path: root/src/H5Zscaleoffset.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 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/HDF5/releases.  *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#define H5Z_PACKAGE		/*suppress error about including H5Zpkg	  */

#include "H5private.h"		/* Generic Functions			*/
#include "H5ACprivate.h"	/* Metadata cache			*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5Iprivate.h"		/* IDs			  		*/
#include "H5MMprivate.h"	/* Memory management			*/
#include "H5Pprivate.h"         /* Property lists                       */
#include "H5Oprivate.h"         /* Object headers                       */
#include "H5Sprivate.h"		/* Dataspaces         			*/
#include "H5Tprivate.h"		/* Datatypes         			*/
#include "H5Zpkg.h"		/* Data filters				*/

/* Struct of parameters needed for compressing/decompressing one atomic datatype */
typedef struct {
   size_t size;        /* datatype size */
   uint32_t minbits;   /* minimum bits to compress one value of such datatype */
   unsigned mem_order; /* current memory endianness order */
} parms_atomic;

enum H5Z_scaleoffset_t {t_bad=0, t_uchar=1, t_ushort, t_uint, t_ulong, t_ulong_long,
                           t_schar, t_short, t_int, t_long, t_long_long,
                           t_float, t_double};

/* Local function prototypes */
static double H5Z_scaleoffset_rnd(double val);
static htri_t H5Z_can_apply_scaleoffset(hid_t dcpl_id, hid_t type_id, hid_t space_id);
static enum H5Z_scaleoffset_t H5Z_scaleoffset_get_type(unsigned dtype_class,
    unsigned dtype_size, unsigned dtype_sign);
static herr_t H5Z_scaleoffset_set_parms_fillval(H5P_genplist_t *dcpl_plist,
    H5T_t *type, enum H5Z_scaleoffset_t scale_type, unsigned cd_values[],
    int need_convert, hid_t dxpl_id);
static herr_t H5Z_set_local_scaleoffset(hid_t dcpl_id, hid_t type_id, hid_t space_id);
static size_t H5Z_filter_scaleoffset(unsigned flags, size_t cd_nelmts,
    const unsigned cd_values[], size_t nbytes, size_t *buf_size, void **buf);
static void H5Z_scaleoffset_convert(void *buf, unsigned d_nelmts, size_t dtype_size);
static unsigned H5Z_scaleoffset_log2(unsigned long long num);
static void H5Z_scaleoffset_precompress_i(void *data, unsigned d_nelmts,
    enum H5Z_scaleoffset_t type, unsigned filavail, const unsigned cd_values[],
    uint32_t *minbits, unsigned long long *minval);
static void H5Z_scaleoffset_postdecompress_i(void *data, unsigned d_nelmts,
    enum H5Z_scaleoffset_t type, unsigned filavail, const unsigned cd_values[],
    uint32_t minbits, unsigned long long minval);
static herr_t H5Z_scaleoffset_precompress_fd(void *data, unsigned d_nelmts,
    enum H5Z_scaleoffset_t type, unsigned filavail, const unsigned cd_values[],
    uint32_t *minbits, unsigned long long *minval, double D_val);
static herr_t H5Z_scaleoffset_postdecompress_fd(void *data, unsigned d_nelmts,
    enum H5Z_scaleoffset_t type, unsigned filavail, const unsigned cd_values[],
    uint32_t minbits, unsigned long long minval, double D_val);
static void H5Z_scaleoffset_next_byte(size_t *j, unsigned *buf_len);
static void H5Z_scaleoffset_decompress_one_byte(unsigned char *data, size_t data_offset,
    unsigned k, unsigned begin_i, unsigned char *buffer, size_t *j, unsigned *buf_len,
    parms_atomic p, unsigned dtype_len);
static void H5Z_scaleoffset_compress_one_byte(unsigned char *data, size_t data_offset,
    unsigned k, unsigned begin_i, unsigned char *buffer, size_t *j, unsigned *buf_len,
    parms_atomic p, unsigned dtype_len);
static void H5Z_scaleoffset_decompress_one_atomic(unsigned char *data, size_t data_offset,
    unsigned char *buffer, size_t *j, unsigned *buf_len, parms_atomic p);
static void H5Z_scaleoffset_compress_one_atomic(unsigned char *data, size_t data_offset,
    unsigned char *buffer, size_t *j, unsigned *buf_len, parms_atomic p);
static void H5Z_scaleoffset_decompress(unsigned char *data, unsigned d_nelmts,
    unsigned char *buffer, parms_atomic p);
static void H5Z_scaleoffset_compress(unsigned char *data, unsigned d_nelmts, unsigned char *buffer,
    size_t buffer_size, parms_atomic p);

/* This message derives from H5Z */
H5Z_class2_t H5Z_SCALEOFFSET[1] = {{
    H5Z_CLASS_T_VERS,       /* H5Z_class_t version */
    H5Z_FILTER_SCALEOFFSET, /* Filter id number		*/
    1,              /* Assume encoder present: check before registering */
    1,              /* decoder_present flag (set to true) */
    "scaleoffset",		/* Filter name for debugging	*/
    H5Z_can_apply_scaleoffset,	/* The "can apply" callback     */
    H5Z_set_local_scaleoffset,  /* The "set local" callback     */
    H5Z_filter_scaleoffset,	/* The actual filter function	*/
}};

/* Local macros */
#define H5Z_SCALEOFFSET_TOTAL_NPARMS     20   /* Total number of parameters for filter */
#define H5Z_SCALEOFFSET_PARM_SCALETYPE   0    /* "User" parameter for scale type */
#define H5Z_SCALEOFFSET_PARM_SCALEFACTOR 1    /* "User" parameter for scale factor */
#define H5Z_SCALEOFFSET_PARM_NELMTS      2    /* "Local" parameter for number of elements in the chunk */
#define H5Z_SCALEOFFSET_PARM_CLASS       3    /* "Local" parameter for datatype class */
#define H5Z_SCALEOFFSET_PARM_SIZE        4    /* "Local" parameter for datatype size */
#define H5Z_SCALEOFFSET_PARM_SIGN        5    /* "Local" parameter for integer datatype sign */
#define H5Z_SCALEOFFSET_PARM_ORDER       6    /* "Local" parameter for datatype byte order */
#define H5Z_SCALEOFFSET_PARM_FILAVAIL    7    /* "Local" parameter for dataset fill value existence */
#define H5Z_SCALEOFFSET_PARM_FILVAL      8    /* "Local" parameter for start location to store dataset fill value */

#define H5Z_SCALEOFFSET_CLS_INTEGER      0    /* Integer (datatype class) */
#define H5Z_SCALEOFFSET_CLS_FLOAT        1    /* Floatig-point (datatype class) */

