/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF.  The full HDF copyright notice, including       *
 * terms governing use, modification, and redistribution, is contained in    *
 * the COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://support.hdfgroup.org/ftp/HDF/releases/.  *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/* General HDF includes */

#include "hdf_priv.h"

#ifdef H4_HAVE_LIBSZ
#include "szlib.h"
#endif

/* HDF compression includes */
#include "hcomp_priv.h" /* Internal definitions for compression */

/* internal defines */
#define TMP_BUF_SIZE 8192 /* size of throw-away buffer */

/* functions to perform szip encoding */
funclist_t cszip_funcs = {HCPcszip_stread,
                          HCPcszip_stwrite,
                          HCPcszip_seek,
                          HCPcszip_inquire,
                          HCPcszip_read,
                          HCPcszip_write,
                          HCPcszip_endaccess,
                          NULL,
                          NULL};

/* declaration of the functions provided in this module */
static int32 HCIcszip_staccess(accrec_t *access_rec, int16 acc_mode);

static int32 HCIcszip_init(accrec_t *access_rec);

static int32 HCIcszip_decode(compinfo_t *info, int32 length, uint8 *buf);

#ifdef H4_HAVE_LIBSZ
static int32 HCIcszip_encode(compinfo_t *info, int32 length, const uint8 *buf);
#endif

static int32 HCIcszip_term(compinfo_t *info);

/*--------------------------------------------------------------------------
 NAME
    HCIcszip_init -- Initialize a SZIP compressed data element.

 USAGE
    int32 HCIcszip_init(access_rec)
    accrec_t *access_rec;   IN: the access record of the data element

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Common code called by HCIcszip_staccess and HCIcszip_seek
--------------------------------------------------------------------------*/
static int32
HCIcszip_init(accrec_t *access_rec)
{
    compinfo_t             *info;      /* special element information */
    comp_coder_szip_info_t *szip_info; /* ptr to SZIP info */
    int                     ret_value = SUCCEED;

#ifdef H4_HAVE_LIBSZ
    /* Sanity check to make certain that we haven't drifted out of date with
     * the mask options from the SZIP ricehdf.h header */
    assert(H4_SZ_ALLOW_K13_OPTION_MASK == SZ_ALLOW_K13_OPTION_MASK);
    assert(H4_SZ_CHIP_OPTION_MASK == SZ_CHIP_OPTION_MASK);
    assert(H4_SZ_EC_OPTION_MASK == SZ_EC_OPTION_MASK);
    assert(H4_SZ_LSB_OPTION_MASK == SZ_LSB_OPTION_MASK);
    assert(H4_SZ_MSB_OPTION_MASK == SZ_MSB_OPTION_MASK);
    assert(H4_SZ_NN_OPTION_MASK == SZ_NN_OPTION_MASK);
    assert(H4_SZ_RAW_OPTION_MASK == SZ_RAW_OPTION_MASK);
#endif

    info = (compinfo_t *)access_rec->special_info;
    if (Hseek(info->aid, 0, DF_START) == FAIL) /* seek to beginning of element */
        HGOTO_ERROR(DFE_SEEKERROR, FAIL);

    szip_info = &(info->cinfo.coder_info.szip_info);

    /* Initialize SZIP state information */
    szip_info->szip_state = SZIP_INIT; /* start in initial state */
    if (szip_info->buffer_size != 0) {
        szip_info->buffer_size = 0; /* offset into the file */
        free(szip_info->buffer);
        szip_info->buffer = NULL;
    }
    szip_info->offset     = 0; /* offset into the file */
    szip_info->szip_dirty = SZIP_CLEAN;

done:
    return ret_value;
} /* end HCIcszip_init() */

/*--------------------------------------------------------------------------
 NAME
    HCIcszip_decode -- Decode SZIP compressed data into a buffer.

 USAGE
    int32 HCIcszip_decode(info,length,buf)
    compinfo_t *info;   IN: the info about the compressed element
    int32 length;       IN: number of bytes to read into the buffer
    uint8 *buf;         OUT: buffer to store the bytes read

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Common code called to decode SZIP data from the file.
--------------------------------------------------------------------------*/
static int32
HCIcszip_decode(compinfo_t *info, int32 length, uint8 *buf)
{
#ifdef H4_HAVE_LIBSZ
    accrec_t               *access_rec;
    comp_coder_szip_info_t *szip_info; /* ptr to SZIP info */
    uint8                  *in_buffer;
    uint8                  *out_buffer;
    int32                   in_length;
    int32                   out_length;
    int                     bytes_per_pixel;
    int32                   rbytes;
    uint16                  tag, ref;
    int32                   len1;
    int32                   aid;
    int32                   status;
    size_t                  size_out;
    uint8                  *cp;
    int32                   good_bytes;
    int32                   old_way;
    SZ_com_t                sz_param;
#endif

