/*

 * 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/emms.h"

#include "libavutil/intmath.h"

#include "libavutil/log.h"

#include "libavutil/mem.h"

#include "avcodec.h"

#include "codec_internal.h"

#include "decode.h"

#include "snow_dwt.h"

#include "snow.h"

#include "rangecoder.h"

#include "mathops.h"

static inline int get_symbol(RangeCoder *c, uint8_t *state, int is_signed)

{

    if (get_rac(c, state + 0))

        return 0;

    else {

        int e;

        unsigned a;

        e = 0;

        while (get_rac(c, state + 1 + FFMIN(e, 9))) { //1..10

            e++;

            if (e > 31)

                return AVERROR_INVALIDDATA;

        }

        a = 1;

        for (int i = e - 1; i >= 0; i--)

            a += a + get_rac(c, state + 22 + FFMIN(i, 9)); //22..31

        e = -(is_signed && get_rac(c, state + 11 + FFMIN(e, 10))); //11..21

        return (a ^ e) - e;

    }

}

static inline int get_symbol2(RangeCoder *c, uint8_t *state, int log2)

{

    int r = log2 >= 0 ? 1 << log2 : 1;

    int v = 0;

    av_assert2(log2 >= -4);

    while (log2 < 28 && get_rac(c, state + 4 + log2)) {

        v += r;

        log2++;

        if (log2 > 0) r += r;

    }

    for (int i = log2 - 1; i >= 0; i--)

        v += get_rac(c, state + 31 - i) << i;

    return v;

}

static void unpack_coeffs(SnowContext *s, SubBand *b, SubBand * parent, int orientation)

{

    const int w = b->width;

    const int h = b->height;

    int run, runs;

    x_and_coeff *xc = b->x_coeff;

    x_and_coeff *prev_xc = NULL;

    x_and_coeff *prev2_xc = xc;

    x_and_coeff *parent_xc = parent ? parent->x_coeff : NULL;

    x_and_coeff *prev_parent_xc = parent_xc;

    runs = get_symbol2(&s->c, b->state[30], 0);

    if (runs-- > 0) run = get_symbol2(&s->c, b->state[1], 3);

    else            run = INT_MAX;

    for (int y = 0; y < h; y++) {

        int v = 0;

        int lt = 0, t = 0, rt = 0;

        if (y && prev_xc->x == 0)

            rt = prev_xc->coeff;

        for (int x = 0; x < w; x++) {

            int p = 0;

            const int l = v;

            lt= t; t= rt;

            if (y) {

                if (prev_xc->x <= x)

                    prev_xc++;

                if (prev_xc->x == x + 1)

                    rt = prev_xc->coeff;

                else

                    rt = 0;

            }

            if (parent_xc) {

                if (x>>1 > parent_xc->x)

                    parent_xc++;

                if (x>>1 == parent_xc->x)

                    p = parent_xc->coeff;

            }

            if (/*ll|*/l|lt|t|rt|p) {

                int context = av_log2(/*FFABS(ll) + */3*(l>>1) + (lt>>1) + (t&~1) + (rt>>1) + (p>>1));

                v = get_rac(&s->c, &b->state[0][context]);

                if (v) {

                    v  = 2*(get_symbol2(&s->c, b->state[context + 2], context-4) + 1);

                    v += get_rac(&s->c, &b->state[0][16 + 1 + 3 + ff_quant3bA[l&0xFF] + 3 * ff_quant3bA[t&0xFF]]);

                    if ((uint16_t)v != v) {

                        av_log(s->avctx, AV_LOG_ERROR, "Coefficient damaged\n");

                        v = 1;

                    }

                    xc->x = x;

                    (xc++)->coeff = v;

                }

            } else {

                if (!run) {

                    if (runs-- > 0) run = get_symbol2(&s->c, b->state[1], 3);

                    else            run = INT_MAX;

                    v  = 2 * (get_symbol2(&s->c, b->state[0 + 2], 0-4) + 1);

                    v += get_rac(&s->c, &b->state[0][16 + 1 + 3]);

                    if ((uint16_t)v != v) {

                        av_log(s->avctx, AV_LOG_ERROR, "Coefficient damaged\n");

