/*
 * JPEG 2000 image decoder
 * Copyright (c) 2007 Kamil Nowosad
 * Copyright (c) 2013 Nicolas Bertrand <nicoinattendu@gmail.com>
 *
 * 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
 */

/**
 * JPEG2000 image decoder
 * @file
 * @author Kamil Nowosad
 */

#include "libavutil/common.h"
#include "libavutil/opt.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "thread.h"
#include "j2k.h"

#define JP2_SIG_TYPE    0x6A502020
#define JP2_SIG_VALUE   0x0D0A870A
#define JP2_CODESTREAM  0x6A703263

#define HAD_COC 0x01
#define HAD_QCC 0x02

typedef struct Jpeg2000Tile {
    Jpeg2000Component  *comp;
    uint8_t             properties[4];
    Jpeg2000CodingStyle codsty[4];
    Jpeg2000QuantStyle  qntsty[4];
} Jpeg2000Tile;

typedef struct Jpeg2000DecoderContext {
    AVClass         *class;
    AVCodecContext  *avctx;
    AVFrame         *picture;
    GetByteContext  g;

    int             width, height;
    int             image_offset_x, image_offset_y;
    int             tile_offset_x, tile_offset_y;
    uint8_t         cbps[4];    // bits per sample in particular components
    uint8_t         sgnd[4];    // if a component is signed
    uint8_t         properties[4];
    int             cdx[4], cdy[4];
    int             precision;
    int             ncomponents;
    int             tile_width, tile_height;
    int             numXtiles, numYtiles;
    int             maxtilelen;

    Jpeg2000CodingStyle codsty[4];
    Jpeg2000QuantStyle  qntsty[4];

    int             bit_index;

    int             curtileno;

    Jpeg2000Tile    *tile;

    /*options parameters*/
    int             lowres;
    int             reduction_factor;
} Jpeg2000DecoderContext;

static int get_bits(Jpeg2000DecoderContext *s, int n)
{
    int res = 0;

    while (--n >= 0) {
        res <<= 1;
        if (s->bit_index == 0) {
            s->bit_index = 7 + (bytestream2_get_byte(&s->g) != 0xFFu);
        }
        s->bit_index--;
        res |= (bytestream2_peek_byte(&s->g) >> s->bit_index) & 1;
    }
    return res;
}

static void j2k_flush(Jpeg2000DecoderContext *s)
{
    if (bytestream2_get_byte(&s->g) == 0xff)
        bytestream2_skip(&s->g, 1);
    s->bit_index = 8;
}

/* decode the value stored in node */
static int tag_tree_decode(Jpeg2000DecoderContext *s, Jpeg2000TgtNode *node,
                           int threshold)
{
    Jpeg2000TgtNode *stack[30];
    int sp = -1, curval = 0;

    if (!node)
        return AVERROR(EINVAL);

    while (node && !node->vis) {
        stack[++sp] = node;
        node        = node->parent;
    }

    if (node)
        curval = node->val;
    else
        curval = stack[sp]->val;

    while (curval < threshold && sp >= 0) {
        if (curval < stack[sp]->val)
            curval = stack[sp]->val;
        while (curval < threshold) {
            int ret;
            if ((ret = get_bits(s, 1)) > 0) {
                stack[sp]->vis++;
                break;
            } else if (!ret)
                curval++;
            else
                return ret;
        }
        stack[sp]->val = curval;
        sp--;
    }
    return curval;
}

/* marker segments */
/* get sizes and offsets of image, tiles; number of components */
static int get_siz(Jpeg2000DecoderContext *s)
{
    int i, ret;
    ThreadFrame frame = { .f = s->picture };

    if (bytestream2_get_bytes_left(&s->g) < 36)
        return AVERROR(EINVAL);

    s->avctx->profile = bytestream2_get_be16u(&s->g); // Rsiz
    s->width          = bytestream2_get_be32u(&s->g); // Width
    s->height         = bytestream2_get_be32u(&s->g); // Height
    s->image_offset_x = bytestream2_get_be32u(&s->g); // X0Siz
    s->image_offset_y = bytestream2_get_be32u(&s->g); // Y0Siz
    s->tile_width     = bytestream2_get_be32u(&s->g); // XTSiz
    s->tile_height    = bytestream2_get_be32u(&s->g); // YTSiz
    s->tile_offset_x  = bytestream2_get_be32u(&s->g); // XT0Siz
    s->tile_offset_y  = bytestream2_get_be32u(&s->g); // YT0Siz
    s->ncomponents    = bytestream2_get_be16u(&s->g); // CSiz

    if (s->ncomponents <= 0 || s->ncomponents > 4) {
        av_log(s->avctx, AV_LOG_ERROR, "unsupported/invalid ncomponents: %d\n", s->ncomponents);
        return AVERROR(EINVAL);
    }
    if (s->tile_width<=0 || s->tile_height<=0)
        return AVERROR(EINVAL);

    if (bytestream2_get_bytes_left(&s->g) < 3 * s->ncomponents)
        return AVERROR(EINVAL);

    for (i = 0; i < s->ncomponents; i++) { // Ssiz_i XRsiz_i, YRsiz_i
        uint8_t x = bytestream2_get_byteu(&s->g);
        s->cbps[i]   = (x & 0x7f) + 1;
        s->precision = FFMAX(s->cbps[i], s->precision);
        s->sgnd[i] = !!(x & 0x80);
        s->cdx[i] = bytestream2_get_byteu(&s->g);
        s->cdy[i] = bytestream2_get_byteu(&s->g);
        if (s->cdx[i] != 1 || s->cdy[i] != 1) {
            av_log(s->avctx, AV_LOG_ERROR, "unsupported/ CDxy values\n");
        }
    }

