Stash::_parse_fraction PHP Method

    private function _parse_fraction($fraction, $offset = 0, $total)
    {
        if (strstr($fraction, '/')) {
            $fraction = explode('/', $fraction);
            if (isset($fraction[1]) && $fraction[1] > 0) {
                $p = $fraction[1];
                // the default number of partitions
                $start = 0;
                // index of the first partition
                $end = $fraction[0];
                // index of the last partition
                // do we have an offset?
                if ($offset) {
                    if (strstr($offset, '/')) {
                        // we were passed a fraction
                        $offset = explode('/', $offset);
                    } elseif (intval($offset) === $offset) {
                        // we were passed an integer, convert to a fraction of the total
                        $offset = array($offset, $total);
                    }
                    if (isset($offset[1]) && $offset[1] > 0) {
                        // do the denominators match?
                        if ($offset[1] !== $fraction[1]) {
                            // no, find the least common denominator for those numbers
                            $p = $this->_lcd(array($offset[1], $fraction[1]));
                            // multiply the numerators accordingly
                            $offset[0] = $p / $offset[1] * $offset[0];
                            $fraction[0] = $p / $fraction[1] * $fraction[0];
                        }
                        // update indexes of start/end partitions
                        $start = $offset[0];
                        $end = $start + $fraction[0];
                    } else {
                        $offset = 0;
                    }
                }
                // partition a temporary list
                $partlen = floor($total / $p);
                $partrem = $total % $p;
                $partition = array();
                $mark = 0;
                $list = array_fill(0, $total, 0);
                for ($px = 0; $px < $p; $px++) {
                    $incr = $px < $partrem ? $partlen + 1 : $partlen;
                    $partition[$px] = array_slice($list, $mark, $incr);
                    $mark += $incr;
                }
                unset($list);
                $i = $start;
                $index = 0;
                while ($i < $end) {
                    if (isset($partition[$i])) {
                        $index += count($partition[$i]);
                    } else {
                        break;
                    }
                    $i++;
                }
                return $index;
            }
        } else {
            return (int) $fraction;
        }
    }