#ifdef H4_HAVE_LIBSZ

    szip_info = &(info->cinfo.coder_info.szip_info);
    if (szip_info->szip_state == SZIP_INIT) {
        /*  Load from disk, decode the data */

        if ((access_rec = HAatom_object(info->aid)) == NULL) /* get the access_rec pointer */
            HRETURN_ERROR(DFE_ARGS, FAIL);

        /* Discover how much data must be read */
        if (HTPinquire(access_rec->ddid, &tag, &ref, NULL, &in_length) == FAIL)
            HRETURN_ERROR(DFE_INTERNAL, FAIL);

        if (in_length == -1)
            HRETURN_ERROR(DFE_INTERNAL, FAIL);

        if (tag & 0x4000) {
            /* this is linked list -- get the length of the data */
            aid = Hstartread(access_rec->file_id, tag, ref);
            if (HDinqblockinfo(aid, &len1, NULL, NULL, NULL) == FAIL) {
                Hendaccess(aid);
                HRETURN_ERROR(DFE_INTERNAL, FAIL);
            }
            in_length = len1;
            Hendaccess(aid);
        }

        old_way = (int)(szip_info->options_mask & SZ_H4_REV_2);
        if (old_way == 0) {
            /* special case: read data encoded in V4.2r0 */
            old_way    = 1;
            good_bytes = in_length;
            in_length  = in_length + 5;
            if ((in_buffer = (uint8 *)malloc((size_t)in_length)) == NULL)
                HRETURN_ERROR(DFE_NOSPACE, FAIL);
            cp  = in_buffer;
            *cp = 0;
            cp++;
            INT32ENCODE(cp, good_bytes);
        }
        else {
            /*  V4.2r1: in_length is correct */
            old_way = 0;
            if ((in_buffer = (uint8 *)malloc((size_t)in_length)) == NULL)
                HRETURN_ERROR(DFE_NOSPACE, FAIL);
        }

        /* Allocate memory for the uncompressed data */
        bytes_per_pixel = (szip_info->bits_per_pixel + 7) >> 3;
        if (bytes_per_pixel == 3)
            bytes_per_pixel++;

        out_length = szip_info->pixels * bytes_per_pixel;
        if ((out_buffer = (uint8 *)malloc((size_t)out_length)) == NULL)
            HRETURN_ERROR(DFE_NOSPACE, FAIL);

        /* Read the unompressed data */
        if (old_way == 1) {
            /* this is encoded in V4.2r0 */
            /* the preamble isn't in the file, so read only the data */
            if ((rbytes = Hread(info->aid, in_length - 5, in_buffer + 5)) == FAIL) {
                free(out_buffer);
                free(in_buffer);
                HRETURN_ERROR(DFE_READERROR, FAIL);
            }
            if (rbytes == 0 || rbytes != (in_length - 5)) {
                /* is this possible? */
                free(out_buffer);
                free(in_buffer);
                HRETURN_ERROR(DFE_READERROR, FAIL);
            }
        }
        else {
            /* HDF4.2R1: read the data plus preamble */
            if ((rbytes = Hread(info->aid, in_length, in_buffer)) == FAIL) {
                free(out_buffer);
                free(in_buffer);
                HRETURN_ERROR(DFE_READERROR, FAIL);
            }
            if (rbytes == 0 || rbytes != in_length) {
                /* is this possible? */
                free(out_buffer);
                free(in_buffer);
                HRETURN_ERROR(DFE_READERROR, FAIL);
            }
        }
        cp = in_buffer;
        cp++;
        INT32DECODE(cp, good_bytes);
        if (in_buffer[0] == 1) {
            /* This byte means the data was not compressed -- just copy out */
            szip_info->szip_state = SZIP_RUN;
            memcpy(out_buffer, in_buffer + 5, (size_t)good_bytes);
            szip_info->buffer      = out_buffer;
            szip_info->buffer_pos  = 0;
            szip_info->buffer_size = good_bytes;
            szip_info->offset      = 0;
            if (good_bytes > length) {
                /* partial read */
                memcpy(buf, in_buffer + 5, (size_t)length);
                szip_info->buffer_pos += length;
                szip_info->buffer_size -= length;
            }
            else {
                /* read the whole data block to the user buffer */
                memcpy(buf, in_buffer + 5, (size_t)good_bytes);
                szip_info->buffer_pos += good_bytes;
                szip_info->buffer_size -= good_bytes;
            }
            szip_info->offset = szip_info->buffer_pos;
            free(in_buffer);
            if (szip_info->buffer_size == 0) {
                free(szip_info->buffer);
                szip_info->buffer = NULL;
            }
            return SUCCEED;
        }

