/*
 * Copyright 2005 by the Massachusetts Institute of Technology.
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

/**
 * @description
 * This file contains functions that allow one to decode MPEG-2 compliant video. 
 * The code is based on the MPEG-2 specification (ISO/IEC 13818-2). The MPEG-2 decoding
 * is a work in progress, although it works within a limited test range. Throughout the 
 * source code, citations are made in cases where an understanding of the code would be
 * helped by looking at an outside source. The format I have chosen is 
 * (cite NUM#, LOOKUP_INFO). NUM=1 refers to ISO/IEC: 13818-2, and NUM=2 refers to the reference
 * MPEG implementation written in C, available at [www.mpeg.org].
 *
 * @author <a href="mailto:madrake@gmail.com">Matthew Drake</a>
 * @file ZigZag.str
 * @version 1.0
 */

/**
 * @internal
 */
int->int filter ZigZagUnordering {
    work pop 64 push 64 {
        for (int i = 0; i < 64; i++) {
            push(peek(ZigZagUnorder[i]));
        }
        for (int i = 0; i < 64; i++) {
            pop();
        }
    }
}

/**
 * @internal
 */
int->int filter ZigZagOrdering {
    int[64] Ordering = {00, 01, 08, 16, 09, 02, 03, 10,
                        17, 24, 32, 25, 18, 11, 04, 05,
                        12, 19, 26, 33, 40, 48, 41, 34,
                        27, 20, 13, 06, 07, 14, 21, 28,
                        35, 42, 49, 56, 57, 50, 43, 36,
                        29, 22, 15, 23, 30, 37, 44, 51,
                        58, 59, 52, 45, 38, 31, 39, 46,
                        53, 60, 61, 54, 47, 55, 62, 63};
    work pop 64 push 64 {
        for (int i = 0; i < 64; i++) {
            push(peek(Ordering[i]));
        }
        for (int i = 0; i < 64; i++) {
            pop();
        }
    }
}