#define H5Z_SCALEOFFSET_SGN_NONE         0    /* Unsigned integer type */
#define H5Z_SCALEOFFSET_SGN_2            1    /* Two's complement signed integer type */

#define H5Z_SCALEOFFSET_ORDER_LE         0    /* Little endian (datatype byte order) */
#define H5Z_SCALEOFFSET_ORDER_BE         1    /* Big endian (datatype byte order) */

#define H5Z_SCALEOFFSET_FILL_UNDEFINED   0    /* Fill value is not defined */
#define H5Z_SCALEOFFSET_FILL_DEFINED     1    /* Fill value is defined */

/* Store fill value in cd_values[] */
#define H5Z_scaleoffset_save_filval(type, cd_values, fill_val)                   \
{                                                                                \
    unsigned _i = H5Z_SCALEOFFSET_PARM_FILVAL; /* index into cd_values  */       \
    uint32_t _cd_value;         /* Current cd_value */                           \
    char *_fv_p;                /* Pointer to current byte in fill_val */        \
    size_t _copy_size = 4;      /* # of bytes to copy this iteration */          \
    size_t _size_rem = sizeof(type); /* # of bytes left to copy to cd_values */  \
                                                                                 \
    /* Store the fill value as the last entry in cd_values[]                     \
     * Store byte by byte from least significant byte to most significant byte   \
     * Plenty of space left for the fill value (from index 8 to 19)              \
     * H5O_pline_encode will byte-swap each individual cd value, but we still    \
     * need to swap the cd values as a whole if we are on a BE machine.  Note    \
     * that we need to make sure to put the data only in the lowest 4 bytes of   \
     * each, if sizeof(unsigned) > 4.                                            \
     */                                                                          \
    if(H5T_native_order_g == H5T_ORDER_LE) {                                     \
        _fv_p = (char *)&(fill_val);                                             \
        /* Copy 4 bytes at a time to each cd value */                            \
        do {                                                                     \
            if(_size_rem < 4) {                                                  \
                /* Amount left to copy is smaller than a cd_value, adjust copy   \
                 * size and initialize cd_value as it will not be fully          \
                 * overwritten */                                                \
                _copy_size = _size_rem;                                          \
                _cd_value = (uint32_t)0;                                         \
            } /* end if */                                                       \
                                                                                 \
            /* Copy the value */                                                 \
            HDmemcpy(&_cd_value, _fv_p, _copy_size);                             \
            (cd_values)[_i] = (unsigned)_cd_value;                               \
                                                                                 \
            /* Next field */                                                     \
            _i++;                                                                \
            _fv_p += _copy_size;                                                 \
            _size_rem -= _copy_size;                                             \
        } while(_size_rem);                                                      \
    } /* end if */                                                               \
    else {                                                                       \
        HDassert(H5T_native_order_g == H5T_ORDER_BE);                            \
                                                                                 \
        /* Copy 4 bytes at a time to each cd value, but start at the end         \
         * (highest address) of fill_val */                                      \
        _fv_p = ((char *)&(fill_val)) + sizeof(type) - MIN(4, _size_rem);        \
        while(_size_rem >= 4) {                                                  \
            /* Copy the value */                                                 \
            HDmemcpy(&_cd_value, _fv_p, _copy_size);                             \
            (cd_values)[_i] = (unsigned)_cd_value;                               \
                                                                                 \
            /* Next field */                                                     \
            _i++;                                                                \
            _size_rem -= 4;                                                      \
            if(_size_rem >= 4)                                                   \
                _fv_p -= 4;                                                      \
            else                                                                 \
                _fv_p -= _size_rem;                                              \
        } /* end while */                                                        \
                                                                                 \
        HDassert(_fv_p == (char *)&(fill_val));                                  \
        if(_size_rem) {                                                          \
            /* Amount left to copy is smaller than a cd_value, initialize        \
             * _cd_value as it will not be fully overwritten and copy to the end \
             * of _cd value as it is BE. */                                      \
            _cd_value = (uint32_t)0;                                             \
            HDmemcpy((char *)&_cd_value + 4 - _size_rem, _fv_p, _size_rem);      \
            (cd_values)[_i] = (unsigned)_cd_value;                               \
        } /* end if */                                                           \
    } /* end else */                                                             \
}

/* Set the fill value parameter in cd_values[] for unsigned integer type */
#define H5Z_scaleoffset_set_filval_1(type, dcpl_plist, dt, cd_values, need_convert, dxpl_id)\
{                                                                                    \
    type fill_val;                                                                   \
                                                                                     \
    /* Get dataset fill value */                                                     \
    if(H5P_get_fill_value(dcpl_plist, dt, &fill_val, dxpl_id) < 0)                   \
        HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "unable to get fill value")        \
                                                                                     \
    if(need_convert)                                                                 \
       H5Z_scaleoffset_convert(&fill_val, 1, sizeof(type));                          \
                                                                                     \
    H5Z_scaleoffset_save_filval(type, cd_values, fill_val)                           \
}

/* Set the fill value parameter in cd_values[] for signed integer type */
#define H5Z_scaleoffset_set_filval_2(type, dcpl_plist, dt, cd_values, need_convert, dxpl_id)\
{                                                                                    \
    type fill_val;                                                                   \
                                                                                     \
    /* Get dataset fill value */                                                     \
    if(H5P_get_fill_value(dcpl_plist, dt, &fill_val, dxpl_id) < 0)                   \
        HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "unable to get fill value")        \
                                                                                     \
    if(need_convert)                                                                 \
       H5Z_scaleoffset_convert(&fill_val, 1, sizeof(type));                          \
                                                                                     \
    H5Z_scaleoffset_save_filval(unsigned type, cd_values, fill_val)                  \
}

/* Set the fill value parameter in cd_values[] for character integer type */
#define H5Z_scaleoffset_set_filval_3(type, dcpl_plist, dt, cd_values, need_convert, dxpl_id)\
{                                                                                    \
    type fill_val;                                                                   \
                                                                                     \
    /* Get dataset fill value */                                                     \
    if(H5P_get_fill_value(dcpl_plist, dt, &fill_val, dxpl_id) < 0)                   \
        HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "unable to get fill value")        \
                                                                                     \
    /* Store the fill value as the last entry in cd_values[] */                      \
    (cd_values)[H5Z_SCALEOFFSET_PARM_FILVAL] = (unsigned)((unsigned char)fill_val);  \
}

/* Set the fill value parameter in cd_values[] for floating-point type */
#define H5Z_scaleoffset_set_filval_4(type, dcpl_plist, dt, cd_values, need_convert, dxpl_id)\
{                                                                             \
    type fill_val;                                                            \
                                                                              \
    /* Get dataset fill value */                                              \
    if(H5P_get_fill_value(dcpl_plist, dt, &fill_val, dxpl_id) < 0)            \
        HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "unable to get fill value") \
                                                                              \
    if(need_convert)                                                          \
       H5Z_scaleoffset_convert(&fill_val, 1, sizeof(type));                   \
                                                                              \
    H5Z_scaleoffset_save_filval(type, cd_values, fill_val)                    \
}

