how to drive a speaker from a r2r ladder

Using Arduino Audio
8

i'm still not sure about that: what that code does is to check again and again if "N"uS has passed and then run the instructions i want, which should be:

digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, MSBFIRST, Sample[i]);  
digitalWrite(latchPin, HIGH);
i++;

right? but what's the purpose of the toggle variable? furthermore, where do i have to put my for-loop? please check this:

while(i<SAMPLES_NUMBER)
{
  currentMicros = micros();
  if (currentMicros - previousMicros >= 32)
  {
    previousMicros = currentMicros;
    toggle = 1-toggle;
    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, Sample[i]);
    digitalWrite(latchPin, HIGH);
    i++;
  }
};

is it what i was supposed to write? i'm wondering if direct port manipulation would simplify the whole thing..