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/*

 * VBLE Decoder

 * Copyright (c) 2011 Derek Buitenhuis

 *

 * 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

 * VBLE Decoder

 */

#define BITSTREAM_READER_LE

#include "avcodec.h"

#include "dsputil.h"

#include "get_bits.h"

#include "internal.h"

#include "mathops.h"

typedef struct {

    AVCodecContext *avctx;

    DSPContext dsp;

    int            size;

    uint8_t        *val; ///< This array first holds the lengths of vlc symbols and then their value.

} VBLEContext;

static int vble_unpack(VBLEContext *ctx, GetBitContext *gb)

{

    int i;

    int allbits = 0;

    static const uint8_t LUT[256] = {

        8,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

        6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

        7,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

        6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

        5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,

    };

    /* Read all the lengths in first */

    for (i = 0; i < ctx->size; i++) {

        /* At most we need to read 9 bits total to get indices up to 8 */

        int val = show_bits(gb, 8);

        // read reverse unary

        if (val) {

            val = LUT[val];

            skip_bits(gb, val + 1);

            ctx->val[i] = val;

        } else {

            skip_bits(gb, 8);

            if (!get_bits1(gb))

                return -1;

            ctx->val[i] = 8;

        }

        allbits += ctx->val[i];

    }

    /* Check we have enough bits left */

    if (get_bits_left(gb) < allbits)

        return -1;

    return 0;

}

static void vble_restore_plane(VBLEContext *ctx, AVFrame *pic,

                               GetBitContext *gb, int plane,

                               int offset, int width, int height)

{

    uint8_t *dst = pic->data[plane];

    uint8_t *val = ctx->val + offset;

    int stride = pic->linesize[plane];

    int i, j, left, left_top;

    for (i = 0; i < height; i++) {

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

            /* get_bits can't take a length of 0 */

            if (val[j]) {

                int v = (1 << val[j]) + get_bits(gb, val[j]) - 1;

                val[j] = (v >> 1) ^ -(v & 1);

            }

        }

        if (i) {

            left = 0;

            left_top = dst[-stride];

            ctx->dsp.add_hfyu_median_prediction(dst, dst-stride, val, width, &left, &left_top);

        } else {

            dst[0] = val[0];

            for (j = 1; j < width; j++)

                dst[j] = val[j] + dst[j - 1];

        }

        dst += stride;

        val += width;

    }

}

static int vble_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

                             AVPacket *avpkt)

{

    VBLEContext *ctx = avctx->priv_data;

    AVFrame *pic     = data;

    GetBitContext gb;

    const uint8_t *src = avpkt->data;

    int version;

    int offset = 0;

    int width_uv = avctx->width / 2, height_uv = avctx->height / 2;

    int ret;

    if (avpkt->size < 4 || avpkt->size - 4 > INT_MAX/8) {

        av_log(avctx, AV_LOG_ERROR, "Invalid packet size\n");

        return AVERROR_INVALIDDATA;

    }

    /* Allocate buffer */

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

        return ret;

    /* Set flags */

    pic->key_frame = 1;

    pic->pict_type = AV_PICTURE_TYPE_I;

    /* Version should always be 1 */

    version = AV_RL32(src);

    if (version != 1)

        av_log(avctx, AV_LOG_WARNING, "Unsupported VBLE Version: %d\n", version);

    init_get_bits(&gb, src + 4, (avpkt->size - 4) * 8);

    /* Unpack */

    if (vble_unpack(ctx, &gb) < 0) {

        av_log(avctx, AV_LOG_ERROR, "Invalid Code\n");

        return AVERROR_INVALIDDATA;

    }

    /* Restore planes. Should be almost identical to Huffyuv's. */

    vble_restore_plane(ctx, pic, &gb, 0, offset, avctx->width, avctx->height);

    /* Chroma */

    if (!(ctx->avctx->flags & CODEC_FLAG_GRAY)) {

        offset += avctx->width * avctx->height;

        vble_restore_plane(ctx, pic, &gb, 1, offset, width_uv, height_uv);

        offset += width_uv * height_uv;

        vble_restore_plane(ctx, pic, &gb, 2, offset, width_uv, height_uv);

    }

    *got_frame       = 1;

    return avpkt->size;

}

static av_cold int vble_decode_close(AVCodecContext *avctx)

{

    VBLEContext *ctx = avctx->priv_data;

    av_freep(&ctx->val);

    return 0;

}

static av_cold int vble_decode_init(AVCodecContext *avctx)

{

    VBLEContext *ctx = avctx->priv_data;

    /* Stash for later use */

    ctx->avctx = avctx;

    ff_dsputil_init(&ctx->dsp, avctx);

    avctx->pix_fmt = AV_PIX_FMT_YUV420P;

    avctx->bits_per_raw_sample = 8;

    ctx->size = avpicture_get_size(avctx->pix_fmt,

                                   avctx->width, avctx->height);

    ctx->val = av_malloc(ctx->size * sizeof(*ctx->val));

    if (!ctx->val) {

        av_log(avctx, AV_LOG_ERROR, "Could not allocate values buffer.\n");

        vble_decode_close(avctx);

        return AVERROR(ENOMEM);

    }

    return 0;

}

AVCodec ff_vble_decoder = {

    .name           = "vble",

    .long_name      = NULL_IF_CONFIG_SMALL("VBLE Lossless Codec"),

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_VBLE,

    .priv_data_size = sizeof(VBLEContext),

    .init           = vble_decode_init,

    .close          = vble_decode_close,

    .decode         = vble_decode_frame,

    .capabilities   = CODEC_CAP_DR1,

};