/*
  * Copyright (C) 2004 Michael Niedermayer <michaelni@gmx.at>
  *

  * 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
  */
 
 #include "libavutil/intmath.h"
 #include "libavutil/log.h"
 #include "libavutil/opt.h"
 #include "avcodec.h"

 #include "snow_dwt.h"

 #include "internal.h"

 #include "snow.h"
 
 #include "rangecoder.h"
 #include "mathops.h"
 
 #include "mpegvideo.h"
 #include "h263.h"
 
 static av_always_inline void predict_slice_buffered(SnowContext *s, slice_buffer * sb, IDWTELEM * old_buffer, int plane_index, int add, int mb_y){
     Plane *p= &s->plane[plane_index];
     const int mb_w= s->b_width  << s->block_max_depth;
     const int mb_h= s->b_height << s->block_max_depth;
     int x, y, mb_x;
     int block_size = MB_SIZE >> s->block_max_depth;

     int block_w    = plane_index ? block_size>>s->chroma_h_shift : block_size;
     int block_h    = plane_index ? block_size>>s->chroma_v_shift : block_size;
     const uint8_t *obmc  = plane_index ? ff_obmc_tab[s->block_max_depth+s->chroma_h_shift] : ff_obmc_tab[s->block_max_depth];
     int obmc_stride= plane_index ? (2*block_size)>>s->chroma_h_shift : 2*block_size;

     int ref_stride= s->current_picture->linesize[plane_index];
     uint8_t *dst8= s->current_picture->data[plane_index];

     int w= p->width;
     int h= p->height;
 
     if(s->keyframe || (s->avctx->debug&512)){
         if(mb_y==mb_h)
             return;
 
         if(add){

             for(y=block_h*mb_y; y<FFMIN(h,block_h*(mb_y+1)); y++){

 //                DWTELEM * line = slice_buffer_get_line(sb, y);
                 IDWTELEM * line = sb->line[y];
                 for(x=0; x<w; x++){
 //                    int v= buf[x + y*w] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
                     int v= line[x] + (128<<FRAC_BITS) + (1<<(FRAC_BITS-1));
                     v >>= FRAC_BITS;
                     if(v&(~255)) v= ~(v>>31);
                     dst8[x + y*ref_stride]= v;
                 }
             }
         }else{

             for(y=block_h*mb_y; y<FFMIN(h,block_h*(mb_y+1)); y++){

 //                DWTELEM * line = slice_buffer_get_line(sb, y);
                 IDWTELEM * line = sb->line[y];
                 for(x=0; x<w; x++){
                     line[x] -= 128 << FRAC_BITS;
 //                    buf[x + y*w]-= 128<<FRAC_BITS;
                 }
             }
         }
 
         return;
     }
 
     for(mb_x=0; mb_x<=mb_w; mb_x++){
         add_yblock(s, 1, sb, old_buffer, dst8, obmc,
                    block_w*mb_x - block_w/2,

                    block_h*mb_y - block_h/2,
                    block_w, block_h,

                    w, h,
                    w, ref_stride, obmc_stride,
                    mb_x - 1, mb_y - 1,
                    add, 0, plane_index);
     }

 
     if(s->avmv && mb_y < mb_h && plane_index == 0)
         for(mb_x=0; mb_x<mb_w; mb_x++){

             AVMotionVector *avmv = s->avmv + s->avmv_index;

             const int b_width = s->b_width  << s->block_max_depth;
             const int b_stride= b_width;
             BlockNode *bn= &s->block[mb_x + mb_y*b_stride];
 
             if (bn->type)
                 continue;
 

             s->avmv_index++;
 

             avmv->w = block_w;
             avmv->h = block_h;
             avmv->dst_x = block_w*mb_x - block_w/2;
             avmv->dst_y = block_h*mb_y - block_h/2;

