/*
  * Bethesda VID video decoder
  * Copyright (C) 2007 Nicholas Tung
  *
  * 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

  * @brief Bethesda Softworks VID Video Decoder
  * @author Nicholas Tung [ntung (at. ntung com] (2007-03)
  * @sa http://wiki.multimedia.cx/index.php?title=Bethsoft_VID
  * @sa http://www.svatopluk.com/andux/docs/dfvid.html
  */
 

 #include "libavutil/common.h"

 #include "dsputil.h"
 #include "bethsoftvideo.h"
 #include "bytestream.h"
 
 typedef struct BethsoftvidContext {
     AVFrame frame;
 } BethsoftvidContext;
 

 static av_cold int bethsoftvid_decode_init(AVCodecContext *avctx)

 {
     BethsoftvidContext *vid = avctx->priv_data;

     avcodec_get_frame_defaults(&vid->frame);

     vid->frame.reference = 1;
     vid->frame.buffer_hints = FF_BUFFER_HINTS_VALID |
         FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;

     avctx->pix_fmt = PIX_FMT_PAL8;

     return 0;
 }
 

 static void set_palette(AVFrame * frame, const uint8_t * palette_buffer)

 {
     uint32_t * palette = (uint32_t *)frame->data[1];
     int a;

     for(a = 0; a < 256; a++){

         palette[a] = AV_RB24(&palette_buffer[a * 3]) * 4;

     }
     frame->palette_has_changed = 1;
 }
 
 static int bethsoftvid_decode_frame(AVCodecContext *avctx,
                               void *data, int *data_size,

                               AVPacket *avpkt)

 {

     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

     BethsoftvidContext * vid = avctx->priv_data;
     char block_type;

     uint8_t * dst;

     uint8_t * frame_end;

     int remaining = avctx->width;          // number of bytes remaining on a line

     const int wrap_to_next_line = vid->frame.linesize[0] - avctx->width;

     int code;

     int yoffset;
 
     if (avctx->reget_buffer(avctx, &vid->frame)) {
         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
         return -1;
     }

     dst = vid->frame.data[0];

     frame_end = vid->frame.data[0] + vid->frame.linesize[0] * avctx->height;
 

     switch(block_type = *buf++){
         case PALETTE_BLOCK:
             set_palette(&vid->frame, buf);
             return 0;

         case VIDEO_YOFF_P_FRAME:

             yoffset = bytestream_get_le16(&buf);

             if(yoffset >= avctx->height)
                 return -1;

             dst += vid->frame.linesize[0] * yoffset;

     }
 
     // main code

     while((code = *buf++)){
         int length = code & 0x7f;

 
         // copy any bytes starting at the current position, and ending at the frame width

         while(length > remaining){
             if(code < 0x80)
                 bytestream_get_buffer(&buf, dst, remaining);

             else if(block_type == VIDEO_I_FRAME)

                 memset(dst, buf[0], remaining);
             length -= remaining;      // decrement the number of bytes to be copied
             dst += remaining + wrap_to_next_line;    // skip over extra bytes at end of frame
             remaining = avctx->width;
             if(dst == frame_end)

                 goto end;

         }
 
         // copy any remaining bytes after / if line overflows

         if(code < 0x80)
             bytestream_get_buffer(&buf, dst, length);

         else if(block_type == VIDEO_I_FRAME)

             memset(dst, *buf++, length);
         remaining -= length;
         dst += length;

     }
     end:
 
     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = vid->frame;
 
     return buf_size;
 }
 

 static av_cold int bethsoftvid_decode_end(AVCodecContext *avctx)

 {
     BethsoftvidContext * vid = avctx->priv_data;

     if(vid->frame.data[0])
         avctx->release_buffer(avctx, &vid->frame);

     return 0;
 }
 

 AVCodec ff_bethsoftvid_decoder = {

     .name = "bethsoftvid",

     .type = AVMEDIA_TYPE_VIDEO,

     .id = CODEC_ID_BETHSOFTVID,
     .priv_data_size = sizeof(BethsoftvidContext),
     .init = bethsoftvid_decode_init,
     .close = bethsoftvid_decode_end,
     .decode = bethsoftvid_decode_frame,

     .capabilities = CODEC_CAP_DR1,

     .long_name = NULL_IF_CONFIG_SMALL("Bethesda VID video"),

 };