/*
 * JPEG-LS decoder
 * Copyright (c) 2003 Michael Niedermayer
 * Copyright (c) 2006 Konstantin Shishkov
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file libavcodec/jpeglsdec.c
 * JPEG-LS decoder.
 */

#include "avcodec.h"
#include "bitstream.h"
#include "golomb.h"
#include "mathops.h"
#include "mjpeg.h"
#include "mjpegdec.h"
#include "jpegls.h"
#include "jpeglsdec.h"


/*
* Uncomment this to significantly speed up decoding of broken JPEG-LS
* (or test broken JPEG-LS decoder) and slow down ordinary decoding a bit.
*
* There is no Golomb code with length >= 32 bits possible, so check and
* avoid situation of 32 zeros, FFmpeg Golomb decoder is painfully slow
* on this errors.
*/
//#define JLS_BROKEN


/**
 * Decode LSE block with initialization parameters
 */
int ff_jpegls_decode_lse(MJpegDecodeContext *s)
{
    int len, id;

    /* XXX: verify len field validity */
    len = get_bits(&s->gb, 16);
    id = get_bits(&s->gb, 8);

    switch(id){
    case 1:
        s->maxval= get_bits(&s->gb, 16);
        s->t1= get_bits(&s->gb, 16);
        s->t2= get_bits(&s->gb, 16);
        s->t3= get_bits(&s->gb, 16);
        s->reset= get_bits(&s->gb, 16);

//        ff_jpegls_reset_coding_parameters(s, 0);
        //FIXME quant table?
        break;
    case 2:
    case 3:
        av_log(s->avctx, AV_LOG_ERROR, "palette not supported\n");
        return -1;
    case 4:
        av_log(s->avctx, AV_LOG_ERROR, "oversize image not supported\n");
        return -1;
    default:
        av_log(s->avctx, AV_LOG_ERROR, "invalid id %d\n", id);
        return -1;
    }
//    av_log(s->avctx, AV_LOG_DEBUG, "ID=%i, T=%i,%i,%i\n", id, s->t1, s->t2, s->t3);

    return 0;
}

/**
 * Get context-dependent Golomb code, decode it and update context
 */
static inline int ls_get_code_regular(GetBitContext *gb, JLSState *state, int Q){
    int k, ret;

    for(k = 0; (state->N[Q] << k) < state->A[Q]; k++);

#ifdef JLS_BROKEN
    if(!show_bits_long(gb, 32))return -1;
#endif
    ret = get_ur_golomb_jpegls(gb, k, state->limit, state->qbpp);

    /* decode mapped error */
    if(ret & 1)
        ret = -((ret + 1) >> 1);
    else
        ret >>= 1;

    /* for NEAR=0, k=0 and 2*B[Q] <= - N[Q] mapping is reversed */
    if(!state->near && !k && (2 * state->B[Q] <= -state->N[Q]))
        ret = -(ret + 1);

    ret= ff_jpegls_update_state_regular(state, Q, ret);

    return ret;
}

/**
 * Get Golomb code, decode it and update state for run termination
 */
static inline int ls_get_code_runterm(GetBitContext *gb, JLSState *state, int RItype, int limit_add){
    int k, ret, temp, map;
    int Q = 365 + RItype;

    temp=  state->A[Q];
    if(RItype)
        temp += state->N[Q] >> 1;

    for(k = 0; (state->N[Q] << k) < temp; k++);

#ifdef JLS_BROKEN
    if(!show_bits_long(gb, 32))return -1;
#endif
    ret = get_ur_golomb_jpegls(gb, k, state->limit - limit_add - 1, state->qbpp);

