/* Copyright (C) 2001-2021 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  1305 Grant Avenue - Suite 200, Novato,
   CA 94945, U.S.A., +1(415)492-9861, for further information.
*/

/*
    jbig2dec
*/

/* symbol dictionary segment decode and support */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "os_types.h"

#include <stddef.h>
#include <string.h>             /* memset() */

#if defined(OUTPUT_PBM) || defined(DUMP_SYMDICT)
#include <stdio.h>
#endif

#include "jbig2.h"
#include "jbig2_priv.h"
#include "jbig2_arith.h"
#include "jbig2_arith_int.h"
#include "jbig2_arith_iaid.h"
#include "jbig2_generic.h"
#include "jbig2_huffman.h"
#include "jbig2_image.h"
#include "jbig2_mmr.h"
#include "jbig2_refinement.h"
#include "jbig2_segment.h"
#include "jbig2_symbol_dict.h"
#include "jbig2_text.h"

/* Table 13 */
typedef struct {
    bool SDHUFF;
    bool SDREFAGG;
    uint32_t SDNUMINSYMS;
    Jbig2SymbolDict *SDINSYMS;
    uint32_t SDNUMNEWSYMS;
    uint32_t SDNUMEXSYMS;
    Jbig2HuffmanTable *SDHUFFDH;
    Jbig2HuffmanTable *SDHUFFDW;
    Jbig2HuffmanTable *SDHUFFBMSIZE;
    Jbig2HuffmanTable *SDHUFFAGGINST;
    int SDTEMPLATE;
    int8_t sdat[8];
    bool SDRTEMPLATE;
    int8_t sdrat[4];
} Jbig2SymbolDictParams;

/* Utility routines */

#ifdef DUMP_SYMDICT
void
jbig2_dump_symbol_dict(Jbig2Ctx *ctx, Jbig2Segment *segment)
{
    Jbig2SymbolDict *dict = (Jbig2SymbolDict *) segment->result;
    uint32_t index;
    char filename[24];
    int code;

    if (dict == NULL)
        return;
    jbig2_error(ctx, JBIG2_SEVERITY_INFO, segment->number, "dumping symbol dictionary as %d individual png files", dict->n_symbols);
    for (index = 0; index < dict->n_symbols; index++) {
        snprintf(filename, sizeof(filename), "symbol_%02d-%04d.png", segment->number, index);
        jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "dumping symbol %d/%d as '%s'", index, dict->n_symbols, filename);
#ifdef HAVE_LIBPNG
        code = jbig2_image_write_png_file(dict->glyphs[index], filename);
#else
        code = jbig2_image_write_pbm_file(dict->glyphs[index], filename);
#endif
        if (code < 0)
            return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to dump symbol %d/%d as '%s'", index, dict->n_symbols, filename);
    }
}
#endif /* DUMP_SYMDICT */

/* return a new empty symbol dict */
Jbig2SymbolDict *
jbig2_sd_new(Jbig2Ctx *ctx, uint32_t n_symbols)
{
    Jbig2SymbolDict *new_dict = NULL;

    new_dict = jbig2_new(ctx, Jbig2SymbolDict, 1);
    if (new_dict != NULL) {
        new_dict->glyphs = jbig2_new(ctx, Jbig2Image *, n_symbols);
        new_dict->n_symbols = n_symbols;
    } else {
        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to allocate new empty symbol dictionary");
        return NULL;
    }

    if (new_dict->glyphs != NULL) {
        memset(new_dict->glyphs, 0, n_symbols * sizeof(Jbig2Image *));
    } else if (new_dict->n_symbols > 0) {
        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to allocate glyphs for new empty symbol dictionary");
        jbig2_free(ctx->allocator, new_dict);
        return NULL;
    }

    return new_dict;
}

/* release the memory associated with a symbol dict */
void
jbig2_sd_release(Jbig2Ctx *ctx, Jbig2SymbolDict *dict)
{
    uint32_t i;

    if (dict == NULL)
        return;
    if (dict->glyphs != NULL)
        for (i = 0; i < dict->n_symbols; i++)
            jbig2_image_release(ctx, dict->glyphs[i]);
    jbig2_free(ctx->allocator, dict->glyphs);
    jbig2_free(ctx->allocator, dict);
}

/* get a particular glyph by index */
Jbig2Image *
jbig2_sd_glyph(Jbig2SymbolDict *dict, unsigned int id)
{
    if (dict == NULL)
        return NULL;
    return dict->glyphs[id];
}

/* count the number of dictionary segments referred to by the given segment */
uint32_t
jbig2_sd_count_referred(Jbig2Ctx *ctx, Jbig2Segment *segment)
{
    int index;
    Jbig2Segment *rsegment;
    uint32_t n_dicts = 0;

    for (index = 0; index < segment->referred_to_segment_count; index++) {
        rsegment = jbig2_find_segment(ctx, segment->referred_to_segments[index]);
        if (rsegment && ((rsegment->flags & 63) == 0) &&
            rsegment->result && (((Jbig2SymbolDict *) rsegment->result)->n_symbols > 0) && ((*((Jbig2SymbolDict *) rsegment->result)->glyphs) != NULL))
            n_dicts++;
    }

    return (n_dicts);
}

/* return an array of pointers to symbol dictionaries referred to by the given segment */
Jbig2SymbolDict **
jbig2_sd_list_referred(Jbig2Ctx *ctx, Jbig2Segment *segment)
{
    int index;
    Jbig2Segment *rsegment;
    Jbig2SymbolDict **dicts;
    uint32_t n_dicts = jbig2_sd_count_referred(ctx, segment);
    uint32_t dindex = 0;

