shithub: jbig2

ref: bd3d8ebb98beec5fdb3e93534569dc0bc3d50e7a
dir: /jbig2_generic.c/

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/* Copyright (C) 2001-2018 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
*/

/**
 * Generic region handlers.
 **/

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

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

#ifdef OUTPUT_PBM
#include <stdio.h>
#endif

#include "jbig2.h"
#include "jbig2_priv.h"
#include "jbig2_arith.h"
#include "jbig2_generic.h"
#include "jbig2_image.h"
#include "jbig2_mmr.h"
#include "jbig2_page.h"
#include "jbig2_segment.h"

#if !defined (UINT32_MAX)
#define UINT32_MAX 0xffffffff
#endif

/* return the appropriate context size for the given template */
int
jbig2_generic_stats_size(Jbig2Ctx *ctx, int template)
{
    int stats_size = template == 0 ? 1 << 16 : template == 1 ? 1 << 1 << 13 : 1 << 10;

    return stats_size;
}

static int
jbig2_decode_generic_template0(Jbig2Ctx *ctx,
                               Jbig2Segment *segment,
                               const Jbig2GenericRegionParams *params, Jbig2ArithState *as,
                               Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    const uint32_t rowstride = image->stride;
    uint32_t x, y;
    byte *line2 = NULL;
    byte *line1 = NULL;
    byte *gbreg_line = (byte *) image->data;

#ifdef OUTPUT_PBM
    printf("P4\n%d %d\n", GBW, GBH);
#endif

    if (GBW <= 0)
        return 0;

    for (y = 0; y < GBH; y++) {
        uint32_t CONTEXT;
        uint32_t line_m1;
        uint32_t line_m2;
        int padded_width = (GBW + 7) & -8;
        int code = 0;

        line_m1 = line1 ? line1[0] : 0;
        line_m2 = line2 ? line2[0] << 6 : 0;
        CONTEXT = (line_m1 & 0x7f0) | (line_m2 & 0xf800);

        /* 6.2.5.7 3d */
        for (x = 0; x < padded_width; x += 8) {
            byte result = 0;
            int x_minor;
            int minor_width = GBW - x > 8 ? 8 : GBW - x;

            if (line1)
                line_m1 = (line_m1 << 8) | (x + 8 < GBW ? line1[(x >> 3) + 1] : 0);

            if (line2)
                line_m2 = (line_m2 << 8) | (x + 8 < GBW ? line2[(x >> 3) + 1] << 6 : 0);

            /* This is the speed-critical inner loop. */
            for (x_minor = 0; x_minor < minor_width; x_minor++) {
                bool bit;

                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template0 optimized");
                result |= bit << (7 - x_minor);
                CONTEXT = ((CONTEXT & 0x7bf7) << 1) | bit | ((line_m1 >> (7 - x_minor)) & 0x10) | ((line_m2 >> (7 - x_minor)) & 0x800);
            }
            gbreg_line[x >> 3] = result;
        }
#ifdef OUTPUT_PBM
        fwrite(gbreg_line, 1, rowstride, stdout);
#endif
        line2 = line1;
        line1 = gbreg_line;
        gbreg_line += rowstride;
    }

    return 0;
}

#define pixel_outside_field(x, y) \
    ((y) < -128 || (y) > 0 || (x) < -128 || ((y) < 0 && (x) > 127) || ((y) == 0 && (x) >= 0))

static int
jbig2_decode_generic_template0_unopt(Jbig2Ctx *ctx,
                                     Jbig2Segment *segment,
                                     const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]) ||
        pixel_outside_field(params->gbat[2], params->gbat[3]) ||
        pixel_outside_field(params->gbat[4], params->gbat[5]) ||
        pixel_outside_field(params->gbat[6], params->gbat[7]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    /* this version is generic and easy to understand, but very slow */