        /* Decompress the data */

        /* set up the parameters */
        sz_param.options_mask        = (szip_info->options_mask & ~SZ_H4_REV_2);
        sz_param.bits_per_pixel      = szip_info->bits_per_pixel;
        sz_param.pixels_per_block    = szip_info->pixels_per_block;
        sz_param.pixels_per_scanline = szip_info->pixels_per_scanline;
        size_out                     = (size_t)out_length;
        if (SZ_OK != (status = SZ_BufftoBuffDecompress(out_buffer, &size_out, (in_buffer + 5),
                                                       (size_t)good_bytes, &sz_param))) {
            free(out_buffer);
            free(in_buffer);
            HRETURN_ERROR(DFE_CDECODE, FAIL);
        }

        if ((int32)size_out != out_length) {
            /* This should never happen?? */
            printf("status: %d ??bytes != out_length %zu != %d\n", status, size_out, out_length);
        }

        /* The data is successfully decompressed. Put into the szip struct */
        free(in_buffer);
        szip_info->szip_state  = SZIP_RUN;
        szip_info->buffer      = out_buffer;
        szip_info->buffer_pos  = 0;
        szip_info->buffer_size = out_length;
        szip_info->offset      = 0;
    }

    /* copy the data into the return buffer */
    if (length > szip_info->buffer_size) {
        /*  can't happen?? panic?? */
        free(szip_info->buffer);
        szip_info->buffer = NULL;
        return FAIL;
    }

    memcpy(buf, szip_info->buffer + szip_info->buffer_pos, (size_t)length);
    szip_info->buffer_pos += length;
    szip_info->buffer_size -= length;
    szip_info->offset = szip_info->buffer_pos;

    if (szip_info->buffer_size == 0) {
        free(szip_info->buffer);
        szip_info->buffer = NULL;
    }

    return SUCCEED;

#else  /* ifdef H4_HAVE_LIBSZ */
    (void)info;
    (void)length;
    (void)buf;

    HRETURN_ERROR(DFE_CANTCOMP, FAIL);
#endif /* H4_HAVE_LIBSZ */

} /* end HCIcszip_decode() */

/*--------------------------------------------------------------------------
 NAME
    HCIcszip_encode -- Encode data from a buffer into SZIP compressed data

 USAGE
    int32 HCIcszip_encode(info,length,buf)
    compinfo_t *info;   IN: the info about the compressed element
    int32 length;       IN: number of bytes to store from the buffer
    const uint8 *buf;         OUT: buffer to get the bytes from

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Common code called to encode SZIP data into a file.
--------------------------------------------------------------------------*/
#ifdef H4_HAVE_LIBSZ
static int32
HCIcszip_encode(compinfo_t *info, int32 length, const uint8 *buf)
{
#ifdef H4_HAVE_SZIP_ENCODER
    int                     bytes_per_pixel;
    comp_coder_szip_info_t *szip_info; /* ptr to SZIP info */
    int32                   buffer_size;

    if (SZ_encoder_enabled() == 0)
        HRETURN_ERROR(DFE_NOENCODER, FAIL);

    szip_info = &(info->cinfo.coder_info.szip_info);
    if (szip_info->szip_state == SZIP_INIT) {
        /* Need to initialize */
        bytes_per_pixel = (szip_info->bits_per_pixel + 7) >> 3;
        if (bytes_per_pixel == 3)
            bytes_per_pixel = 4;

        buffer_size = szip_info->pixels * bytes_per_pixel;
        if ((szip_info->buffer = malloc((size_t)buffer_size)) == NULL)
            HRETURN_ERROR(DFE_NOSPACE, FAIL);

        szip_info->buffer_size = buffer_size;
        szip_info->buffer_pos  = 0;
        szip_info->szip_state  = SZIP_RUN;
    }

    /* copy the data into the buffer.  This will be written in 'term' function */
    memcpy(szip_info->buffer + szip_info->buffer_pos, buf, (size_t)length);
    szip_info->buffer_pos += length;
    szip_info->buffer_size -= length;
    szip_info->offset     = szip_info->buffer_pos;
    szip_info->szip_dirty = SZIP_DIRTY;

    return SUCCEED;

#else  /* ifdef H4_HAVE_SZIP_ENCODER */
    (void)info;
    (void)length;
    (void)buf;

    HRETURN_ERROR(DFE_CANTCOMP, FAIL);
#endif /* H4_HAVE_SZIP_ENCODER */

} /* end HCIcszip_encode() */
#endif /* H4_HAVE_LIBSZ */

/*--------------------------------------------------------------------------
 NAME
    HCIcszip_term -- Flush encoded data from internal buffer to SZIP compressed data

