};
+
+pub struct VM {
+    vm_return: Option<Data>,
+    stack: Stack,
+}
+
+impl VM {
+    fn new() -> Self {
+        Self {
+            vm_return: None,
+            stack: Stack::default(),
+        }
+    }
+
+    fn execute(&mut self) {
+        loop {
+            self.execute_once();
+        }
+    }
+
+    fn execute_once(&mut self) {
+        //
+    }
+
+    fn run(&mut self, chunk: &Chunk) {
+        let mut pointer = 0;
+
+        loop {
+            let instruction = Instruction::disassemble(&chunk.code, &mut pointer);
+
+            match instruction {
+                Instruction::Constant(idx) => {
+                    let value = chunk.constants[idx as usize];
+                    self.stack.push(value);
+                }
+                Instruction::Load(_) => todo!(),
+                Instruction::Push(_) => todo!(),
+                Instruction::Dup => {
+                    let value = self.stack.pop();
+                    self.stack.push(value);
+                    self.stack.push(value);
+                }
+                Instruction::Del => {
+                    self.stack.pop();
+                }
+                Instruction::Add => {
+                    let value = match self.stack.pop2() {
+                        (Data::Integer(lhs), Data::Integer(rhs)) => Data::Integer(lhs + rhs),
+                        (Data::Float(lhs), Data::Float(rhs)) => Data::Float(lhs + rhs),
+                        _ => panic!(),
+                    };
+
+                    self.stack.push(value);
+                }
+                Instruction::Sub => {
+                    let value = match self.stack.pop2() {
+                        (Data::Integer(lhs), Data::Integer(rhs)) => Data::Integer(lhs - rhs),
+                        (Data::Float(lhs), Data::Float(rhs)) => Data::Float(lhs - rhs),
+                        _ => panic!(),
+                    };
+
+                    self.stack.push(value);
+                }
+                Instruction::Mul => {
+                    let value = match self.stack.pop2() {
+                        (Data::Integer(lhs), Data::Integer(rhs)) => Data::Integer(lhs * rhs),
+                        (Data::Float(lhs), Data::Float(rhs)) => Data::Float(lhs * rhs),
+                        _ => panic!(),
+                    };
+
+                    self.stack.push(value);
+                }
+                Instruction::Div => {
+                    let value = match self.stack.pop2() {
+                        (Data::Integer(lhs), Data::Integer(rhs)) => Data::Integer(lhs / rhs),
+                        (Data::Float(lhs), Data::Float(rhs)) => Data::Float(lhs / rhs),
+                        _ => panic!(),
+                    };
+
+                    self.stack.push(value);
+                }
+                Instruction::Mod => {
+                    let value = match self.stack.pop2() {
+                        (Data::Integer(lhs), Data::Integer(rhs)) => Data::Integer(lhs % rhs),
+                        (Data::Float(lhs), Data::Float(rhs)) => Data::Float(lhs % rhs),
+                        _ => panic!(),
+                    };
+
+                    self.stack.push(value);
+                }
+                Instruction::Hlt => break,
+                Instruction::Exit => break,
+                Instruction::VMReturn => {
+                    let value = self.stack.pop();
+                    self.vm_return = Some(value);
+                    break;
+                }
+                _ => unimplemented!(),
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{Chunk, Data, VM};
+
+    #[test]
+    fn arithmetic_ops() {
+        let mut vm = VM::new();
+
+        // Addition
+        vm.run(&Chunk {
+            constants: vec![Data::Integer(7)],
+            code: vec![
+                0x00, 0, 0, 0, 0,    // Load constant from 0
+                0x10, // Duplicate
+                0x20, // Add
+                0xF0, // Return VM
+            ],
+        });
+
+        assert_eq!(vm.vm_return, Some(Data::Integer(14)));
+
+        vm.run(&Chunk {
+            constants: vec![Data::Integer(2), Data::Integer(11)],
+            code: vec![
+                0x00, 0, 0, 0, 0, // Load constant from 0
+                0x00, 0, 0, 0, 1,    // Load constant from 1
+                0x20, // Add
+                0xF0, // Return VM
+            ],
+        });
+
+        assert_eq!(vm.vm_return, Some(Data::Integer(13)));
+    }
+}