/* Get the fill value for integer type */
#define H5Z_scaleoffset_get_filval_1(type, cd_values, fill_val)                  \
{                                                                                \
    unsigned _i = H5Z_SCALEOFFSET_PARM_FILVAL; /* index into cd_values  */       \
    uint32_t _cd_value;         /* Current cd_value */                           \
    char *_fv_p;                /* Pointer to current byte in fill_val */        \
    size_t _copy_size = 4;      /* # of bytes to copy this iteration */          \
    size_t _size_rem = sizeof(type); /* # of bytes left to copy to filval */     \
                                                                                 \
    /* Retrieve the fill value from the last entry in cd_values[]                \
     * Store byte by byte from least significant byte to most significant byte   \
     * Plenty of space left for the fill value (from index 8 to 19)              \
     * H5O_pline_encode will byte-swap each individual cd value, but we still    \
     * need to swap the cd values as a whole if we are on a BE machine.  Note    \
     * that we need to make sure to put the data only in the lowest 4 bytes of   \
     * each, if sizeof(unsigned) > 4.                                            \
     */                                                                          \
    if(H5T_native_order_g == H5T_ORDER_LE) {                                     \
        _fv_p = (char *)&(fill_val);                                             \
        /* Copy 4 bytes at a time to each cd value */                            \
        do {                                                                     \
            if(_size_rem < 4)                                                    \
                /* Amount left to copy is smaller than a cd_value, adjust copy   \
                 * size and initialize cd_value as it will not be fully          \
                 * overwritten */                                                \
                _copy_size = _size_rem;                                          \
                                                                                 \
            /* Copy the value */                                                 \
            _cd_value = (uint32_t)(cd_values)[_i];                               \
            HDmemcpy(_fv_p, &_cd_value, _copy_size);                             \
                                                                                 \
            /* Next field */                                                     \
            _i++;                                                                \
            _fv_p += _copy_size;                                                 \
            _size_rem -= _copy_size;                                             \
        } while(_size_rem);                                                      \
    } /* end if */                                                               \
    else {                                                                       \
        HDassert(H5T_native_order_g == H5T_ORDER_BE);                            \
                                                                                 \
        /* Copy 4 bytes at a time to each cd value, but start at the end         \
         * (highest address) of fill_val */                                      \
        _fv_p = ((char *)&(fill_val)) + sizeof(type) - MIN(4, _size_rem);        \
        while(_size_rem >= 4) {                                                  \
            /* Copy the value */                                                 \
            _cd_value = (uint32_t)(cd_values)[_i];                               \
            HDmemcpy(_fv_p, &_cd_value, _copy_size);                             \
                                                                                 \
            /* Next field */                                                     \
            _i++;                                                                \
            _size_rem -= 4;                                                      \
            if(_size_rem >=4)                                                    \
                _fv_p -= 4;                                                      \
            else                                                                 \
                _fv_p -= _size_rem;                                              \
        } /* end while */                                                        \
                                                                                 \
        HDassert(_fv_p == (char *)&(fill_val));                                  \
        if(_size_rem) {                                                          \
            /* Amount left to copy is smaller than a cd_value, initialize        \
             * _cd_value as it will not be fully overwritten and copy to the end \
             * of _cd value as it is BE. */                                      \
            _cd_value = (uint32_t)(cd_values)[_i];                               \
            HDmemcpy(_fv_p, (char *)&_cd_value + 4 - _size_rem, _size_rem);      \
        } /* end if */                                                           \
    } /* end else */                                                             \
}

/* Get the fill value for floating-point type */
#define H5Z_scaleoffset_get_filval_2(type, cd_values, filval)                          \
{                                                                                      \
   if(sizeof(type) <= sizeof(long long))                                               \
      H5Z_scaleoffset_get_filval_1(type, cd_values, filval)                            \
   else                                                                                \
      HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype") \
}

/* Find maximum and minimum values of a buffer with fill value defined for integer type */
#define H5Z_scaleoffset_max_min_1(i, d_nelmts, buf, filval, max, min)\
{                                                                  \
   i = 0; while(i < d_nelmts && buf[i]== filval) i++;              \
   if(i < d_nelmts) min = max = buf[i];                            \
   for(; i < d_nelmts; i++) {                                      \
      if(buf[i] == filval) continue; /* ignore fill value */       \
      if(buf[i] > max) max = buf[i];                               \
      if(buf[i] < min) min = buf[i];                               \
   }                                                               \
}

/* Find maximum and minimum values of a buffer with fill value undefined */
#define H5Z_scaleoffset_max_min_2(i, d_nelmts, buf, max, min)\
{                                                            \
   min = max = buf[0];                                       \
   for(i = 0; i < d_nelmts; i++) {                           \
      if(buf[i] > max) max = buf[i];                         \
      if(buf[i] < min) min = buf[i];                         \
   }                                                         \
}

/* Find maximum and minimum values of a buffer with fill value defined for floating-point type */
#define H5Z_scaleoffset_max_min_3(i, d_nelmts, buf, filval, max, min, D_val)      \
{                                                                                 \
   i = 0; while(i < d_nelmts && HDfabs(buf[i] - filval) < HDpow(10.0f, -D_val)) i++; \
   if(i < d_nelmts) min = max = buf[i];                                           \
   for(; i < d_nelmts; i++) {                                                     \
      if(HDfabs(buf[i] - filval) < HDpow(10.0f, -D_val))                          \
         continue; /* ignore fill value */                                        \
      if(buf[i] > max) max = buf[i];                                              \
      if(buf[i] < min) min = buf[i];                                              \
   }                                                                              \
}

/* Find minimum value of a buffer with fill value defined for integer type */
#define H5Z_scaleoffset_min_1(i, d_nelmts, buf, filval, min) \
{                                                            \
   i = 0; while(i < d_nelmts && buf[i]== filval) i++;        \
   if(i < d_nelmts) min = buf[i];                            \
   for(; i < d_nelmts; i++) {                                \
      if(buf[i] == filval) continue; /* ignore fill value */ \
      if(buf[i] < min) min = buf[i];                         \
   }                                                         \
}

/* Find minimum value of a buffer with fill value undefined */
#define H5Z_scaleoffset_min_2(i, d_nelmts, buf, min)\
{                                                   \
   min = buf[0];                                    \
   for(i = 0; i < d_nelmts; i++)                    \
      if(buf[i] < min) min = buf[i];                \
}