             avmv->motion_scale = 8;
             avmv->motion_x = bn->mx * s->mv_scale;
             avmv->motion_y = bn->my * s->mv_scale;
             avmv->src_x = avmv->dst_x + avmv->motion_x / 8;
             avmv->src_y = avmv->dst_y + avmv->motion_y / 8;

             avmv->source= -1 - bn->ref;
             avmv->flags = 0;
         }

 }
 
 static inline void decode_subband_slice_buffered(SnowContext *s, SubBand *b, slice_buffer * sb, int start_y, int h, int save_state[1]){
     const int w= b->width;
     int y;
     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);

     int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);

     int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
     int new_index = 0;
 
     if(b->ibuf == s->spatial_idwt_buffer || s->qlog == LOSSLESS_QLOG){
         qadd= 0;
         qmul= 1<<QEXPSHIFT;
     }
 
     /* If we are on the second or later slice, restore our index. */
     if (start_y != 0)
         new_index = save_state[0];
 
 
     for(y=start_y; y<h; y++){
         int x = 0;
         int v;
         IDWTELEM * line = slice_buffer_get_line(sb, y * b->stride_line + b->buf_y_offset) + b->buf_x_offset;
         memset(line, 0, b->width*sizeof(IDWTELEM));
         v = b->x_coeff[new_index].coeff;
         x = b->x_coeff[new_index++].x;
         while(x < w){

             register int t= (int)( (v>>1)*(unsigned)qmul + qadd)>>QEXPSHIFT;

             register int u= -(v&1);
             line[x] = (t^u) - u;
 
             v = b->x_coeff[new_index].coeff;
             x = b->x_coeff[new_index++].x;
         }
     }
 
     /* Save our variables for the next slice. */
     save_state[0] = new_index;
 
     return;
 }
 

 static int decode_q_branch(SnowContext *s, int level, int x, int y){

     const int w= s->b_width << s->block_max_depth;
     const int rem_depth= s->block_max_depth - level;
     const int index= (x + y*w) << rem_depth;
     int trx= (x+1)<<rem_depth;
     const BlockNode *left  = x ? &s->block[index-1] : &null_block;
     const BlockNode *top   = y ? &s->block[index-w] : &null_block;
     const BlockNode *tl    = y && x ? &s->block[index-w-1] : left;
     const BlockNode *tr    = y && trx<w && ((x&1)==0 || level==0) ? &s->block[index-w+(1<<rem_depth)] : tl; //FIXME use lt
     int s_context= 2*left->level + 2*top->level + tl->level + tr->level;

     int res;

 
     if(s->keyframe){
         set_blocks(s, level, x, y, null_block.color[0], null_block.color[1], null_block.color[2], null_block.mx, null_block.my, null_block.ref, BLOCK_INTRA);

         return 0;

     }
 
     if(level==s->block_max_depth || get_rac(&s->c, &s->block_state[4 + s_context])){
         int type, mx, my;
         int l = left->color[0];
         int cb= left->color[1];
         int cr= left->color[2];

         unsigned ref = 0;

         int ref_context= av_log2(2*left->ref) + av_log2(2*top->ref);
         int mx_context= av_log2(2*FFABS(left->mx - top->mx)) + 0*av_log2(2*FFABS(tr->mx - top->mx));
         int my_context= av_log2(2*FFABS(left->my - top->my)) + 0*av_log2(2*FFABS(tr->my - top->my));
 
         type= get_rac(&s->c, &s->block_state[1 + left->type + top->type]) ? BLOCK_INTRA : 0;
         if(type){

             int ld, cbd, crd;

             pred_mv(s, &mx, &my, 0, left, top, tr);

             ld = get_symbol(&s->c, &s->block_state[32], 1);
             if (ld < -255 || ld > 255) {
                 return AVERROR_INVALIDDATA;
             }
             l += ld;

             if (s->nb_planes > 2) {

                 cbd = get_symbol(&s->c, &s->block_state[64], 1);
                 crd = get_symbol(&s->c, &s->block_state[96], 1);
                 if (cbd < -255 || cbd > 255 || crd < -255 || crd > 255) {
                     return AVERROR_INVALIDDATA;
                 }
                 cb += cbd;
                 cr += crd;