 USAGE
    int32 HCIcszip_term(info)
    compinfo_t *info;   IN: the info about the compressed element

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Common code called to flush SZIP data into a file.
--------------------------------------------------------------------------*/
static int32
HCIcszip_term(compinfo_t *info)
{
#ifdef H4_HAVE_SZIP_ENCODER
    comp_coder_szip_info_t *szip_info; /* ptr to SZIP info */
    uint8                  *out_buffer;
    uint8                  *ob;
    int32                   out_buffer_size;
    int                     bytes_per_pixel;
    int32                   current_size;
    accrec_t               *access_rec;
    uint16                  tag, ref;
    int32                   len1;
    int32                   aid;
    SZ_com_t                sz_param;
    size_t                  size_out;
    int32                   status;
    uint8                  *cp;

    szip_info = &(info->cinfo.coder_info.szip_info);
    if (szip_info->szip_state != SZIP_RUN)
        return SUCCEED; /* nothing to do */

    if (szip_info->szip_dirty != SZIP_DIRTY) /* Should never happen?? */
    {
        if (szip_info->buffer_size == 0) {
            free(szip_info->buffer);
            szip_info->buffer = NULL;
        }
        return SUCCEED;
    }

    szip_info->szip_state = SZIP_TERM;

    current_size = 0;
    if ((access_rec = HAatom_object(info->aid)) == NULL) /* get the access_rec pointer */
        HRETURN_ERROR(DFE_INTERNAL, FAIL);

    /* Discover how much data must be read */
    if (HTPinquire(access_rec->ddid, &tag, &ref, NULL, &current_size) == FAIL)
        HRETURN_ERROR(DFE_INTERNAL, FAIL);
    if (tag & 0x4000) {
        /* this is linked list -- get the length of the data */
        aid = Hstartread(access_rec->file_id, tag, ref);
        if (HDinqblockinfo(aid, &len1, NULL, NULL, NULL) == FAIL) {
            Hendaccess(aid);
            HRETURN_ERROR(DFE_INTERNAL, FAIL);
        }
        current_size = len1;
        Hendaccess(aid);
    }

    /* Compute how much memory is needed to hold compressed data */
    bytes_per_pixel = (szip_info->bits_per_pixel + 7) >> 3;
    if (bytes_per_pixel == 3)
        bytes_per_pixel = 4;

    /* temporary buffer for compression -- leave extra space in case of
          overflow in the SZIP algorithm. (This number corresponds to
          the current internal buffer of szip lib.)  Sigh. */
    /* allocate one byte to indicate when data is written uncompressed */
    /* allocate 4 bytes to store the amount of data written:
        after compression may be less than the previous size  */
    out_buffer_size = (szip_info->pixels * 2 * bytes_per_pixel) + 5;

    /* heuristic for tiny data -- really shouldn't compress stuff this small,
       but there isn't any way to prevent it from getting here */
    if (out_buffer_size < 1024)
        out_buffer_size = 1024;
    if ((out_buffer = malloc((size_t)out_buffer_size)) == NULL)
        HRETURN_ERROR(DFE_NOSPACE, FAIL);

    /* set params */
    sz_param.options_mask        = szip_info->options_mask;
    sz_param.bits_per_pixel      = szip_info->bits_per_pixel;
    sz_param.pixels_per_block    = szip_info->pixels_per_block;
    sz_param.pixels_per_scanline = szip_info->pixels_per_scanline;
    size_out                     = (size_t)out_buffer_size - 5;

    *out_buffer = 0;
    if (SZ_OK != (status = SZ_BufftoBuffCompress((out_buffer + 5), &size_out, szip_info->buffer,
                                                 (size_t)szip_info->buffer_pos, &sz_param))) {
        /* Compression Failed.  Analyse several cases, and clean up the mess */
        if ((int32)size_out > out_buffer_size) {
            /* Should never happen */
            printf("PANIC: overwrote memory\n");
            fflush(stdout);
        }
        if (status == 2 /*SZ_OUTBUF_FULL*/) {
            /* SZIP internal overflow: data not successfully compressed */
            /* Write out the uncompressed data */
            *out_buffer = 1; /* 1 = don't decompress */
            cp          = out_buffer;
            cp++;
            INT32ENCODE(cp, szip_info->buffer_pos);
            memcpy((out_buffer + 5), szip_info->buffer, (size_t)szip_info->buffer_pos);
            free(out_buffer);
            szip_info->szip_dirty = SZIP_CLEAN;

            if (szip_info->buffer_size == 0) {
                free(szip_info->buffer);
                szip_info->buffer = NULL;
            }
            return SUCCEED;
        }