/* Check and handle special situation for unsigned integer type */
#define H5Z_scaleoffset_check_1(type, max, min, minbits) \
{                                                        \
   if(max - min > (type)(~(type)0 - 2))                  \
   { *minbits = sizeof(type)*8; return; }                \
}

/* Check and handle special situation for signed integer type */
#define H5Z_scaleoffset_check_2(type, max, min, minbits)                   \
{                                                                          \
   if((unsigned type)(max - min) > (unsigned type)(~(unsigned type)0 - 2)) \
   { *minbits = sizeof(type)*8; return; }                                  \
}

/* Check and handle special situation for floating-point type */
#define H5Z_scaleoffset_check_3(i, type, max, min, minbits, D_val)                    \
{                                                                                     \
   if(sizeof(type)==sizeof(int)) {                                                    \
      if(H5Z_scaleoffset_rnd(max*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val))       \
         > HDpow(2.0f, (double)(sizeof(int)*8 - 1))) {                                \
         *minbits = sizeof(int)*8; goto done;                                         \
      }                                                                               \
   } else if(sizeof(type)==sizeof(long)) {                                            \
      if(H5Z_scaleoffset_rnd(max*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val))       \
         > HDpow(2.0f, (double)(sizeof(long)*8 - 1))) {                               \
         *minbits = sizeof(long)*8; goto done;                                        \
      }                                                                               \
   } else if(sizeof(type)==sizeof(long long)) {                                       \
      if(H5Z_scaleoffset_rnd(max*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val))       \
         > HDpow(2.0f, (double)(sizeof(long long)*8 - 1))) {                          \
         *minbits = sizeof(long long)*8; goto done;                                   \
      }                                                                               \
   } else                                                                             \
      HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype")\
}

/* Precompress for unsigned integer type */
#define H5Z_scaleoffset_precompress_1(type, data, d_nelmts, filavail, cd_values, minbits, minval)\
{                                                                                          \
    type *buf = (type *)data, min = 0, max = 0, span, filval = 0;                          \
    unsigned i;                                                                            \
                                                                                           \
    if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */                \
        H5Z_scaleoffset_get_filval_1(type, cd_values, filval)                              \
        if(*minbits == H5Z_SO_INT_MINBITS_DEFAULT) { /* minbits not set yet, calculate max, min, and minbits */ \
            H5Z_scaleoffset_max_min_1(i, d_nelmts, buf, filval, max, min)                  \
            H5Z_scaleoffset_check_1(type, max, min, minbits)                               \
            span = (type)(max - min + 1);                                                  \
            *minbits = H5Z_scaleoffset_log2((unsigned long long)(span+1));                 \
        } else /* minbits already set, only calculate min */                               \
            H5Z_scaleoffset_min_1(i, d_nelmts, buf, filval, min)                           \
        if(*minbits != sizeof(type)*8) /* change values if minbits != full precision */    \
            for(i = 0; i < d_nelmts; i++)                                                  \
                buf[i] = (type)((buf[i] == filval) ? (((type)1 << *minbits) - 1) : (buf[i] - min)); \
    } else { /* fill value undefined */                                                    \
        if(*minbits == H5Z_SO_INT_MINBITS_DEFAULT ) { /* minbits not set yet, calculate max, min, and minbits */ \
            H5Z_scaleoffset_max_min_2(i, d_nelmts, buf, max, min)                          \
            H5Z_scaleoffset_check_1(type, max, min, minbits)                               \
            span = (type)(max - min + 1);                                                  \
            *minbits = H5Z_scaleoffset_log2((unsigned long long)span);                     \
        } else /* minbits already set, only calculate min */                               \
            H5Z_scaleoffset_min_2(i, d_nelmts, buf, min)                                   \
        if(*minbits != sizeof(type)*8) /* change values if minbits != full precision */    \
            for(i = 0; i < d_nelmts; i++)                                                  \
                buf[i] = (type)(buf[i] - min);                                             \
    }                                                                                      \
    *minval = min;                                                                         \
}

/* Precompress for signed integer type */
#define H5Z_scaleoffset_precompress_2(type, data, d_nelmts, filavail, cd_values, minbits, minval)\
{                                                                                            \
   type *buf = (type *)data, min = 0, max = 0, filval = 0;                                   \
   unsigned type span; unsigned i;                                                           \
                                                                                             \
   if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */                   \
      H5Z_scaleoffset_get_filval_1(type, cd_values, filval)                                  \
      if(*minbits == H5Z_SO_INT_MINBITS_DEFAULT) { /* minbits not set yet, calculate max, min, and minbits */ \
         H5Z_scaleoffset_max_min_1(i, d_nelmts, buf, filval, max, min)                       \
         H5Z_scaleoffset_check_2(type, max, min, minbits)                                    \
         span = (unsigned type)(max - min + 1);                                              \
         *minbits = H5Z_scaleoffset_log2((unsigned long long)(span + 1));                    \
      } else /* minbits already set, only calculate min */                                   \
         H5Z_scaleoffset_min_1(i, d_nelmts, buf, filval, min)                                \
      if(*minbits != sizeof(type) * 8) /* change values if minbits != full precision */      \
         for(i = 0; i < d_nelmts; i++)                                                       \
            buf[i] = (type)((buf[i] == filval) ? (type)(((unsigned type)1 << *minbits) - 1) : (buf[i] - min)); \
   } else { /* fill value undefined */                                                       \
      if(*minbits == H5Z_SO_INT_MINBITS_DEFAULT ) { /* minbits not set yet, calculate max, min, and minbits */\
         H5Z_scaleoffset_max_min_2(i, d_nelmts, buf, max, min)                               \
         H5Z_scaleoffset_check_2(type, max, min, minbits)                                    \
         span = (unsigned type)(max - min + 1);                                              \
         *minbits = H5Z_scaleoffset_log2((unsigned long long)span);                          \
      } else /* minbits already set, only calculate min */                                   \
         H5Z_scaleoffset_min_2(i, d_nelmts, buf, min)                                        \
      if(*minbits != sizeof(type) * 8) /* change values if minbits != full precision */      \
         for(i = 0; i < d_nelmts; i++)                                                       \
            buf[i] = (type)(buf[i] - min);                                                   \
   }                                                                                         \
   *minval = (unsigned long long)min;                                                        \
}

