/*

 * RLE encoder

 * Copyright (c) 2007 Bobby Bingham

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include <string.h>

#include "libavutil/macros.h"

#include "rle.h"

int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same)

{

    const uint8_t *pos;

    int count = 1;

    for (pos = start + bpp; count < FFMIN(127, len); pos += bpp, count++) {

        if (same != !memcmp(pos - bpp, pos, bpp)) {

            if (!same) {

                /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a

                 * single raw block of pixels. For larger bpp, RLE is as good

                 * or better */

                if (bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos + 1))

                    continue;

                /* if RLE can encode the next block better than as a raw block,

                 * back up and leave _all_ the identical pixels for RLE */

                count--;

            }

            break;

        }

    }

    return count;

}

int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr, int bpp,

                  int w, int add_rep, int xor_rep, int add_raw, int xor_raw)

{

    int count, x;

    uint8_t *out = outbuf;

    for (x = 0; x < w; x += count) {

        /* see if we can encode the next set of pixels with RLE */

        if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) {

            if (out + bpp + 1 > outbuf + out_size)

                return -1;

            *out++ = (count ^ xor_rep) + add_rep;

            memcpy(out, ptr, bpp);

            out += bpp;

        } else {

            /* fall back on uncompressed */

            count = ff_rle_count_pixels(ptr, w - x, bpp, 0);

            if (out + bpp * count >= outbuf + out_size)

                return -1;

            *out++ = (count ^ xor_raw) + add_raw;

            memcpy(out, ptr, bpp * count);

            out += bpp * count;

        }

        ptr += count * bpp;

    }

    return out - outbuf;

}