    for (y = 0; y < GBH; y++) {
        for (x = 0; x < GBW; x++) {
            if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                jbig2_image_set_pixel(image, x, y, 0);
                continue;
            }
            CONTEXT = 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y) << 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
            CONTEXT |= jbig2_image_get_pixel(image, x - 3, y) << 2;
            CONTEXT |= jbig2_image_get_pixel(image, x - 4, y) << 3;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 4;
            CONTEXT |= jbig2_image_get_pixel(image, x + 2, y - 1) << 5;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 6;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 1) << 7;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 8;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 9;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[2], y + params->gbat[3]) << 10;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[4], y + params->gbat[5]) << 11;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 2) << 12;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 2) << 13;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 2) << 14;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[6], y + params->gbat[7]) << 15;
            bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
            if (code)
                return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template0 unoptimized");
            jbig2_image_set_pixel(image, x, y, bit);
        }
    }
    return 0;
}

static int
jbig2_decode_generic_template1_unopt(Jbig2Ctx *ctx,
                                     Jbig2Segment *segment,
                                     const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    /* this version is generic and easy to understand, but very slow */

    for (y = 0; y < GBH; y++) {
        for (x = 0; x < GBW; x++) {
            if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                jbig2_image_set_pixel(image, x, y, 0);
                continue;
            }
            CONTEXT = 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y) << 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
            CONTEXT |= jbig2_image_get_pixel(image, x - 3, y) << 2;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 3;
            CONTEXT |= jbig2_image_get_pixel(image, x + 2, y - 1) << 4;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 5;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 1) << 6;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 7;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 8;
            CONTEXT |= jbig2_image_get_pixel(image, x + 2, y - 2) << 9;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 2) << 10;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 2) << 11;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 2) << 12;
            bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
            if (code)
                return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template1 unoptimized");
            jbig2_image_set_pixel(image, x, y, bit);
        }
    }
    return 0;
}

static int
jbig2_decode_generic_template1(Jbig2Ctx *ctx,
                               Jbig2Segment *segment,
                               const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    const uint32_t rowstride = image->stride;
    uint32_t x, y;
    byte *line2 = NULL;
    byte *line1 = NULL;
    byte *gbreg_line = (byte *) image->data;
    int code = 0;

#ifdef OUTPUT_PBM
    printf("P4\n%d %d\n", GBW, GBH);
#endif

    if (GBW <= 0)
        return 0;

    for (y = 0; y < GBH; y++) {
        uint32_t CONTEXT;
        uint32_t line_m1;
        uint32_t line_m2;
        int padded_width = (GBW + 7) & -8;

        line_m1 = line1 ? line1[0] : 0;
        line_m2 = line2 ? line2[0] << 5 : 0;
        CONTEXT = ((line_m1 >> 1) & 0x1f8) | ((line_m2 >> 1) & 0x1e00);

        /* 6.2.5.7 3d */
        for (x = 0; x < padded_width; x += 8) {
            byte result = 0;
            int x_minor;
            int minor_width = GBW - x > 8 ? 8 : GBW - x;

            if (line1)
                line_m1 = (line_m1 << 8) | (x + 8 < GBW ? line1[(x >> 3) + 1] : 0);

            if (line2)
                line_m2 = (line_m2 << 8) | (x + 8 < GBW ? line2[(x >> 3) + 1] << 5 : 0);

            /* This is the speed-critical inner loop. */
            for (x_minor = 0; x_minor < minor_width; x_minor++) {
                bool bit;

                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template1 optimized");
                result |= bit << (7 - x_minor);
                CONTEXT = ((CONTEXT & 0xefb) << 1) | bit | ((line_m1 >> (8 - x_minor)) & 0x8) | ((line_m2 >> (8 - x_minor)) & 0x200);
            }
            gbreg_line[x >> 3] = result;
        }
#ifdef OUTPUT_PBM
        fwrite(gbreg_line, 1, rowstride, stdout);
#endif
        line2 = line1;
        line1 = gbreg_line;
        gbreg_line += rowstride;
    }

    return 0;
}

static int
jbig2_decode_generic_template2_unopt(Jbig2Ctx *ctx,
                               Jbig2Segment *segment,
                               const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    /* this version is generic and easy to understand, but very slow */

    for (y = 0; y < GBH; y++) {
        for (x = 0; x < GBW; x++) {
            if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                jbig2_image_set_pixel(image, x, y, 0);
                continue;
            }
            CONTEXT = 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y) << 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 2;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 3;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 1) << 4;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 5;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 6;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 2) << 7;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 2) << 8;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 2) << 9;
            bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
            if (code)
                return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template2 unoptimized");
            jbig2_image_set_pixel(image, x, y, bit);
        }
    }

    return 0;
}

static int
jbig2_decode_generic_template2(Jbig2Ctx *ctx,
                                Jbig2Segment *segment,
                                const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    const uint32_t rowstride = image->stride;
    uint32_t x, y;
    byte *line2 = NULL;
    byte *line1 = NULL;
    byte *gbreg_line = (byte *) image->data;
    int code = 0;

