/*

 * RL2 Video Decoder

 * Copyright (C) 2008 Sascha Sommer (saschasommer@freenet.de)

 *

 * 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

 */

/**

 * @file

 * RL2 Video Decoder

 * @author Sascha Sommer (saschasommer@freenet.de)

 * @see http://wiki.multimedia.cx/index.php?title=RL2

 */

#include <string.h>

#include "libavutil/internal.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/mem.h"

#include "avcodec.h"

#include "codec_internal.h"

#include "decode.h"

#define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette

typedef struct Rl2Context {

    AVCodecContext *avctx;

    uint16_t video_base;  ///< initial drawing offset

    uint32_t clr_count;   ///< number of used colors (currently unused)

    uint8_t *back_frame;  ///< background frame

    uint32_t palette[AVPALETTE_COUNT];

} Rl2Context;

/**

 * Run Length Decode a single 320x200 frame

 * @param s rl2 context

 * @param in input buffer

 * @param size input buffer size

 * @param out output buffer

 * @param stride stride of the output buffer

 * @param video_base offset of the rle data inside the frame

 */

static void rl2_rle_decode(Rl2Context *s, const uint8_t *in, int size,

                           uint8_t *out, ptrdiff_t stride, int video_base)

{

    int base_x = video_base % s->avctx->width;

    int base_y = video_base / s->avctx->width;

    ptrdiff_t stride_adj = stride - s->avctx->width;

    const uint8_t *back_frame = s->back_frame;

    const uint8_t *in_end     = in + size;

    const uint8_t *out_end    = out + stride * s->avctx->height - stride_adj;

    uint8_t *line_end;

    /** copy start of the background frame */

    if (s->back_frame) {

        for (int i = 0; i <= base_y; i++) {

            memcpy(out, back_frame, s->avctx->width);

            out        += stride;

            back_frame += s->avctx->width;

        }

        back_frame += base_x - s->avctx->width;

    } else {

        out += stride * (base_y + 1);

    }

    line_end    = out - stride_adj;

    out        += base_x - stride;

    /** decode the variable part of the frame */

    while (in < in_end) {

        uint8_t val = *in++;

        int len     = 1;

        if (val >= 0x80) {

            if (in >= in_end)

                break;

            len = *in++;

            if (!len)

                break;

            val &= 0x7F;

        }

        if (back_frame) {

            if (!val) {

                do {

                    size_t copy = FFMIN(line_end - out, len);

                    memcpy(out, back_frame, copy);

                    out        += copy;

                    back_frame += copy;

                    len        -= copy;

                    if (out == line_end) {

                        if (out == out_end)

                            return;

                        out      += stride_adj;

                        line_end += stride;

                    }

                } while (len > 0);

                continue;

            }

            back_frame += len;

            val |= 0x80;

        }

        while (len--) {

            *out++ = val;

            if (out == line_end) {

                if (out == out_end)

                    return;

                out      += stride_adj;

                line_end += stride;

            }

        }

    }

    /** copy the rest from the background frame */

    if (s->back_frame) {

        while (1) {

            memcpy(out, back_frame, line_end - out);

            if (line_end == out_end)

                break;

            back_frame += line_end - out;

            out         = line_end + stride_adj;

            line_end   += stride;

        }

    }

}

/**

 * Initialize the decoder

 * @param avctx decoder context

 * @return 0 success, -1 on error

 */

static av_cold int rl2_decode_init(AVCodecContext *avctx)

{

    Rl2Context *s = avctx->priv_data;

    int back_size;

    int i;

    int ret;

    s->avctx       = avctx;

    avctx->pix_fmt = AV_PIX_FMT_PAL8;

    ret = ff_set_dimensions(avctx, 320, 200);

    if (ret < 0)

        return ret;

    /** parse extra data */

    if (!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE) {

        av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");

        return AVERROR(EINVAL);

    }

    /** get frame_offset */

    s->video_base = AV_RL16(&avctx->extradata[0]);

    s->clr_count  = AV_RL32(&avctx->extradata[2]);

    if (s->video_base >= avctx->width * avctx->height) {

        av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");

        return AVERROR_INVALIDDATA;

    }

    /** initialize palette */

    for (i = 0; i < AVPALETTE_COUNT; i++)

        s->palette[i] = 0xFFU << 24 | AV_RB24(&avctx->extradata[6 + i * 3]);

    /** decode background frame if present */

    back_size = avctx->extradata_size - EXTRADATA1_SIZE;

    if (back_size > 0) {

        /* The 254 are padding to ensure that pointer arithmetic stays within

         * the buffer. */

        uint8_t *back_frame = av_mallocz(avctx->width * avctx->height + 254);

        if (!back_frame)

            return AVERROR(ENOMEM);

        rl2_rle_decode(s, avctx->extradata + EXTRADATA1_SIZE, back_size,

                       back_frame, avctx->width, 0);

        s->back_frame = back_frame;

    }

    return 0;

}

static int rl2_decode_frame(AVCodecContext *avctx, AVFrame *frame,

                            int *got_frame, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int ret, buf_size  = avpkt->size;

    Rl2Context *s = avctx->priv_data;

    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

        return ret;

    /** run length decode */

    rl2_rle_decode(s, buf, buf_size, frame->data[0], frame->linesize[0],

                   s->video_base);

    /** make the palette available on the way out */

    memcpy(frame->data[1], s->palette, AVPALETTE_SIZE);

    *got_frame = 1;

    /** report that the buffer was completely consumed */

    return buf_size;

}

/**

 * Uninit decoder

 * @param avctx decoder context

 * @return 0 success, -1 on error

 */

static av_cold int rl2_decode_end(AVCodecContext *avctx)

{

    Rl2Context *s = avctx->priv_data;

    av_freep(&s->back_frame);

    return 0;

}

const FFCodec ff_rl2_decoder = {

    .p.name         = "rl2",

    CODEC_LONG_NAME("RL2 video"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_RL2,

    .priv_data_size = sizeof(Rl2Context),

    .init           = rl2_decode_init,

    .close          = rl2_decode_end,

    FF_CODEC_DECODE_CB(rl2_decode_frame),

    .p.capabilities = AV_CODEC_CAP_DR1,

};