text: /*
   * American Laser Games MM Video Decoder
   * Copyright (c) 2006,2008 Peter Ross
   *
   * 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
   * American Laser Games MM Video Decoder
   * by Peter Ross (pross@xvid.org)
   *
   * The MM format was used by IBM-PC ports of ALG's "arcade shooter" games,
   * including Mad Dog McCree and Crime Patrol.
   *
   * Technical details here:
   *  http://wiki.multimedia.cx/index.php?title=American_Laser_Games_MM
   */
  
  #include "libavutil/intreadwrite.h"
  #include "avcodec.h"
  #include "bytestream.h"
  
  #define MM_PREAMBLE_SIZE    6
  
  #define MM_TYPE_INTER       0x5
  #define MM_TYPE_INTRA       0x8
  #define MM_TYPE_INTRA_HH    0xc
  #define MM_TYPE_INTER_HH    0xd
  #define MM_TYPE_INTRA_HHV   0xe
  #define MM_TYPE_INTER_HHV   0xf
  #define MM_TYPE_PALETTE     0x31
  
  typedef struct MmContext {
      AVCodecContext *avctx;
      AVFrame frame;
      int palette[AVPALETTE_COUNT];
      GetByteContext gb;
  } MmContext;
  
  static av_cold int mm_decode_init(AVCodecContext *avctx)
  {
      MmContext *s = avctx->priv_data;
  
      s->avctx = avctx;
  
      avctx->pix_fmt = AV_PIX_FMT_PAL8;
  
      avcodec_get_frame_defaults(&s->frame);
      s->frame.reference = 3;
  
      return 0;
  }
  
  static int mm_decode_pal(MmContext *s)
  {
      int i;
  
      bytestream2_skip(&s->gb, 4);
      for (i = 0; i < 128; i++) {
          s->palette[i] = 0xFFU << 24 | bytestream2_get_be24(&s->gb);
          s->palette[i+128] = s->palette[i]<<2;
      }
  
      return 0;
  }
  
  /**
   * @param half_horiz Half horizontal resolution (0 or 1)
   * @param half_vert Half vertical resolution (0 or 1)
   */
  static int mm_decode_intra(MmContext * s, int half_horiz, int half_vert)
  {
      int x = 0, y = 0;
  
      while (bytestream2_get_bytes_left(&s->gb) > 0) {
          int run_length, color;
  
          if (y >= s->avctx->height)
              return 0;
  
          color = bytestream2_get_byte(&s->gb);
          if (color & 0x80) {
              run_length = 1;
          }else{
              run_length = (color & 0x7f) + 2;
              color = bytestream2_get_byte(&s->gb);
          }
  
          if (half_horiz)
              run_length *=2;
  
          if (run_length > s->avctx->width - x)
              return AVERROR_INVALIDDATA;
  
          if (color) {
              memset(s->frame.data[0] + y*s->frame.linesize[0] + x, color, run_length);
              if (half_vert)
                  memset(s->frame.data[0] + (y+1)*s->frame.linesize[0] + x, color, run_length);
          }
          x+= run_length;
  
          if (x >= s->avctx->width) {
              x=0;
              y += 1 + half_vert;
          }
      }
  
      return 0;
  }
  
  /**
   * @param half_horiz Half horizontal resolution (0 or 1)
   * @param half_vert Half vertical resolution (0 or 1)
   */
  static int mm_decode_inter(MmContext * s, int half_horiz, int half_vert)
  {
      int data_off = bytestream2_get_le16(&s->gb), y = 0;
      GetByteContext data_ptr;
  
      if (bytestream2_get_bytes_left(&s->gb) < data_off)
          return AVERROR_INVALIDDATA;
  
      bytestream2_init(&data_ptr, s->gb.buffer + data_off, bytestream2_get_bytes_left(&s->gb) - data_off);
      while (s->gb.buffer < data_ptr.buffer_start) {
          int i, j;
          int length = bytestream2_get_byte(&s->gb);
          int x = bytestream2_get_byte(&s->gb) + ((length & 0x80) << 1);
          length &= 0x7F;
  
          if (length==0) {
              y += x;
              continue;
          }
  
          if (y + half_vert >= s->avctx->height)
              return 0;
  
          for(i=0; i<length; i++) {
              int replace_array = bytestream2_get_byte(&s->gb);
              for(j=0; j<8; j++) {
                  int replace = (replace_array >> (7-j)) & 1;
                  if (x + half_horiz >= s->avctx->width)
                      return AVERROR_INVALIDDATA;
                  if (replace) {
                      int color = bytestream2_get_byte(&data_ptr);
                      s->frame.data[0][y*s->frame.linesize[0] + x] = color;
                      if (half_horiz)
                          s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;
                      if (half_vert) {
                          s->frame.data[0][(y+1)*s->frame.linesize[0] + x] = color;
                          if (half_horiz)
                              s->frame.data[0][(y+1)*s->frame.linesize[0] + x + 1] = color;
                      }
                  }
                  x += 1 + half_horiz;
              }
          }
  
          y += 1 + half_vert;
      }
  
      return 0;
  }
  
  static int mm_decode_frame(AVCodecContext *avctx,
                              void *data, int *got_frame,
                              AVPacket *avpkt)
  {
      const uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      MmContext *s = avctx->priv_data;
      int type, res;
  
      if (buf_size < MM_PREAMBLE_SIZE)
          return AVERROR_INVALIDDATA;
      type = AV_RL16(&buf[0]);
      buf += MM_PREAMBLE_SIZE;
      buf_size -= MM_PREAMBLE_SIZE;
      bytestream2_init(&s->gb, buf, buf_size);
  
      if ((res = avctx->reget_buffer(avctx, &s->frame)) < 0) {
          av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
          return res;
      }
  
      switch(type) {
      case MM_TYPE_PALETTE   : res = mm_decode_pal(s); return avpkt->size;
      case MM_TYPE_INTRA     : res = mm_decode_intra(s, 0, 0); break;
      case MM_TYPE_INTRA_HH  : res = mm_decode_intra(s, 1, 0); break;
      case MM_TYPE_INTRA_HHV : res = mm_decode_intra(s, 1, 1); break;
      case MM_TYPE_INTER     : res = mm_decode_inter(s, 0, 0); break;
      case MM_TYPE_INTER_HH  : res = mm_decode_inter(s, 1, 0); break;
      case MM_TYPE_INTER_HHV : res = mm_decode_inter(s, 1, 1); break;
      default:
          res = AVERROR_INVALIDDATA;
          break;
      }
      if (res < 0)
          return res;
  
      memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
  
      *got_frame      = 1;
      *(AVFrame*)data = s->frame;
  
      return avpkt->size;
  }
  
  static av_cold int mm_decode_end(AVCodecContext *avctx)
  {
      MmContext *s = avctx->priv_data;
  
      if(s->frame.data[0])
          avctx->release_buffer(avctx, &s->frame);
  
      return 0;
  }
  
  AVCodec ff_mmvideo_decoder = {
      .name           = "mmvideo",
      .type           = AVMEDIA_TYPE_VIDEO,
      .id             = AV_CODEC_ID_MMVIDEO,
      .priv_data_size = sizeof(MmContext),
      .init           = mm_decode_init,
      .close          = mm_decode_end,
      .decode         = mm_decode_frame,
      .capabilities   = CODEC_CAP_DR1,
      .long_name      = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),
  };
  