#ifdef OUTPUT_PBM
    printf("P4\n%d %d\n", GBW, GBH);
#endif

    if (GBW <= 0)
        return 0;

    for (y = 0; y < GBH; y++) {
        uint32_t CONTEXT;
        uint32_t line_m1;
        uint32_t line_m2;
        int padded_width = (GBW + 7) & -8;

        line_m1 = line1 ? line1[0] : 0;
        line_m2 = line2 ? line2[0] << 4 : 0;
        CONTEXT = ((line_m1 >> 3) & 0x7c) | ((line_m2 >> 3) & 0x380);

        /* 6.2.5.7 3d */
        for (x = 0; x < padded_width; x += 8) {
            byte result = 0;
            int x_minor;
            int minor_width = GBW - x > 8 ? 8 : GBW - x;

            if (line1)
                line_m1 = (line_m1 << 8) | (x + 8 < GBW ? line1[(x >> 3) + 1] : 0);

            if (line2)
                line_m2 = (line_m2 << 8) | (x + 8 < GBW ? line2[(x >> 3) + 1] << 4 : 0);

            /* This is the speed-critical inner loop. */
            for (x_minor = 0; x_minor < minor_width; x_minor++) {
                bool bit;

                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template2 optimized");
                result |= bit << (7 - x_minor);
                CONTEXT = ((CONTEXT & 0x1bd) << 1) | bit | ((line_m1 >> (10 - x_minor)) & 0x4) | ((line_m2 >> (10 - x_minor)) & 0x80);
            }
            gbreg_line[x >> 3] = result;
        }
#ifdef OUTPUT_PBM
        fwrite(gbreg_line, 1, rowstride, stdout);
#endif
        line2 = line1;
        line1 = gbreg_line;
        gbreg_line += rowstride;
    }

    return 0;
}

static int
jbig2_decode_generic_template3(Jbig2Ctx *ctx,
                               Jbig2Segment *segment,
                               const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    const uint32_t rowstride = image->stride;
    byte *line1 = NULL;
    byte *gbreg_line = (byte *) image->data;
    uint32_t x, y;
    int code;

#ifdef OUTPUT_PBM
    printf("P4\n%d %d\n", GBW, GBH);
#endif

    if (GBW <= 0)
        return 0;

    for (y = 0; y < GBH; y++) {
        uint32_t CONTEXT;
        uint32_t line_m1;
        int padded_width = (GBW + 7) & -8;

        line_m1 = line1 ? line1[0] : 0;
        CONTEXT = (line_m1 >> 1) & 0x3f0;

        /* 6.2.5.7 3d */
        for (x = 0; x < padded_width; x += 8) {
            byte result = 0;
            int x_minor;
            int minor_width = GBW - x > 8 ? 8 : GBW - x;

            if (line1)
                line_m1 = (line_m1 << 8) | (x + 8 < GBW ? line1[(x >> 3) + 1] : 0);

            /* This is the speed-critical inner loop. */
            for (x_minor = 0; x_minor < minor_width; x_minor++) {
                bool bit;

                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template3 optimized");
                result |= bit << (7 - x_minor);
                CONTEXT = ((CONTEXT & 0x1f7) << 1) | bit | ((line_m1 >> (8 - x_minor)) & 0x10);
            }
            gbreg_line[x >> 3] = result;
        }
#ifdef OUTPUT_PBM
        fwrite(gbreg_line, 1, rowstride, stdout);
#endif
        line1 = gbreg_line;
        gbreg_line += rowstride;
    }

    return 0;
}

static int
jbig2_decode_generic_template3_unopt(Jbig2Ctx *ctx,
                                     Jbig2Segment *segment,
                                     const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    /* this version is generic and easy to understand, but very slow */