             }

         }else{
             if(s->ref_frames > 1)
                 ref= get_symbol(&s->c, &s->block_state[128 + 1024 + 32*ref_context], 0);

             if (ref >= s->ref_frames) {
                 av_log(s->avctx, AV_LOG_ERROR, "Invalid ref\n");

                 return AVERROR_INVALIDDATA;

             }

             pred_mv(s, &mx, &my, ref, left, top, tr);
             mx+= get_symbol(&s->c, &s->block_state[128 + 32*(mx_context + 16*!!ref)], 1);
             my+= get_symbol(&s->c, &s->block_state[128 + 32*(my_context + 16*!!ref)], 1);
         }
         set_blocks(s, level, x, y, l, cb, cr, mx, my, ref, type);
     }else{

         if ((res = decode_q_branch(s, level+1, 2*x+0, 2*y+0)) < 0 ||
             (res = decode_q_branch(s, level+1, 2*x+1, 2*y+0)) < 0 ||
             (res = decode_q_branch(s, level+1, 2*x+0, 2*y+1)) < 0 ||
             (res = decode_q_branch(s, level+1, 2*x+1, 2*y+1)) < 0)
             return res;

     }

     return 0;

 }
 
 static void dequantize_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int start_y, int end_y){
     const int w= b->width;
     const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);

     const int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);

     const int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
     int x,y;
 
     if(s->qlog == LOSSLESS_QLOG) return;
 
     for(y=start_y; y<end_y; y++){
 //        DWTELEM * line = slice_buffer_get_line_from_address(sb, src + (y * stride));
         IDWTELEM * line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
         for(x=0; x<w; x++){
             int i= line[x];
             if(i<0){

                 line[x]= -((-i*(unsigned)qmul + qadd)>>(QEXPSHIFT)); //FIXME try different bias

             }else if(i>0){

                 line[x]=  (( i*(unsigned)qmul + qadd)>>(QEXPSHIFT));

             }
         }
     }
 }
 
 static void correlate_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int inverse, int use_median, int start_y, int end_y){
     const int w= b->width;
     int x,y;
 
     IDWTELEM * line=0; // silence silly "could be used without having been initialized" warning
     IDWTELEM * prev;
 
     if (start_y != 0)
         line = slice_buffer_get_line(sb, ((start_y - 1) * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
 
     for(y=start_y; y<end_y; y++){
         prev = line;
 //        line = slice_buffer_get_line_from_address(sb, src + (y * stride));
         line = slice_buffer_get_line(sb, (y * b->stride_line) + b->buf_y_offset) + b->buf_x_offset;
         for(x=0; x<w; x++){
             if(x){
                 if(use_median){
                     if(y && x+1<w) line[x] += mid_pred(line[x - 1], prev[x], prev[x + 1]);
                     else  line[x] += line[x - 1];
                 }else{
                     if(y) line[x] += mid_pred(line[x - 1], prev[x], line[x - 1] + prev[x] - prev[x - 1]);
                     else  line[x] += line[x - 1];
                 }
             }else{
                 if(y) line[x] += prev[x];
             }
         }
     }
 }
 
 static void decode_qlogs(SnowContext *s){
     int plane_index, level, orientation;
 

     for(plane_index=0; plane_index < s->nb_planes; plane_index++){

         for(level=0; level<s->spatial_decomposition_count; level++){
             for(orientation=level ? 1:0; orientation<4; orientation++){
                 int q;
                 if     (plane_index==2) q= s->plane[1].band[level][orientation].qlog;
                 else if(orientation==2) q= s->plane[plane_index].band[level][1].qlog;
                 else                    q= get_symbol(&s->c, s->header_state, 1);
                 s->plane[plane_index].band[level][orientation].qlog= q;
             }
         }
     }
 }
 