/* Modify values of data in precompression if fill value defined for floating-point type */
#define H5Z_scaleoffset_modify_1(i, type, buf, d_nelmts, filval, minbits, min, D_val) \
{                                                                                     \
   if(sizeof(type)==sizeof(int))                                                      \
      for(i = 0; i < d_nelmts; i++) {                                                 \
         if(HDfabs(buf[i] - filval) < HDpow(10.0f, -D_val))                           \
            *(int *)&buf[i] = (int)(((unsigned int)1 << *minbits) - 1);               \
         else                                                                         \
            *(int *)&buf[i] = H5Z_scaleoffset_rnd(                                    \
                              buf[i]*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val));  \
      }                                                                               \
   else if(sizeof(type)==sizeof(long))                                                \
      for(i = 0; i < d_nelmts; i++) {                                                 \
         if(HDfabs(buf[i] - filval) < HDpow(10.0f, -D_val))                           \
            *(long *)&buf[i] = (long)(((unsigned long)1 << *minbits) - 1);            \
         else                                                                         \
            *(long *)&buf[i] = H5Z_scaleoffset_rnd(                                   \
                               buf[i]*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val)); \
      }                                                                               \
   else if(sizeof(type)==sizeof(long long))                                           \
      for(i = 0; i < d_nelmts; i++) {                                                 \
         if(HDfabs(buf[i] - filval) < HDpow(10.0f, -D_val))                           \
            *(long long *)&buf[i] = (long long)(((unsigned long long)1 << *minbits) - 1); \
         else                                                                         \
            *(long long *)&buf[i] = H5Z_scaleoffset_rnd(                              \
                                    buf[i]*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val)); \
      }                                                                               \
   else                                                                               \
      HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype")\
}

/* Modify values of data in precompression if fill value undefined for floating-point type */
#define H5Z_scaleoffset_modify_2(i, type, buf, d_nelmts, min, D_val)                  \
{                                                                                     \
   if(sizeof(type)==sizeof(int))                                                      \
      for(i = 0; i < d_nelmts; i++)                                                   \
         *(int *)&buf[i] = H5Z_scaleoffset_rnd(                                       \
                           buf[i]*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val));     \
   else if(sizeof(type)==sizeof(long))                                                \
      for(i = 0; i < d_nelmts; i++)                                                   \
         *(long *)&buf[i] = H5Z_scaleoffset_rnd(                                      \
                            buf[i]*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val));    \
   else if(sizeof(type)==sizeof(long long))                                           \
      for(i = 0; i < d_nelmts; i++)                                                   \
         *(long long *)&buf[i] = H5Z_scaleoffset_rnd(                                 \
                                 buf[i]*HDpow(10.0f, D_val) - min*HDpow(10.0f, D_val)); \
   else                                                                               \
      HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype")\
}

/* Save the minimum value for floating-point type */
#define H5Z_scaleoffset_save_min(i, type, minval, min)                                \
{                                                                                     \
    if(sizeof(type) <= sizeof(long long))                                             \
        /* Save min value to corresponding position                                   \
         * byte-order will be swapped as appropriate, but be sure to                  \
         * account for offset in BE if sizes differ                                   \
         */                                                                           \
        if(H5T_native_order_g == H5T_ORDER_LE)                                        \
            HDmemcpy(minval, &min, sizeof(type));                                     \
        else {                                                                        \
            HDassert(H5T_native_order_g == H5T_ORDER_BE);                             \
            HDmemcpy(((char *)minval) + (sizeof(long long) - sizeof(type)),           \
                    &min, sizeof(type));                                              \
        } /* end else */                                                              \
    else                                                                              \
        HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype") \
}

/* Precompress for floating-point type using variable-minimum-bits method */
#define H5Z_scaleoffset_precompress_3(type, data, d_nelmts, filavail, cd_values,         \
                                      minbits, minval, D_val)                            \
{                                                                                        \
   type *buf = (type *)data, min = 0, max = 0, filval = 0;                               \
   unsigned long long span;                                                              \
   unsigned i;                                                                           \
                                                                                         \
   *minval = 0;                                                                          \
   if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */               \
      H5Z_scaleoffset_get_filval_2(type, cd_values, filval)                              \
      H5Z_scaleoffset_max_min_3(i, d_nelmts, buf, filval, max, min, D_val)               \
      H5Z_scaleoffset_check_3(i, type, max, min, minbits, D_val)                         \
      span = H5Z_scaleoffset_rnd(max * HDpow(10.0f, D_val) - min * HDpow(10.0f, D_val)) + 1; \
      *minbits = H5Z_scaleoffset_log2((unsigned long long)(span + 1));                   \
      if(*minbits != sizeof(type) * 8) /* change values if minbits != full precision */  \
         H5Z_scaleoffset_modify_1(i, type, buf, d_nelmts, filval, minbits, min, D_val)   \
   } else { /* fill value undefined */                                                   \
      H5Z_scaleoffset_max_min_2(i, d_nelmts, buf, max, min)                              \
      H5Z_scaleoffset_check_3(i, type, max, min, minbits, D_val)                         \
      span = H5Z_scaleoffset_rnd(max * HDpow(10.0f, D_val) - min * HDpow(10.0f, D_val)) + 1; \
      *minbits = H5Z_scaleoffset_log2((unsigned long long)span);                         \
      if(*minbits != sizeof(type) * 8) /* change values if minbits != full precision */  \
         H5Z_scaleoffset_modify_2(i, type, buf, d_nelmts, min, D_val)                    \
   }                                                                                     \
   H5Z_scaleoffset_save_min(i, type, minval, min)                                        \
}

/* Postdecompress for unsigned integer type */
#define H5Z_scaleoffset_postdecompress_1(type, data, d_nelmts, filavail, cd_values, minbits, minval)\
{                                                                                 \
   type *buf = (type *)data, filval = 0; unsigned i;                              \
                                                                                  \
   if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */        \
      H5Z_scaleoffset_get_filval_1(type, cd_values, filval)                       \
      for(i = 0; i < d_nelmts; i++)                                               \
         buf[i] = (type)((buf[i] == (((type)1 << minbits) - 1)) ? filval : (buf[i] + minval)); \
   } else /* fill value undefined */                                              \
      for(i = 0; i < d_nelmts; i++) buf[i] = (type)(buf[i] + (type)(minval));     \
}

/* Postdecompress for signed integer type */
#define H5Z_scaleoffset_postdecompress_2(type, data, d_nelmts, filavail, cd_values, minbits, minval)\
{                                                                                          \
   type *buf = (type *)data, filval = 0;                                                   \
   unsigned i;                                                                             \
                                                                                           \
   if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */                 \
      H5Z_scaleoffset_get_filval_1(type, cd_values, filval)                                \
      for(i = 0; i < d_nelmts; i++)                                                        \
         buf[i] = (type)(((unsigned type)buf[i] == (((unsigned type)1 << minbits) - 1)) ? filval : (buf[i] + minval));\
   } else /* fill value undefined */                                                       \
      for(i = 0; i < d_nelmts; i++)                                                        \
          buf[i] = (type)(buf[i] + (type)(minval));                                        \
}