    s->numXtiles = ff_jpeg2000_ceildiv(s->width  - s->tile_offset_x, s->tile_width);
    s->numYtiles = ff_jpeg2000_ceildiv(s->height - s->tile_offset_y, s->tile_height);

    if (s->numXtiles * (uint64_t)s->numYtiles > INT_MAX/sizeof(Jpeg2000Tile))
        return AVERROR(EINVAL);

    s->tile = av_mallocz(s->numXtiles * s->numYtiles * sizeof(*s->tile));
    if (!s->tile)
        return AVERROR(ENOMEM);

    for (i = 0; i < s->numXtiles * s->numYtiles; i++) {
        Jpeg2000Tile *tile = s->tile + i;

        tile->comp = av_mallocz(s->ncomponents * sizeof(*tile->comp));
        if (!tile->comp)
            return AVERROR(ENOMEM);
    }

    /* compute image size with reduction factor */
    s->avctx->width  = ff_jpeg2000_ceildivpow2(s->width  - s->image_offset_x,
                                               s->reduction_factor);
    s->avctx->height = ff_jpeg2000_ceildivpow2(s->height - s->image_offset_y,
                                               s->reduction_factor);
    switch(s->ncomponents) {
    case 1:
        if (s->precision > 8) {
            s->avctx->pix_fmt = AV_PIX_FMT_GRAY16;
        } else {
            s->avctx->pix_fmt = AV_PIX_FMT_GRAY8;
        }
        break;
    case 3:
        if (s->precision > 8) {
            s->avctx->pix_fmt = AV_PIX_FMT_RGB48;
        } else {
            s->avctx->pix_fmt = AV_PIX_FMT_RGB24;
        }
        break;
    case 4:
        s->avctx->pix_fmt = AV_PIX_FMT_RGBA;
        break;
    }


    if ((ret = ff_thread_get_buffer(s->avctx, &frame, 0)) < 0)
        return ret;

    s->picture->pict_type = AV_PICTURE_TYPE_I;
    s->picture->key_frame = 1;

    return 0;
}

/* get common part for COD and COC segments */
static int get_cox(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c)
{
    uint8_t byte;

    if (bytestream2_get_bytes_left(&s->g) < 5)
        return AVERROR(EINVAL);
    c->nreslevels = bytestream2_get_byteu(&s->g) + 1; // num of resolution levels - 1
    if (c->nreslevels >= JPEG2000_MAX_RESLEVELS) {
        av_log(s->avctx, AV_LOG_ERROR, "nreslevels %d is invalid\n", c->nreslevels);
        return AVERROR_INVALIDDATA;
    }

    /* compute number of resolution levels to decode */
    if (c->nreslevels < s->reduction_factor)
        c->nreslevels2decode = 1;
    else
        c->nreslevels2decode = c->nreslevels - s->reduction_factor;

    c->log2_cblk_width  = (bytestream2_get_byteu(&s->g) & 15) + 2; // cblk width
    c->log2_cblk_height = (bytestream2_get_byteu(&s->g) & 15) + 2; // cblk height

    if (c->log2_cblk_width > 10 || c->log2_cblk_height > 10 ||
        c->log2_cblk_width + c->log2_cblk_height > 14) {
        av_log(s->avctx, AV_LOG_ERROR, "cblk size invalid\n");
        return AVERROR_INVALIDDATA;
    }

    c->cblk_style = bytestream2_get_byteu(&s->g);
    if (c->cblk_style != 0) { // cblk style
        av_log(s->avctx, AV_LOG_WARNING, "extra cblk styles %X\n", c->cblk_style);
    }
    c->transform = bytestream2_get_byteu(&s->g); // transformation
    if (c->csty & JPEG2000_CSTY_PREC) {
        int i;
        for (i = 0; i < c->nreslevels; i++) {
            byte = bytestream2_get_byte(&s->g);
            c->log2_prec_widths[i]  =  byte       & 0x0F;    // precinct PPx
            c->log2_prec_heights[i] = (byte >> 4) & 0x0F;    // precinct PPy
        }
    } else {
        memset(c->log2_prec_widths , 15, sizeof(c->log2_prec_widths ));
        memset(c->log2_prec_heights, 15, sizeof(c->log2_prec_heights));
    }
    return 0;
}

/* get coding parameters for a particular tile or whole image*/
static int get_cod(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c,
                   uint8_t *properties)
{
    Jpeg2000CodingStyle tmp;
    int compno;

    if (bytestream2_get_bytes_left(&s->g) < 5)
        return AVERROR(EINVAL);

    tmp.csty = bytestream2_get_byteu(&s->g);

    // get progression order
    tmp.prog_order = bytestream2_get_byteu(&s->g);
    if (tmp.prog_order) {
        av_log(s->avctx, AV_LOG_ERROR, "only LRCP progression supported\n");
    }

    tmp.nlayers = bytestream2_get_be16u(&s->g);
    tmp.mct     = bytestream2_get_byteu(&s->g); // multiple component transformation

    get_cox(s, &tmp);
    for (compno = 0; compno < s->ncomponents; compno++)
        if (!(properties[compno] & HAD_COC))
            memcpy(c + compno, &tmp, sizeof(tmp));
    return 0;
}