 #define GET_S(dst, check) \
     tmp= get_symbol(&s->c, s->header_state, 0);\
     if(!(check)){\
         av_log(s->avctx, AV_LOG_ERROR, "Error " #dst " is %d\n", tmp);\

         return AVERROR_INVALIDDATA;\

     }\
     dst= tmp;
 
 static int decode_header(SnowContext *s){
     int plane_index, tmp;
     uint8_t kstate[32];
 
     memset(kstate, MID_STATE, sizeof(kstate));
 
     s->keyframe= get_rac(&s->c, kstate);
     if(s->keyframe || s->always_reset){
         ff_snow_reset_contexts(s);
         s->spatial_decomposition_type=
         s->qlog=
         s->qbias=
         s->mv_scale=
         s->block_max_depth= 0;
     }
     if(s->keyframe){
         GET_S(s->version, tmp <= 0U)
         s->always_reset= get_rac(&s->c, s->header_state);
         s->temporal_decomposition_type= get_symbol(&s->c, s->header_state, 0);
         s->temporal_decomposition_count= get_symbol(&s->c, s->header_state, 0);
         GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
         s->colorspace_type= get_symbol(&s->c, s->header_state, 0);

         if (s->colorspace_type == 1) {
             s->avctx->pix_fmt= AV_PIX_FMT_GRAY8;
             s->nb_planes = 1;
         } else if(s->colorspace_type == 0) {
             s->chroma_h_shift= get_symbol(&s->c, s->header_state, 0);
             s->chroma_v_shift= get_symbol(&s->c, s->header_state, 0);
 
             if(s->chroma_h_shift == 1 && s->chroma_v_shift==1){
                 s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
             }else if(s->chroma_h_shift == 0 && s->chroma_v_shift==0){
                 s->avctx->pix_fmt= AV_PIX_FMT_YUV444P;
             }else if(s->chroma_h_shift == 2 && s->chroma_v_shift==2){
                 s->avctx->pix_fmt= AV_PIX_FMT_YUV410P;
             } else {
                 av_log(s, AV_LOG_ERROR, "unsupported color subsample mode %d %d\n", s->chroma_h_shift, s->chroma_v_shift);
                 s->chroma_h_shift = s->chroma_v_shift = 1;
                 s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;
                 return AVERROR_INVALIDDATA;
             }
             s->nb_planes = 3;

         } else {

             av_log(s, AV_LOG_ERROR, "unsupported color space\n");

             s->chroma_h_shift = s->chroma_v_shift = 1;

             s->avctx->pix_fmt= AV_PIX_FMT_YUV420P;

             return AVERROR_INVALIDDATA;
         }
 

         s->spatial_scalability= get_rac(&s->c, s->header_state);
 //        s->rate_scalability= get_rac(&s->c, s->header_state);
         GET_S(s->max_ref_frames, tmp < (unsigned)MAX_REF_FRAMES)
         s->max_ref_frames++;
 
         decode_qlogs(s);
     }
 
     if(!s->keyframe){
         if(get_rac(&s->c, s->header_state)){

             for(plane_index=0; plane_index<FFMIN(s->nb_planes, 2); plane_index++){

                 int htaps, i, sum=0;
                 Plane *p= &s->plane[plane_index];
                 p->diag_mc= get_rac(&s->c, s->header_state);
                 htaps= get_symbol(&s->c, s->header_state, 0)*2 + 2;

                 if((unsigned)htaps >= HTAPS_MAX || htaps==0)

                     return AVERROR_INVALIDDATA;

                 p->htaps= htaps;
                 for(i= htaps/2; i; i--){
                     p->hcoeff[i]= get_symbol(&s->c, s->header_state, 0) * (1-2*(i&1));
                     sum += p->hcoeff[i];
                 }
                 p->hcoeff[0]= 32-sum;
             }
             s->plane[2].diag_mc= s->plane[1].diag_mc;
             s->plane[2].htaps  = s->plane[1].htaps;
             memcpy(s->plane[2].hcoeff, s->plane[1].hcoeff, sizeof(s->plane[1].hcoeff));
         }
         if(get_rac(&s->c, s->header_state)){
             GET_S(s->spatial_decomposition_count, 0 < tmp && tmp <= MAX_DECOMPOSITIONS)
             decode_qlogs(s);
         }
     }
 