    dicts = jbig2_new(ctx, Jbig2SymbolDict *, n_dicts);
    if (dicts == NULL) {
        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to allocate referred list of symbol dictionaries");
        return NULL;
    }

    for (index = 0; index < segment->referred_to_segment_count; index++) {
        rsegment = jbig2_find_segment(ctx, segment->referred_to_segments[index]);
        if (rsegment && ((rsegment->flags & 63) == 0) && rsegment->result &&
                (((Jbig2SymbolDict *) rsegment->result)->n_symbols > 0) && ((*((Jbig2SymbolDict *) rsegment->result)->glyphs) != NULL)) {
            /* add this referred to symbol dictionary */
            dicts[dindex++] = (Jbig2SymbolDict *) rsegment->result;
        }
    }

    if (dindex != n_dicts) {
        /* should never happen */
        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "counted %d symbol dictionaries but built a list with %d.", n_dicts, dindex);
        jbig2_free(ctx->allocator, dicts);
        return NULL;
    }

    return (dicts);
}

/* generate a new symbol dictionary by concatenating a list of
   existing dictionaries */
Jbig2SymbolDict *
jbig2_sd_cat(Jbig2Ctx *ctx, uint32_t n_dicts, Jbig2SymbolDict **dicts)
{
    uint32_t i, j, k, symbols;
    Jbig2SymbolDict *new_dict = NULL;

    /* count the imported symbols and allocate a new array */
    symbols = 0;
    for (i = 0; i < n_dicts; i++)
        symbols += dicts[i]->n_symbols;

    /* fill a new array with new references to glyph pointers */
    new_dict = jbig2_sd_new(ctx, symbols);
    if (new_dict != NULL) {
        k = 0;
        for (i = 0; i < n_dicts; i++)
            for (j = 0; j < dicts[i]->n_symbols; j++)
                new_dict->glyphs[k++] = jbig2_image_reference(ctx, dicts[i]->glyphs[j]);
    } else {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to allocate new symbol dictionary");
    }

    return new_dict;
}

/* Decoding routines */

/* 6.5 */
static Jbig2SymbolDict *
jbig2_decode_symbol_dict(Jbig2Ctx *ctx,
                         Jbig2Segment *segment,
                         const Jbig2SymbolDictParams *params, const byte *data, size_t size, Jbig2ArithCx *GB_stats, Jbig2ArithCx *GR_stats)
{
    Jbig2SymbolDict *SDNEWSYMS = NULL;
    Jbig2SymbolDict *SDEXSYMS = NULL;
    uint32_t HCHEIGHT;
    uint32_t NSYMSDECODED;
    uint32_t SYMWIDTH, TOTWIDTH;
    uint32_t HCFIRSTSYM;
    uint32_t *SDNEWSYMWIDTHS = NULL;
    uint8_t SBSYMCODELEN = 0;
    Jbig2WordStream *ws = NULL;
    Jbig2HuffmanState *hs = NULL;
    Jbig2ArithState *as = NULL;
    Jbig2ArithIntCtx *IADH = NULL;
    Jbig2ArithIntCtx *IADW = NULL;
    Jbig2ArithIntCtx *IAEX = NULL;
    Jbig2ArithIntCtx *IAAI = NULL;
    int code = 0;
    Jbig2SymbolDict **refagg_dicts = NULL;
    uint32_t i;
    Jbig2TextRegionParams tparams;
    Jbig2Image *image = NULL;
    Jbig2Image *glyph = NULL;
    uint32_t emptyruns = 0;

    memset(&tparams, 0, sizeof(tparams));

    /* 6.5.5 (3) */
    HCHEIGHT = 0;
    NSYMSDECODED = 0;

    ws = jbig2_word_stream_buf_new(ctx, data, size);
    if (ws == NULL) {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate word stream when decoding symbol dictionary");
        return NULL;
    }

    as = jbig2_arith_new(ctx, ws);
    if (as == NULL) {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate arithmetic coding state when decoding symbol dictionary");
        jbig2_word_stream_buf_free(ctx, ws);
        return NULL;
    }

    for (SBSYMCODELEN = 0; ((uint64_t) 1 << SBSYMCODELEN) < ((uint64_t) params->SDNUMINSYMS + params->SDNUMNEWSYMS); SBSYMCODELEN++);

