VM basics (#5)

Co-authored-by: Andre Wagner <WagnerAndre@JohnDeere.com>
Reviewed-on: https://192.168.5.48/andre/tyche/pulls/5

src/vm/vm.cc

@@ -0,0 +1,79 @@
+#include "vm.hh"
+
+#include "vm_exceptions.hh"
+#include "expr.hh"
+
+namespace tyche::vm {
+
+void VM::load_bytecode(ByteArray const& ba)
+{
+    FunctionId f_id = code_.import_bytecode(ba);
+    stack_.push(Value::CreateFunctionId(f_id));
+}
+
+void VM::call(size_t n_params)
+{
+    // TODO - parameters
+
+    Value f = stack_.pop();
+    if (f.type() != Type::Function)
+        throw VMTypeError(Type::Function, f.type());
+
+    loc_.emplace(f.as_function_id(), 0);
+    stack_.push_fp();
+    run_until_return();
+    // stack_.pop_fp();
+    loc_.pop();
+}
+
+int32_t VM::to_integer(int index) const
+{
+    Value i = stack_.at(index);
+    assert_type(i, Type::Integer);
+    return i.as_integer();
+}
+
+void VM::push_integer(int32_t value)
+{
+    stack_.push(Value::CreateInteger(value));
+}
+
+void VM::run_until_return()
+{
+    size_t level = stack_.fp_level();
+
+    while (stack_.fp_level() >= level)
+        step();
+}
+
+void VM::step()
+{
+    Operation op = code_.operation(loc_.top());
+    switch (op.instruction) {
+        case Instruction::PushInt8:
+        case Instruction::PushInt16:
+        case Instruction::PushInt32:
+            push_integer(op.operator_);
+            break;
+        case Instruction::Sum:
+            stack_.push(binary_operation(stack_.pop(), stack_.pop(), BinaryOperationType::Sum));
+            break;
+        case Instruction::Return: {
+            Value v = stack_.pop();
+            stack_.pop_fp();
+            stack_.push(v);
+            return;
+        }
+        default:
+            throw VMInvalidOpcode((uint8_t) op.instruction);
+    }
+    loc_.top() = op.next_location;
+}
+
+void VM::assert_type(Value const& val, Type type)
+{
+    if (val.type() != type)
+        throw VMTypeError(type, val.type());
+}
+
+} // tyche