     s->spatial_decomposition_type+= (unsigned)get_symbol(&s->c, s->header_state, 1);

     if(s->spatial_decomposition_type > 1U){

         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_type %d not supported\n", s->spatial_decomposition_type);

         return AVERROR_INVALIDDATA;

     }
     if(FFMIN(s->avctx-> width>>s->chroma_h_shift,

              s->avctx->height>>s->chroma_v_shift) >> (s->spatial_decomposition_count-1) <= 1){

         av_log(s->avctx, AV_LOG_ERROR, "spatial_decomposition_count %d too large for size\n", s->spatial_decomposition_count);

         return AVERROR_INVALIDDATA;

     }

     if (s->avctx->width > 65536-4) {
         av_log(s->avctx, AV_LOG_ERROR, "Width %d is too large\n", s->avctx->width);
         return AVERROR_INVALIDDATA;
     }

     s->qlog           += (unsigned)get_symbol(&s->c, s->header_state, 1);
     s->mv_scale       += (unsigned)get_symbol(&s->c, s->header_state, 1);
     s->qbias          += (unsigned)get_symbol(&s->c, s->header_state, 1);
     s->block_max_depth+= (unsigned)get_symbol(&s->c, s->header_state, 1);

     if(s->block_max_depth > 1 || s->block_max_depth < 0 || s->mv_scale > 256U){

         av_log(s->avctx, AV_LOG_ERROR, "block_max_depth= %d is too large\n", s->block_max_depth);

         s->block_max_depth= 0;

         s->mv_scale = 0;

         return AVERROR_INVALIDDATA;

     }
     if (FFABS(s->qbias) > 127) {
         av_log(s->avctx, AV_LOG_ERROR, "qbias %d is too large\n", s->qbias);
         s->qbias = 0;
         return AVERROR_INVALIDDATA;

     }
 
     return 0;
 }
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {

     int ret;
 
     if ((ret = ff_snow_common_init(avctx)) < 0) {
         return ret;
     }

 
     return 0;
 }
 

 static int decode_blocks(SnowContext *s){

     int x, y;
     int w= s->b_width;
     int h= s->b_height;

     int res;

 
     for(y=0; y<h; y++){
         for(x=0; x<w; x++){

             if (s->c.bytestream >= s->c.bytestream_end)
                 return AVERROR_INVALIDDATA;

             if ((res = decode_q_branch(s, 0, x, y)) < 0)
                 return res;

         }
     }

     return 0;

 }
 

 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                         AVPacket *avpkt)
 {

     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;
     SnowContext *s = avctx->priv_data;
     RangeCoder * const c= &s->c;
     int bytes_read;
     AVFrame *picture = data;
     int level, orientation, plane_index;

     int res;

 
     ff_init_range_decoder(c, buf, buf_size);
     ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);
 

     s->current_picture->pict_type= AV_PICTURE_TYPE_I; //FIXME I vs. P

     if ((res = decode_header(s)) < 0)
         return res;

     if ((res=ff_snow_common_init_after_header(avctx)) < 0)
         return res;

 
     // realloc slice buffer for the case that spatial_decomposition_count changed
     ff_slice_buffer_destroy(&s->sb);

     if ((res = ff_slice_buffer_init(&s->sb, s->plane[0].height,
                                     (MB_SIZE >> s->block_max_depth) +