    if (params->SDHUFF) {
        jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "huffman coded symbol dictionary");
        hs = jbig2_huffman_new(ctx, ws);
        tparams.SBHUFFRDX = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_O);   /* Table B.15 */
        tparams.SBHUFFRDY = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_O);   /* Table B.15 */
        tparams.SBHUFFRSIZE = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_A); /* Table B.1 */
        if (hs == NULL || tparams.SBHUFFRDX == NULL ||
                tparams.SBHUFFRDY == NULL || tparams.SBHUFFRSIZE == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate for symbol bitmap");
            goto cleanup;
        }
        /* 6.5.5 (2) */
        if (!params->SDREFAGG) {
            SDNEWSYMWIDTHS = jbig2_new(ctx, uint32_t, params->SDNUMNEWSYMS);
            if (SDNEWSYMWIDTHS == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to allocate symbol widths (%u)", params->SDNUMNEWSYMS);
                goto cleanup;
            }
        } else {
            tparams.SBHUFFFS = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_F);    /* Table B.6 */
            tparams.SBHUFFDS = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_H);    /* Table B.8 */
            tparams.SBHUFFDT = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_K);    /* Table B.11 */
            tparams.SBHUFFRDW = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_O);   /* Table B.15 */
            tparams.SBHUFFRDH = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_O);   /* Table B.15 */
            if (tparams.SBHUFFFS == NULL || tparams.SBHUFFDS == NULL ||
                    tparams.SBHUFFDT == NULL || tparams.SBHUFFRDW == NULL ||
                    tparams.SBHUFFRDH == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "out of memory creating text region huffman decoder entries");
                goto cleanup;
            }
        }
    } else {
        IADH = jbig2_arith_int_ctx_new(ctx);
        IADW = jbig2_arith_int_ctx_new(ctx);
        IAEX = jbig2_arith_int_ctx_new(ctx);
        IAAI = jbig2_arith_int_ctx_new(ctx);
        if (IADH == NULL || IADW == NULL || IAEX == NULL || IAAI == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate symbol bitmap");
            goto cleanup;
        }
        tparams.IAID = jbig2_arith_iaid_ctx_new(ctx, SBSYMCODELEN);
        tparams.IARDX = jbig2_arith_int_ctx_new(ctx);
        tparams.IARDY = jbig2_arith_int_ctx_new(ctx);
        if (tparams.IAID == NULL || tparams.IARDX == NULL ||
                tparams.IARDY == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate text region arithmetic decoder contexts");
            goto cleanup;
        }
        if (params->SDREFAGG) {
            /* Values from Table 17, section 6.5.8.2 (2) */
            tparams.IADT = jbig2_arith_int_ctx_new(ctx);
            tparams.IAFS = jbig2_arith_int_ctx_new(ctx);
            tparams.IADS = jbig2_arith_int_ctx_new(ctx);
            tparams.IAIT = jbig2_arith_int_ctx_new(ctx);
            /* Table 31 */
            tparams.IARI = jbig2_arith_int_ctx_new(ctx);
            tparams.IARDW = jbig2_arith_int_ctx_new(ctx);
            tparams.IARDH = jbig2_arith_int_ctx_new(ctx);
            if (tparams.IADT == NULL || tparams.IAFS == NULL ||
                    tparams.IADS == NULL || tparams.IAIT == NULL ||
                    tparams.IARI == NULL || tparams.IARDW == NULL ||
                    tparams.IARDH == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate text region arith decoder contexts");
            }
        }
    }
    tparams.SBHUFF = params->SDHUFF;
    tparams.SBREFINE = 1;
    tparams.SBSTRIPS = 1;
    tparams.SBDEFPIXEL = 0;
    tparams.SBCOMBOP = JBIG2_COMPOSE_OR;
    tparams.TRANSPOSED = 0;
    tparams.REFCORNER = JBIG2_CORNER_TOPLEFT;
    tparams.SBDSOFFSET = 0;
    tparams.SBRTEMPLATE = params->SDRTEMPLATE;

    /* 6.5.5 (1) */
    SDNEWSYMS = jbig2_sd_new(ctx, params->SDNUMNEWSYMS);
    if (SDNEWSYMS == NULL) {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate new symbols (%u)", params->SDNUMNEWSYMS);
        goto cleanup;
    }

    refagg_dicts = jbig2_new(ctx, Jbig2SymbolDict *, 2);
    if (refagg_dicts == NULL) {
        code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "Out of memory allocating dictionary array");
        goto cleanup;
    }
    refagg_dicts[0] = jbig2_sd_new(ctx, params->SDNUMINSYMS);
    if (refagg_dicts[0] == NULL) {
        code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "out of memory allocating symbol dictionary");
        goto cleanup;
    }
    for (i = 0; i < params->SDNUMINSYMS; i++) {
        refagg_dicts[0]->glyphs[i] = jbig2_image_reference(ctx, params->SDINSYMS->glyphs[i]);
    }
    refagg_dicts[1] = SDNEWSYMS;

    /* 6.5.5 (4a) */
    while (NSYMSDECODED < params->SDNUMNEWSYMS) {
        int32_t HCDH, DW;

        /* 6.5.6 */
        if (params->SDHUFF) {
            HCDH = jbig2_huffman_get(hs, params->SDHUFFDH, &code);
        } else {
            code = jbig2_arith_int_decode(ctx, IADH, as, &HCDH);
        }
        if (code < 0) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode height class delta");
            goto cleanup;
        }
        if (code > 0) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "OOB decoding height class delta");
            goto cleanup;
        }

        /* 6.5.5 (4b) */
        HCHEIGHT = HCHEIGHT + HCDH;
        SYMWIDTH = 0;
        TOTWIDTH = 0;
        HCFIRSTSYM = NSYMSDECODED;

        if ((int32_t) HCHEIGHT < 0) {
            code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "invalid HCHEIGHT value");
            goto cleanup;
        }
#ifdef JBIG2_DEBUG
        jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "HCHEIGHT = %d", HCHEIGHT);
#endif
        jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "decoding height class %d with %d syms decoded", HCHEIGHT, NSYMSDECODED);

        for (;;) {
            /* 6.5.7 */
            if (params->SDHUFF) {
                DW = jbig2_huffman_get(hs, params->SDHUFFDW, &code);
            } else {
                code = jbig2_arith_int_decode(ctx, IADW, as, &DW);
            }
            if (code < 0)
            {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode DW");
                goto cleanup;
            }
            /* 6.5.5 (4c.i) */
            if (code > 0) {
                jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "OOB when decoding DW signals end of height class %d", HCHEIGHT);
                break;
            }

