/*
  * 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/internal.h"

 #include "libavutil/intreadwrite.h"

 #include "libavutil/mem.h"

 #include "avcodec.h"

 #include "internal.h"

 
 
 #define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
 
 typedef struct Rl2Context {
     AVCodecContext *avctx;
 

     uint16_t video_base;  ///< initial drawing offset
     uint32_t clr_count;   ///< number of used colors (currently unused)
     uint8_t *back_frame;  ///< background frame
     uint32_t 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 output 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 uint8_t *in, int size,
                                uint8_t *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 uint8_t *back_frame = s->back_frame;

     const uint8_t *in_end     = in + size;
     const uint8_t *out_end    = out + stride * s->avctx->height;

     uint8_t *line_end;

 
     /** 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) {

         uint8_t 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 = AV_PIX_FMT_PAL8;

 
     /** parse extra data */

     if (!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE) {

         av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");

         return AVERROR(EINVAL);

     }
 
     /** 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 AVERROR_INVALIDDATA;

     }
 
     /** initialize palette */

     for (i = 0; i < AVPALETTE_COUNT; i++)

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

 
     /** decode background frame if present */
     back_size = avctx->extradata_size - EXTRADATA1_SIZE;
 

     if (back_size > 0) {

         uint8_t *back_frame = av_mallocz(avctx->width*avctx->height);

         if (!back_frame)

             return AVERROR(ENOMEM);

         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 *got_frame,
                             AVPacket *avpkt)

 {

     AVFrame *frame     = data;

     const uint8_t *buf = avpkt->data;

     int ret, buf_size  = avpkt->size;

     Rl2Context *s = avctx->priv_data;
 

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

         return ret;

 
     /** run length decode */

     rl2_rle_decode(s, buf, buf_size, frame->data[0], frame->linesize[0],

                    s->video_base);

 
     /** make the palette available on the way out */

     memcpy(frame->data[1], s->palette, AVPALETTE_SIZE);

     *got_frame = 1;

 
     /** 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;
 

     av_freep(&s->back_frame);

 
     return 0;
 }
 
 

 AVCodec ff_rl2_decoder = {

     .name           = "rl2",

     .long_name      = NULL_IF_CONFIG_SMALL("RL2 video"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_RL2,

     .priv_data_size = sizeof(Rl2Context),
     .init           = rl2_decode_init,
     .close          = rl2_decode_end,
     .decode         = rl2_decode_frame,

     .capabilities   = AV_CODEC_CAP_DR1,

 };