# Matrix multiplication with asm.js

## JavaScript performance comparison

Revision 6 of this test case created

## Info

Trying super-fast matrix multiplication with asm.js by using a huge pool of matrices exclusively used as asm.js heap. User code indexes matrices by their position in that pool.

github.com/acgessler Matrix mult code from Brandon Jones's Gl-matrix

## Preparation code

``<script>// trying super-fast matrix multiplication with asm.js by using a huge pool// of matrices exclusively used as asm.js heap. User code indexes matrices// by their position in that pool.// Alexander Gessler, 2013 (github.com/acgessler)var COUNT = 100;var elements = 16 * COUNT * 4;var matrixpool = new ArrayBuffer((Math.ceil(elements / 4096.0) * 4096) | 0); // multiple of 4096 bytesconsole.log('mpool: ' + matrixpool.length);function mat_mod(stdlib, foreign, heap) {  "use asm";  var m = new stdlib.Float32Array(heap);  function multiply(idx_a, idx_b, idx_dest) {    idx_a = idx_a | 0;    idx_b = idx_b | 0;    idx_dest = idx_dest | 0;    var i = 0,      j = 0,      c = 0.0,      k = 0,      t0 = 0.0,      t1 = 0.0,      i0 = 0,      i1 = 1;    idx_a = idx_a << 4;    idx_b = idx_b << 4;    idx_dest = idx_dest << 4;    for (i = 0;      (i | 0) < 4; i = (i + 1) | 0) {      for (j = 0;        (j | 0) < 4; j = (j + 1) | 0) {        c = 0.0;        for (k = 0;          (k | 0) < 4; k = (k + 1) | 0) {          i0 = (idx_a + (i << 2) + k) | 0;          i1 = (idx_b + (k << 2) + j) | 0;          t0 = +m[i0 >> 2];          t1 = +m[i1 >> 2];          c = +(c + t0 * t1);        }        i1 = (idx_dest + (i << 2) + j) | 0;        m[i1 >> 2] = c;      }    }  }  function multiplyUnrolled(idx_a, idx_b, idx_dest) {    idx_a = idx_a | 0;    idx_b = idx_b | 0;    idx_dest = idx_dest | 0;    var    a00 = 0.0,      a01 = 0.0,      a02 = 0.0,      a03 = 0.0,      a10 = 0.0,      a11 = 0.0,      a12 = 0.0,      a13 = 0.0,      a20 = 0.0,      a21 = 0.0,      a22 = 0.0,      a23 = 0.0,      a30 = 0.0,      a31 = 0.0,      a32 = 0.0,      a33 = 0.0;    var    b00 = 0.0,      b01 = 0.0,      b02 = 0.0,      b03 = 0.0,      b10 = 0.0,      b11 = 0.0,      b12 = 0.0,      b13 = 0.0,      b20 = 0.0,      b21 = 0.0,      b22 = 0.0,      b23 = 0.0,      b30 = 0.0,      b31 = 0.0,      b32 = 0.0,      b33 = 0.0;    idx_a = idx_a << 4;    idx_b = idx_b << 4;    idx_dest = idx_dest << 4;    a00 = +m[(idx_a + 0) >> 2];    a01 = +m[(idx_a + 1) >> 2];    a02 = +m[(idx_a + 2) >> 2];    a03 = +m[(idx_a + 3) >> 2];    a10 = +m[(idx_a + 4) >> 2];    a11 = +m[(idx_a + 5) >> 2];    a12 = +m[(idx_a + 6) >> 2];    a13 = +m[(idx_a + 7) >> 2];    a20 = +m[(idx_a + 8) >> 2];    a21 = +m[(idx_a + 9) >> 2];    a22 = +m[(idx_a + 10) >> 