            /* check for broken symbol table */
            if (NSYMSDECODED >= params->SDNUMNEWSYMS) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "no OOB signaling end of height class %d, continuing", HCHEIGHT);
                break;
            }

            if (DW < 0 && SYMWIDTH < (uint32_t) -DW) {
                code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "DW value (%d) would make SYMWIDTH (%u) negative at symbol %u", DW, SYMWIDTH, NSYMSDECODED + 1);
                goto cleanup;
            }
            if (DW > 0 && (uint32_t) DW > UINT32_MAX - SYMWIDTH) {
                code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "DW value (%d) would make SYMWIDTH (%u) too large at symbol %u", DW, SYMWIDTH, NSYMSDECODED + 1);
                goto cleanup;
            }

            SYMWIDTH = SYMWIDTH + DW;
            if (SYMWIDTH > UINT32_MAX - TOTWIDTH) {
                code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "SYMWIDTH value (%u) would make TOTWIDTH (%u) too large at symbol %u", SYMWIDTH, TOTWIDTH, NSYMSDECODED + 1);
                goto cleanup;
            }

            TOTWIDTH = TOTWIDTH + SYMWIDTH;
#ifdef JBIG2_DEBUG
            jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "SYMWIDTH = %u TOTWIDTH = %u", SYMWIDTH, TOTWIDTH);
#endif
            /* 6.5.5 (4c.ii) */
            if (!params->SDHUFF || params->SDREFAGG) {
#ifdef JBIG2_DEBUG
                jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "SDHUFF = %d; SDREFAGG = %d", params->SDHUFF, params->SDREFAGG);
#endif
                /* 6.5.8 */
                if (!params->SDREFAGG) {
                    Jbig2GenericRegionParams region_params;
                    int sdat_bytes;

                    /* Table 16 */
                    region_params.MMR = 0;
                    region_params.GBTEMPLATE = params->SDTEMPLATE;
                    region_params.TPGDON = 0;
                    region_params.USESKIP = 0;
                    sdat_bytes = params->SDTEMPLATE == 0 ? 8 : 2;
                    memcpy(region_params.gbat, params->sdat, sdat_bytes);

                    image = jbig2_image_new(ctx, SYMWIDTH, HCHEIGHT);
                    if (image == NULL) {
                        code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate image");
                        goto cleanup;
                    }

                    code = jbig2_decode_generic_region(ctx, segment, &region_params, as, image, GB_stats);
                    if (code < 0) {
                        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode generic region");
                        goto cleanup;
                    }

                    SDNEWSYMS->glyphs[NSYMSDECODED] = image;
                    image = NULL;
                } else {
                    /* 6.5.8.2 refinement/aggregate symbol */
                    uint32_t REFAGGNINST;

                    if (params->SDHUFF) {
                        REFAGGNINST = jbig2_huffman_get(hs, params->SDHUFFAGGINST, &code);
                    } else {
                        code = jbig2_arith_int_decode(ctx, IAAI, as, (int32_t *) &REFAGGNINST);
                    }
                    if (code < 0) {
                        code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode number of symbols in aggregate glyph");
                        goto cleanup;
                    }
                    if (code > 0) {
                        code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "OOB in number of symbols in aggregate glyph");
                        goto cleanup;
                    }
                    if ((int32_t) REFAGGNINST <= 0) {
                        code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "invalid number of symbols in aggregate glyph");
                        goto cleanup;
                    }

                    jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "aggregate symbol coding (%d instances)", REFAGGNINST);

                    if (REFAGGNINST > 1) {
                        tparams.SBNUMINSTANCES = REFAGGNINST;

                        image = jbig2_image_new(ctx, SYMWIDTH, HCHEIGHT);
                        if (image == NULL) {
                            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate symbol image");
                            goto cleanup;
                        }

                        /* multiple symbols are handled as a text region */
                        code = jbig2_decode_text_region(ctx, segment, &tparams, (const Jbig2SymbolDict * const *)refagg_dicts,
                                                        2, image, data, size, GR_stats, as, ws);
                        if (code < 0) {
                            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode text region");
                            goto cleanup;
                        }

                        SDNEWSYMS->glyphs[NSYMSDECODED] = image;
                        image = NULL;
                    } else {
                        /* 6.5.8.2.2 */
                        /* bool SBHUFF = params->SDHUFF; */
                        Jbig2RefinementRegionParams rparams;
                        uint32_t ID;
                        int32_t RDX, RDY;
                        int BMSIZE = 0;
                        uint32_t ninsyms = params->SDNUMINSYMS;
                        int code1 = 0;
                        int code2 = 0;
                        int code3 = 0;
                        int code4 = 0;
                        int code5 = 0;

                        /* 6.5.8.2.2 (2, 3, 4, 5) */
                        if (params->SDHUFF) {
                            ID = jbig2_huffman_get_bits(hs, SBSYMCODELEN, &code1);
                            RDX = jbig2_huffman_get(hs, tparams.SBHUFFRDX, &code2);
                            RDY = jbig2_huffman_get(hs, tparams.SBHUFFRDY, &code3);
                            BMSIZE = jbig2_huffman_get(hs, tparams.SBHUFFRSIZE, &code4);
                            code5 = jbig2_huffman_skip(hs);
                        } else {
                            code1 = jbig2_arith_iaid_decode(ctx, tparams.IAID, as, (int32_t *) &ID);
                            code2 = jbig2_arith_int_decode(ctx, tparams.IARDX, as, &RDX);
                            code3 = jbig2_arith_int_decode(ctx, tparams.IARDY, as, &RDY);
                        }

