Mon, 05 Apr 2010 17:03:06 +0100
Implement OP_MOVE, OP_LOADNIL and OP_RETURN. Also change the way OP_CALL is implemented, and update the test code with a more complicated (kind of) sample.
var OP_MOVE = 0; var OP_LOADK = 1; var OP_LOADNIL = 3; var OP_GETGLOBAL = 5; var OP_CALL = 28; var OP_RETURN = 30; function LValue(type, value) { this.type = type||"nil"; this.value = value||null; } LValue.prototype = { call: function (args) { return this.value; }, index: function (key) { if(this.type == "table") { return this.value[key.value]; } }, setIndex: function (key, value) { if(this.type == "table") { this.value[key.value] = value; } } }; function LValueFromString(string) { return new LValue("string", string); } function LValueFromFunction(func) { return new LValue("function", func); } var default_environment = new LValue("table", {}); var print; if(typeof(document) == "object") print = function (a) { document.write(a+"<br/>") }; // Browser else print = require("sys").puts; // Nodejs default_environment.setIndex(LValueFromString("print"), LValueFromFunction(print)); function LFunction() { this.constants = []; this.instructions = []; this.environment = default_environment; return this; } LFunction.prototype = { addInstruction: function (instruction) { this.instructions.push(instruction); }, addConstant: function (constant) { this.constants.push(constant); } }; function LVM() { this.callstack = []; this.stack = []; return this; } LVM.prototype = { run: function (lfFunction) { this.frame = {f:lfFunction,pc:0,reg:[]}; this.callstack.push(this.frame); var instruction; while(this.callstack.length>0) { instruction = this.frame.f.instructions[this.frame.pc++]; switch(instruction[0]) { case OP_MOVE: this.frame.reg[instruction[1]] = this.frame.reg[instruction[2]]; break; case OP_LOADNIL: for(var i = instruction[1];i<=instruction[2];i++) this.frame.reg[i] = new LValue("nil", null); break; case OP_GETGLOBAL: var name = this.frame.f.constants[instruction[2]]; this.frame.reg[instruction[1]] = this.frame.f.environment.index(name); break; case OP_LOADK: var value = this.frame.f.constants[instruction[2]]; this.frame.reg[instruction[1]] = value; break; case OP_CALL: var f = this.frame.reg[instruction[1]].call(); // return JS or LValue var args = this.frame.reg.splice(instruction[1]+1, instruction[1]+(instruction[2]-1)); if(typeof(f) == "function") { // JS native function var ret = f.apply(null, args.map(function (a) { return a.value; })); } else { // Lua function } break; case OP_RETURN: this.callstack.pop(); break; default: } } } }; var testvm = new LVM(); var mycode = new LFunction(); mycode.addConstant(LValueFromString("hello")); mycode.addConstant(LValueFromString("print")); mycode.addInstruction([OP_LOADK, 0, 0]); mycode.addInstruction([OP_LOADNIL, 1, 1]); mycode.addInstruction([OP_MOVE, 1, 0]); mycode.addInstruction([OP_GETGLOBAL, 2, 1]); mycode.addInstruction([OP_MOVE, 3, 1]); mycode.addInstruction([OP_CALL, 2, 2, 1]); mycode.addInstruction([OP_RETURN, 0, 1]); testvm.run(mycode);