2];    a23 = +m[(idx_a + 11) >> 2];    a30 = +m[(idx_a + 12) >> 2];    a31 = +m[(idx_a + 13) >> 2];    a32 = +m[(idx_a + 14) >> 2];    a33 = +m[(idx_a + 15) >> 2];    b00 = +m[(idx_b + 0) >> 2];    b01 = +m[(idx_b + 1) >> 2];    b02 = +m[(idx_b + 2) >> 2];    b03 = +m[(idx_b + 3) >> 2];    b10 = +m[(idx_b + 4) >> 2];    b11 = +m[(idx_b + 5) >> 2];    b12 = +m[(idx_b + 6) >> 2];    b13 = +m[(idx_b + 7) >> 2];    b20 = +m[(idx_b + 8) >> 2];    b21 = +m[(idx_b + 9) >> 2];    b22 = +m[(idx_b + 10) >> 2];    b23 = +m[(idx_b + 11) >> 2];    b30 = +m[(idx_b + 12) >> 2];    b31 = +m[(idx_b + 13) >> 2];    b32 = +m[(idx_b + 14) >> 2];    b33 = +m[(idx_b + 15) >> 2];    m[(idx_dest + 0) >> 2] = b00 * a00 + b01 * a10 + b02 * a20 + b03 * a30;    m[(idx_dest + 1) >> 2] = b00 * a01 + b01 * a11 + b02 * a21 + b03 * a31;    m[(idx_dest + 2) >> 2] = b00 * a02 + b01 * a12 + b02 * a22 + b03 * a32;    m[(idx_dest + 3) >> 2] = b00 * a03 + b01 * a13 + b02 * a23 + b03 * a33;    m[(idx_dest + 4) >> 2] = b10 * a00 + b11 * a10 + b12 * a20 + b13 * a30;    m[(idx_dest + 5) >> 2] = b10 * a01 + b11 * a11 + b12 * a21 + b13 * a31;    m[(idx_dest + 6) >> 2] = b10 * a02 + b11 * a12 + b12 * a22 + b13 * a32;    m[(idx_dest + 7) >> 2] = b10 * a03 + b11 * a13 + b12 * a23 + b13 * a33;    m[(idx_dest + 8) >> 2] = b20 * a00 + b21 * a10 + b22 * a20 + b23 * a30;    m[(idx_dest + 9) >> 2] = b20 * a01 + b21 * a11 + b22 * a21 + b23 * a31;    m[(idx_dest + 10) >> 2] = b20 * a02 + b21 * a12 + b22 * a22 + b23 * a32;    m[(idx_dest + 11) >> 2] = b20 * a03 + b21 * a13 + b22 * a23 + b23 * a33;    m[(idx_dest + 12) >> 2] = b30 * a00 + b31 * a10 + b32 * a20 + b33 * a30;    m[(idx_dest + 13) >> 2] = b30 * a01 + b31 * a11 + b32 * a21 + b33 * a31;    m[(idx_dest + 14) >> 2] = b30 * a02 + b31 * a12 + b32 * a22 + b33 * a32;    m[(idx_dest + 15) >> 2] = b30 * a03 + b31 * a13 + b32 * a23 + b33 * a33  }  return {    multiply: multiply,    multiplyUnrolled: multiplyUnrolled  }}var mod = mat_mod(window, undefined, matrixpool);// fill all matrices with valuesfor (var i = matrixpool - 1; i >= 0; --i) {  matrixpool[i] = i % 2 ? 0.5 : 2.0;}</script>``

## Test runner

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Testing in unknown unknown
Test Ops/sec
matrix multiplication
``// multiply lots of matricesfor (var k = 0; k < 5; ++k) {  for (var i = 0; i < COUNT; ++i) {    for (var j = COUNT - 1; j >= 0; --j) {      mod.multiply(i, j, (i + j) % COUNT);    }  }}``
pending…
unrolled
``// multiply lots of matricesfor (var k = 0; k < 5; ++k) {  for (var i = 0; i < COUNT; ++i) {    for (var j = COUNT - 1; j >= 0; --j) {      mod.multiplyUnrolled(i, j, (i + j) % COUNT);    }  }}``
pending…

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