                        if (code1 < 0 || code2 < 0 || code3 < 0 || code4 < 0 || code5 < 0) {
                            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode data");
                            goto cleanup;
                        }
                        if (code1 > 0 || code2 > 0 || code3 > 0 || code4 > 0 || code5 > 0) {
                            code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "OOB in single refinement/aggregate coded symbol data");
                            goto cleanup;
                        }

                        if (ID >= ninsyms + NSYMSDECODED) {
                            code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "refinement references unknown symbol %d", ID);
                            goto cleanup;
                        }

                        jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number,
                                    "symbol is a refinement of ID %d with the refinement applied at (%d,%d)", ID, RDX, RDY);

                        image = jbig2_image_new(ctx, SYMWIDTH, HCHEIGHT);
                        if (image == NULL) {
                            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate symbol image");
                            goto cleanup;
                        }

                        /* Table 18 */
                        rparams.GRTEMPLATE = params->SDRTEMPLATE;
                        rparams.GRREFERENCE = (ID < ninsyms) ? params->SDINSYMS->glyphs[ID] : SDNEWSYMS->glyphs[ID - ninsyms];
                        /* SumatraPDF: fail on missing glyphs */
                        if (rparams.GRREFERENCE == NULL) {
                            code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "missing glyph %d/%d", ID, ninsyms);
                            goto cleanup;
                        }
                        rparams.GRREFERENCEDX = RDX;
                        rparams.GRREFERENCEDY = RDY;
                        rparams.TPGRON = 0;
                        memcpy(rparams.grat, params->sdrat, 4);
                        code = jbig2_decode_refinement_region(ctx, segment, &rparams, as, image, GR_stats);
                        if (code < 0) {
                            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode refinement region");
                            goto cleanup;
                        }

                        SDNEWSYMS->glyphs[NSYMSDECODED] = image;
                        image = NULL;

                        /* 6.5.8.2.2 (7) */
                        if (params->SDHUFF) {
                            if (BMSIZE == 0)
                                BMSIZE = (size_t) SDNEWSYMS->glyphs[NSYMSDECODED]->height *
                                    SDNEWSYMS->glyphs[NSYMSDECODED]->stride;
                            code = jbig2_huffman_advance(hs, BMSIZE);
                            if (code < 0) {
                                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to advance after huffman decoding in refinement region");
                                goto cleanup;
                            }
                        }
                    }
                }

#ifdef OUTPUT_PBM
                {
                    char name[64];
                    FILE *out;
                    int code;

                    snprintf(name, 64, "sd.%04d.%04d.pbm", segment->number, NSYMSDECODED);
                    out = fopen(name, "wb");
                    code = jbig2_image_write_pbm(SDNEWSYMS->glyphs[NSYMSDECODED], out);
                    fclose(out);
                    if (code < 0) {
                        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to write glyph");
                        goto cleanup;
                    }
                    jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "writing out glyph as '%s' ...", name);
                }
#endif

            }

            /* 6.5.5 (4c.iii) */
            if (params->SDHUFF && !params->SDREFAGG) {
                SDNEWSYMWIDTHS[NSYMSDECODED] = SYMWIDTH;
            }

            /* 6.5.5 (4c.iv) */
            NSYMSDECODED = NSYMSDECODED + 1;

            jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "decoded symbol %u of %u (%ux%u)", NSYMSDECODED, params->SDNUMNEWSYMS, SYMWIDTH, HCHEIGHT);

        }                       /* end height class decode loop */

        /* 6.5.5 (4d) */
        if (params->SDHUFF && !params->SDREFAGG) {
            /* 6.5.9 */
            size_t BMSIZE;
            uint32_t j;
            int x;

            BMSIZE = jbig2_huffman_get(hs, params->SDHUFFBMSIZE, &code);
            if (code < 0) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "error decoding size of collective bitmap");
                goto cleanup;
            }
            if (code > 0) {
                jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "OOB obtained when decoding size of collective bitmap");
                goto cleanup;
            }

            /* skip any bits before the next byte boundary */
            code = jbig2_huffman_skip(hs);
            if (code < 0) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to skip to next byte when decoding collective bitmap");
            }

            image = jbig2_image_new(ctx, TOTWIDTH, HCHEIGHT);
            if (image == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate collective bitmap image");
                goto cleanup;
            }

            if (BMSIZE == 0) {
                /* if BMSIZE == 0 bitmap is uncompressed */
                const byte *src = data + jbig2_huffman_offset(hs);
                const int stride = (image->width >> 3) + ((image->width & 7) ? 1 : 0);
                byte *dst = image->data;

                /* SumatraPDF: prevent read access violation */
                if (size < jbig2_huffman_offset(hs) || (size - jbig2_huffman_offset(hs) < (size_t) image->height * stride) || (size < jbig2_huffman_offset(hs))) {
                    jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "not enough data for decoding uncompressed (%d/%li)", image->height * stride,
                                (long) (size - jbig2_huffman_offset(hs)));
                    goto cleanup;
                }

                BMSIZE = (size_t) image->height * stride;
                jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number,
                            "reading %dx%d uncompressed bitmap for %d symbols (%li bytes)", image->width, image->height, NSYMSDECODED - HCFIRSTSYM, (long) BMSIZE);

                for (j = 0; j < image->height; j++) {
                    memcpy(dst, src, stride);
                    dst += image->stride;
                    src += stride;
                }
            } else {
                Jbig2GenericRegionParams rparams;

