text: /*
   * LOCO codec
   * Copyright (c) 2005 Konstantin Shishkov
   *
   * 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
   * LOCO codec.
   */
  
  #include "avcodec.h"
  #include "get_bits.h"
  #include "golomb.h"
  #include "mathops.h"
  
  enum LOCO_MODE {LOCO_UNKN=0, LOCO_CYUY2=-1, LOCO_CRGB=-2, LOCO_CRGBA=-3, LOCO_CYV12=-4,
   LOCO_YUY2=1, LOCO_UYVY=2, LOCO_RGB=3, LOCO_RGBA=4, LOCO_YV12=5};
  
  typedef struct LOCOContext{
      AVCodecContext *avctx;
      AVFrame pic;
      int lossy;
      int mode;
  } LOCOContext;
  
  typedef struct RICEContext{
      GetBitContext gb;
      int save, run, run2; /* internal rice decoder state */
      int sum, count; /* sum and count for getting rice parameter */
      int lossy;
  }RICEContext;
  
  static int loco_get_rice_param(RICEContext *r)
  {
      int cnt = 0;
      int val = r->count;
  
      while(r->sum > val && cnt < 9) {
          val <<= 1;
          cnt++;
      }
  
      return cnt;
  }
  
  static inline void loco_update_rice_param(RICEContext *r, int val)
  {
      r->sum += val;
      r->count++;
  
      if(r->count == 16) {
          r->sum >>= 1;
          r->count >>= 1;
      }
  }
  
  static inline int loco_get_rice(RICEContext *r)
  {
      int v;
      if (r->run > 0) { /* we have zero run */
          r->run--;
          loco_update_rice_param(r, 0);
          return 0;
      }
      v = get_ur_golomb_jpegls(&r->gb, loco_get_rice_param(r), INT_MAX, 0);
      loco_update_rice_param(r, (v+1)>>1);
      if (!v) {
          if (r->save >= 0) {
              r->run = get_ur_golomb_jpegls(&r->gb, 2, INT_MAX, 0);
              if(r->run > 1)
                  r->save += r->run + 1;
              else
                  r->save -= 3;
          }
          else
              r->run2++;
      } else {
          v = ((v>>1) + r->lossy) ^ -(v&1);
          if (r->run2 > 0) {
              if (r->run2 > 2)
                  r->save += r->run2;
              else
                  r->save -= 3;
              r->run2 = 0;
          }
      }
  
      return v;
  }
  
  /* LOCO main predictor - LOCO-I/JPEG-LS predictor */
  static inline int loco_predict(uint8_t* data, int stride, int step)
  {
      int a, b, c;
  
      a = data[-stride];
      b = data[-step];
      c = data[-stride - step];
  
      return mid_pred(a, a + b - c, b);
  }
  
  static int loco_decode_plane(LOCOContext *l, uint8_t *data, int width, int height,
                               int stride, const uint8_t *buf, int buf_size, int step)
  {
      RICEContext rc;
      int val;
      int i, j;
  
      init_get_bits(&rc.gb, buf, buf_size*8);
      rc.save = 0;
      rc.run = 0;
      rc.run2 = 0;
      rc.lossy = l->lossy;
  
      rc.sum = 8;
      rc.count = 1;
  
      /* restore top left pixel */
      val = loco_get_rice(&rc);
      data[0] = 128 + val;
      /* restore top line */
      for (i = 1; i < width; i++) {
          val = loco_get_rice(&rc);
          data[i * step] = data[i * step - step] + val;
      }
      data += stride;
      for (j = 1; j < height; j++) {
          /* restore left column */
          val = loco_get_rice(&rc);
          data[0] = data[-stride] + val;
          /* restore all other pixels */
          for (i = 1; i < width; i++) {
              val = loco_get_rice(&rc);
              data[i * step] = loco_predict(&data[i * step], stride, step) + val;
          }
          data += stride;
      }
  
      return (get_bits_count(&rc.gb) + 7) >> 3;
  }
  
  static int decode_frame(AVCodecContext *avctx,
                          void *data, int *data_size,
                          AVPacket *avpkt)
  {
      const uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      LOCOContext * const l = avctx->priv_data;
      AVFrame * const p= (AVFrame*)&l->pic;
      int decoded;
  
      if(p->data[0])
          avctx->release_buffer(avctx, p);
  
      p->reference = 0;
      if(avctx->get_buffer(avctx, p) < 0){
          av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
          return -1;
      }
      p->key_frame = 1;
  