/* Retrive minimum value of floating-point type */
#define H5Z_scaleoffset_get_min(type, minval, min)                                 \
{                                                                                  \
    if(sizeof(type) <= sizeof(long long))                                          \
        /* retrieve min value from corresponding position                          \
         * byte-order has already been swapped as appropriate, but be sure to      \
         * account for offset in BE if sizes differ                                \
         */                                                                        \
        if(H5T_native_order_g == H5T_ORDER_LE)                                     \
            HDmemcpy(&min, &minval, sizeof(type));                                 \
        else {                                                                     \
            HDassert(H5T_native_order_g == H5T_ORDER_BE);                          \
            HDmemcpy(&min, ((char *)&minval) + (sizeof(long long)                  \
                    - sizeof(type)), sizeof(type));                                \
        } /* end else */                                                           \
    else                                                                           \
        HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype") \
}

/* Modify values of data in postdecompression if fill value defined for floating-point type */
#define H5Z_scaleoffset_modify_3(i, type, buf, d_nelmts, filval, minbits, min, D_val)     \
{                                                                                         \
   if(sizeof(type)==sizeof(int))                                                          \
      for(i = 0; i < d_nelmts; i++)                                                       \
         buf[i] = (type)((*(int *)&buf[i] == (int)(((unsigned int)1 << minbits) - 1)) ?   \
                  filval : (double)(*(int *)&buf[i]) / HDpow(10.0f, D_val) + min);        \
   else if(sizeof(type)==sizeof(long))                                                    \
      for(i = 0; i < d_nelmts; i++)                                                       \
         buf[i] = (type)((*(long *)&buf[i] == (long)(((unsigned long)1 << minbits) - 1)) ? \
                  filval : (double)(*(long *)&buf[i]) / HDpow(10.0f, D_val) + min);       \
   else if(sizeof(type)==sizeof(long long))                                               \
      for(i = 0; i < d_nelmts; i++)                                                       \
         buf[i] = (type)((*(long long *)&buf[i] == (long long)(((unsigned long long)1 << minbits) - 1)) ? \
                  filval : (double)(*(long long *)&buf[i]) / HDpow(10.0f, D_val) + min);  \
   else                                                                                   \
      HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype")    \
}

/* Modify values of data in postdecompression if fill value undefined for floating-point type */
#define H5Z_scaleoffset_modify_4(i, type, buf, d_nelmts, min, D_val)                   \
{                                                                                      \
   if(sizeof(type)==sizeof(int))                                                       \
      for(i = 0; i < d_nelmts; i++)                                                    \
         buf[i] = (type)((double)(*(int *)&buf[i]) / HDpow(10.0f, D_val) + min);       \
   else if(sizeof(type)==sizeof(long))                                                 \
      for(i = 0; i < d_nelmts; i++)                                                    \
         buf[i] = (type)((double)(*(long *)&buf[i]) / HDpow(10.0f, D_val) + min);      \
   else if(sizeof(type)==sizeof(long long))                                            \
      for(i = 0; i < d_nelmts; i++)                                                    \
         buf[i] = (type)((double)(*(long long *)&buf[i]) / HDpow(10.0f, D_val) + min); \
   else                                                                                \
      HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot find matched integer dataype") \
}

/* Postdecompress for floating-point type using variable-minimum-bits method */
#define H5Z_scaleoffset_postdecompress_3(type, data, d_nelmts, filavail, cd_values,    \
                                         minbits, minval, D_val)                       \
{                                                                                      \
   type *buf = (type *)data, filval = 0, min = 0;                                      \
   unsigned i;                                                                         \
                                                                                       \
   H5Z_scaleoffset_get_min(type, minval, min)                                          \
                                                                                       \
   if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */             \
      H5Z_scaleoffset_get_filval_2(type, cd_values, filval)                            \
      H5Z_scaleoffset_modify_3(i, type, buf, d_nelmts, filval, minbits, min, D_val)    \
   } else /* fill value undefined */                                                   \
      H5Z_scaleoffset_modify_4(i, type, buf, d_nelmts, min, D_val)                     \
}


/*-------------------------------------------------------------------------
 * Function:	H5Z_can_apply_scaleoffset
 *
 * Purpose:	Check the parameters for scaleoffset compression for
 *              validity and whether they fit a particular dataset.
 *
 * Return:	Success: Non-negative
 *		Failure: Negative
 *
 * Programmer:  Xiaowen Wu
 *              Friday, February 4, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static htri_t
H5Z_can_apply_scaleoffset(hid_t H5_ATTR_UNUSED dcpl_id, hid_t type_id, hid_t H5_ATTR_UNUSED space_id)
{
    const H5T_t	*type;                  /* Datatype */
    H5T_class_t dtype_class;            /* Datatype's class */
    H5T_order_t dtype_order;            /* Datatype's endianness order */
    htri_t ret_value = TRUE;            /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Get datatype */
    if(NULL == (type = (H5T_t *)H5I_object_verify(type_id, H5I_DATATYPE)))
	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a datatype")

    /* Get datatype's class, for checking the "datatype class" */
    if((dtype_class = H5T_get_class(type, TRUE)) == H5T_NO_CLASS)
	HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype class")

    /* Get datatype's size, for checking the "datatype size" */
    if(H5T_get_size(type) == 0)
	HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype size")

    if(dtype_class == H5T_INTEGER || dtype_class == H5T_FLOAT) {
        /* Get datatype's endianness order */
        if((dtype_order = H5T_get_order(type)) == H5T_ORDER_ERROR)
	    HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "can't retrieve datatype endianness order")

        /* Range check datatype's endianness order */
        if(dtype_order != H5T_ORDER_LE && dtype_order != H5T_ORDER_BE)
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FALSE, "bad datatype endianness order")
    } else
        HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FALSE, "datatype class not supported by scaleoffset")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5Z_can_apply_scaleoffset() */


/*-------------------------------------------------------------------------
 * Function:	H5Z_scaleoffset_get_type
 *
 * Purpose:	Get the specific integer type based on datatype size and sign
 *              or floating-point type based on size
 *
 * Return:	Success: id number of integer type
 *		Failure: 0
 *
 * Programmer:	Xiaowen Wu
 *              Wednesday, April 13, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static enum H5Z_scaleoffset_t
H5Z_scaleoffset_get_type(unsigned dtype_class, unsigned dtype_size, unsigned dtype_sign)
{
    enum H5Z_scaleoffset_t type = t_bad; /* integer type */
    enum H5Z_scaleoffset_t ret_value;             /* return value */

