js MIPS乘法模擬的方法簡單介紹

antzone發表於2017-04-06
JS

關於這個演算法是什麼，完全不知道，網上有這樣的程式碼，於是想來分享一下。也許會對一些朋友帶來幫助，看如下程式碼例項:

[HTML] 純文字檢視 複製程式碼
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.51texiao.cn/" />
<title>螞蟻部落</title>
 <script type="text/javascript">
  /* CREATED BY SERKAN SENDUR */
  function StringToNumberArray(Bin) {
   var numberArray = [];
   for (var i = 0; i < Bin.length; i++) {
    numberArray.push(Bin.substring(i, i + 1));
   }
   return numberArray;
  }
  function ConvertToDecimal(Bin) {
   var decimalNumber = 0;
   var numberArray = StringToNumberArray(Bin);
   numberArray.reverse();
   for (var i = 0; i < numberArray.length; i++) {
    decimalNumber += numberArray[i] * Math.pow(2, i);
   }
   return decimalNumber;
  }
  function ConvertToBinary(dec) {
   var bits = [];
   var dividend = dec;
   var remainder = 0;
   while (dividend >= 2) {
    remainder = dividend % 2;
    bits.push(remainder);
    dividend = (dividend - remainder) / 2;
   }
   bits.push(dividend);
   bits.reverse();
   return bits.join("");
  }
  function Multiply() {
   var firstNumber = document.getElementById("txtFirst").value;
   var secondNumber = document.getElementById("txtSecond").value;
   var multiplier = ConvertToBinary(firstNumber);
   var multiplicant = ConvertToBinary(secondNumber);
   var product = 0;
   var step = "Initial values";
   var iteration = 0;
   AppendToTable(iteration, step, multiplier, multiplicant, product);
   multiplicationAlgoritm(multiplier, multiplicant, product, 4);
  }
  function multiplicationAlgoritm(multiplier, multiplicant, product, counter) {
   if (counter > 0) {
    var iteration = 5 - counter;
    var decProduct = ConvertToDecimal(product);
    var decMultiplier = ConvertToDecimal(multiplier);
    var decMultiplicant = ConvertToDecimal(multiplicant);
    if (Right(multiplier, 1) == "1") {
     decProduct = decProduct + decMultiplicant;
     product = ConvertToBinary(decProduct);
     AppendToTable(iteration, "1a", multiplier, multiplicant, product);
    }
    else {
     AppendToTable(iteration, 1, multiplier, multiplicant, product);
    }
    decMultiplicant = ConvertToDecimal(multiplicant);
    decMultiplicant = decMultiplicant << 1;
    multiplicant = ConvertToBinary(decMultiplicant);
    AppendToTable(iteration, 2, multiplier, multiplicant, product);
    decMultiplier = ConvertToDecimal(multiplier);
    decMultiplier = decMultiplier >> 1;
    multiplier = ConvertToBinary(decMultiplier);
    AppendToTable(iteration, 3, multiplier, multiplicant, product);
    counter--;
    multiplicationAlgoritm(multiplier, multiplicant, product, counter);
   }
  }
  function AppendToTable(iteration, step, multiplier, multiplicant, product) {
   var row = document.getElementById("tblResults").insertRow();
   var cell = row.insertCell();
   cell.innerText = iteration;
   var cell = row.insertCell();
   cell.innerText = step;
   var cell = row.insertCell();
   cell.innerText = multiplier;
   var cell = row.insertCell();
   cell.innerText = multiplicant;
   var cell = row.insertCell();
   cell.innerText = product;
  }
  function ResetTable() {
   for (var i = document.getElementById("tblResults").rows.length; i > 1; i--) {
    document.getElementById("tblResults").deleteRow(i - 1);
   }
  }
  function Right(str, n) {
   if (n <= 0)
    return "";
   else if (n > String(str).length)
    return str;
   else {
    var iLen = String(str).length;
    return String(str).substring(iLen, iLen - n);
   }
  }
 </script>
 <style type="text/css">
  .style1
  {
   border-collapse: collapse;
   border-style: solid;
   border-width: 1px;
  }
  .style2
  {
   width: 6px;
  }
  .style4
  {
   color: #3366FF;
  }
  .style5
  {
   color: #0066FF;
  }
 </style>
</head>
<body>
 <br />
 <h3 class="style4">
   WELCOME TO MIPS MULTIPLICATION SIMULATOR</h3>
 <hr style="color: #0033CC" />
 <table>
  <tr>
   <td class="style5">
    Multiplier :
   </td>
   <td>
    <input id="txtFirst" type="text" />
   </td>
  </tr>
  <tr>
   <td class="style5">
    Multiplicant :
   </td>
   <td>
    <input id="txtSecond" type="text" />
   </td>
  </tr>
  <tr>
   <td align="center" colspan="2">
    <input id="btnMultiply" type="button" value="Multiply"
 onclick="ResetTable();Multiply();"
     style="color: #3399FF" />
   </td>
  </tr>
 </table>
 <table class="style1" cellpadding="2" cellspacing="2"
 id="tblResults">
  <tr style="color: White">
   <td bgcolor="#3366FF">
    Iteration
   </td>
   <td bgcolor="#3366FF">
    Step
   </td>
   <td bgcolor="#3366FF">
    Multiplier
   </td>
   <td bgcolor="#3366FF" class="style2">
    Multiplicant
   </td>
   <td bgcolor="#3366FF">
    Product
   </td>
  </tr>
 </table>
</body>
</html>

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