/* 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

*/

/* Annex A.3 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "os_types.h"

#include <stddef.h>

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

#ifdef VERBOSE

#include <stdio.h>              /* for debug printing only */

#endif

#include "jbig2.h"

#include "jbig2_priv.h"

#include "jbig2_arith.h"

#include "jbig2_arith_iaid.h"

struct _Jbig2ArithIaidCtx {

    uint8_t SBSYMCODELEN;

    Jbig2ArithCx *IAIDx;

};

Jbig2ArithIaidCtx *

jbig2_arith_iaid_ctx_new(Jbig2Ctx *ctx, uint8_t SBSYMCODELEN)

{

    Jbig2ArithIaidCtx *result;

    size_t ctx_size;

    if (sizeof(ctx_size) * 8 <= SBSYMCODELEN)

    {

        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, JBIG2_UNKNOWN_SEGMENT_NUMBER, "requested IAID arithmetic coding state size too large");

        return NULL;

    }

    ctx_size = (size_t) 1U << SBSYMCODELEN;

    result = jbig2_new(ctx, Jbig2ArithIaidCtx, 1);

    if (result == NULL) {

        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to allocate IAID arithmetic coding state");

        return NULL;

    }

    result->SBSYMCODELEN = SBSYMCODELEN;

    result->IAIDx = jbig2_new(ctx, Jbig2ArithCx, ctx_size);

    if (result->IAIDx == NULL)

    {

        jbig2_free(ctx->allocator, result);

        jbig2_error(ctx, JBIG2_SEVERITY_FATAL, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to allocate symbol ID in IAID arithmetic coding state");

        return NULL;

    }

    memset(result->IAIDx, 0, ctx_size);

    return result;

}

/* A.3 */

/* Return value: -1 on error, 0 on normal value */

int

jbig2_arith_iaid_decode(Jbig2Ctx *ctx, Jbig2ArithIaidCtx *actx, Jbig2ArithState *as, int32_t *p_result)

{

    Jbig2ArithCx *IAIDx = actx->IAIDx;

    uint8_t SBSYMCODELEN = actx->SBSYMCODELEN;

    /* A.3 (1) */

    int PREV = 1;

    int D;

    int i;

    /* A.3 (2) */

    for (i = 0; i < SBSYMCODELEN; i++) {

        D = jbig2_arith_decode(ctx, as, &IAIDx[PREV]);

        if (D < 0)

            return jbig2_error(ctx, JBIG2_SEVERITY_WARNING, JBIG2_UNKNOWN_SEGMENT_NUMBER, "failed to decode IAIDx code");

#ifdef VERBOSE

        fprintf(stderr, "IAID%x: D = %d\n", PREV, D);

#endif

        PREV = (PREV << 1) | D;

    }

    /* A.3 (3) */

    PREV -= 1 << SBSYMCODELEN;

#ifdef VERBOSE

    fprintf(stderr, "IAID result: %d\n", PREV);

#endif

    *p_result = PREV;

    return 0;

}

void

jbig2_arith_iaid_ctx_free(Jbig2Ctx *ctx, Jbig2ArithIaidCtx *iax)

{

    if (iax != NULL) {

        jbig2_free(ctx->allocator, iax->IAIDx);

        jbig2_free(ctx->allocator, iax);

    }

}