Prelude interpreter

JavaScript interpreter for the esoteric programming language Prelude: http://esolangs.org/wiki/Prelude

by Martin BĂĽttner

HTML

<div style="font-size:12px;font-family:Verdana, Geneva, sans-serif;">Code:
    <br>
    <textarea id="code" rows="4" style="overflow:scroll;overflow-x:hidden;width:90%;">1(  #^    #^^   (#^+!
6 9+ 05+5+^#^+! #^ ^+!
   (((1- )#^##)^^+   )7-!)1433545514232323344949145353495314235494040404232323013334492349532333344953493435343584233475234501333449530423232349495323232323495323230494)</textarea>
    <br>Input:
    <br>
    <textarea id="input" rows="2" style="overflow:scroll;overflow-x:hidden;width:90%;">5a-13 11 2e3</textarea>
    <p>Numeric Input:
        <input id="num_input" type="checkbox">&nbsp; Numeric Output:
        <input id="num_output" type="checkbox">&nbsp; Timeout:
        <input id="timeout" type="checkbox" checked="checked">&nbsp;
        <br>
        <br>
        <input id="run" type="button" value="Run" onclick="run()">
        <input id="stop" type="button" value="Stop" onclick="interrupt()" disabled="disabled">
        <input id="clear" type="button" value="Clear" onclick="clear_output()">&nbsp; <span id="stderr" style="color:red"></span>

    </p>Output:
    <br>
    <textarea id="output" rows="6" style="overflow:scroll;width:90%;"></textarea>
</div>

JavaScript

var ITERS_PER_SEC = 100000;
var TIMEOUT_MILLISECS = 5000;
var ERROR_LOOP_MISMATCH = "Mismatched parentheses";
var ERROR_LOOP_MULTI = "Multiple parentheses in the same column";
var ERROR_TIMEOUT = "Timeout";
var ERROR_INTERRUPT = "Interrupted by user";

var code, input, timeout, num_input, num_output, loop_stack, loop_map;
var running, start_time, code_ptr, width, input_ptr, voices, iterations;

function clear_output() {
    document.getElementById("output").value = "";
    document.getElementById("stderr").innerHTML = "";
}

function stop() {
    running = false;
    document.getElementById("run").disabled = false;
    document.getElementById("stop").disabled = true;
    document.getElementById("clear").disabled = false;
    document.getElementById("num_input").disabled = false;
    document.getElementById("num_output").disabled = false;
    document.getElementById("timeout").disabled = false;
}

function interrupt() {
    error(ERROR_INTERRUPT);
}

function error(msg) {
    document.getElementById("stderr").innerHTML = msg;
    stop();
}

function run() {
    clear_output();

    document.getElementById("run").disabled = true;
    document.getElementById("stop").disabled = false;
    document.getElementById("clear").disabled = true;
    document.getElementById("num_input").disabled = false;
    document.getElementById("num_output").disabled = false;
    document.getElementById("timeout").disabled = false;

    code = document.getElementById("code").value;
    input = document.getElementById("input").value;
    num_input = document.getElementById("num_input").checked;
    num_output = document.getElementById("num_output").checked;
    timeout = document.getElementById("timeout").checked;

    loop_stack = [];
    loop_map = {};

    if (num_input) {
        input = input.match(/-?\d+/g).map(function (n) {
            return +n;
        });
    } else {
        input = input.split("").map(function (s) {
            return s.charCodeAt(0);
        });
    }

   ...