/* Get coding parameters for a component in the whole image or a
 * particular tile. */
static int get_coc(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c,
                   uint8_t *properties)
{
    int compno;

    if (bytestream2_get_bytes_left(&s->g) < 2)
        return AVERROR(EINVAL);

    compno = bytestream2_get_byteu(&s->g);

    c += compno;
    c->csty = bytestream2_get_byte(&s->g);
    get_cox(s, c);

    properties[compno] |= HAD_COC;
    return 0;
}

/* Get common part for QCD and QCC segments. */
static int get_qcx(Jpeg2000DecoderContext *s, int n, Jpeg2000QuantStyle *q)
{
    int i, x;

    if (bytestream2_get_bytes_left(&s->g) < 1)
        return AVERROR(EINVAL);

    x = bytestream2_get_byteu(&s->g); // Sqcd

    q->nguardbits = x >> 5;
    q->quantsty   = x & 0x1f;

    if (q->quantsty == JPEG2000_QSTY_NONE) {
        n -= 3;
        if (bytestream2_get_bytes_left(&s->g) < n || 32*3 < n)
            return AVERROR(EINVAL);
        for (i = 0; i < n; i++)
            q->expn[i] = bytestream2_get_byteu(&s->g) >> 3;
    } else if (q->quantsty == JPEG2000_QSTY_SI) {
        if (bytestream2_get_bytes_left(&s->g) < 2)
            return AVERROR(EINVAL);
        x          = bytestream2_get_be16u(&s->g);
        q->expn[0] = x >> 11;
        q->mant[0] = x & 0x7ff;
        for (i = 1; i < 32 * 3; i++) {
            int curexpn = FFMAX(0, q->expn[0] - (i - 1) / 3);
            q->expn[i] = curexpn;
            q->mant[i] = q->mant[0];
        }
    } else {
        n = (n - 3) >> 1;
        if (bytestream2_get_bytes_left(&s->g) < 2 * n || 32*3 < n)
            return AVERROR(EINVAL);
        for (i = 0; i < n; i++) {
            x          = bytestream2_get_be16u(&s->g);
            q->expn[i] = x >> 11;
            q->mant[i] = x & 0x7ff;
        }
    }
    return 0;
}

/* Get quantization parameters for a particular tile or a whole image. */
static int get_qcd(Jpeg2000DecoderContext *s, int n, Jpeg2000QuantStyle *q,
                   uint8_t *properties)
{
    Jpeg2000QuantStyle tmp;
    int compno;

    if (get_qcx(s, n, &tmp))
        return -1;
    for (compno = 0; compno < s->ncomponents; compno++)
        if (!(properties[compno] & HAD_QCC))
            memcpy(q + compno, &tmp, sizeof(Jpeg2000QuantStyle));
    return 0;
}

/* Get quantization parameters for a component in the whole image
 * on in a particular tile. */
static int get_qcc(Jpeg2000DecoderContext *s, int n, Jpeg2000QuantStyle *q,
                   uint8_t *properties)
{
    int compno;

    if (bytestream2_get_bytes_left(&s->g) < 1)
        return AVERROR(EINVAL);

    compno              = bytestream2_get_byteu(&s->g);
    properties[compno] |= HAD_QCC;
    return get_qcx(s, n - 1, q + compno);
}

/** get start of tile segment */
static int get_sot(Jpeg2000DecoderContext *s)
{
    if (bytestream2_get_bytes_left(&s->g) < 8)
        return AVERROR(EINVAL);

    s->curtileno = bytestream2_get_be16u(&s->g); ///< Isot
    if ((unsigned)s->curtileno >= s->numXtiles * s->numYtiles) {
        s->curtileno=0;
        return AVERROR(EINVAL);
    }

    bytestream2_skipu(&s->g, 4); ///< Psot (ignored)

    if (!bytestream2_get_byteu(&s->g)) { ///< TPsot
        Jpeg2000Tile *tile = s->tile + s->curtileno;

        /* copy defaults */
        memcpy(tile->codsty, s->codsty, s->ncomponents * sizeof(Jpeg2000CodingStyle));
        memcpy(tile->qntsty, s->qntsty, s->ncomponents * sizeof(Jpeg2000QuantStyle));
    }
    bytestream2_get_byteu(&s->g); ///< TNsot

    return 0;
}

static int init_tile(Jpeg2000DecoderContext *s, int tileno)
{
    int compno;
    int tilex = tileno % s->numXtiles;
    int tiley = tileno / s->numXtiles;
    Jpeg2000Tile *tile = s->tile + tileno;

    if (!tile->comp)
        return AVERROR(ENOMEM);
    for (compno = 0; compno < s->ncomponents; compno++) {
        Jpeg2000Component *comp = tile->comp + compno;
        Jpeg2000CodingStyle *codsty = tile->codsty + compno;
        Jpeg2000QuantStyle  *qntsty = tile->qntsty + compno;
        int ret; // global bandno

        comp->coord_o[0][0] = FFMAX(tilex       * s->tile_width  + s->tile_offset_x, s->image_offset_x);
        comp->coord_o[0][1] = FFMIN((tilex + 1) * s->tile_width  + s->tile_offset_x, s->width);
        comp->coord_o[1][0] = FFMAX(tiley       * s->tile_height + s->tile_offset_y, s->image_offset_y);
        comp->coord_o[1][1] = FFMIN((tiley + 1) * s->tile_height + s->tile_offset_y, s->height);

        comp->coord[0][0] = ff_jpeg2000_ceildivpow2(comp->coord_o[0][0], s->reduction_factor);
        comp->coord[0][1] = ff_jpeg2000_ceildivpow2(comp->coord_o[0][1], s->reduction_factor);
        comp->coord[1][0] = ff_jpeg2000_ceildivpow2(comp->coord_o[1][0], s->reduction_factor);
        comp->coord[1][1] = ff_jpeg2000_ceildivpow2(comp->coord_o[1][1], s->reduction_factor);

        if (ret = ff_j2k_init_component(comp, codsty, qntsty, s->cbps[compno], s->cdx[compno], s->cdy[compno], s->avctx))
            return ret;
    }
    return 0;
}

