/*
  * 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 <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 

 #include "libavutil/intreadwrite.h"

 #include "avcodec.h"
 
 
 #define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
 
 typedef struct Rl2Context {
     AVCodecContext *avctx;
     AVFrame frame;
 
     unsigned short video_base; ///< initial drawing offset
     unsigned int clr_count;    ///< number of used colors (currently unused)
     unsigned char* back_frame; ///< background frame
     unsigned int 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 ouput 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 unsigned char* in,int size,
                                unsigned char* out,int stride,int video_base){
     int base_x = video_base % s->avctx->width;
     int base_y = video_base / s->avctx->width;
     int stride_adj = stride - s->avctx->width;
     int i;
     const unsigned char* back_frame = s->back_frame;
     const unsigned char* in_end = in + size;
     const unsigned char* out_end = out + stride * s->avctx->height;
     unsigned char* line_end = out + s->avctx->width;
 
     /** copy start of the background frame */
     for(i=0;i<=base_y;i++){
         if(s->back_frame)
             memcpy(out,back_frame,s->avctx->width);
         out += stride;
         back_frame += s->avctx->width;
     }
     back_frame += base_x - s->avctx->width;
     line_end = out - stride_adj;
     out += base_x - stride;
 
     /** decode the variable part of the frame */
     while(in < in_end){
         unsigned char val = *in++;
         int len = 1;
         if(val >= 0x80){
             if(in >= in_end)
                 break;
             len = *in++;
             if(!len)
                 break;
         }
 
         if(len >= out_end - out)
             break;
 
         if(s->back_frame)
             val |= 0x80;
         else
             val &= ~0x80;
 
         while(len--){
             *out++ = (val == 0x80)? *back_frame:val;
             back_frame++;
             if(out == line_end){
                  out += stride_adj;
                  line_end += stride;
                  if(len >= out_end - out)
                      break;
             }
         }
     }
 
     /** copy the rest from the background frame */
     if(s->back_frame){
         while(out < out_end){
             memcpy(out, back_frame, line_end - out);
             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;
     s->avctx = avctx;
     avctx->pix_fmt = PIX_FMT_PAL8;

     avcodec_get_frame_defaults(&s->frame);

 
     /** parse extra data */
     if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
         av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
         return -1;
     }
 
     /** 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 -1;
     }
 
     /** initialize palette */
     for(i=0;i<AVPALETTE_COUNT;i++)

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

 
     /** decode background frame if present */
     back_size = avctx->extradata_size - EXTRADATA1_SIZE;
 
     if(back_size > 0){
         unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
         if(!back_frame)
             return -1;
         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,
                               void *data, int *data_size,

                               AVPacket *avpkt)

 {

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

     Rl2Context *s = avctx->priv_data;
 
     if(s->frame.data[0])
         avctx->release_buffer(avctx, &s->frame);
 
     /** get buffer */
     s->frame.reference= 0;
     if(avctx->get_buffer(avctx, &s->frame)) {
         av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return -1;
     }
 
     /** run length decode */
     rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
 
     /** make the palette available on the way out */
     memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
 
     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = s->frame;
 
     /** 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;
 
     if(s->frame.data[0])
         avctx->release_buffer(avctx, &s->frame);
 
     av_free(s->back_frame);
 
     return 0;
 }
 
 

 AVCodec ff_rl2_decoder = {

     .name           = "rl2",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = CODEC_ID_RL2,
     .priv_data_size = sizeof(Rl2Context),
     .init           = rl2_decode_init,
     .close          = rl2_decode_end,
     .decode         = rl2_decode_frame,
     .capabilities   = CODEC_CAP_DR1,

     .long_name = NULL_IF_CONFIG_SMALL("RL2 video"),

 };