    FUNC_ENTER_NOAPI_NOINIT

    if(dtype_class==H5Z_SCALEOFFSET_CLS_INTEGER) {
        if(dtype_sign==H5Z_SCALEOFFSET_SGN_NONE) { /* unsigned integer */
            if     (dtype_size == sizeof(unsigned char))      type = t_uchar;
            else if(dtype_size == sizeof(unsigned short))     type = t_ushort;
            else if(dtype_size == sizeof(unsigned int))       type = t_uint;
            else if(dtype_size == sizeof(unsigned long))      type = t_ulong;
            else if(dtype_size == sizeof(unsigned long long)) type = t_ulong_long;
            else
                HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, t_bad, "cannot find matched memory dataype")
        }

        if(dtype_sign==H5Z_SCALEOFFSET_SGN_2) { /* signed integer */
            if     (dtype_size == sizeof(signed char)) type = t_schar;
            else if(dtype_size == sizeof(short))       type = t_short;
            else if(dtype_size == sizeof(int))         type = t_int;
            else if(dtype_size == sizeof(long))        type = t_long;
            else if(dtype_size == sizeof(long long))   type = t_long_long;
            else
                HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, t_bad, "cannot find matched memory dataype")
        }
    }

    if(dtype_class==H5Z_SCALEOFFSET_CLS_FLOAT) {
        if(dtype_size == sizeof(float))       type = t_float;
        else if(dtype_size == sizeof(double)) type = t_double;
        else
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, t_bad, "cannot find matched memory dataype")
    }

    /* Set return value */
    ret_value = type;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5Z_scaleoffset_set_parms_fillval
 *
 * Purpose:	Get the fill value of the dataset and store in cd_values[]
 *
 * Return:	Success: Non-negative
 *		Failure: Negative
 *
 * Programmer:  Xiaowen Wu
 *              Monday, March 7, 2005
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5Z_scaleoffset_set_parms_fillval(H5P_genplist_t *dcpl_plist,
    H5T_t *type, enum H5Z_scaleoffset_t scale_type,
    unsigned cd_values[], int need_convert, hid_t dxpl_id)
{
    herr_t ret_value = SUCCEED;          /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    if(scale_type == t_uchar)
        H5Z_scaleoffset_set_filval_3(unsigned char, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_ushort)
        H5Z_scaleoffset_set_filval_1(unsigned short, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_uint)
        H5Z_scaleoffset_set_filval_1(unsigned int, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_ulong)
        H5Z_scaleoffset_set_filval_1(unsigned long, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_ulong_long)
        H5Z_scaleoffset_set_filval_1(unsigned long long, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_schar)
        H5Z_scaleoffset_set_filval_3(signed char, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_short)
        H5Z_scaleoffset_set_filval_2(short, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_int)
        H5Z_scaleoffset_set_filval_2(int, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_long)
        H5Z_scaleoffset_set_filval_2(long, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_long_long)
        H5Z_scaleoffset_set_filval_2(long long, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_float)
        H5Z_scaleoffset_set_filval_4(float, dcpl_plist, type, cd_values, need_convert, dxpl_id)
    else if(scale_type == t_double)
        H5Z_scaleoffset_set_filval_4(double, dcpl_plist, type, cd_values, need_convert, dxpl_id)

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5Z_scaleoffset_set_parms_fillval() */


/*-------------------------------------------------------------------------
 * Function:	H5Z_set_local_scaleoffset
 *
 * Purpose:	Set the "local" dataset parameters for scaleoffset
 *              compression.
 *
 * Return:	Success: Non-negative
 *		Failure: Negative
 *
 * Programmer:	Xiaowen Wu
 *              Friday, February 4, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5Z_set_local_scaleoffset(hid_t dcpl_id, hid_t type_id, hid_t space_id)
{
    H5P_genplist_t *dcpl_plist;     /* Property list pointer */
    H5T_t	*type;              /* Datatype */
    const H5S_t	*ds;                /* Dataspace */
    unsigned flags;                 /* Filter flags */
    size_t cd_nelmts = H5Z_SCALEOFFSET_USER_NPARMS;  /* Number of filter parameters */
    unsigned cd_values[H5Z_SCALEOFFSET_TOTAL_NPARMS]; /* Filter parameters */
    hssize_t npoints;               /* Number of points in the dataspace */
    H5T_class_t dtype_class;        /* Datatype's class */
    H5T_order_t dtype_order;        /* Datatype's endianness order */
    size_t dtype_size;              /* Datatype's size (in bytes) */
    H5T_sign_t dtype_sign;          /* Datatype's sign */
    enum H5Z_scaleoffset_t scale_type; /* Specific datatype */
    H5D_fill_value_t status;        /* Status of fill value in property list */
    herr_t ret_value = SUCCEED;     /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Get the plist structure */
    if(NULL == (dcpl_plist = H5P_object_verify(dcpl_id, H5P_DATASET_CREATE)))
        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")

    /* Get datatype */
    if(NULL == (type = (H5T_t *)H5I_object_verify(type_id, H5I_DATATYPE)))
	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a datatype")

#ifdef H5_CLEAR_MEMORY
    /* Initialize the parameters to a known state */
    HDmemset(cd_values, 0, sizeof(cd_values));
#endif /* H5_CLEAR_MEMORY */

    /* Get the filter's current parameters */
    if(H5P_get_filter_by_id(dcpl_plist, H5Z_FILTER_SCALEOFFSET, &flags, &cd_nelmts, cd_values, (size_t)0, NULL, NULL) < 0)
	HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "can't get scaleoffset parameters")

    /* Get dataspace */
    if(NULL == (ds = (H5S_t *)H5I_object_verify(space_id, H5I_DATASPACE)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")

    /* Get total number of elements in the chunk */
    if((npoints = H5S_GET_EXTENT_NPOINTS(ds)) < 0)
        HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "unable to get number of points in the dataspace")

    /* Set "local" parameter for this dataset's number of elements */
    H5_CHECKED_ASSIGN(cd_values[H5Z_SCALEOFFSET_PARM_NELMTS], unsigned, npoints, hssize_t);

    /* Get datatype's class */
    if((dtype_class = H5T_get_class(type, TRUE)) == H5T_NO_CLASS)
        HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype class")

    /* Set "local" parameter for datatype's class */
    switch(dtype_class) {
        case H5T_INTEGER:
            cd_values[H5Z_SCALEOFFSET_PARM_CLASS] = H5Z_SCALEOFFSET_CLS_INTEGER;
            break;

        case H5T_FLOAT:
            cd_values[H5Z_SCALEOFFSET_PARM_CLASS] = H5Z_SCALEOFFSET_CLS_FLOAT;
            break;

        case H5T_NO_CLASS:
        case H5T_TIME:
        case H5T_STRING:
        case H5T_BITFIELD:
        case H5T_OPAQUE:
        case H5T_COMPOUND:
        case H5T_REFERENCE:
        case H5T_ENUM:
        case H5T_VLEN:
        case H5T_ARRAY:
        case H5T_NCLASSES:
        default:
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "datatype class not supported by scaleoffset")
    } /* end switch */

