Function decode_header

libavcodec/snow.c:1584–1664

    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){
        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);
        s->chroma_h_shift= get_symbol(&s->c, s->header_state, 0);
        s->chroma_v_shift= get_symbol(&s->c, s->header_state, 0);
        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<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 -1;
                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);
        }
    }