gistfile1.txt

function ComputeSliceBounds(len, id, n) {
  // Computes the bounds for slice |id| of |len| items, assuming |n|
  // total slices.  If len is not evenly divisible by n, then the
  // initial threads may have a bit more work.
  var slice = ((len + n - 1) / n) | 0; // i.e. ceil(len / n).
  var prevDone = slice * id; // work distributed to threads before this one.
  var start = (prevDone >= len) ? len : prevDone; // clamp start by len.
  var end = (start + slice) > len ? len : (start + slice); // clamp end by len.
  return [start, end];
}