        /* compress failed, return error */
        szip_info->szip_dirty = SZIP_CLEAN;
        free(out_buffer);
        if (szip_info->buffer_size == 0) {
            free(szip_info->buffer);
            szip_info->buffer = NULL;
        }
        HRETURN_ERROR(DFE_CENCODE, FAIL);
    }

    /* Compression Succeeded, write out the compressed data */

    if ((int32)size_out >= out_buffer_size)
        printf("PANIC: overwrote memory but returned OK?\n");
    fflush(stdout);
    if ((int32)size_out > (szip_info->pixels * bytes_per_pixel)) {
        /* The compression succeeded, but is larger than the original data! */
        /*  Write the original data, discard the output  */
        *out_buffer = 1; /* 1 = don't decompress */
        cp          = out_buffer;
        cp++;
        INT32ENCODE(cp, szip_info->buffer_pos);
        memcpy((out_buffer + 5), szip_info->buffer, (size_t)szip_info->buffer_pos);
        Hwrite(info->aid, (szip_info->buffer_pos + 5), out_buffer);
        szip_info->szip_dirty = SZIP_CLEAN;
        free(out_buffer);
        if (szip_info->buffer_size == 0) {
            free(szip_info->buffer);
            szip_info->buffer = NULL;
        }
        return SUCCEED;
    }

    if ((current_size > 0) && (((int32)size_out + 5) < current_size)) {
        /* SZIP freaks out if there is junk at the end of the good data */
        /* need to have enough data to overwrite the existing data */
        /* allocate a buffer, fill in the good data. The rest must be
            zeroes */
        if ((ob = malloc((size_t)current_size)) == NULL)
            HRETURN_ERROR(DFE_NOSPACE, FAIL);
        *ob = 0; /* data needs to be decompressed */
        cp  = ob;
        cp++;
        INT32ENCODE(cp, size_out); /* how much to decompress  (< total size)*/
        memcpy((ob + 5), out_buffer + 5, size_out);
        Hwrite(info->aid, current_size, ob); /* write out at least 'current_size' bytes */
        szip_info->szip_dirty = SZIP_CLEAN;
        free(out_buffer);
        free(ob);
        if (szip_info->buffer_size == 0) {
            free(szip_info->buffer);
            szip_info->buffer = NULL;
        }
        return SUCCEED;
    }

    /* Finally!  Write the compressed data. Byte 0 is '0' */
    *out_buffer = 0; /* data needs to be decompressed */
    cp          = out_buffer;
    cp++;
    INT32ENCODE(cp, size_out); /* whole buffer needs to be decompressed */
    status = Hwrite(info->aid, (int32)size_out + 5, out_buffer);

    szip_info->szip_dirty = SZIP_CLEAN;
    if (szip_info->buffer_size == 0) {
        free(szip_info->buffer);
        szip_info->buffer = NULL;
    }
    free(out_buffer);

    return SUCCEED;

#else  /* H4_HAVE_SZIP_ENCODER */
    (void)info;

    HRETURN_ERROR(DFE_CANTCOMP, FAIL);
#endif /* H4_HAVE_SZIP_ENCODER */

} /* end HCIcszip_term() */

/*--------------------------------------------------------------------------
 NAME
    HCIcszip_staccess -- Start accessing a SZIP compressed data element.

 USAGE
    int32 HCIcszip_staccess(access_rec, access)
    accrec_t *access_rec;   IN: the access record of the data element
    int16 access;           IN: the type of access wanted

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Common code called by HCIcszip_stread and HCIcszip_stwrite
--------------------------------------------------------------------------*/
static int32
HCIcszip_staccess(accrec_t *access_rec, int16 acc_mode)
{
    compinfo_t *info; /* special element information */

    info = (compinfo_t *)access_rec->special_info;
    if (acc_mode == DFACC_READ)
        info->aid = Hstartread(access_rec->file_id, DFTAG_COMPRESSED, info->comp_ref);
    else
#ifdef H4_HAVE_SZIP_ENCODER
    {
        if (SZ_encoder_enabled() == 0)
            HRETURN_ERROR(DFE_NOENCODER, FAIL);
        info->aid = Hstartaccess(access_rec->file_id, DFTAG_COMPRESSED, info->comp_ref,
                                 DFACC_RDWR | DFACC_APPENDABLE);
    }
#else
        HRETURN_ERROR(DFE_DENIED, FAIL);
#endif

    if (info->aid == FAIL)
        HRETURN_ERROR(DFE_DENIED, FAIL);

    return HCIcszip_init(access_rec); /* initialize the SZIP info */
} /* end HCIcszip_staccess() */