    for (y = 0; y < GBH; y++) {
        for (x = 0; x < GBW; x++) {
            if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                jbig2_image_set_pixel(image, x, y, 0);
                continue;
            }
            CONTEXT = 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y) << 0;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
            CONTEXT |= jbig2_image_get_pixel(image, x - 3, y) << 2;
            CONTEXT |= jbig2_image_get_pixel(image, x - 4, y) << 3;
            CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 4;
            CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 5;
            CONTEXT |= jbig2_image_get_pixel(image, x + 0, y - 1) << 6;
            CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 7;
            CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 8;
            CONTEXT |= jbig2_image_get_pixel(image, x - 3, y - 1) << 9;
            bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
            if (code)
                return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template3 unoptimized");
            jbig2_image_set_pixel(image, x, y, bit);
        }
    }
    return 0;
}

static void
copy_prev_row(Jbig2Image *image, int row)
{
    if (!row) {
        /* no previous row */
        memset(image->data, 0, image->stride);
    } else {
        /* duplicate data from the previous row */
        uint8_t *src = image->data + (row - 1) * image->stride;

        memcpy(src + image->stride, src, image->stride);
    }
}

static int
jbig2_decode_generic_template0_TPGDON(Jbig2Ctx *ctx,
                                      Jbig2Segment *segment,
                                      const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int LTP = 0;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]) ||
        pixel_outside_field(params->gbat[2], params->gbat[3]) ||
        pixel_outside_field(params->gbat[4], params->gbat[5]) ||
        pixel_outside_field(params->gbat[6], params->gbat[7]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    for (y = 0; y < GBH; y++) {
        LTP ^= jbig2_arith_decode(as, &GB_stats[0x9B25], &code);
        if (code)
            return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template0 TPGDON1");
        if (!LTP) {
            for (x = 0; x < GBW; x++) {
                if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                    jbig2_image_set_pixel(image, x, y, 0);
                    continue;
                }
                CONTEXT = jbig2_image_get_pixel(image, x - 1, y);
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
                CONTEXT |= jbig2_image_get_pixel(image, x - 3, y) << 2;
                CONTEXT |= jbig2_image_get_pixel(image, x - 4, y) << 3;
                CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 4;
                CONTEXT |= jbig2_image_get_pixel(image, x + 2, y - 1) << 5;
                CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 6;
                CONTEXT |= jbig2_image_get_pixel(image, x, y - 1) << 7;
                CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 8;
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 9;
                CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[2], y + params->gbat[3]) << 10;
                CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[4], y + params->gbat[5]) << 11;
                CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 2) << 12;
                CONTEXT |= jbig2_image_get_pixel(image, x, y - 2) << 13;
                CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 2) << 14;
                CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[6], y + params->gbat[7]) << 15;
                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template0 TPGDON2");
                jbig2_image_set_pixel(image, x, y, bit);
            }
        } else {
            copy_prev_row(image, y);
        }
    }

    return 0;
}

static int
jbig2_decode_generic_template1_TPGDON(Jbig2Ctx *ctx,
                                      Jbig2Segment *segment,
                                      const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int LTP = 0;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    for (y = 0; y < GBH; y++) {
        LTP ^= jbig2_arith_decode(as, &GB_stats[0x0795], &code);
        if (code)
            return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template1 TPGDON1");
        if (!LTP) {
            for (x = 0; x < GBW; x++) {
                if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                    jbig2_image_set_pixel(image, x, y, 0);
                    continue;
                }
                CONTEXT = jbig2_image_get_pixel(image, x - 1, y);
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
                CONTEXT |= jbig2_image_get_pixel(image, x - 3, y) << 2;
                CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 3;
                CONTEXT |= jbig2_image_get_pixel(image, x + 2, y - 1) << 4;
                CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 5;
                CONTEXT |= jbig2_image_get_pixel(image, x, y - 1) << 6;
                CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 7;
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 8;
                CONTEXT |= jbig2_image_get_pixel(image, x + 2, y - 2) << 9;
                CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 2) << 10;
                CONTEXT |= jbig2_image_get_pixel(image, x, y - 2) << 11;
                CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 2) << 12;
                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template1 TPGDON2");
                jbig2_image_set_pixel(image, x, y, bit);
            }
        } else {
            copy_prev_row(image, y);
        }
    }