    /* decode mapped error */
    map = 0;
    if(!k && (RItype || ret) && (2 * state->B[Q] < state->N[Q]))
        map = 1;
    ret += RItype + map;

    if(ret & 1){
        ret = map - ((ret + 1) >> 1);
        state->B[Q]++;
    } else {
        ret = ret >> 1;
    }

    if(FFABS(ret) > 0xFFFF)
        return -0x10000;
    /* update state */
    state->A[Q] += FFABS(ret) - RItype;
    ret *= state->twonear;
    ff_jpegls_downscale_state(state, Q);

    return ret;
}

/**
 * Decode one line of image
 */
static inline void ls_decode_line(JLSState *state, MJpegDecodeContext *s, void *last, void *dst, int last2, int w, int stride, int comp, int bits){
    int i, x = 0;
    int Ra, Rb, Rc, Rd;
    int D0, D1, D2;

    while(x < w) {
        int err, pred;

        /* compute gradients */
        Ra = x ? R(dst, x - stride) : R(last, x);
        Rb = R(last, x);
        Rc = x ? R(last, x - stride) : last2;
        Rd = (x >= w - stride) ? R(last, x) : R(last, x + stride);
        D0 = Rd - Rb;
        D1 = Rb - Rc;
        D2 = Rc - Ra;
        /* run mode */
        if((FFABS(D0) <= state->near) && (FFABS(D1) <= state->near) && (FFABS(D2) <= state->near)) {
            int r;
            int RItype;

            /* decode full runs while available */
            while(get_bits1(&s->gb)) {
                int r;
                r = 1 << ff_log2_run[state->run_index[comp]];
                if(x + r * stride > w) {
                    r = (w - x) / stride;
                }
                for(i = 0; i < r; i++) {
                    W(dst, x, Ra);
                    x += stride;
                }
                /* if EOL reached, we stop decoding */
                if(r != (1 << ff_log2_run[state->run_index[comp]]))
                    return;
                if(state->run_index[comp] < 31)
                    state->run_index[comp]++;
                if(x + stride > w)
                    return;
            }
            /* decode aborted run */
            r = ff_log2_run[state->run_index[comp]];
            if(r)
                r = get_bits_long(&s->gb, r);
            for(i = 0; i < r; i++) {
                W(dst, x, Ra);
                x += stride;
            }

            /* decode run termination value */
            Rb = R(last, x);
            RItype = (FFABS(Ra - Rb) <= state->near) ? 1 : 0;
            err = ls_get_code_runterm(&s->gb, state, RItype, ff_log2_run[state->run_index[comp]]);
            if(state->run_index[comp])
                state->run_index[comp]--;

            if(state->near && RItype){
                pred = Ra + err;
            } else {
                if(Rb < Ra)
                    pred = Rb - err;
                else
                    pred = Rb + err;
            }
        } else { /* regular mode */
            int context, sign;

            context = ff_jpegls_quantize(state, D0) * 81 + ff_jpegls_quantize(state, D1) * 9 + ff_jpegls_quantize(state, D2);
            pred = mid_pred(Ra, Ra + Rb - Rc, Rb);

            if(context < 0){
                context = -context;
                sign = 1;
            }else{
                sign = 0;
            }

            if(sign){
                pred = av_clip(pred - state->C[context], 0, state->maxval);
                err = -ls_get_code_regular(&s->gb, state, context);
            } else {
                pred = av_clip(pred + state->C[context], 0, state->maxval);
                err = ls_get_code_regular(&s->gb, state, context);
            }

            /* we have to do something more for near-lossless coding */
            pred += err;
        }
        if(state->near){
            if(pred < -state->near)
                pred += state->range * state->twonear;
            else if(pred > state->maxval + state->near)
                pred -= state->range * state->twonear;
            pred = av_clip(pred, 0, state->maxval);
        }

        pred &= state->maxval;
        W(dst, x, pred);
        x += stride;
    }
}

int ff_jpegls_decode_picture(MJpegDecodeContext *s, int near, int point_transform, int ilv){
    int i, t = 0;
    uint8_t *zero, *last, *cur;
    JLSState *state;
    int off = 0, stride = 1, width, shift;

    zero = av_mallocz(s->picture.linesize[0]);
    last = zero;
    cur = s->picture.data[0];

    state = av_mallocz(sizeof(JLSState));
    /* initialize JPEG-LS state from JPEG parameters */
    state->near = near;
    state->bpp = (s->bits < 2) ? 2 : s->bits;
    state->maxval = s->maxval;
    state->T1 = s->t1;
    state->T2 = s->t2;
    state->T3 = s->t3;
    state->reset = s->reset;
    ff_jpegls_reset_coding_parameters(state, 0);
    ff_jpegls_init_state(state);

    if(s->bits <= 8)
        shift = point_transform + (8 - s->bits);
    else
        shift = point_transform + (16 - s->bits);