/** read the number of coding passes */
static int getnpasses(Jpeg2000DecoderContext *s)
{
    int num;
    if (!get_bits(s, 1))
        return 1;
    if (!get_bits(s, 1))
        return 2;
    if ((num = get_bits(s, 2)) != 3)
        return num < 0 ? num : 3 + num;
    if ((num = get_bits(s, 5)) != 31)
        return num < 0 ? num : 6 + num;
    num = get_bits(s, 7);
    return num < 0 ? num : 37 + num;
}

static int getlblockinc(Jpeg2000DecoderContext *s)
{
    int res = 0, ret;
    while (ret = get_bits(s, 1)) {
        if (ret < 0)
            return ret;
        res++;
    }
    return res;
}

static int decode_packet(Jpeg2000DecoderContext *s,
                         Jpeg2000CodingStyle *codsty,
                         Jpeg2000ResLevel *rlevel, int precno,
                         int layno, uint8_t *expn, int numgbits)
{
    int bandno, cblkno, ret, nb_code_blocks;

    if (!(ret = get_bits(s, 1))) {
        j2k_flush(s);
        return 0;
    } else if (ret < 0)
        return ret;

    for (bandno = 0; bandno < rlevel->nbands; bandno++) {
        Jpeg2000Band *band = rlevel->band + bandno;
        Jpeg2000Prec *prec = band->prec + precno;

        if (band->coord[0][0] == band->coord[0][1] ||
            band->coord[1][0] == band->coord[1][1])
            continue;

        nb_code_blocks =  prec->nb_codeblocks_height *
                          prec->nb_codeblocks_width;
        for (cblkno = 0; cblkno < nb_code_blocks; cblkno++) {
            Jpeg2000Cblk *cblk = prec->cblk + cblkno;
            int incl, newpasses, llen;

            if (cblk->npasses)
                incl = get_bits(s, 1);
            else
                incl = tag_tree_decode(s, prec->cblkincl + cblkno, layno + 1) == layno;
            if (!incl)
                continue;
            else if (incl < 0)
                return incl;

            if (!cblk->npasses)
                cblk->nonzerobits = expn[bandno] + numgbits - 1 -
                                    tag_tree_decode(s, prec->zerobits + cblkno,
                                                    100);
            if ((newpasses = getnpasses(s)) < 0)
                return newpasses;
            if ((llen = getlblockinc(s)) < 0)
                return llen;
            cblk->lblock += llen;
            if ((ret = get_bits(s, av_log2(newpasses) + cblk->lblock)) < 0)
                return ret;
            cblk->lengthinc = ret;
            cblk->npasses  += newpasses;
        }
    }
    j2k_flush(s);

    if (codsty->csty & JPEG2000_CSTY_EPH) {
        if (bytestream2_peek_be16(&s->g) == JPEG2000_EPH)
            bytestream2_skip(&s->g, 2);
        else
            av_log(s->avctx, AV_LOG_ERROR, "EPH marker not found.\n");
    }

    for (bandno = 0; bandno < rlevel->nbands; bandno++) {
        Jpeg2000Band *band = rlevel->band + bandno;
        Jpeg2000Prec *prec = band->prec + precno;

        nb_code_blocks = prec->nb_codeblocks_height * prec->nb_codeblocks_width;
        for (cblkno = 0; cblkno < nb_code_blocks; cblkno++) {
            Jpeg2000Cblk *cblk = prec->cblk + cblkno;
            if (   bytestream2_get_bytes_left(&s->g) < cblk->lengthinc
                || sizeof(cblk->data) < cblk->lengthinc
            )
                return AVERROR(EINVAL);
            /* Code-block data can be empty. In that case initialize data
             * with 0xFFFF. */
            if (cblk->lengthinc > 0) {
                 bytestream2_get_bufferu(&s->g, cblk->data, cblk->lengthinc);
            } else {
                cblk->data[0] = 0xFF;
                cblk->data[1] = 0xFF;
            }
            cblk->length   += cblk->lengthinc;
            cblk->lengthinc = 0;
        }
    }
    return 0;
}

static int jpeg2000_decode_packets(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile)
{
    int layno, reslevelno, compno, precno, ok_reslevel;
    s->bit_index = 8;
    for (layno = 0; layno < tile->codsty[0].nlayers; layno++) {
        ok_reslevel = 1;
        for (reslevelno = 0; ok_reslevel; reslevelno++) {
            ok_reslevel = 0;
            for (compno = 0; compno < s->ncomponents; compno++) {
                Jpeg2000CodingStyle *codsty = tile->codsty + compno;
                Jpeg2000QuantStyle  *qntsty = tile->qntsty + compno;
                if (reslevelno < codsty->nreslevels) {
                    Jpeg2000ResLevel *rlevel = tile->comp[compno].reslevel + reslevelno;
                    ok_reslevel = 1;
                    for (precno = 0; precno < rlevel->num_precincts_x * rlevel->num_precincts_y; precno++) {
                        if (decode_packet(s, codsty, rlevel, precno, layno, qntsty->expn +
                                          (reslevelno ? 3*(reslevelno-1)+1 : 0), qntsty->nguardbits))
                            return -1;
                    }
                }
            }
        }
    }
    return 0;
}