    return 0;
}

static int
jbig2_decode_generic_template2_TPGDON(Jbig2Ctx *ctx,
                                      Jbig2Segment *segment,
                                      const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int LTP = 0;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    for (y = 0; y < GBH; y++) {
        LTP ^= jbig2_arith_decode(as, &GB_stats[0xE5], &code);
        if (code)
            return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template2 TPGDON1");
        if (!LTP) {
            for (x = 0; x < GBW; x++) {
                if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                    jbig2_image_set_pixel(image, x, y, 0);
                    continue;
                }
                CONTEXT = jbig2_image_get_pixel(image, x - 1, y);
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
                CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 2;
                CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 3;
                CONTEXT |= jbig2_image_get_pixel(image, x, y - 1) << 4;
                CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 5;
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 6;
                CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 2) << 7;
                CONTEXT |= jbig2_image_get_pixel(image, x, y - 2) << 8;
                CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 2) << 9;
                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template2 TPGDON2");
                jbig2_image_set_pixel(image, x, y, bit);
            }
        } else {
            copy_prev_row(image, y);
        }
    }

    return 0;
}

static int
jbig2_decode_generic_template3_TPGDON(Jbig2Ctx *ctx,
                                      Jbig2Segment *segment,
                                      const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const uint32_t GBW = image->width;
    const uint32_t GBH = image->height;
    uint32_t CONTEXT;
    uint32_t x, y;
    bool bit;
    int LTP = 0;
    int code = 0;

    if (pixel_outside_field(params->gbat[0], params->gbat[1]))
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "adaptive template pixel is out of field");

    for (y = 0; y < GBH; y++) {
        LTP ^= jbig2_arith_decode(as, &GB_stats[0x0195], &code);
        if (code)
            return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template3 TPGDON1");
        if (!LTP) {
            for (x = 0; x < GBW; x++) {
                if (params->USESKIP && jbig2_image_get_pixel(params->SKIP, x, y)) {
                    jbig2_image_set_pixel(image, x, y, 0);
                    continue;
                }
                CONTEXT = jbig2_image_get_pixel(image, x - 1, y);
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y) << 1;
                CONTEXT |= jbig2_image_get_pixel(image, x - 3, y) << 2;
                CONTEXT |= jbig2_image_get_pixel(image, x - 4, y) << 3;
                CONTEXT |= jbig2_image_get_pixel(image, x + params->gbat[0], y + params->gbat[1]) << 4;
                CONTEXT |= jbig2_image_get_pixel(image, x + 1, y - 1) << 5;
                CONTEXT |= jbig2_image_get_pixel(image, x, y - 1) << 6;
                CONTEXT |= jbig2_image_get_pixel(image, x - 1, y - 1) << 7;
                CONTEXT |= jbig2_image_get_pixel(image, x - 2, y - 1) << 8;
                CONTEXT |= jbig2_image_get_pixel(image, x - 3, y - 1) << 9;
                bit = jbig2_arith_decode(as, &GB_stats[CONTEXT], &code);
                if (code)
                    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to decode arithmetic code when handling generic template3 TPGDON2");
                jbig2_image_set_pixel(image, x, y, bit);
            }
        } else {
            copy_prev_row(image, y);
        }
    }

    return 0;
}

static int
jbig2_decode_generic_region_TPGDON(Jbig2Ctx *ctx,
                                   Jbig2Segment *segment,
                                   const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    switch (params->GBTEMPLATE) {
    case 0:
        return jbig2_decode_generic_template0_TPGDON(ctx, segment, params, as, image, GB_stats);
    case 1:
        return jbig2_decode_generic_template1_TPGDON(ctx, segment, params, as, image, GB_stats);
    case 2:
        return jbig2_decode_generic_template2_TPGDON(ctx, segment, params, as, image, GB_stats);
    case 3:
        return jbig2_decode_generic_template3_TPGDON(ctx, segment, params, as, image, GB_stats);
    }

    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "unsupported GBTEMPLATE (%d)", params->GBTEMPLATE);
}