                /* SumatraPDF: prevent read access violation */
                if (size < jbig2_huffman_offset(hs) || size < BMSIZE || size - jbig2_huffman_offset(hs) < BMSIZE) {
                    jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "not enough data for decoding (%li/%li)", (long) BMSIZE, (long) (size - jbig2_huffman_offset(hs)));
                    goto cleanup;
                }

                jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number,
                            "reading %dx%d collective bitmap for %d symbols (%li bytes)", image->width, image->height, NSYMSDECODED - HCFIRSTSYM, (long) BMSIZE);

                rparams.MMR = 1;
                code = jbig2_decode_generic_mmr(ctx, segment, &rparams, data + jbig2_huffman_offset(hs), BMSIZE, image);
                if (code) {
                    jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode MMR-coded generic region");
                    goto cleanup;
                }
            }

            /* advance past the data we've just read */
            code = jbig2_huffman_advance(hs, BMSIZE);
            if (code < 0) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to advance after huffman decoding MMR bitmap image");
                goto cleanup;
            }

            /* copy the collective bitmap into the symbol dictionary */
            x = 0;
            for (j = HCFIRSTSYM; j < NSYMSDECODED; j++) {
                glyph = jbig2_image_new(ctx, SDNEWSYMWIDTHS[j], HCHEIGHT);
                if (glyph == NULL) {
                    jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to copy the collective bitmap into symbol dictionary");
                    goto cleanup;
                }
                code = jbig2_image_compose(ctx, glyph, image, -x, 0, JBIG2_COMPOSE_REPLACE);
                if (code) {
                    jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to compose image into glyph");
                    goto cleanup;
                }
                x += SDNEWSYMWIDTHS[j];
                SDNEWSYMS->glyphs[j] = glyph;
                glyph = NULL;
            }
            jbig2_image_release(ctx, image);
            image = NULL;
        }

    }                           /* end of symbol decode loop */

    /* 6.5.10 */
    SDEXSYMS = jbig2_sd_new(ctx, params->SDNUMEXSYMS);
    if (SDEXSYMS == NULL) {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate symbols exported from symbols dictionary");
        goto cleanup;
    } else {
        uint32_t i = 0;
        uint32_t j = 0;
        uint32_t k;
        int exflag = 0;
        uint32_t limit = params->SDNUMINSYMS + params->SDNUMNEWSYMS;
        uint32_t EXRUNLENGTH;

        while (i < limit) {
            if (params->SDHUFF)
                EXRUNLENGTH = jbig2_huffman_get(hs, tparams.SBHUFFRSIZE, &code);
            else
                code = jbig2_arith_int_decode(ctx, IAEX, as, (int32_t *) &EXRUNLENGTH);
            if (code < 0) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode runlength for exported symbols");
                /* skip to the cleanup code and return SDEXSYMS = NULL */
                jbig2_sd_release(ctx, SDEXSYMS);
                SDEXSYMS = NULL;
                break;
            }
            if (code > 0) {
                jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "OOB when decoding runlength for exported symbols");
                /* skip to the cleanup code and return SDEXSYMS = NULL */
                jbig2_sd_release(ctx, SDEXSYMS);
                SDEXSYMS = NULL;
                break;
            }

            /* prevent infinite list of empty runs, 1000 is just an arbitrary number */
            if (EXRUNLENGTH <= 0 && ++emptyruns == 1000) {
                jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "runlength too small in export symbol table (%u == 0 i = %u limit = %u)", EXRUNLENGTH, i, limit);
                /* skip to the cleanup code and return SDEXSYMS = NULL */
                jbig2_sd_release(ctx, SDEXSYMS);
                SDEXSYMS = NULL;
                break;
            } else if (EXRUNLENGTH > 0) {
                emptyruns = 0;
            }

            if (EXRUNLENGTH > limit - i) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "exporting more symbols than available (%u > %u), capping", i + EXRUNLENGTH, limit);
                EXRUNLENGTH = limit - i;
            }
            if (exflag && j + EXRUNLENGTH > params->SDNUMEXSYMS) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "exporting more symbols than may be exported (%u > %u), capping", j + EXRUNLENGTH, params->SDNUMEXSYMS);
                EXRUNLENGTH = params->SDNUMEXSYMS - j;
            }

            for (k = 0; k < EXRUNLENGTH; k++) {
                if (exflag) {
                    Jbig2Image *img;
                    if (i < params->SDNUMINSYMS) {
                        img = params->SDINSYMS->glyphs[i];
                    } else {
                        img = SDNEWSYMS->glyphs[i - params->SDNUMINSYMS];
                    }
                    SDEXSYMS->glyphs[j++] = jbig2_image_reference(ctx, img);
                }
                i++;
            }
            exflag = !exflag;
        }
    }

