text: /*
   * CDToons video decoder
   * Copyright (C) 2020 Alyssa Milburn <amilburn@zall.org>
   *
   * 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
   * CDToons video decoder
   * @author Alyssa Milburn <amilburn@zall.org>
   */
  
  #include <stdint.h>
  
  #include "libavutil/attributes.h"
  #include "libavutil/internal.h"
  #include "avcodec.h"
  #include "bytestream.h"
  #include "internal.h"
  
  #define CDTOONS_HEADER_SIZE   44
  #define CDTOONS_MAX_SPRITES 1200
  
  typedef struct CDToonsSprite {
      uint16_t flags;
      uint16_t owner_frame;
      uint16_t start_frame;
      uint16_t end_frame;
      unsigned int alloc_size;
      uint32_t size;
      uint8_t *data;
      int      active;
  } CDToonsSprite;
  
  typedef struct CDToonsContext {
      AVFrame *frame;
  
      uint16_t last_pal_id;   ///< The index of the active palette sprite.
      uint32_t pal[256];      ///< The currently-used palette data.
      CDToonsSprite sprites[CDTOONS_MAX_SPRITES];
  } CDToonsContext;
  
  static int cdtoons_render_sprite(AVCodecContext *avctx, const uint8_t *data,
                                   uint32_t data_size,
                                   int dst_x, int dst_y, int width, int height)
  {
      CDToonsContext *c = avctx->priv_data;
      const uint8_t *next_line = data;
      const uint8_t *end = data + data_size;
      uint16_t line_size;
      uint8_t *dest;
      int skip = 0, to_skip, x;
  
      if (dst_x + width > avctx->width)
          width = avctx->width - dst_x;
      if (dst_y + height > avctx->height)
          height = avctx->height - dst_y;
  
      if (dst_x < 0) {
          /* we need to skip the start of the scanlines */
          skip = -dst_x;
          if (width <= skip)
              return 0;
          dst_x = 0;
      }
  
      for (int y = 0; y < height; y++) {
          /* one scanline at a time, size is provided */
          data      = next_line;
          if (end - data < 2)
              return 1;
          line_size = bytestream_get_be16(&data);
          if (end - data < line_size)
              return 1;
          next_line = data + line_size;
          if (dst_y + y < 0)
              continue;
  
          dest = c->frame->data[0] + (dst_y + y) * c->frame->linesize[0] + dst_x;
  
          to_skip = skip;
          x       = 0;
          while (x < width - skip) {
              int raw, size, step;
              uint8_t val;
  
              if (data >= end)
                  return 1;
  
              val  = bytestream_get_byte(&data);
              raw  = !(val & 0x80);
              size = (int)(val & 0x7F) + 1;
  
              /* skip the start of a scanline if it is off-screen */
              if (to_skip >= size) {
                  to_skip -= size;
                  if (raw) {
                      step = size;
                  } else {
                      step = 1;
                  }
                  if (next_line - data < step)
                      return 1;
                  data += step;
                  continue;
              } else if (to_skip) {
                  size -= to_skip;
                  if (raw) {
                      if (next_line - data < to_skip)
                          return 1;
                      data += to_skip;
                  }
                  to_skip = 0;
              }
  
              if (x + size >= width - skip)
                  size = width - skip - x;
  
              /* either raw data, or a run of a single color */
              if (raw) {
                  if (next_line - data < size)
                      return 1;
                  memcpy(dest + x, data, size);
                  data += size;
              } else {
                  uint8_t color = bytestream_get_byte(&data);
                  /* ignore transparent runs */
                  if (color)
                      memset(dest + x, color, size);
              }
              x += size;
          }
      }
  
      return 0;
  }
  
  static int cdtoons_decode_frame(AVCodecContext *avctx, void *data,
                                  int *got_frame, AVPacket *avpkt)
  {
      CDToonsContext *c = avctx->priv_data;
      const uint8_t *buf = avpkt->data;
      const uint8_t *eod = avpkt->data + avpkt->size;
      const int buf_size = avpkt->size;
      uint16_t frame_id;
      uint8_t background_color;
      uint16_t sprite_count, sprite_offset;
      uint8_t referenced_count;
      uint16_t palette_id;
      uint8_t palette_set;
      int ret;
      int saw_embedded_sprites = 0;
  
      if (buf_size < CDTOONS_HEADER_SIZE)
          return AVERROR_INVALIDDATA;
  
      if ((ret = ff_reget_buffer(avctx, c->frame, 0)) < 0)
          return ret;
  
      /* a lot of the header is useless junk in the absence of
       * dirty rectangling etc */
      buf               += 2; /* version? (always 9?) */
      frame_id           = bytestream_get_be16(&buf);
      buf               += 2; /* blocks_valid_until */
      buf               += 1;
      background_color   = bytestream_get_byte(&buf);
      buf               += 16; /* clip rect, dirty rect */
      buf               += 4; /* flags */
      sprite_count       = bytestream_get_be16(&buf);
      sprite_offset      = bytestream_get_be16(&buf);
      buf               += 2; /* max block id? */
      referenced_count   = bytestream_get_byte(&buf);
      buf               += 1;
      palette_id         = bytestream_get_be16(&buf);
      palette_set        = bytestream_get_byte(&buf);
      buf               += 5;
  
      if (sprite_offset > buf_size)
          return AVERROR_INVALIDDATA;
  