/**
 * jbig2_decode_generic_region: Decode a generic region.
 * @ctx: The context for allocation and error reporting.
 * @segment: A segment reference for error reporting.
 * @params: Decoding parameter set.
 * @as: Arithmetic decoder state.
 * @image: Where to store the decoded data.
 * @GB_stats: Arithmetic stats.
 *
 * Decodes a generic region, according to section 6.2. The caller should
 * pass an already allocated Jbig2Image object for @image
 *
 * Because this API is based on an arithmetic decoding state, it is
 * not suitable for MMR decoding.
 *
 * Return code: 0 on success.
 **/
int
jbig2_decode_generic_region(Jbig2Ctx *ctx,
                            Jbig2Segment *segment, const Jbig2GenericRegionParams *params, Jbig2ArithState *as, Jbig2Image *image, Jbig2ArithCx *GB_stats)
{
    const int8_t *gbat = params->gbat;

    if (image->stride * image->height > (1 << 26) && segment->data_length < image->stride * image->height / (1 << 16)) {
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number,
                           "region is far larger than data provided (%d << %d), aborting to prevent DOS", segment->data_length, image->stride * image->height);
    }

    if (!params->MMR && params->TPGDON)
        return jbig2_decode_generic_region_TPGDON(ctx, segment, params, as, image, GB_stats);

    if (!params->MMR && params->GBTEMPLATE == 0) {
        if (!params->USESKIP && gbat[0] == +3 && gbat[1] == -1 && gbat[2] == -3 && gbat[3] == -1 && gbat[4] == +2 && gbat[5] == -2 && gbat[6] == -2 && gbat[7] == -2)
            return jbig2_decode_generic_template0(ctx, segment, params, as, image, GB_stats);
        else
            return jbig2_decode_generic_template0_unopt(ctx, segment, params, as, image, GB_stats);
    } else if (!params->MMR && params->GBTEMPLATE == 1) {
        if (!params->USESKIP && gbat[0] == +3 && gbat[1] == -1)
            return jbig2_decode_generic_template1(ctx, segment, params, as, image, GB_stats);
        else
            return jbig2_decode_generic_template1_unopt(ctx, segment, params, as, image, GB_stats);
    }
    else if (!params->MMR && params->GBTEMPLATE == 2) {
        if (!params->USESKIP && gbat[0] == 2 && gbat[1] == -1)
            return jbig2_decode_generic_template2(ctx, segment, params, as, image, GB_stats);
        else
            return jbig2_decode_generic_template2_unopt(ctx, segment, params, as, image, GB_stats);
    } else if (!params->MMR && params->GBTEMPLATE == 3) {
        if (!params->USESKIP && gbat[0] == 2 && gbat[1] == -1)
            return jbig2_decode_generic_template3(ctx, segment, params, as, image, GB_stats);
        else
            return jbig2_decode_generic_template3_unopt(ctx, segment, params, as, image, GB_stats);
    }

    {
        int i;

        for (i = 0; i < 8; i++)
            jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "gbat[%d] = %d", i, params->gbat[i]);
    }

    return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "unsupported generic region (MMR=%d, GBTEMPLATE=%d)", params->MMR, params->GBTEMPLATE);
}

/**
 * Handler for immediate generic region segments
 */
int
jbig2_immediate_generic_region(Jbig2Ctx *ctx, Jbig2Segment *segment, const byte *segment_data)
{
    Jbig2RegionSegmentInfo rsi;
    byte seg_flags;
    int8_t gbat[8];
    int offset;
    uint32_t gbat_bytes = 0;
    Jbig2GenericRegionParams params;
    int code = 0;
    Jbig2Image *image = NULL;
    Jbig2WordStream *ws = NULL;
    Jbig2ArithState *as = NULL;
    Jbig2ArithCx *GB_stats = NULL;
    uint32_t height;
    Jbig2Page *page = &ctx->pages[ctx->current_page];

    /* 7.4.6 */
    if (segment->data_length < 18)
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "segment too short");

    jbig2_get_region_segment_info(&rsi, segment_data);
    jbig2_error(ctx, JBIG2_SEVERITY_INFO, segment->number, "generic region: %d x %d @ (%d, %d), flags = %02x", rsi.width, rsi.height, rsi.x, rsi.y, rsi.flags);

    /* 7.4.6.4 */
    height = rsi.height;
    if (segment->rows != UINT32_MAX) {
        if (segment->rows > rsi.height)
            return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "segment contains more rows than stated in header");
        height = segment->rows;
    }