/* TIER-1 routines */
static void decode_sigpass(Jpeg2000T1Context *t1, int width, int height, int bpno, int bandno, int bpass_csty_symbol,
                           int vert_causal_ctx_csty_symbol)
{
    int mask = 3 << (bpno - 1), y0, x, y;

    for (y0 = 0; y0 < height; y0 += 4)
        for (x = 0; x < width; x++)
            for (y = y0; y < height && y < y0+4; y++) {
                if ((t1->flags[y+1][x+1] & JPEG2000_T1_SIG_NB)
                && !(t1->flags[y+1][x+1] & (JPEG2000_T1_SIG | JPEG2000_T1_VIS))) {
                    int flags_mask = -1;
                    if (vert_causal_ctx_csty_symbol && y == y0 + 3)
                        flags_mask &= ~(JPEG2000_T1_SIG_S | JPEG2000_T1_SIG_SW | JPEG2000_T1_SIG_SE);
                    if (ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ff_jpeg2000_getsigctxno(t1->flags[y+1][x+1] & flags_mask, bandno))) {
                        int xorbit, ctxno = ff_jpeg2000_getsgnctxno(t1->flags[y+1][x+1], &xorbit);
                        if (bpass_csty_symbol)
                             t1->data[y][x] = ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ctxno) ? -mask : mask;
                        else
                             t1->data[y][x] = (ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ctxno) ^ xorbit) ?
                                               -mask : mask;

                        ff_j2k_set_significant(t1, x, y, t1->data[y][x] < 0);
                    }
                    t1->flags[y + 1][x + 1] |= JPEG2000_T1_VIS;
                }
            }
}

static void decode_refpass(Jpeg2000T1Context *t1, int width, int height,
                           int bpno)
{
    int phalf, nhalf;
    int y0, x, y;

    phalf = 1 << (bpno - 1);
    nhalf = -phalf;

    for (y0 = 0; y0 < height; y0 += 4)
        for (x = 0; x < width; x++)
            for (y = y0; y < height && y < y0 + 4; y++)
                if ((t1->flags[y + 1][x + 1] & (JPEG2000_T1_SIG | JPEG2000_T1_VIS)) == JPEG2000_T1_SIG) {
                    int ctxno = ff_jpeg2000_getrefctxno(t1->flags[y + 1][x + 1]);
                    int r     = ff_mqc_decode(&t1->mqc,
                                              t1->mqc.cx_states + ctxno)
                                ? phalf : nhalf;
                    t1->data[y][x]          += t1->data[y][x] < 0 ? -r : r;
                    t1->flags[y + 1][x + 1] |= JPEG2000_T1_REF;
                }
}

static void decode_clnpass(Jpeg2000DecoderContext *s, Jpeg2000T1Context *t1, int width, int height,
                           int bpno, int bandno, int seg_symbols, int vert_causal_ctx_csty_symbol)
{
    int mask = 3 << (bpno - 1), y0, x, y, runlen, dec;

    for (y0 = 0; y0 < height; y0 += 4) {
        for (x = 0; x < width; x++) {
            if (y0 + 3 < height &&
                !((t1->flags[y0 + 1][x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG)) ||
                  (t1->flags[y0 + 2][x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG)) ||
                  (t1->flags[y0 + 3][x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG)) ||
                  (t1->flags[y0 + 4][x + 1] & (JPEG2000_T1_SIG_NB | JPEG2000_T1_VIS | JPEG2000_T1_SIG)))) {
                if (!ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_RL))
                    continue;
                runlen = ff_mqc_decode(&t1->mqc,
                                       t1->mqc.cx_states + MQC_CX_UNI);
                runlen = (runlen << 1) | ff_mqc_decode(&t1->mqc,
                                                       t1->mqc.cx_states +
                                                       MQC_CX_UNI);
                dec = 1;
            } else {
                runlen = 0;
                dec    = 0;
            }

            for (y = y0 + runlen; y < y0 + 4 && y < height; y++) {
                if (!dec) {
                    if (!(t1->flags[y+1][x+1] & (JPEG2000_T1_SIG | JPEG2000_T1_VIS))) {
                        int flags_mask = -1;
                        if (vert_causal_ctx_csty_symbol && y == y0 + 3)
                            flags_mask &= ~(JPEG2000_T1_SIG_S | JPEG2000_T1_SIG_SW | JPEG2000_T1_SIG_SE);
                        dec = ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + ff_jpeg2000_getsigctxno(t1->flags[y+1][x+1] & flags_mask,
                                                                                             bandno));
                    }
                }
                if (dec) {
                    int xorbit;
                    int ctxno = ff_jpeg2000_getsgnctxno(t1->flags[y + 1][x + 1],
                                                        &xorbit);
                    t1->data[y][x] = (ff_mqc_decode(&t1->mqc,
                                                    t1->mqc.cx_states + ctxno) ^
                                      xorbit)
                                     ? -mask : mask;
                    ff_j2k_set_significant(t1, x, y, t1->data[y][x] < 0);
                }
                dec = 0;
                t1->flags[y + 1][x + 1] &= ~JPEG2000_T1_VIS;
            }
        }
    }
    if (seg_symbols) {
        int val;
        val = ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        val = (val << 1) + ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        val = (val << 1) + ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        val = (val << 1) + ff_mqc_decode(&t1->mqc, t1->mqc.cx_states + MQC_CX_UNI);
        if (val != 0xa)
            av_log(s->avctx, AV_LOG_ERROR,
                   "Segmentation symbol value incorrect\n");
    }
}

