Additional device for Espruino to support 8 pins in parallel (for discussion)

Thanks, that's really interesting! What is push data out?

I just committed those changes I mentioned above - it should be useful in a bunch of cases since it applies even to SPI/I2C/etc.

Basically this should mean that the setup is done only once - even in BytePort you had to grab the binary data out of a variable each call, but this should avoid that since it'll be stored on the stack - so I'm hopeful that with these changes we may end up with something even faster.

I don't have a P3 matrix here so this is what I did for the LPD6416 - hopefully the change is pretty straightforward.

// original
connect1 = function(pins) {
  var s = shiftOut.bind(null, [pins.nG,pins.nR], { clk : pins.S, repeat : 4 });
  var d = digitalWrite.bind(null, [pins.nEN,pins.L,pins.L,pins.D,pins.C,pins.B,pins.A,pins.nEN]);
  var en = pins.nEN;
  var g = Graphics.createArrayBuffer(64,16,2);
  var u = g.buffer;
  g.scan = function() {
    en.reset();
    for (var y=0;y<16;y++) {s(new Uint8Array(u,y*16,16));d(33|y<<1);}
    en.set();
  };
  g.setBgColor(3);
  g.setColor(0);
  g.clear();
  return g;
};

// fast
connect2 = function(pins) {
  var s = shiftOut.bind(null, [pins.nG,pins.nR], { clk : pins.S, repeat : 4 });
  var d = digitalWrite.bind(null, [pins.nEN,pins.L,pins.L,pins.D,pins.C,pins.B,pins.A,pins.nEN]);
  var en = pins.nEN;
  var g = Graphics.createArrayBuffer(64,16,2);
  var u = g.buffer;
  var arr = [];
  g.prep = function() {
    arr = [];
    for (var y=0;y<16;y++) {
      arr.push(new Uint8Array(u,y*16,16));
      arr.push({callback:d.bind(null,33|y<<1)});
    }
  };
  g.scan = function() {
    en.reset();
    s(arr);
    en.set();
  };
  g.setBgColor(3);
  g.setColor(0);
  g.clear();
  return g;
};

function time(fn) {
  var g = fn({A:B15, B:B14, C:B13, D:B10,
                      nG:B1, L:A6, S:A5, nEN:A8, nR:A7});
  if (g.prep) g.prep();
  var t=getTime();
  var n=100;
  while (n--)g.scan();
  print(getTime()-t);
}

// normal
time(connect1);
// save the loop and function calls - roughly twice as fast on STM32
time(connect2);