/*--------------------------------------------------------------------------
 NAME
    HCPcszip_stread -- start read access for compressed file

 USAGE
    int32 HCPcszip_stread(access_rec)
    accrec_t *access_rec;   IN: the access record of the data element

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Start read access on a compressed data element using a simple SZIP scheme.
--------------------------------------------------------------------------*/
int32
HCPcszip_stread(accrec_t *access_rec)
{
    int32 ret;

    if ((ret = HCIcszip_staccess(access_rec, DFACC_READ)) == FAIL)
        HRETURN_ERROR(DFE_CINIT, FAIL);
    return ret;
} /* HCPcszip_stread() */

/*--------------------------------------------------------------------------
 NAME
    HCPcszip_stwrite -- start write access for compressed file

 USAGE
    int32 HCPcszip_stwrite(access_rec)
    accrec_t *access_rec;   IN: the access record of the data element

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Start write access on a compressed data element using a simple SZIP scheme.
--------------------------------------------------------------------------*/
int32
HCPcszip_stwrite(accrec_t *access_rec)
{
    int32 ret;

    if ((ret = HCIcszip_staccess(access_rec, DFACC_WRITE)) == FAIL)
        HRETURN_ERROR(DFE_CINIT, FAIL);
    return ret;
} /* HCPcszip_stwrite() */

/*--------------------------------------------------------------------------
 NAME
    HCPcszip_seek -- Seek to offset within the data element

 USAGE
    int32 HCPcszip_seek(access_rec,offset,origin)
    accrec_t *access_rec;   IN: the access record of the data element
    int32 offset;       IN: the offset in bytes from the origin specified
    int origin;        IN: the origin to seek from [UNUSED!]

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Seek to a position with a compressed data element.  The 'origin'
    calculations have been taken care of at a higher level, it is an
    un-used parameter.  The 'offset' is used as an absolute offset
    because of this.
--------------------------------------------------------------------------*/
int32
HCPcszip_seek(accrec_t *access_rec, int32 offset, int origin)
{
    compinfo_t             *info;      /* special element information */
    comp_coder_szip_info_t *szip_info; /* ptr to SZIP info */
    uint8                  *tmp_buf;   /* pointer to throw-away buffer */

    (void)origin;

    info      = (compinfo_t *)access_rec->special_info;
    szip_info = &(info->cinfo.coder_info.szip_info);

    if (offset < szip_info->offset) { /* need to seek from the beginning */
        if (szip_info->szip_dirty == SZIP_DIRTY && szip_info->szip_state != SZIP_INIT) {
            if (HCIcszip_term(info) == FAIL)
                HRETURN_ERROR(DFE_CTERM, FAIL);
        }
        if (HCIcszip_init(access_rec) == FAIL)
            HRETURN_ERROR(DFE_CINIT, FAIL);
    } /* end if */

    if ((tmp_buf = (uint8 *)malloc(TMP_BUF_SIZE)) == NULL) /* get tmp buffer */
        HRETURN_ERROR(DFE_NOSPACE, FAIL);

    while (szip_info->offset + TMP_BUF_SIZE < offset) /* grab chunks */
    {
        if (HCIcszip_decode(info, TMP_BUF_SIZE, tmp_buf) == FAIL) {
            free(tmp_buf);
            HRETURN_ERROR(DFE_CDECODE, FAIL);
        }
    }
    if (szip_info->offset < offset) /* grab the last chunk */
    {
        if (HCIcszip_decode(info, offset - szip_info->offset, tmp_buf) == FAIL) {
            free(tmp_buf);
            HRETURN_ERROR(DFE_CDECODE, FAIL);
        }
    }

    free(tmp_buf);
    return SUCCEED;
} /* HCPcszip_seek() */

/*--------------------------------------------------------------------------
 NAME
    HCPcszip_read -- Read in a portion of data from a compressed data element.

 USAGE
    int32 HCPcszip_read(access_rec,length,data)
    accrec_t *access_rec;   IN: the access record of the data element
    int32 length;           IN: the number of bytes to read
    void * data;             OUT: the buffer to place the bytes read

 RETURNS
    Returns the number of bytes read or FAIL

 DESCRIPTION
    Read in a number of bytes from a SZIP compressed data element.
--------------------------------------------------------------------------*/
int32
HCPcszip_read(accrec_t *access_rec, int32 length, void *data)
{
    compinfo_t *info; /* special element information */

    info = (compinfo_t *)access_rec->special_info;

    if (HCIcszip_decode(info, length, data) == FAIL)
        HRETURN_ERROR(DFE_CDECODE, FAIL);

    return length;
} /* HCPcszip_read() */

/*--------------------------------------------------------------------------
 NAME
    HCPcszip_write -- Write out a portion of data from a compressed data element.

