brainFuck

brainfuck.markdown

brainFuck

A Pen by Kyah Rindlisbacher on CodePen.

License.

index.html

<h3> status: <span id='info'></span></h3><br/>
<label for="input">input</label><br/>
<input id="input" type="textfield" /><br/>
<label for="output">output</label><br/>
<textarea id="output" rows="4" cols="50"></textarea><br/>
<label for="code">your code</label><br/>
<textarea id="code" rows="10" cols="50" >++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.</textarea>
<button  id="run"> Run </button></br>
<textarea id="mem" rows="10" cols="50" ></textarea>

script.js

(function(){
  var p = 0, // memory pointer
    m = [0], // memory
    lcp = 0, // last code pointer
    cp = 0, // code pointer
    stack = [], // loop stack
    codes = '', // code
    opc = '', // op code
    o = document.querySelector('#output'),
    i = document.querySelector('#input'),
    info = document.querySelector('#info'),
    code = document.querySelector('#code'),
    run = document.querySelector('#run'),
    mem = document.querySelector('#mem'),
    read = function() {
      if (i.value.length != 0) {
        m[p] = i.value.charCodeAt(0); i.value = '';
        i.removeEventListener('change', read);
        info.textContent = 'running';
        step();
      }
    },
    opcodes = {
      '+': function () {
        m[p]++;
        cp++;
      },
      '-': function () {
        m[p]--;
        cp++;
      },
      '>': function () {
        if (m.length - 1 == p) {
          m.push(0)
        }
        p++;
        cp++;
      },
      '<': function () {
        if (p == 0) {console.error('negative mems')} else {p--;}
        cp++;
      },
      '.': function () {
        o.value = o.value + String.fromCharCode(m[p]);
        cp++;
      },
      ',': function () {
        info.textContent = 'Waiting for input';
        i.addEventListener('change', read);
        cp++;
        return 1;
      },
      '[': function () {
        if (m[p] == 0) {
          var opens = 0;
          cp++;
          while (opens != 0 || codes[cp] != ']') {
            if (codes[cp] == '[') {
              opens++;
            }
            else if (codes[cp] == ']' && opens > 0) {
              opens--;
            }
            cp++;
          }
          cp++;
        } else {
          stack.push(cp);
          cp++;
        }},
      ']': function () {
        if (m[p] == 0) {
          stack.pop();
          cp++;
        } else {
          cp = stack.pop();
        }}
    },
    reset = function() {
      info.textContent = 'Finished';
      if (isNaN(cp)) {
        var lcp_less_5 = lcp - 5;
        var str = '';
        for (var j = lcp_less_5; j < lcp + 5 && j < codes.length; j++) {
          str = str + ' ' + ((j == lcp)? '*': '') + j + ':' + codes[j];
        }
        info.textContent = 'Error: ' + codes.substr(lcp  - 5, 10) + '(' + str + ')';
      }
      p = 0;
      m = [0];
      cp = 0;
      stack = [];
      run.disabled = false;
      run.addEventListener('click', interpret)
    },
    step = function() {
      var counter = 0;
      var t0 = performance.now();
      while (true) {
        if (counter > 50000 && performance.now() - t0 > 1000) {
          mem.value = "" +
            " p :" + p + "\n" +
            " cp :" + cp + "\n" +
            " lcp :" + lcp + "\n" +
            " opc :" + opc + "\n" +
            " stack :" + JSON.stringify(stack) + "\n" +
            " m :" + JSON.stringify(m) + "\n";
          setTimeout(step,0);
          break;
        }
        if (codes.length - 1 < cp || isNaN(cp)) {
          reset();
          break;
        }
        var opc = codes[cp];
        if (opcodes.hasOwnProperty(opc)) {
          lcp = cp;
          if (opcodes[opc]()) {
            break;
          }
        }
        else {
          cp++;
        }
        counter++;
      }
    },
    interpret = function() {
      o.value = '';
      codes = code.value;
      run.removeEventListener('click', interpret)
      run.disabled = true;
      step();
    };
  info.textContent = 'Waiting';
  run.addEventListener('click', interpret)
})();