cleanup:
    jbig2_image_release(ctx, glyph);
    jbig2_image_release(ctx, image);
    if (refagg_dicts != NULL) {
        if (refagg_dicts[0] != NULL)
            jbig2_sd_release(ctx, refagg_dicts[0]);
        /* skip releasing refagg_dicts[1] as that is the same as SDNEWSYMS */
        jbig2_free(ctx->allocator, refagg_dicts);
    }
    jbig2_sd_release(ctx, SDNEWSYMS);
    if (params->SDHUFF) {
        jbig2_release_huffman_table(ctx, tparams.SBHUFFRSIZE);
        jbig2_release_huffman_table(ctx, tparams.SBHUFFRDY);
        jbig2_release_huffman_table(ctx, tparams.SBHUFFRDX);
        jbig2_release_huffman_table(ctx, tparams.SBHUFFRDH);
        jbig2_release_huffman_table(ctx, tparams.SBHUFFRDW);
        jbig2_release_huffman_table(ctx, tparams.SBHUFFDT);
        jbig2_release_huffman_table(ctx, tparams.SBHUFFDS);
        jbig2_release_huffman_table(ctx, tparams.SBHUFFFS);
        if (!params->SDREFAGG) {
            jbig2_free(ctx->allocator, SDNEWSYMWIDTHS);
        }
        jbig2_huffman_free(ctx, hs);
    } else {
        jbig2_arith_int_ctx_free(ctx, tparams.IARDY);
        jbig2_arith_int_ctx_free(ctx, tparams.IARDX);
        jbig2_arith_int_ctx_free(ctx, tparams.IARDH);
        jbig2_arith_int_ctx_free(ctx, tparams.IARDW);
        jbig2_arith_int_ctx_free(ctx, tparams.IARI);
        jbig2_arith_iaid_ctx_free(ctx, tparams.IAID);
        jbig2_arith_int_ctx_free(ctx, tparams.IAIT);
        jbig2_arith_int_ctx_free(ctx, tparams.IADS);
        jbig2_arith_int_ctx_free(ctx, tparams.IAFS);
        jbig2_arith_int_ctx_free(ctx, tparams.IADT);
        jbig2_arith_int_ctx_free(ctx, IAAI);
        jbig2_arith_int_ctx_free(ctx, IAEX);
        jbig2_arith_int_ctx_free(ctx, IADW);
        jbig2_arith_int_ctx_free(ctx, IADH);
    }
    jbig2_free(ctx->allocator, as);
    jbig2_word_stream_buf_free(ctx, ws);

    return SDEXSYMS;
}

/* 7.4.2 */
int
jbig2_symbol_dictionary(Jbig2Ctx *ctx, Jbig2Segment *segment, const byte *segment_data)
{
    Jbig2SymbolDictParams params;
    uint16_t flags;
    uint32_t sdat_bytes;
    uint32_t offset;
    Jbig2ArithCx *GB_stats = NULL;
    Jbig2ArithCx *GR_stats = NULL;
    int table_index = 0;
    const Jbig2HuffmanParams *huffman_params;

    params.SDHUFF = 0;

    if (segment->data_length < 10)
        goto too_short;

    /* 7.4.2.1.1 */
    flags = jbig2_get_uint16(segment_data);

    /* zero params to ease cleanup later */
    memset(&params, 0, sizeof(Jbig2SymbolDictParams));

    params.SDHUFF = flags & 1;
    params.SDREFAGG = (flags >> 1) & 1;
    params.SDTEMPLATE = (flags >> 10) & 3;
    params.SDRTEMPLATE = (flags >> 12) & 1;

    if (params.SDHUFF) {
        switch ((flags & 0x000c) >> 2) {
        case 0:                /* Table B.4 */
            params.SDHUFFDH = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_D);
            break;
        case 1:                /* Table B.5 */
            params.SDHUFFDH = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_E);
            break;
        case 3:                /* Custom table from referred segment */
            huffman_params = jbig2_find_table(ctx, segment, table_index);
            if (huffman_params == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "custom DH huffman table not found (%d)", table_index);
                goto cleanup;
            }
            params.SDHUFFDH = jbig2_build_huffman_table(ctx, huffman_params);
            ++table_index;
            break;
        case 2:
        default:
            return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "symbol dictionary specified invalid huffman table");
        }
        if (params.SDHUFFDH == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate DH huffman table");
            goto cleanup;
        }

        switch ((flags & 0x0030) >> 4) {
        case 0:                /* Table B.2 */
            params.SDHUFFDW = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_B);
            break;
        case 1:                /* Table B.3 */
            params.SDHUFFDW = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_C);
            break;
        case 3:                /* Custom table from referred segment */
            huffman_params = jbig2_find_table(ctx, segment, table_index);
            if (huffman_params == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "custom DW huffman table not found (%d)", table_index);
                goto cleanup;
            }
            params.SDHUFFDW = jbig2_build_huffman_table(ctx, huffman_params);
            ++table_index;
            break;
        case 2:
        default:
            jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "symbol dictionary specified invalid huffman table");
            goto cleanup;       /* Jump direct to cleanup to avoid 2 errors being given */
        }
        if (params.SDHUFFDW == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate DW huffman table");
            goto cleanup;
        }

        if (flags & 0x0040) {
            /* Custom table from referred segment */
            huffman_params = jbig2_find_table(ctx, segment, table_index);
            if (huffman_params == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "custom BMSIZE huffman table not found (%d)", table_index);
                goto cleanup;
            }
            params.SDHUFFBMSIZE = jbig2_build_huffman_table(ctx, huffman_params);
            ++table_index;
        } else {
            /* Table B.1 */
            params.SDHUFFBMSIZE = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_A);
        }
        if (params.SDHUFFBMSIZE == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate BMSIZE huffman table");
            goto cleanup;
        }

        if (flags & 0x0080) {
            /* Custom table from referred segment */
            huffman_params = jbig2_find_table(ctx, segment, table_index);
            if (huffman_params == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "custom REFAGG huffman table not found (%d)", table_index);
                goto cleanup;
            }
            params.SDHUFFAGGINST = jbig2_build_huffman_table(ctx, huffman_params);
            ++table_index;
        } else {
            /* Table B.1 */
            params.SDHUFFAGGINST = jbig2_build_huffman_table(ctx, &jbig2_huffman_params_A);
        }
        if (params.SDHUFFAGGINST == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate REFAGG huffman table");
            goto cleanup;
        }
    }