      /* read new sprites introduced in this frame */
      buf = avpkt->data + sprite_offset;
      while (sprite_count--) {
          uint32_t size;
          uint16_t sprite_id;
  
          if (buf + 14 > eod)
              return AVERROR_INVALIDDATA;
  
          sprite_id = bytestream_get_be16(&buf);
          if (sprite_id >= CDTOONS_MAX_SPRITES) {
              av_log(avctx, AV_LOG_ERROR,
                     "Sprite ID %d is too high.\n", sprite_id);
              return AVERROR_INVALIDDATA;
          }
          if (c->sprites[sprite_id].active) {
              av_log(avctx, AV_LOG_ERROR,
                     "Sprite ID %d is a duplicate.\n", sprite_id);
              return AVERROR_INVALIDDATA;
          }
  
          c->sprites[sprite_id].flags = bytestream_get_be16(&buf);
          size                        = bytestream_get_be32(&buf);
          if (size < 14) {
              av_log(avctx, AV_LOG_ERROR,
                     "Sprite only has %d bytes of data.\n", size);
              return AVERROR_INVALIDDATA;
          }
          size -= 14;
          c->sprites[sprite_id].size        = size;
          c->sprites[sprite_id].owner_frame = frame_id;
          c->sprites[sprite_id].start_frame = bytestream_get_be16(&buf);
          c->sprites[sprite_id].end_frame   = bytestream_get_be16(&buf);
          buf += 2;
  
          if (size > buf_size || buf + size > eod)
              return AVERROR_INVALIDDATA;
  
          av_fast_padded_malloc(&c->sprites[sprite_id].data, &c->sprites[sprite_id].alloc_size, size);
          if (!c->sprites[sprite_id].data)
              return AVERROR(ENOMEM);
  
          c->sprites[sprite_id].active = 1;
  
          bytestream_get_buffer(&buf, c->sprites[sprite_id].data, size);
      }
  
      /* render any embedded sprites */
      while (buf < eod) {
          uint32_t tag, size;
          if (buf + 8 > eod) {
              av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for embedded sprites.\n");
              return AVERROR_INVALIDDATA;
          }
          tag  = bytestream_get_be32(&buf);
          size = bytestream_get_be32(&buf);
          if (tag == MKBETAG('D', 'i', 'f', 'f')) {
              uint16_t diff_count;
              if (buf + 10 > eod) {
                  av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for Diff frame.\n");
                  return AVERROR_INVALIDDATA;
              }
              diff_count = bytestream_get_be16(&buf);
              buf       += 8; /* clip rect? */
              for (int i = 0; i < diff_count; i++) {
                  int16_t top, left;
                  uint16_t diff_size, width, height;
  
                  if (buf + 16 > eod) {
                      av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for Diff frame header.\n");
                      return AVERROR_INVALIDDATA;
                  }
  
                  top        = bytestream_get_be16(&buf);
                  left       = bytestream_get_be16(&buf);
                  buf       += 4; /* bottom, right */
                  diff_size  = bytestream_get_be32(&buf);
                  width      = bytestream_get_be16(&buf);
                  height     = bytestream_get_be16(&buf);
                  if (diff_size < 8 || diff_size - 4 > eod - buf) {
                      av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for Diff frame data.\n");
                      return AVERROR_INVALIDDATA;
                  }
                  if (cdtoons_render_sprite(avctx, buf + 4, diff_size - 8,
                                        left, top, width, height)) {
                      av_log(avctx, AV_LOG_WARNING, "Ran beyond end of sprite while rendering.\n");
                  }
                  buf += diff_size - 4;
              }
              saw_embedded_sprites = 1;
          } else {
              /* we don't care about any other entries */
              if (size < 8 || size - 8 > eod - buf) {
                  av_log(avctx, AV_LOG_WARNING, "Ran out of data for ignored entry (size %X, %d left).\n", size, (int)(eod - buf));
                  return AVERROR_INVALIDDATA;
              }
              buf += (size - 8);
          }
      }
  
      /* was an intra frame? */
      if (saw_embedded_sprites)
          goto done;
  