    /* 7.4.6.2 */
    seg_flags = segment_data[17];
    jbig2_error(ctx, JBIG2_SEVERITY_INFO, segment->number, "segment flags = %02x", seg_flags);
    if ((seg_flags & 1) && (seg_flags & 6))
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "MMR is 1, but GBTEMPLATE is not 0");

    /* 7.4.6.3 */
    if (!(seg_flags & 1)) {
        gbat_bytes = (seg_flags & 6) ? 2 : 8;
        if (18 + gbat_bytes > segment->data_length)
            return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "segment too short");
        memcpy(gbat, segment_data + 18, gbat_bytes);
        jbig2_error(ctx, JBIG2_SEVERITY_INFO, segment->number, "gbat: %d, %d", gbat[0], gbat[1]);
    }

    offset = 18 + gbat_bytes;

    /* Check for T.88 amendment 2 */
    if ((seg_flags >> 5) & 1)
        return jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "segment uses 12 adaptive template pixels (NYI)");

    /* Table 34 */
    params.MMR = seg_flags & 1;
    params.GBTEMPLATE = (seg_flags & 6) >> 1;
    params.TPGDON = (seg_flags & 8) >> 3;
    params.USESKIP = 0;
    memcpy(params.gbat, gbat, gbat_bytes);

    if (page->height == 0xffffffff && page->striped && page->stripe_size > 0) {
        if (rsi.y >= page->end_row + page->stripe_size) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "ignoring %u x %u region at (%u, %u) outside of stripe at row %u covering %u rows, on page of height %u", rsi.width, rsi.height, rsi.x, rsi.y, page->end_row, page->stripe_size, page->image->height);
            return 0;
        }
        if (height > page->end_row + page->stripe_size) {
            height = page->end_row + page->stripe_size;
        }
    } else {
        if (rsi.y >= page->height) {
            jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "ignoring %u x %u region at (%u, %u) outside of page of height %u", rsi.width, rsi.height, rsi.x, rsi.y, page->height);
            return 0;
        }
        if (height > page->height - rsi .y) {
            height = page->height - rsi.y;
        }
    }
    if (height == 0) {
        jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "nothing remains of region, ignoring");
        return 0;
    }

    image = jbig2_image_new(ctx, rsi.width, height);
    if (image == NULL)
        return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate generic image");
    jbig2_error(ctx, JBIG2_SEVERITY_DEBUG, segment->number, "allocated %d x %d image buffer for region decode results", rsi.width, height);

    if (params.MMR) {
        code = jbig2_decode_generic_mmr(ctx, segment, &params, segment_data + offset, segment->data_length - offset, image);
        if (code < 0) {
            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode MMR-coded generic region");
            goto cleanup;
        }
    } else {
        int stats_size = jbig2_generic_stats_size(ctx, params.GBTEMPLATE);

        GB_stats = jbig2_new(ctx, Jbig2ArithCx, stats_size);
        if (GB_stats == NULL) {
            code = jbig2_error(ctx, JBIG2_SEVERITY_FATAL, segment->number, "failed to allocate arithmetic decoder states when handling immediate generic region");
            goto cleanup;
        }
        memset(GB_stats, 0, stats_size);

        ws = jbig2_word_stream_buf_new(ctx, segment_data + offset, segment->data_length - offset);
        if (ws == NULL) {
            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocated word stream when handling immediate generic region");
            goto cleanup;
        }
        as = jbig2_arith_new(ctx, ws);
        if (as == NULL) {
            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to allocate arithmetic coding state when handling immediate generic region");
            goto cleanup;
        }
        code = jbig2_decode_generic_region(ctx, segment, &params, as, image, GB_stats);
        if (code < 0) {
            code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "failed to decode immediate generic region");
            goto cleanup;
        }
    }

    code = jbig2_page_add_result(ctx, &ctx->pages[ctx->current_page], image, rsi.x, rsi.y, rsi.op);
    if (code < 0)
        code = jbig2_error(ctx, JBIG2_SEVERITY_WARNING, segment->number, "unable to add result to page");

cleanup:
    jbig2_free(ctx->allocator, as);
    jbig2_word_stream_buf_free(ctx, ws);
    jbig2_free(ctx->allocator, GB_stats);
    jbig2_image_release(ctx, image);

    return code;
}