 USAGE
    int32 HCPcszip_write(access_rec,length,data)
    accrec_t *access_rec;   IN: the access record of the data element
    int32 length;           IN: the number of bytes to write
    void * data;             IN: the buffer to retrieve the bytes written

 RETURNS
    Returns the number of bytes written or FAIL

 DESCRIPTION
    Write out a number of bytes to a SZIP compressed data element.
--------------------------------------------------------------------------*/
int32
HCPcszip_write(accrec_t *access_rec, int32 length, const void *data)
{
#ifdef H4_HAVE_SZIP_ENCODER
    compinfo_t             *info;      /* special element information */
    comp_coder_szip_info_t *szip_info; /* ptr to SZIP info */

    if (SZ_encoder_enabled() == 0)
        HRETURN_ERROR(DFE_NOENCODER, FAIL);
    info      = (compinfo_t *)access_rec->special_info;
    szip_info = &(info->cinfo.coder_info.szip_info);

    /* Don't allow random write in a dataset unless: */
    /*  1 - append onto the end */
    /*  2 - start at the beginning and rewrite (at least) the whole dataset */
    if ((info->length != szip_info->offset) && (szip_info->offset != 0 || length < info->length))
        HRETURN_ERROR(DFE_UNSUPPORTED, FAIL);

    if (HCIcszip_encode(info, length, data) == FAIL)
        HRETURN_ERROR(DFE_CENCODE, FAIL);

    return length;
#else /* ifdef H4_HAVE_SZIP_ENCODER */
    (void)access_rec;
    (void)length;
    (void)data;

    HRETURN_ERROR(DFE_CANTDECOMP, FAIL);

#endif /* H4_HAVE_SZIP_ENCODER */
} /* HCPcszip_write() */

/*--------------------------------------------------------------------------
 NAME
    HCPcszip_inquire -- Inquire information about the access record and data element.

 USAGE
    int32 HCPcszip_inquire(access_rec,pfile_id,ptag,pref,plength,poffset,pposn,
            paccess,pspecial)
    accrec_t *access_rec;   IN: the access record of the data element
    int32 *pfile_id;        OUT: ptr to file id
    uint16 *ptag;           OUT: ptr to tag of information
    uint16 *pref;           OUT: ptr to ref of information
    int32 *plength;         OUT: ptr to length of data element
    int32 *poffset;         OUT: ptr to offset of data element
    int32 *pposn;           OUT: ptr to position of access in element
    int16 *paccess;         OUT: ptr to access mode
    int16 *pspecial;        OUT: ptr to special code

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Inquire information about the access record and data element.
    [Currently a NOP].
--------------------------------------------------------------------------*/
int32
HCPcszip_inquire(accrec_t *access_rec, int32 *pfile_id, uint16 *ptag, uint16 *pref, int32 *plength,
                 int32 *poffset, int32 *pposn, int16 *paccess, int16 *pspecial)
{
    (void)access_rec;
    (void)pfile_id;
    (void)ptag;
    (void)pref;
    (void)plength;
    (void)poffset;
    (void)pposn;
    (void)paccess;
    (void)pspecial;

    return SUCCEED;
} /* HCPcszip_inquire() */

/*--------------------------------------------------------------------------
 NAME
    HCPcszip_endaccess -- Close the compressed data element

 USAGE
    int32 HCPcszip_endaccess(access_rec)
    accrec_t *access_rec;   IN: the access record of the data element

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION
    Close the compressed data element and free encoding info.
--------------------------------------------------------------------------*/
int
HCPcszip_endaccess(accrec_t *access_rec)
{
    compinfo_t             *info;      /* special element information */
    comp_coder_szip_info_t *szip_info; /* ptr to SZIP info */

    info      = (compinfo_t *)access_rec->special_info;
    szip_info = &(info->cinfo.coder_info.szip_info);

    /* flush out SZIP buffer if there is unwritten data */
    if (szip_info->szip_dirty == SZIP_DIRTY && szip_info->szip_state != SZIP_INIT) {
        if (HCIcszip_term(info) == FAIL)
            HRETURN_ERROR(DFE_CTERM, FAIL);
    }

    /* close the compressed data AID */
    if (Hendaccess(info->aid) == FAIL)
        HRETURN_ERROR(DFE_CANTCLOSE, FAIL);

    return SUCCEED;
} /* HCPcszip_endaccess() */

/*--------------------------------------------------------------------------
 NAME
    HCPsetup_szip_parms -- Initialize SZIP parameters