                                     s->spatial_decomposition_count * 11 + 1,

                                     s->plane[0].width,
                                     s->spatial_idwt_buffer)) < 0)
         return res;

     for(plane_index=0; plane_index < s->nb_planes; plane_index++){

         Plane *p= &s->plane[plane_index];
         p->fast_mc= p->diag_mc && p->htaps==6 && p->hcoeff[0]==40
                                               && p->hcoeff[1]==-10
                                               && p->hcoeff[2]==2;
     }
 
     ff_snow_alloc_blocks(s);
 

     if((res = ff_snow_frame_start(s)) < 0)
         return res;

 
     s->current_picture->pict_type = s->keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
 

     //keyframe flag duplication mess FIXME
     if(avctx->debug&FF_DEBUG_PICT_INFO)

         av_log(avctx, AV_LOG_ERROR,

                "keyframe:%d qlog:%d qbias: %d mvscale: %d "
                "decomposition_type:%d decomposition_count:%d\n",
                s->keyframe, s->qlog, s->qbias, s->mv_scale,

                s->spatial_decomposition_type,
                s->spatial_decomposition_count
               );

     av_assert0(!s->avmv);

     if (s->avctx->flags2 & AV_CODEC_FLAG2_EXPORT_MVS) {

         s->avmv = av_malloc_array(s->b_width * s->b_height, sizeof(AVMotionVector) << (s->block_max_depth*2));
     }
     s->avmv_index = 0;
 

     if ((res = decode_blocks(s)) < 0)
         return res;

     for(plane_index=0; plane_index < s->nb_planes; plane_index++){

         Plane *p= &s->plane[plane_index];
         int w= p->width;
         int h= p->height;
         int x, y;
         int decode_state[MAX_DECOMPOSITIONS][4][1]; /* Stored state info for unpack_coeffs. 1 variable per instance. */
 
         if(s->avctx->debug&2048){
             memset(s->spatial_dwt_buffer, 0, sizeof(DWTELEM)*w*h);
             predict_plane(s, s->spatial_idwt_buffer, plane_index, 1);
 
             for(y=0; y<h; y++){
                 for(x=0; x<w; x++){

                     int v= s->current_picture->data[plane_index][y*s->current_picture->linesize[plane_index] + x];
                     s->mconly_picture->data[plane_index][y*s->mconly_picture->linesize[plane_index] + x]= v;

                 }
             }
         }
 
         for(level=0; level<s->spatial_decomposition_count; level++){
             for(orientation=level ? 1 : 0; orientation<4; orientation++){
                 SubBand *b= &p->band[level][orientation];
                 unpack_coeffs(s, b, b->parent, orientation);
             }
         }
 
         {
         const int mb_h= s->b_height << s->block_max_depth;
         const int block_size = MB_SIZE >> s->block_max_depth;

         const int block_h    = plane_index ? block_size>>s->chroma_v_shift : block_size;

         int mb_y;
         DWTCompose cs[MAX_DECOMPOSITIONS];
         int yd=0, yq=0;
         int y;
         int end_y;
 
         ff_spatial_idwt_buffered_init(cs, &s->sb, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count);
         for(mb_y=0; mb_y<=mb_h; mb_y++){
 

             int slice_starty = block_h*mb_y;
             int slice_h = block_h*(mb_y+1);
 

             if (!(s->keyframe || s->avctx->debug&512)){

                 slice_starty = FFMAX(0, slice_starty - (block_h >> 1));
                 slice_h -= (block_h >> 1);

             }
 
             for(level=0; level<s->spatial_decomposition_count; level++){
                 for(orientation=level ? 1 : 0; orientation<4; orientation++){
                     SubBand *b= &p->band[level][orientation];
                     int start_y;
                     int end_y;
                     int our_mb_start = mb_y;
                     int our_mb_end = (mb_y + 1);
                     const int extra= 3;

                     start_y = (mb_y ? ((block_h * our_mb_start) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra: 0);
                     end_y = (((block_h * our_mb_end) >> (s->spatial_decomposition_count - level)) + s->spatial_decomposition_count - level + extra);

                     if (!(s->keyframe || s->avctx->debug&512)){

                         start_y = FFMAX(0, start_y - (block_h >> (1+s->spatial_decomposition_count - level)));
                         end_y = FFMAX(0, end_y - (block_h >> (1+s->spatial_decomposition_count - level)));

