230-Examples/float.html at master · twopiharris/230-Examples · GitHub

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<!DOCTYPE html>
<html lang = "en-us">
<head>
  <title>Floating point conversion practice</title>
  <meta charset = "utf-8">
  <style type = "text/css">
  form {
    width: 600px;
    margin: auto;
    background-color: lightblue;
    display: grid;
    grid-template-columns: 1fr 2fr;
  }

  label {
    grid-column: 1/2;
    text-align: right;
    padding-right: 1em;
  }

  input {
    grid-column: 2/3;
  }

  output {
    grid-column: 2/3;
    background-color: white;
    border: 1px solid black;
    padding-left: .5em;
  }

  button {
    grid-column: 1/3;
    background-color: lightgray;
  }
  </style>

  <script lang = "javascript">
    // Andy Harris, Feb 2021

    function calculate(){

      if (checkAll()){

        sm = document.getElementById("txtSM").value;
        man = document.getElementById("txtMan").value;
        sExp = document.getElementById("txtSexp").value;
        exp = document.getElementById("txtExp").value;
        bin = sm + man + sExp + exp;

        result = binToDec(sm, man, sExp, exp);

        document.getElementById("outBin").innerText = bin;
        document.getElementById("outDec").innerText = result;

      } // end if

    } // end calculate

    function binToDec(sm, man, sExp, exp){
      // calculate results
      result = parseInt(man, 2);

      //check for sign of mantissa
      if (sm == "1"){
        result *= -1;
      } // end if

      // get exponent
      ex = parseInt(exp, 2);
      if (sExp == "1"){
        ex *= -1;
      } // end if

      result = result * Math.pow(2, ex);
      return result;
    }  // end binToDec


    function checkInput(elementName, element, length){
      result = true;
      val = document.getElementById(elementName).value;
      let re = /^[01]+$/
      result = re.test(val);
      if (!result){
        alert(element + " is not binary");
        result = false;
      } // end if
      if (val.length != length){
        alert(element + " should be " + length + " bits long");
        result = false;
      } // end if
      return result;
    } // end checkInput

    function checkAll(){
      result = false;
      if (checkInput("txtSM", "sign of mantissa", 1)){
        if (checkInput("txtMan", "mantissa", 4)){
          if (checkInput("txtSexp", "sign of exponent", 1)){
            if (checkInput("txtExp", "exponent", 2)){
              result = true;
            } // end if
          } // end if
        } // end if
      } // end if
      return result;
    } // end checkAll

    function generate(){
      sm = makeBin(1);
      man = makeBin(4);
      sExp = makeBin(1);
      exp = makeBin(2);
      bin = sm + man + sExp + exp;

      document.getElementById("txtSM").value = sm;
      document.getElementById("txtMan").value = man;
      document.getElementById("txtSexp").value = sExp;
      document.getElementById("txtExp").value = exp;
      document.getElementById("outBin").value = bin;
      document.getElementById("outDec").innerText = "";
    } // end generate

    function makeBin(length){
      outString = "";
      for (i = 0; i < length; i++){
        // returns a binary string of the given length
        val = parseInt(Math.random()*2);
        outString += val;
      } // end for
      return outString;
    } // end makeBin

    function makeDec(){
      // generate a decimal that can be resolved
      // into this format
      sm = makeBin(1);
      man = makeBin(4);
      sExp = makeBin(1);
      exp = makeBin(2);

      // clear the form
      document.getElementById("txtSM").value = "0";
      document.getElementById("txtMan").value = "0000";
      document.getElementById("txtSexp").value = "0";
      document.getElementById("txtExp").value = "00";
      document.getElementById("outBin").value = "";

      result = binToDec(sm, man, sExp, exp);
      bin = sm + man + sExp + exp;
      //write the 'answer' to the console
      console.log(bin);

      document.getElementById("outDec").innerText = result;

      alert("Try to make this: " + result);
    } // end make dec
  </script>


</head>

<body>
  <h1>Floating point conversion</h1>

  <form>

    <label>sign of mantissa (1)</label>
    <input type = "text"
           id = "txtSM"
           value = "0" />

    <label>mantissa (4)</label>
    <input type = "text"
           id = "txtMan"
           value = "0000" />

    <label>sign of exponent (1)</label>
    <input type = "text"
           id = "txtSexp"
           value = "0">

    <label>exponent (2)</label>
    <input type = "text"
           id = "txtExp"
           value = "00" />

    <label>binary value</label>
    <output id = "outBin">
    </output>

    <label>decimal value</label>
    <output id = "outDec">
    </output>

    <button type = "button"
            onclick = "calculate()">
      calculate
    </button>

    <button type = "button"
            onclick = "generate()">
      generate a problem
    </button>

    <button type = "button"
            onclick = "makeDec()">
      generate a decimal challenge
    </button>

  </form>

  <div id = "instructions">
    <h2>Instructions</h2>
    <p>
      This is a tool to experiment with a simplified floating point format
      described in CSCI 23000 at IUPUI.  It is an eight-bit format with
      a mantissa and exponent in signed magnitude notation.
    <p>

    <p>
      The format is ABBBBCDD where:
    </p>

    <ul>
      <li>A is the sign of the mantissa (0 for positive, 1 for negative)</li>
      <li>B is the mantissa, four digits of binary</li>
      <li>C is the sign of the exponent (0 for positive, 1 for negative)</li>
      <li>D is the exponent, two digits of binary</li>
    </ul>

    <p>
      Enter values into the text fields, noting the program requires binary input
      of the given length. Incorrect inputs will be ignored. Hit the 'calculate'
      button to calculate the results of the current inputs.
    </p>

    <p>
      Use the "generate a problem" button to generate a random set of legal inputs.
    </p>

    <p>
      Use the "generate a decimal challenge" to get a decimal value.  This value will
      have at least one solution, and perhaps more than one.  You might want to write
      the number down and experiment until you can find a way to generate it.
    </p>

    <p>
      Note that each binary input has exactly one correct result, but a decimal number
      could potentially have more than one solution in this floating-point notation.
    </p>

    <p>
      This notation is far too limited for use in real life, but it is a good simplified
      example of how floating point notations work.
    </p>
</body>
</html>