//    av_log(s->avctx, AV_LOG_DEBUG, "JPEG-LS params: %ix%i NEAR=%i MV=%i T(%i,%i,%i) RESET=%i, LIMIT=%i, qbpp=%i, RANGE=%i\n",s->width,s->height,state->near,state->maxval,state->T1,state->T2,state->T3,state->reset,state->limit,state->qbpp, state->range);
//    av_log(s->avctx, AV_LOG_DEBUG, "JPEG params: ILV=%i Pt=%i BPP=%i, scan = %i\n", ilv, point_transform, s->bits, s->cur_scan);
    if(ilv == 0) { /* separate planes */
        off = s->cur_scan - 1;
        stride = (s->nb_components > 1) ? 3 : 1;
        width = s->width * stride;
        cur += off;
        for(i = 0; i < s->height; i++) {
            if(s->bits <= 8){
                ls_decode_line(state, s, last, cur, t, width, stride, off,  8);
                t = last[0];
            }else{
                ls_decode_line(state, s, last, cur, t, width, stride, off, 16);
                t = *((uint16_t*)last);
            }
            last = cur;
            cur += s->picture.linesize[0];

            if (s->restart_interval && !--s->restart_count) {
                align_get_bits(&s->gb);
                skip_bits(&s->gb, 16); /* skip RSTn */
            }
        }
    } else if(ilv == 1) { /* line interleaving */
        int j;
        int Rc[3] = {0, 0, 0};
        memset(cur, 0, s->picture.linesize[0]);
        width = s->width * 3;
        for(i = 0; i < s->height; i++) {
            for(j = 0; j < 3; j++) {
                ls_decode_line(state, s, last + j, cur + j, Rc[j], width, 3, j, 8);
                Rc[j] = last[j];

                if (s->restart_interval && !--s->restart_count) {
                    align_get_bits(&s->gb);
                    skip_bits(&s->gb, 16); /* skip RSTn */
                }
            }
            last = cur;
            cur += s->picture.linesize[0];
        }
    } else if(ilv == 2) { /* sample interleaving */
        av_log(s->avctx, AV_LOG_ERROR, "Sample interleaved images are not supported.\n");
        av_free(state);
        av_free(zero);
        return -1;
    }

    if(shift){ /* we need to do point transform or normalize samples */
        int x, w;

        w = s->width * s->nb_components;

        if(s->bits <= 8){
            uint8_t *src = s->picture.data[0];

            for(i = 0; i < s->height; i++){
                for(x = off; x < w; x+= stride){
                    src[x] <<= shift;
                }
                src += s->picture.linesize[0];
            }
        }else{
            uint16_t *src = (uint16_t*) s->picture.data[0];

            for(i = 0; i < s->height; i++){
                for(x = 0; x < w; x++){
                    src[x] <<= shift;
                }
                src += s->picture.linesize[0]/2;
            }
        }
    }
    av_free(state);
    av_free(zero);

    return 0;
}


AVCodec jpegls_decoder = {
    "jpegls",
    CODEC_TYPE_VIDEO,
    CODEC_ID_JPEGLS,
    sizeof(MJpegDecodeContext),
    ff_mjpeg_decode_init,
    NULL,
    ff_mjpeg_decode_end,
    ff_mjpeg_decode_frame,
    CODEC_CAP_DR1,
    .long_name = NULL_IF_CONFIG_SMALL("JPEG-LS"),
};