static int decode_cblk(Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *codsty,
                       Jpeg2000T1Context *t1, Jpeg2000Cblk *cblk,
                       int width, int height, int bandpos)
{
    int passno = cblk->npasses, pass_t = 2, bpno = cblk->nonzerobits - 1, y, clnpass_cnt = 0;
    int bpass_csty_symbol = JPEG2000_CBLK_BYPASS & codsty->cblk_style;
    int vert_causal_ctx_csty_symbol = JPEG2000_CBLK_VSC & codsty->cblk_style;

    for (y = 0; y < height+2; y++)
        memset(t1->flags[y], 0, (width+2)*sizeof(int));

    for (y = 0; y < height; y++)
        memset(t1->data[y], 0, width*sizeof(int));

    cblk->data[cblk->length] = 0xff;
    cblk->data[cblk->length+1] = 0xff;
    ff_mqc_initdec(&t1->mqc, cblk->data);

    while (passno--) {
        switch(pass_t) {
            case 0: decode_sigpass(t1, width, height, bpno+1, bandpos,
                                  bpass_csty_symbol && (clnpass_cnt >= 4), vert_causal_ctx_csty_symbol);
                    break;
            case 1: decode_refpass(t1, width, height, bpno+1);
                    if (bpass_csty_symbol && clnpass_cnt >= 4)
                        ff_mqc_initdec(&t1->mqc, cblk->data);
                    break;
            case 2: decode_clnpass(s, t1, width, height, bpno+1, bandpos,
                                   codsty->cblk_style & JPEG2000_CBLK_SEGSYM, vert_causal_ctx_csty_symbol);
                    clnpass_cnt = clnpass_cnt + 1;
                    if (bpass_csty_symbol && clnpass_cnt >= 4)
                       ff_mqc_initdec(&t1->mqc, cblk->data);
                    break;
        }

        pass_t++;
        if (pass_t == 3) {
            bpno--;
            pass_t = 0;
        }
    }
    return 0;
}

static void mct_decode(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile)
{
    int i, *src[3], i0, i1, i2, csize = 1;

    for (i = 0; i < 3; i++)
        src[i] = tile->comp[i].data;

    for (i = 0; i < 2; i++)
        csize *= tile->comp[0].coord[i][1] - tile->comp[0].coord[i][0];

    if (tile->codsty[0].transform == FF_DWT97) {
        for (i = 0; i < csize; i++) {
            i0 = *src[0] + (*src[2] * 46802 >> 16);
            i1 = *src[0] - (*src[1] * 22553 + *src[2] * 46802 >> 16);
            i2 = *src[0] + (116130 * *src[1] >> 16);
            *src[0]++ = i0;
            *src[1]++ = i1;
            *src[2]++ = i2;
        }
    } else{
        for (i = 0; i < csize; i++) {
            i1 = *src[0] - (*src[2] + *src[1] >> 2);
            i0 = i1 + *src[2];
            i2 = i1 + *src[1];
            *src[0]++ = i0;
            *src[1]++ = i1;
            *src[2]++ = i2;
        }
    }
}

static int decode_tile(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile)
{
    int compno, reslevelno, bandno;
    int x, y, *src[4];
    uint8_t *line;
    Jpeg2000T1Context t1;

    /* Loop on tile components */
    for (compno = 0; compno < s->ncomponents; compno++) {
        Jpeg2000Component *comp     = tile->comp + compno;
        Jpeg2000CodingStyle *codsty = tile->codsty + compno;

        /* Loop on resolution levels */
        for (reslevelno = 0; reslevelno < codsty->nreslevels2decode; reslevelno++) {
            Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
            /* Loop on bands */
            for (bandno = 0; bandno < rlevel->nbands; bandno++) {
                int nb_precincts, precno;
                Jpeg2000Band *band = rlevel->band + bandno;
                int cblkx, cblky, cblkno=0, bandpos;

                bandpos = bandno + (reslevelno > 0);

                if (band->coord[0][0] == band->coord[0][1] || band->coord[1][0] == band->coord[1][1])
                    continue;

                nb_precincts = rlevel->num_precincts_x * rlevel->num_precincts_y;
                /* Loop on precincts */
                for (precno = 0; precno < nb_precincts; precno++) {
                    Jpeg2000Prec *prec = band->prec + precno;

                    /* Loop on codeblocks */
                    for (cblkno = 0; cblkno < prec->nb_codeblocks_width * prec->nb_codeblocks_height; cblkno++) {
                        int x, y;
                        int i, j;
                        Jpeg2000Cblk *cblk = prec->cblk + cblkno;
                        decode_cblk(s, codsty, &t1, cblk,
                                    cblk->coord[0][1] - cblk->coord[0][0],
                                    cblk->coord[1][1] - cblk->coord[1][0],
                                    bandpos);

                        /* Manage band offsets */
                        x = cblk->coord[0][0];
                        y = cblk->coord[1][0];

