internal-typed-array-vs-vars-sha1

JavaScript performance comparison

Revision 2 of this test case created

Info

This test compares using several local variables vs a Uint32Array for the words (32 bit uints) used internally in the sha1 algorithm. I find it very interesting that the behavior varies a lot by browser.

Preparation code

<script>
function stringToBuffer(string) {
  string = unescape(encodeURIComponent(string));
  var length = string.length;
  var buf = new Uint8Array(length);
  for (var i = 0; i < length; i++) {
    buf[i] = string.charCodeAt(i);
  }
  return buf;
};

// input is a Uint8Array bitstream of the data
function sha1_array(input) {
  var H = new Uint32Array([0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0]),
      m = [],
      l  = input.length * 8,
      w  = [];

  for (var i = 0, b = 0, end=l/8; i < end; i++, b += 8) {
    m[b >>> 5] |= input[i] << (24 - b % 32);
  }

  m[l >> 5] |= 0x80 << (24 - l % 32);
  m[((l + 64 >>> 9) << 4) + 15] = l;

  for (var i = 0, end = m.length; i < end; i += 16) {
    var a = H[0], b = H[1], c = H[2], d = H[3], e = H[4];

    for (var j = 0; j < 80; j++) {
      if (j < 16) {
        w[j] = m[i + j];
      }
      else {
        var n = w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16];
        w[j] = (n << 1) | (n >>> 31);
      }

      var t = ((H[0] << 5) | (H[0] >>> 27)) + H[4] + (w[j] >>> 0) + (
              j < 20 ? (H[1] & H[2] | ~H[1] & H[3]) + 0x5a827999 :
              j < 40 ? (H[1] ^ H[2] ^ H[3]) + 0x6ed9eba1 :
              j < 60 ? (H[1] & H[2] | H[1] & H[3] | H[2] & H[3]) - 0x70e44324 :
                       (H[1] ^ H[2] ^ H[3]) - 0x359d3e2a);

      H[4] = H[3];
      H[3] = H[2];
      H[2] = (H[1] << 30) | (H[1] >>> 2);
      H[1] = H[0];
      H[0] = t;
    }

    H[0] += a;
    H[1] += b;
    H[2] += c;
    H[3] += d;
    H[4] += e;
  }
   
  return new Uint8Array(H.buffer);
}


// input is a Uint8Array bitstream of the data
function sha1_vars(input){

  var H0 = 0x67452301,
        H1 = 0xefcdab89,
        H2 = 0x98badcfe,
        H3 = 0x10325476,
        H4 = 0xc3d2e1f0,
        m = [],
        l  = input.length * 8,
        w  = [];

    for (var i = 0, b = 0; i < l/8; i++, b += 8) m[b >>> 5] |= input[i] << (24 - b % 32);

    m[l >> 5] |= 0x80 << (24 - l % 32);
    m[((l + 64 >>> 9) << 4) + 15] = l;

    for (var i = 0; i < m.length; i += 16) {
      var a = H0, b = H1, c = H2, d = H3, e = H4;

      for (var j = 0; j < 80; j++) {
    if (j < 16)
      w[j] = m[i + j];
        else {
          var n = w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16];
          w[j] = (n << 1) | (n >>> 31);
        }

        var t = ((H0 << 5) | (H0 >>> 27)) + H4 + (w[j] >>> 0) + (
                j < 20 ? (H1 & H2 | ~H1 & H3) + 0x5a827999 :
                j < 40 ? (H1 ^ H2 ^ H3) + 0x6ed9eba1 :
                j < 60 ? (H1 & H2 | H1 & H3 | H2 & H3) - 0x70e44324 :
                         (H1 ^ H2 ^ H3) - 0x359d3e2a);

        H4 = H3;
        H3 = H2;
        H2 = (H1 << 30) | (H1 >>> 2);
        H1 = H0;
        H0 = t;
      }

      H0 += a;
      H1 += b;
      H2 += c;
      H3 += d;
      H4 += e;
    }
    var H = new Uint32Array([H0, H1, H2, H3, H4]);
    return new Uint8Array(H.buffer);
}
</script>
<script>
Benchmark.prototype.setup = function() {
    var inputs = [
      stringToBuffer("Hello World"),
      stringToBuffer("Hello World, This is a much longer message to test multiple chunks")
    ]
};
</script>

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
internal-vars
a = sha1_vars(inputs[0])
b = sha1_vars(inputs[1])
pending…
inner-typed
a = sha1_array(inputs[0])
b = sha1_array(inputs[1])
pending…

Compare results of other browsers

Revisions

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