      /* render any referenced sprites */
      buf = avpkt->data + CDTOONS_HEADER_SIZE;
      eod = avpkt->data + sprite_offset;
      for (int i = 0; i < referenced_count; i++) {
          const uint8_t *block_data;
          uint16_t sprite_id, width, height;
          int16_t top, left, right;
  
          if (buf + 10 > eod) {
              av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data when rendering.\n");
              return AVERROR_INVALIDDATA;
          }
  
          sprite_id = bytestream_get_be16(&buf);
          top       = bytestream_get_be16(&buf);
          left      = bytestream_get_be16(&buf);
          buf      += 2; /* bottom */
          right     = bytestream_get_be16(&buf);
  
          if ((i == 0) && (sprite_id == 0)) {
              /* clear background */
              memset(c->frame->data[0], background_color,
                     c->frame->linesize[0] * avctx->height);
          }
  
          if (!right)
              continue;
          if (sprite_id >= CDTOONS_MAX_SPRITES) {
              av_log(avctx, AV_LOG_ERROR,
                     "Sprite ID %d is too high.\n", sprite_id);
              return AVERROR_INVALIDDATA;
          }
  
          block_data = c->sprites[sprite_id].data;
          if (!c->sprites[sprite_id].active) {
              /* this can happen when seeking around */
              av_log(avctx, AV_LOG_WARNING, "Sprite %d is missing.\n", sprite_id);
              continue;
          }
          if (c->sprites[sprite_id].size < 14) {
              av_log(avctx, AV_LOG_ERROR, "Sprite %d is too small.\n", sprite_id);
              continue;
          }
  
          height      = bytestream_get_be16(&block_data);
          width       = bytestream_get_be16(&block_data);
          block_data += 10;
          if (cdtoons_render_sprite(avctx, block_data,
                                c->sprites[sprite_id].size - 14,
                                left, top, width, height)) {
              av_log(avctx, AV_LOG_WARNING, "Ran beyond end of sprite while rendering.\n");
          }
      }
  
      if (palette_id && (palette_id != c->last_pal_id)) {
          if (palette_id >= CDTOONS_MAX_SPRITES) {
              av_log(avctx, AV_LOG_ERROR,
                     "Palette ID %d is too high.\n", palette_id);
              return AVERROR_INVALIDDATA;
          }
          if (!c->sprites[palette_id].active) {
              /* this can happen when seeking around */
              av_log(avctx, AV_LOG_WARNING,
                     "Palette ID %d is missing.\n", palette_id);
              goto done;
          }
          if (c->sprites[palette_id].size != 256 * 2 * 3) {
              av_log(avctx, AV_LOG_ERROR,
                     "Palette ID %d is wrong size (%d).\n",
                     palette_id, c->sprites[palette_id].size);
              return AVERROR_INVALIDDATA;
          }
          c->last_pal_id = palette_id;
          if (!palette_set) {
              uint8_t *palette_data = c->sprites[palette_id].data;
              for (int i = 0; i < 256; i++) {
                  /* QuickTime-ish palette: 16-bit RGB components */
                  unsigned r, g, b;
                  r             = *palette_data;
                  g             = *(palette_data + 2);
                  b             = *(palette_data + 4);
                  c->pal[i]     = (0xFFU << 24) | (r << 16) | (g << 8) | b;
                  palette_data += 6;
              }
              /* first palette entry indicates transparency */
              c->pal[0]                     = 0;
              c->frame->palette_has_changed = 1;
          }
      }
  
  done:
      /* discard outdated blocks */
      for (int i = 0; i < CDTOONS_MAX_SPRITES; i++) {
          if (c->sprites[i].end_frame > frame_id)
              continue;
          c->sprites[i].active = 0;
      }
  
      memcpy(c->frame->data[1], c->pal, AVPALETTE_SIZE);
  
      if ((ret = av_frame_ref(data, c->frame)) < 0)
          return ret;
  
      *got_frame = 1;
  
      /* always report that the buffer was completely consumed */
      return buf_size;
  }
  
  static av_cold int cdtoons_decode_init(AVCodecContext *avctx)
  {
      CDToonsContext *c = avctx->priv_data;
  
      avctx->pix_fmt = AV_PIX_FMT_PAL8;
      c->last_pal_id = 0;
      c->frame       = av_frame_alloc();
      if (!c->frame)
          return AVERROR(ENOMEM);
  
      return 0;
  }
  
  static void cdtoons_flush(AVCodecContext *avctx)
  {
      CDToonsContext *c = avctx->priv_data;
  
      c->last_pal_id = 0;
      for (int i = 0; i < CDTOONS_MAX_SPRITES; i++)
          c->sprites[i].active = 0;
  }
  
  static av_cold int cdtoons_decode_end(AVCodecContext *avctx)
  {
      CDToonsContext *c = avctx->priv_data;
  
      for (int i = 0; i < CDTOONS_MAX_SPRITES; i++) {
          av_freep(&c->sprites[i].data);
          c->sprites[i].active = 0;
      }
  
      av_frame_free(&c->frame);
  
      return 0;
  }
  
  AVCodec ff_cdtoons_decoder = {
      .name           = "cdtoons",
      .long_name      = NULL_IF_CONFIG_SMALL("CDToons video"),
      .type           = AVMEDIA_TYPE_VIDEO,
      .id             = AV_CODEC_ID_CDTOONS,
      .priv_data_size = sizeof(CDToonsContext),
      .init           = cdtoons_decode_init,
      .close          = cdtoons_decode_end,
      .decode         = cdtoons_decode_frame,
      .capabilities   = AV_CODEC_CAP_DR1,
      .flush          = cdtoons_flush,
      .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
  };
  