/*
  * 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,
 };