dataview vs typed array views

JavaScript performance comparison

Revision 19 of this test case created by

Preparation code


      
      <script>
Benchmark.prototype.setup = function() {
  var source = new Uint8Array([0x32, 0x65, 0x42, 0x56]);
  var nativeEndian = new Uint16Array(new Uint8Array([0x12, 0x34]).buffer)[0] === 0x3412;
  
  var buf = new ArrayBuffer(16);
  var uint8 = new Uint8Array(buf);
  var int8 = new Int8Array(buf);
  var uint16 = new Uint16Array(buf);
  var int16 = new Int16Array(buf);
  var uint32 = new Uint32Array(buf);
  var int32 = new Int32Array(buf);
  var float32 = new Float32Array(buf);
  var float64 = new Float64Array(buf);
  
  function peek(bytes, littleEndian) {
      var i, _i, _j;
      if (littleEndian == null) {
        littleEndian = false;
      }
      if (littleEndian === nativeEndian) {
        for (i = _i = 0; _i < bytes; i = _i += 1) {
          uint8[i] = source[i];
        }
      } else {
        for (i = _j = 0; _j < bytes; i = _j += 1) {
          uint8[bytes - i - 1] = source[i];
        }
      }
    }
  
  function readUInt32_1(littleEndian) {
    peek(4, littleEndian);
    return uint32[0];
  }
  
  var buf2 = new ArrayBuffer(10);
  var uint8_2 = new Uint8Array(buf2);
  var view = new DataView(buf2);
  
  function peek2(bytes) {
    for (var i = 0; i < bytes; i++) {
      uint8_2[i] = source[i];
    }
  }
  
  function readUInt32_2(littleEndian) {
    //peek2(4);
    return view.getUint32(0, littleEndian);
  }
  
  function readUInt32_3(littleEndian) {
    var a0 = source[0],
        a1 = source[1],
        a2 = source[2],
        a3 = source[3];
    
    if (littleEndian)
      return ((a3 << 24) >>> 0) + (a2 << 16) + (a1 << 8) + (a0);
    else
      return ((a0 << 24) >>> 0) + (a1 << 16) + (a2 << 8) + (a3);
  }

};
</script>

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
Typed Arrays No Peek
readUInt32_1();
pending…
DataView
readUInt32_2();
pending…
Bit twiddling
readUInt32_3();
pending…

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