/*

 * AVS video decoder.

 * Copyright (c) 2006  Aurelien Jacobs <aurel@gnuage.org>

 *

 * 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 "avcodec.h"

#include "codec_internal.h"

#include "decode.h"

#include "get_bits.h"

#include "libavutil/attributes.h"

typedef struct AvsContext {

    AVFrame *frame;

} AvsContext;

typedef enum {

    AVS_VIDEO     = 0x01,

    AVS_AUDIO     = 0x02,

    AVS_PALETTE   = 0x03,

    AVS_GAME_DATA = 0x04,

} AvsBlockType;

typedef enum {

    AVS_I_FRAME     = 0x00,

    AVS_P_FRAME_3X3 = 0x01,

    AVS_P_FRAME_2X2 = 0x02,

    AVS_P_FRAME_2X3 = 0x03,

} AvsVideoSubType;

static int avs_decode_frame(AVCodecContext * avctx, AVFrame *picture,

                            int *got_frame, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    const uint8_t *buf_end = avpkt->data + avpkt->size;

    int buf_size = avpkt->size;

    AvsContext *const avs = avctx->priv_data;

    AVFrame *const p =  avs->frame;

    const uint8_t *table, *vect;

    uint8_t *out;

    int i, j, x, y, stride, ret, vect_w = 3, vect_h = 3;

    AvsVideoSubType sub_type;

    AvsBlockType type;

    GetBitContext change_map = {0}; //init to silence warning

    if ((ret = ff_reget_buffer(avctx, p, 0)) < 0)

        return ret;

    p->pict_type = AV_PICTURE_TYPE_P;

    p->flags &= ~AV_FRAME_FLAG_KEY;

    out    = p->data[0];

    stride = p->linesize[0];

    if (buf_end - buf < 4)

        return AVERROR_INVALIDDATA;

    sub_type = buf[0];

    type = buf[1];

    buf += 4;

    if (type == AVS_PALETTE) {

        int first, last;

        uint32_t *pal = (uint32_t *) p->data[1];

        first = AV_RL16(buf);

        last = first + AV_RL16(buf + 2);

        if (first >= 256 || last > 256 || buf_end - buf < 4 + 4 + 3 * (last - first))

            return AVERROR_INVALIDDATA;

        buf += 4;

        for (i=first; i<last; i++, buf+=3) {

            pal[i] = (buf[0] << 18) | (buf[1] << 10) | (buf[2] << 2);

            pal[i] |= 0xFFU << 24 | (pal[i] >> 6) & 0x30303;

        }

        sub_type = buf[0];

        type = buf[1];

        buf += 4;

    }

    if (type != AVS_VIDEO)

        return AVERROR_INVALIDDATA;

    switch (sub_type) {

    case AVS_I_FRAME:

        p->pict_type = AV_PICTURE_TYPE_I;

        p->flags |= AV_FRAME_FLAG_KEY;

        av_fallthrough;

    case AVS_P_FRAME_3X3:

        vect_w = 3;

        vect_h = 3;

        break;

    case AVS_P_FRAME_2X2:

        vect_w = 2;

        vect_h = 2;

        break;

    case AVS_P_FRAME_2X3:

        vect_w = 2;

        vect_h = 3;

        break;

    default:

      return AVERROR_INVALIDDATA;

    }

    if (buf_end - buf < 256 * vect_w * vect_h)

        return AVERROR_INVALIDDATA;

    table = buf + (256 * vect_w * vect_h);

    if (sub_type != AVS_I_FRAME) {

        int map_size = ((318 / vect_w + 7) / 8) * (198 / vect_h);

        if (buf_end - table < map_size)

            return AVERROR_INVALIDDATA;

        init_get_bits(&change_map, table, map_size * 8);

        table += map_size;

    }

    for (y=0; y<198; y+=vect_h) {

        for (x=0; x<318; x+=vect_w) {

            if (sub_type == AVS_I_FRAME || get_bits1(&change_map)) {

                if (buf_end - table < 1)

                    return AVERROR_INVALIDDATA;

                vect = &buf[*table++ * (vect_w * vect_h)];

                for (j=0; j<vect_w; j++) {

                    out[(y + 0) * stride + x + j] = vect[(0 * vect_w) + j];

                    out[(y + 1) * stride + x + j] = vect[(1 * vect_w) + j];

                    if (vect_h == 3)

                        out[(y + 2) * stride + x + j] =

                            vect[(2 * vect_w) + j];

                }

            }

        }

        if (sub_type != AVS_I_FRAME)

            align_get_bits(&change_map);

    }

    if ((ret = av_frame_ref(picture, p)) < 0)

        return ret;

    *got_frame = 1;

    return buf_size;

}

static av_cold int avs_decode_init(AVCodecContext * avctx)

{

    AvsContext *s = avctx->priv_data;

    s->frame = av_frame_alloc();

    if (!s->frame)

        return AVERROR(ENOMEM);

    avctx->pix_fmt = AV_PIX_FMT_PAL8;

    return ff_set_dimensions(avctx, 318, 198);

}

static av_cold int avs_decode_end(AVCodecContext *avctx)

{

    AvsContext *s = avctx->priv_data;

    av_frame_free(&s->frame);

    return 0;

}

const FFCodec ff_avs_decoder = {

    .p.name         = "avs",

    CODEC_LONG_NAME("AVS (Audio Video Standard) video"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_AVS,

    .priv_data_size = sizeof(AvsContext),

    .init           = avs_decode_init,

    FF_CODEC_DECODE_CB(avs_decode_frame),

    .close          = avs_decode_end,

    .p.capabilities = AV_CODEC_CAP_DR1,

};