                        if (codsty->transform == FF_DWT53) {
                            for (j = 0; j < (cblk->coord[1][1] - cblk->coord[1][0]); ++j) {
                                int *datap = &comp->data[(comp->coord[0][1] - comp->coord[0][0]) * (y+j) + x];
                                int *ptr = t1.data[j];
                                for (i = 0; i < (cblk->coord[0][1] - cblk->coord[0][0]); ++i) {
                                    datap[i] = ptr[i] >> 1;
                                }
                            }
                        } else{
                            for (j = 0; j < (cblk->coord[1][1] - cblk->coord[1][0]); ++j) {
                                int *datap = &comp->data[(comp->coord[0][1] - comp->coord[0][0]) * (y+j) + x];
                                int *ptr = t1.data[j];
                                for (i = 0; i < (cblk->coord[0][1] - cblk->coord[0][0]); ++i) {
                                    int tmp = ((int64_t)ptr[i]) * ((int64_t)band->stepsize) >> 16, tmp2;
                                    tmp2 = FFABS(tmp>>1) + (tmp&1);
                                    datap[i] = tmp < 0 ? -tmp2 : tmp2;
                                }
                            }
                        }
                   } /* end cblk */
                } /*end prec */
            } /* end band */
        } /* end reslevel */

        ff_dwt_decode(&comp->dwt, comp->data);
        src[compno] = comp->data;
    } /*end comp */

    /* inverse MCT transformation */
    if (tile->codsty[0].mct)
        mct_decode(s, tile);

    if (s->precision <= 8) {
        for (compno = 0; compno < s->ncomponents; compno++) {
            y = tile->comp[compno].coord[1][0] - s->image_offset_y;
            line = s->picture->data[0] + y * s->picture->linesize[0];
            for (; y < tile->comp[compno].coord[1][1] - s->image_offset_y; y += s->cdy[compno]) {
                uint8_t *dst;

                x   = tile->comp[compno].coord[0][0] - s->image_offset_x;
                dst = line + x * s->ncomponents + compno;

                for (; x < tile->comp[compno].coord[0][1] - s->image_offset_x; x += s->cdx[compno]) {
                    *src[compno] += 1 << (s->cbps[compno]-1);
                    if (*src[compno] < 0)
                        *src[compno] = 0;
                    else if (*src[compno] >= (1 << s->cbps[compno]))
                        *src[compno] = (1 << s->cbps[compno]) - 1;
                    *dst = *src[compno]++;
                    dst += s->ncomponents;
                }
                line += s->picture->linesize[0];
            }
        }
    } else {
        for (compno = 0; compno < s->ncomponents; compno++) {
            y = tile->comp[compno].coord[1][0] - s->image_offset_y;
            line = s->picture->data[0] + y * s->picture->linesize[0];
            for (; y < tile->comp[compno].coord[1][1] - s->image_offset_y; y += s->cdy[compno]) {
                uint16_t *dst;

                x = tile->comp[compno].coord[0][0] - s->image_offset_x;
                dst = (uint16_t *)(line + (x * s->ncomponents + compno) * 2);
                for (; x < tile->comp[compno].coord[0][1] - s->image_offset_x; x += s-> cdx[compno]) {
                    int32_t val;

                    val = *src[compno]++ << (16 - s->cbps[compno]);
                    val += 1 << 15;
                    val = av_clip(val, 0, (1 << 16) - 1);
                    *dst = val;
                    dst += s->ncomponents;
                }
                line += s->picture->linesize[0];
            }
        }
    }
    return 0;
}

static void jpeg2000_dec_cleanup(Jpeg2000DecoderContext *s)
{
    int tileno, compno;
    for (tileno = 0; tileno < s->numXtiles * s->numYtiles; tileno++) {
        for (compno = 0; compno < s->ncomponents; compno++) {
            Jpeg2000Component *comp     = s->tile[tileno].comp   + compno;
            Jpeg2000CodingStyle *codsty = s->tile[tileno].codsty + compno;

            ff_j2k_cleanup(comp, codsty);
        }
        av_freep(&s->tile[tileno].comp);
    }
    av_freep(&s->tile);
}

static int decode_codestream(Jpeg2000DecoderContext *s)
{
    Jpeg2000CodingStyle *codsty = s->codsty;
    Jpeg2000QuantStyle *qntsty  = s->qntsty;
    uint8_t *properties         = s->properties;

    for (;;) {
        int oldpos, marker, len, ret = 0;

        if (bytestream2_get_bytes_left(&s->g) < 2) {
            av_log(s->avctx, AV_LOG_ERROR, "Missing EOC\n");
            break;
        }

        marker = bytestream2_get_be16u(&s->g);
        av_dlog(s->avctx, "marker 0x%.4X at pos 0x%x\n", marker, bytestream2_tell(&s->g) - 4);
        oldpos = bytestream2_tell(&s->g);

        if (marker == JPEG2000_SOD) {
            Jpeg2000Tile *tile = s->tile + s->curtileno;
            if (ret = init_tile(s, s->curtileno)) {
                av_log(s->avctx, AV_LOG_ERROR, "tile initialization failed\n");
                return ret;
            }
            if (ret = jpeg2000_decode_packets(s, tile)) {
                av_log(s->avctx, AV_LOG_ERROR, "packets decoding failed\n");
                return ret;
            }
            continue;
        }
        if (marker == JPEG2000_EOC)
            break;