      switch(l->mode) {
      case LOCO_CYUY2: case LOCO_YUY2: case LOCO_UYVY:
          decoded = loco_decode_plane(l, p->data[0], avctx->width, avctx->height,
                                      p->linesize[0], buf, buf_size, 1);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[1], avctx->width / 2, avctx->height,
                                      p->linesize[1], buf, buf_size, 1);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[2], avctx->width / 2, avctx->height,
                                      p->linesize[2], buf, buf_size, 1);
          break;
      case LOCO_CYV12: case LOCO_YV12:
          decoded = loco_decode_plane(l, p->data[0], avctx->width, avctx->height,
                                      p->linesize[0], buf, buf_size, 1);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[2], avctx->width / 2, avctx->height / 2,
                                      p->linesize[2], buf, buf_size, 1);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[1], avctx->width / 2, avctx->height / 2,
                                      p->linesize[1], buf, buf_size, 1);
          break;
      case LOCO_CRGB: case LOCO_RGB:
          decoded = loco_decode_plane(l, p->data[0] + p->linesize[0]*(avctx->height-1), avctx->width, avctx->height,
                                      -p->linesize[0], buf, buf_size, 3);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[0] + p->linesize[0]*(avctx->height-1) + 1, avctx->width, avctx->height,
                                      -p->linesize[0], buf, buf_size, 3);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[0] + p->linesize[0]*(avctx->height-1) + 2, avctx->width, avctx->height,
                                      -p->linesize[0], buf, buf_size, 3);
          break;
      case LOCO_RGBA:
          decoded = loco_decode_plane(l, p->data[0], avctx->width, avctx->height,
                                      p->linesize[0], buf, buf_size, 4);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[0] + 1, avctx->width, avctx->height,
                                      p->linesize[0], buf, buf_size, 4);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[0] + 2, avctx->width, avctx->height,
                                      p->linesize[0], buf, buf_size, 4);
          buf += decoded; buf_size -= decoded;
          decoded = loco_decode_plane(l, p->data[0] + 3, avctx->width, avctx->height,
                                      p->linesize[0], buf, buf_size, 4);
          break;
      }
  
      *data_size = sizeof(AVFrame);
      *(AVFrame*)data = l->pic;
  
      return buf_size;
  }
  
  static av_cold int decode_init(AVCodecContext *avctx){
      LOCOContext * const l = avctx->priv_data;
      int version;
  
      l->avctx = avctx;
      if (avctx->extradata_size < 12) {
          av_log(avctx, AV_LOG_ERROR, "Extradata size must be >= 12 instead of %i\n",
                 avctx->extradata_size);
          return -1;
      }
      version = AV_RL32(avctx->extradata);
      switch(version) {
      case 1:
          l->lossy = 0;
          break;
      case 2:
          l->lossy = AV_RL32(avctx->extradata + 8);
          break;
      default:
          l->lossy = AV_RL32(avctx->extradata + 8);
          av_log(avctx, AV_LOG_INFO, "This is LOCO codec version %i, please upload file for study\n", version);
      }
  
      l->mode = AV_RL32(avctx->extradata + 4);
      switch(l->mode) {
      case LOCO_CYUY2: case LOCO_YUY2: case LOCO_UYVY:
          avctx->pix_fmt = PIX_FMT_YUV422P;
          break;
      case LOCO_CRGB: case LOCO_RGB:
          avctx->pix_fmt = PIX_FMT_BGR24;
          break;
      case LOCO_CYV12: case LOCO_YV12:
          avctx->pix_fmt = PIX_FMT_YUV420P;
          break;
      case LOCO_CRGBA: case LOCO_RGBA:
          avctx->pix_fmt = PIX_FMT_RGB32;
          break;
      default:
          av_log(avctx, AV_LOG_INFO, "Unknown colorspace, index = %i\n", l->mode);
          return -1;
      }
      if(avctx->debug & FF_DEBUG_PICT_INFO)
          av_log(avctx, AV_LOG_INFO, "lossy:%i, version:%i, mode: %i\n", l->lossy, version, l->mode);
  
      return 0;
  }
  
  static av_cold int decode_end(AVCodecContext *avctx){
      LOCOContext * const l = avctx->priv_data;
      AVFrame *pic = &l->pic;
  
      if (pic->data[0])
          avctx->release_buffer(avctx, pic);
  
      return 0;
  }
  
  AVCodec loco_decoder = {
      "loco",
      AVMEDIA_TYPE_VIDEO,
      CODEC_ID_LOCO,
      sizeof(LOCOContext),
      decode_init,
      NULL,
      decode_end,
      decode_frame,
      CODEC_CAP_DR1,
      .long_name = NULL_IF_CONFIG_SMALL("LOCO"),
  };
  