 USAGE
    int HCPsetup_szip_parms( comp_info *c_info, int32 nt, int32 ndims, int32 *dims, int32 *cdims)
    comp_info *c_info;    IN/OUT: the szip compression params
    int32 nt;             IN: the number type of the data
    int32 ncomp;          IN: components in GR, 1 for SD
    int32 ndims;          IN: The rank of the data
    int32 *dims;          IN: the dimensions
    int32 *cdims;         IN: the dimensions of a chunk, if chunked, or NULL;

 RETURNS
    Returns SUCCEED or FAIL

 DESCRIPTION

    Computes the SZIP parameters for dataset or chunk:
       pixels -- total elements per compression
       pixels_per_scanline
       bits_per_pixel

    This is called from GRsetup_szip_parms and SDsetup_szip_parms
--------------------------------------------------------------------------*/
int
HCPsetup_szip_parms(comp_info *c_info, int32 nt, int32 ncomp, int32 ndims, int32 *dims, int32 *cdims)
{
#ifdef H4_HAVE_SZIP_ENCODER
    int32 scanline;
    int32 npoints;
    int32 sz;
    int   i;
    int   ret_value = SUCCEED;

    if (ndims <= 0) {
        ret_value = FAIL;
        goto done;
    }

    /* compute the number of elements in the compressed unit:
        if chunked, compress each chunk. If not, compress whole
        object
    */
    npoints = ncomp; /* for GR24, treat as 3 D data for szip */
    /* get npoints */
    if (cdims == NULL) {
        /* the whole array */
        for (i = 0; i < ndims; i++) {
            npoints *= dims[i];
        }
    }
    else {
        /* elements in a single chunk */
        for (i = 0; i < ndims; i++) {
            npoints *= cdims[i];
        }
    }
    c_info->szip.pixels = npoints;

    /* compute the pixels per scanline */
    /* start with the n-1th dimension, allow for components of GR */
    if (cdims == NULL) {
        scanline = dims[ndims - 1] * ncomp;
    }
    else {
        scanline = cdims[ndims - 1] * ncomp;
    }

    /* apply restrictions to find the correct value */
    if (scanline < c_info->szip.pixels_per_block) {
        if (c_info->szip.pixels < c_info->szip.pixels_per_block) {
            ret_value = FAIL;
            goto done;
        }
        scanline = MIN((c_info->szip.pixels_per_block * SZ_MAX_BLOCKS_PER_SCANLINE), npoints);
    }
    else {
        if (scanline <= SZ_MAX_PIXELS_PER_SCANLINE) {
            scanline = MIN((c_info->szip.pixels_per_block * SZ_MAX_BLOCKS_PER_SCANLINE), scanline);
        }
        else {
            scanline = c_info->szip.pixels_per_block * SZ_MAX_BLOCKS_PER_SCANLINE;
        }
    }
    c_info->szip.pixels_per_scanline = scanline;

    /* compute the bits per pixel from the HDF NDT */
    if (FAIL == (sz = DFKNTsize(nt | DFNT_NATIVE))) {
        ret_value = FAIL;
        goto done;
    }
    c_info->szip.bits_per_pixel = sz * 8;

done:
    return ret_value;
#else
    /* szip not enabled */
    (void)c_info;
    (void)nt;
    (void)ncomp;
    (void)ndims;
    (void)dims;
    (void)cdims;

    return FAIL;
#endif
}

/*--------------------------------------------------------------------------
 NAME
    HCPrm_szip_special_bit -- Removes the special bit that signals szip revised format

 USAGE
    int HCPrm_szip_special_bit(comp_info *c_info)
    comp_info *c_info;    IN/OUT: the szip compression params

 RETURNS
    Returns SUCCEED

 DESCRIPTION

    A special bit, SZ_H4_REV_2, was introduced to indicate that the szip info
    was stored in a new way.  This bit was set in the options_mask field
    of the szip info struct.  As a result, the value of options_mask became
    incorrect when the special bit was not removed from the options_mask before
    returning to the application.

    This is used in SDgetcompinfo and GRgetcompinfo.

--------------------------------------------------------------------------*/
int
HCPrm_szip_special_bit(comp_info *c_info)
{
    int sz_newway = 0; /* indicates the special bit presents in the options_mask */

    if (c_info == NULL)
        HRETURN_ERROR(DFE_INTERNAL, FAIL);

    /* if the special bit presents for SZIP compression, remove it to
       return the correct options_mask */
    sz_newway = (int)c_info->szip.options_mask & SZ_H4_REV_2;
    if (sz_newway)
        c_info->szip.options_mask = c_info->szip.options_mask & ~SZ_H4_REV_2;

    return SUCCEED;
}