    /* FIXME: there are quite a few of these conditions to check */
    /* maybe #ifdef CONFORMANCE and a separate routine */
    if (!params.SDHUFF) {
        if (flags & 0x000c) {
            jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "SDHUFF is zero, but contrary to spec SDHUFFDH is not.");
            goto cleanup;
        }
        if (flags & 0x0030) {
            jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "SDHUFF is zero, but contrary to spec SDHUFFDW is not.");
            goto cleanup;
        }
    }

    /* 7.4.2.1.2 */
    sdat_bytes = params.SDHUFF ? 0 : params.SDTEMPLATE == 0 ? 8 : 2;
    memcpy(params.sdat, segment_data + 2, sdat_bytes);
    offset = 2 + sdat_bytes;

    /* 7.4.2.1.3 */
    if (params.SDREFAGG && !params.SDRTEMPLATE) {
        if (offset + 4 > segment->data_length)
            goto too_short;
        memcpy(params.sdrat, segment_data + offset, 4);
        offset += 4;
    }

    if (offset + 8 > segment->data_length)
        goto too_short;

    /* 7.4.2.1.4 */
    params.SDNUMEXSYMS = jbig2_get_uint32(segment_data + offset);
    /* 7.4.2.1.5 */
    params.SDNUMNEWSYMS = jbig2_get_uint32(segment_data + offset + 4);
    offset += 8;

    jbig2_error(ctx, JBIG2_SEVERITY_INFO, segment->number,
                "symbol dictionary, flags=%04x, %u exported syms, %u new syms", flags, params.SDNUMEXSYMS, params.SDNUMNEWSYMS);

    /* 7.4.2.2 (2) */
    {
        uint32_t n_dicts = jbig2_sd_count_referred(ctx, segment);
        Jbig2SymbolDict **dicts = NULL;

        if (n_dicts > 0) {
            dicts = jbig2_sd_list_referred(ctx, segment);
            if (dicts == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate dicts in symbol dictionary");
                goto cleanup;
            }
            params.SDINSYMS = jbig2_sd_cat(ctx, n_dicts, dicts);
            if (params.SDINSYMS == NULL) {
                jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate symbol array in symbol dictionary");
                jbig2_free(ctx->allocator, dicts);
                goto cleanup;
            }
            jbig2_free(ctx->allocator, dicts);
        }
        if (params.SDINSYMS != NULL) {
            params.SDNUMINSYMS = params.SDINSYMS->n_symbols;
        }
    }

    /* 7.4.2.2 (3, 4) */
    if (flags & 0x0100) {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "segment marks bitmap coding context as used (NYI)");
        goto cleanup;
    } else {
        int stats_size = params.SDTEMPLATE == 0 ? 65536 : params.SDTEMPLATE == 1 ? 8192 : 1024;

        GB_stats = jbig2_new(ctx, Jbig2ArithCx, stats_size);
        if (GB_stats == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to allocate arithmetic decoder states for generic regions");
            goto cleanup;
        }
        memset(GB_stats, 0, sizeof (Jbig2ArithCx) * stats_size);

        stats_size = params.SDRTEMPLATE ? 1 << 10 : 1 << 13;
        GR_stats = jbig2_new(ctx, Jbig2ArithCx, stats_size);
        if (GR_stats == NULL) {
            jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to allocate arithmetic decoder states for generic refinement regions");
            jbig2_free(ctx->allocator, GB_stats);
            goto cleanup;
        }
        memset(GR_stats, 0, sizeof (Jbig2ArithCx) * stats_size);
    }

    segment->result = (void *)jbig2_decode_symbol_dict(ctx, segment, &params, segment_data + offset, segment->data_length - offset, GB_stats, GR_stats);
#ifdef DUMP_SYMDICT
    if (segment->result)
        jbig2_dump_symbol_dict(ctx, segment);
#endif

    /* 7.4.2.2 (7) */
    if (flags & 0x0200) {
        /* todo: retain GB_stats, GR_stats */
        jbig2_free(ctx->allocator, GR_stats);
        jbig2_free(ctx->allocator, GB_stats);
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "segment marks bitmap coding context as retained (NYI)");
        goto cleanup;
    } else {
        jbig2_free(ctx->allocator, GR_stats);
        jbig2_free(ctx->allocator, GB_stats);
    }

cleanup:
    if (params.SDHUFF) {
        jbig2_release_huffman_table(ctx, params.SDHUFFDH);
        jbig2_release_huffman_table(ctx, params.SDHUFFDW);
        jbig2_release_huffman_table(ctx, params.SDHUFFBMSIZE);
        jbig2_release_huffman_table(ctx, params.SDHUFFAGGINST);
    }
    jbig2_sd_release(ctx, params.SDINSYMS);

    return (segment->result != NULL) ? 0 : -1;

too_short:
    if (params.SDHUFF) {
        jbig2_release_huffman_table(ctx, params.SDHUFFDH);
        jbig2_release_huffman_table(ctx, params.SDHUFFDW);
        jbig2_release_huffman_table(ctx, params.SDHUFFBMSIZE);
        jbig2_release_huffman_table(ctx, params.SDHUFFAGGINST);
    }
    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "segment too short");
}