                     }
                     start_y = FFMIN(b->height, start_y);
                     end_y = FFMIN(b->height, end_y);
 
                     if (start_y != end_y){
                         if (orientation == 0){
                             SubBand * correlate_band = &p->band[0][0];
                             int correlate_end_y = FFMIN(b->height, end_y + 1);
                             int correlate_start_y = FFMIN(b->height, (start_y ? start_y + 1 : 0));
                             decode_subband_slice_buffered(s, correlate_band, &s->sb, correlate_start_y, correlate_end_y, decode_state[0][0]);
                             correlate_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, 1, 0, correlate_start_y, correlate_end_y);
                             dequantize_slice_buffered(s, &s->sb, correlate_band, correlate_band->ibuf, correlate_band->stride, start_y, end_y);
                         }
                         else
                             decode_subband_slice_buffered(s, b, &s->sb, start_y, end_y, decode_state[level][orientation]);
                     }
                 }
             }
 
             for(; yd<slice_h; yd+=4){

                 ff_spatial_idwt_buffered_slice(&s->dwt, cs, &s->sb, s->temp_idwt_buffer, w, h, 1, s->spatial_decomposition_type, s->spatial_decomposition_count, yd);

             }
 
             if(s->qlog == LOSSLESS_QLOG){
                 for(; yq<slice_h && yq<h; yq++){
                     IDWTELEM * line = slice_buffer_get_line(&s->sb, yq);
                     for(x=0; x<w; x++){

                         line[x] *= 1<<FRAC_BITS;

                     }
                 }
             }
 
             predict_slice_buffered(s, &s->sb, s->spatial_idwt_buffer, plane_index, 1, mb_y);
 
             y = FFMIN(p->height, slice_starty);
             end_y = FFMIN(p->height, slice_h);
             while(y < end_y)
                 ff_slice_buffer_release(&s->sb, y++);
         }
 
         ff_slice_buffer_flush(&s->sb);
         }
 
     }
 
     emms_c();
 
     ff_snow_release_buffer(avctx);
 
     if(!(s->avctx->debug&2048))

         res = av_frame_ref(picture, s->current_picture);

     else

         res = av_frame_ref(picture, s->mconly_picture);

     if (res >= 0 && s->avmv_index) {
         AVFrameSideData *sd;
 
         sd = av_frame_new_side_data(picture, AV_FRAME_DATA_MOTION_VECTORS, s->avmv_index * sizeof(AVMotionVector));
         if (!sd)
             return AVERROR(ENOMEM);
         memcpy(sd->data, s->avmv, s->avmv_index * sizeof(AVMotionVector));
     }
 
     av_freep(&s->avmv);

 
     if (res < 0)
         return res;

     *got_frame = 1;

 
     bytes_read= c->bytestream - c->bytestream_start;
     if(bytes_read ==0) av_log(s->avctx, AV_LOG_ERROR, "error at end of frame\n"); //FIXME
 
     return bytes_read;
 }
 
 static av_cold int decode_end(AVCodecContext *avctx)
 {
     SnowContext *s = avctx->priv_data;
 
     ff_slice_buffer_destroy(&s->sb);
 
     ff_snow_common_end(s);
 
     return 0;
 }
 
 AVCodec ff_snow_decoder = {
     .name           = "snow",

     .long_name      = NULL_IF_CONFIG_SMALL("Snow"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_SNOW,

     .priv_data_size = sizeof(SnowContext),
     .init           = decode_init,
     .close          = decode_end,
     .decode         = decode_frame,

     .capabilities   = AV_CODEC_CAP_DR1 /*| AV_CODEC_CAP_DRAW_HORIZ_BAND*/,

     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
                       FF_CODEC_CAP_INIT_CLEANUP,

 };