        if (bytestream2_get_bytes_left(&s->g) < 2)
            return AVERROR(EINVAL);
        len = bytestream2_get_be16u(&s->g);
        switch (marker) {
        case JPEG2000_SIZ:
            ret = get_siz(s);
            if (!s->tile)
                s->numXtiles = s->numYtiles = 0;
            break;
        case JPEG2000_COC:
            ret = get_coc(s, codsty, properties);
            break;
        case JPEG2000_COD:
            ret = get_cod(s, codsty, properties);
            break;
        case JPEG2000_QCC:
            ret = get_qcc(s, len, qntsty, properties);
            break;
        case JPEG2000_QCD:
            ret = get_qcd(s, len, qntsty, properties);
            break;
        case JPEG2000_SOT:
            if (!(ret = get_sot(s))) {
                codsty = s->tile[s->curtileno].codsty;
                qntsty = s->tile[s->curtileno].qntsty;
                properties = s->tile[s->curtileno].properties;
            }
            break;
        case JPEG2000_COM:
            // the comment is ignored
            bytestream2_skip(&s->g, len - 2);
            break;
        default:
            av_log(s->avctx, AV_LOG_ERROR, "unsupported marker 0x%.4X at pos 0x%x\n", marker, bytestream2_tell(&s->g) - 4);
            bytestream2_skip(&s->g, len - 2);
            break;
        }
        if (bytestream2_tell(&s->g) - oldpos != len || ret) {
            av_log(s->avctx, AV_LOG_ERROR, "error during processing marker segment %.4x\n", marker);
            return ret ? ret : -1;
        }
    }
    return 0;
}

static int jp2_find_codestream(Jpeg2000DecoderContext *s)
{
    uint32_t atom_size, atom;
    int found_codestream = 0, search_range = 10;

    while (!found_codestream && search_range && bytestream2_get_bytes_left(&s->g) >= 8) {
        atom_size = bytestream2_get_be32u(&s->g);
        atom      = bytestream2_get_be32u(&s->g);
        if (atom == JP2_CODESTREAM) {
            found_codestream = 1;
        } else {
            if (bytestream2_get_bytes_left(&s->g) < atom_size - 8)
                return 0;
            bytestream2_skipu(&s->g, atom_size - 8);
            search_range--;
        }
    }

    if (found_codestream)
        return 1;
    return 0;
}

static int jpeg2000_decode_frame(AVCodecContext *avctx, void *data,
                                 int *got_frame, AVPacket *avpkt)
{
    Jpeg2000DecoderContext *s = avctx->priv_data;
    AVFrame *picture = data;
    int tileno, ret;

    s->picture = picture;

    s->avctx     = avctx;
    bytestream2_init(&s->g, avpkt->data, avpkt->size);
    s->curtileno = -1;

    // reduction factor, i.e number of resolution levels to skip
    s->reduction_factor = avctx->lowres;

    if (bytestream2_get_bytes_left(&s->g) < 2) {
        ret = AVERROR(EINVAL);
        goto err_out;
    }

    // check if the image is in jp2 format
    if (bytestream2_get_bytes_left(&s->g) >= 12 &&
       (bytestream2_get_be32u(&s->g) == 12) &&
       (bytestream2_get_be32u(&s->g) == JP2_SIG_TYPE) &&
       (bytestream2_get_be32u(&s->g) == JP2_SIG_VALUE)) {
        if (!jp2_find_codestream(s)) {
            av_log(avctx, AV_LOG_ERROR, "couldn't find jpeg2k codestream atom\n");
            ret = -1;
            goto err_out;
        }
    } else {
        bytestream2_seek(&s->g, 0, SEEK_SET);
    }

    if (bytestream2_get_be16u(&s->g) != JPEG2000_SOC) {
        av_log(avctx, AV_LOG_ERROR, "SOC marker not present\n");
        ret = -1;
        goto err_out;
    }
    if (ret = decode_codestream(s))
        goto err_out;

    for (tileno = 0; tileno < s->numXtiles * s->numYtiles; tileno++)
        if (ret = decode_tile(s, s->tile + tileno))
            goto err_out;

    jpeg2000_dec_cleanup(s);

    *got_frame = 1;

    return bytestream2_tell(&s->g);

err_out:
    jpeg2000_dec_cleanup(s);
    return ret;
}

static void jpeg2000_init_static_data(AVCodec *codec)
{
    ff_jpeg2000_init_tier1_luts();
}

#define OFFSET(x) offsetof(Jpeg2000DecoderContext, x)
#define VD AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM

static const AVOption options[] = {
    { "lowres",  "Lower the decoding resolution by a power of two",
        OFFSET(lowres), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, JPEG2000_MAX_RESLEVELS - 1, VD },
    { NULL },
};

static const AVProfile profiles[] = {
    { FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_0,  "JPEG 2000 codestream restriction 0"   },
    { FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_1,  "JPEG 2000 codestream restriction 1"   },
    { FF_PROFILE_JPEG2000_CSTREAM_NO_RESTRICTION, "JPEG 2000 no codestream restrictions" },
    { FF_PROFILE_JPEG2000_DCINEMA_2K,             "JPEG 2000 digital cinema 2K"          },
    { FF_PROFILE_JPEG2000_DCINEMA_4K,             "JPEG 2000 digital cinema 4K"          },
    { FF_PROFILE_UNKNOWN },
};

static const AVClass class = {
    .class_name = "j2k",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

AVCodec ff_j2k_decoder = {
    .name             = "j2k",
    .long_name        = NULL_IF_CONFIG_SMALL("JPEG 2000"),
    .type             = AVMEDIA_TYPE_VIDEO,
    .id               = AV_CODEC_ID_JPEG2000,
    .capabilities     = CODEC_CAP_EXPERIMENTAL | CODEC_CAP_FRAME_THREADS,
    .priv_data_size   = sizeof(Jpeg2000DecoderContext),
    .init_static_data = jpeg2000_init_static_data,
    .decode           = jpeg2000_decode_frame,
    .priv_class       = &class,
    .max_lowres       = 5,
    .profiles         = NULL_IF_CONFIG_SMALL(profiles)
};