                        v = 1;

                    }

                    xc->x = x;

                    (xc++)->coeff = v;

                } else {

                    int max_run;

                    run--;

                    v = 0;

                    av_assert2(run >= 0);

                    if (y) max_run = FFMIN(run, prev_xc->x - x - 2);

                    else   max_run = FFMIN(run, w-x-1);

                    if (parent_xc)

                        max_run = FFMIN(max_run, 2*parent_xc->x - x - 1);

                    av_assert2(max_run >= 0 && max_run <= run);

                    x   += max_run;

                    run -= max_run;

                }

            }

        }

        (xc++)->x = w+1; //end marker

        prev_xc  = prev2_xc;

        prev2_xc = xc;

        if (parent_xc) {

            if (y & 1) {

                while (parent_xc->x != parent->width+1)

                    parent_xc++;

                parent_xc++;

                prev_parent_xc= parent_xc;

            } else {

                parent_xc= prev_parent_xc;

            }

        }

    }

    (xc++)->x = w + 1; //end marker

}

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 + (int64_t)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+= (unsigned)get_symbol(&s->c, &s->block_state[128 + 32*(mx_context + 16*!!ref)], 1);

            my+= (unsigned)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 + (int64_t)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->avctx, 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->avctx, 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);

                if((unsigned)htaps >= HTAPS_MAX/2 - 1)

                    return AVERROR_INVALIDDATA;

                htaps = htaps*2 + 2;

                p->htaps= htaps;

                for(i= htaps/2; i; i--){

                    unsigned hcoeff = get_symbol(&s->c, s->header_state, 0);

                    if (hcoeff > 127)

                        return AVERROR_INVALIDDATA;

                    p->hcoeff[i]= hcoeff * (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 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, AVFrame *picture,

                        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;

    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 (!s->mconly_picture->data[0]) {

        res = ff_get_buffer(avctx, s->mconly_picture, AV_GET_BUFFER_FLAG_REF);

        if (res < 0)

            return res;

    }

    if (s->mconly_picture->format != avctx->pix_fmt) {

        av_log(avctx, AV_LOG_ERROR, "pixel format changed\n");

        return AVERROR_INVALIDDATA;

    }

    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_frames_prepare(s)) < 0)

        return res;

    s->current_picture->width  = s->avctx->width;

    s->current_picture->height = s->avctx->height;

    res = ff_get_buffer(s->avctx, s->current_picture, AV_GET_BUFFER_FLAG_REF);

    if (res < 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

              );

    if (s->avctx->export_side_data & AV_CODEC_EXPORT_DATA_MVS) {

        size_t size;

        res = av_size_mult(s->b_width * s->b_height, sizeof(AVMotionVector) << (s->block_max_depth*2), &size);

        if (res)

            return res;

        av_fast_malloc(&s->avmv, &s->avmv_size, size);

        if (!s->avmv)

            return AVERROR(ENOMEM);

    } else {

        s->avmv_size = 0;

        av_freep(&s->avmv);

    }

    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();

    av_frame_unref(s->last_picture[s->max_ref_frames - 1]);

    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));

    }

    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);

    s->avmv_size = 0;

    av_freep(&s->avmv);

    return 0;

}

const FFCodec ff_snow_decoder = {

    .p.name         = "snow",

    CODEC_LONG_NAME("Snow"),

    .p.type         = AVMEDIA_TYPE_VIDEO,

    .p.id           = AV_CODEC_ID_SNOW,

    .priv_data_size = sizeof(SnowContext),

    .init           = ff_snow_common_init,

    .close          = decode_end,

    FF_CODEC_DECODE_CB(decode_frame),

    .p.capabilities = AV_CODEC_CAP_DR1,

    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,

};