Most efficient way to do bitwise operations on pairs of elements in two ArrayBuffers in Javascript

Question

I have two Javascript ArrayBuffers; each contains 512 bits of data. I would like to do an xor comparison of the two arrays and store the results in a third array.

Currently, I am looping over the elements in the buffers. In the code below 'distance' is an integer and feat_a1 and feat_b1 are ArrayBuffers that are 512 bits in length.

for(var d1=0; d1<512; d1++){
  distance += feat_b1[d1] ^ feat_a1[d1];
}

Is there a more efficient way of doing the pairwise comparison of these two arrays?

Answer 1

as i understand you can't directly use arrayBuffer[i], you have to pass it to some container (like Int8Array). I have made next example http://jsfiddle.net/mLurz/ , tried with different Typed arrays from this list and Uint32Array showed the best performance

var i;
var dist = 0;
var max = Math.pow(2,32);
var buf1 = new ArrayBuffer(1024);
var x = new Uint32Array(buf1);
for (i = 0; i < 256; ++i) {
    x[i] = Math.random()*max;
}

var buf2 = new ArrayBuffer(1024);
var y = new Uint32Array(buf2);
for (i = 0; i < 256; ++i) {
    y[i] = Math.random()*max
}

console.time('Uint32Array');
for (var j = 0; j < 1000000; ++j) {
    for (i = 0; i < 256; ++i) {
        dist += y[i]^x[i];
    }
}
console.timeEnd('Uint32Array');