    /* Get datatype's size */
    if((dtype_size = H5T_get_size(type)) == 0)
	HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype size")

    /* Set "local" parameter for datatype size */
    cd_values[H5Z_SCALEOFFSET_PARM_SIZE] = dtype_size;

    if(dtype_class == H5T_INTEGER) {
        /* Get datatype's sign */
        if((dtype_sign = H5T_get_sign(type)) == H5T_SGN_ERROR)
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype sign")

        /* Set "local" parameter for integer datatype sign */
        switch(dtype_sign) {
            case H5T_SGN_NONE:
                cd_values[H5Z_SCALEOFFSET_PARM_SIGN] = H5Z_SCALEOFFSET_SGN_NONE;
                break;

            case H5T_SGN_2:
                cd_values[H5Z_SCALEOFFSET_PARM_SIGN] = H5Z_SCALEOFFSET_SGN_2;
                break;

            case H5T_SGN_ERROR:
            case H5T_NSGN:
            default:
                HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad integer sign")
        } /* end switch */
    } /* end if */

    /* Get datatype's endianness order */
    if((dtype_order = H5T_get_order(type)) == H5T_ORDER_ERROR)
        HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype endianness order")

    /* Set "local" parameter for datatype endianness */
    switch(dtype_order) {
        case H5T_ORDER_LE:      /* Little-endian byte order */
            cd_values[H5Z_SCALEOFFSET_PARM_ORDER] = H5Z_SCALEOFFSET_ORDER_LE;
            break;

        case H5T_ORDER_BE:      /* Big-endian byte order */
            cd_values[H5Z_SCALEOFFSET_PARM_ORDER] = H5Z_SCALEOFFSET_ORDER_BE;
            break;

        case H5T_ORDER_ERROR:
        case H5T_ORDER_VAX:
        case H5T_ORDER_NONE:
        default:
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype endianness order")
    } /* end switch */

    /* Check whether fill value is defined for dataset */
    if(H5P_fill_value_defined(dcpl_plist, &status) < 0)
        HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "unable to determine if fill value is defined")

    /* Set local parameter for availability of fill value */
    if(status == H5D_FILL_VALUE_UNDEFINED)
        cd_values[H5Z_SCALEOFFSET_PARM_FILAVAIL] = H5Z_SCALEOFFSET_FILL_UNDEFINED;
    else {
        int need_convert = FALSE;       /* Flag indicating convertion of byte order */

        cd_values[H5Z_SCALEOFFSET_PARM_FILAVAIL] = H5Z_SCALEOFFSET_FILL_DEFINED;

        /* Check if memory byte order matches dataset datatype byte order */
        if(H5T_native_order_g != dtype_order)
            need_convert = TRUE;

        /* Before getting fill value, get its type */
        if((scale_type = H5Z_scaleoffset_get_type(cd_values[H5Z_SCALEOFFSET_PARM_CLASS],
                cd_values[H5Z_SCALEOFFSET_PARM_SIZE], cd_values[H5Z_SCALEOFFSET_PARM_SIGN])) == 0)
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "cannot use C integer datatype for cast")

        /* Get dataset fill value and store in cd_values[] */
        if(H5Z_scaleoffset_set_parms_fillval(dcpl_plist, type, scale_type, cd_values, need_convert, H5AC_ind_dxpl_id) < 0)
            HGOTO_ERROR(H5E_PLINE, H5E_CANTSET, FAIL, "unable to set fill value")
    } /* end else */

    /* Modify the filter's parameters for this dataset */
    if(H5P_modify_filter(dcpl_plist, H5Z_FILTER_SCALEOFFSET, flags, (size_t)H5Z_SCALEOFFSET_TOTAL_NPARMS, cd_values) < 0)
	HGOTO_ERROR(H5E_PLINE, H5E_CANTSET, FAIL, "can't set local scaleoffset parameters")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5Z_set_local_scaleoffset() */


/*-------------------------------------------------------------------------
 * Function:	H5Z_filter_scaleoffset
 *
 * Purpose:	Implement an I/O filter for storing packed integer
 *              data using scale and offset method.
 *
 * Return:	Success: Size of buffer filtered
 *		Failure: 0
 *
 * Programmer:	Xiaowen Wu
 *              Monday, February 7, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static size_t
H5Z_filter_scaleoffset(unsigned flags, size_t cd_nelmts, const unsigned cd_values[],
    size_t nbytes, size_t *buf_size, void **buf)
{
    size_t ret_value = 0;           /* return value */
    size_t size_out  = 0;           /* size of output buffer */
    unsigned d_nelmts = 0;          /* number of data elements in the chunk */
    unsigned dtype_class;           /* datatype class */
    unsigned dtype_sign;            /* integer datatype sign */
    unsigned filavail;              /* flag indicating if fill value is defined or not */
    H5Z_SO_scale_type_t scale_type = H5Z_SO_FLOAT_DSCALE;/* scale type */
    int scale_factor = 0;           /* scale factor */
    double D_val = 0.0f;            /* decimal scale factor */
    uint32_t minbits = 0;           /* minimum number of bits to store values */
    unsigned long long minval= 0;   /* minimum value of input buffer */
    enum H5Z_scaleoffset_t type; /* memory type corresponding to dataset datatype */
    int need_convert = FALSE;       /* flag indicating convertion of byte order */
    unsigned char *outbuf = NULL;   /* pointer to new output buffer */
    unsigned buf_offset = 21;       /* buffer offset because of parameters stored in file */
    unsigned i;                     /* index */
    parms_atomic p;                 /* paramters needed for compress/decompress functions */

    FUNC_ENTER_NOAPI_NOINIT

    /* check arguments */
    if(cd_nelmts != H5Z_SCALEOFFSET_TOTAL_NPARMS)
	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, 0, "invalid scaleoffset number of paramters")

    /* Check if memory byte order matches dataset datatype byte order */
    switch(H5T_native_order_g) {
        case H5T_ORDER_LE:      /* memory is little-endian byte order */
            if(cd_values[H5Z_SCALEOFFSET_PARM_ORDER] == H5Z_SCALEOFFSET_ORDER_BE)
                need_convert = TRUE;
            break;

        case H5T_ORDER_BE:      /* memory is big-endian byte order */
            if(cd_values[H5Z_SCALEOFFSET_PARM_ORDER] == H5Z_SCALEOFFSET_ORDER_LE)
                need_convert = TRUE;
            break;

        case H5T_ORDER_ERROR:
        case H5T_ORDER_VAX:
        case H5T_ORDER_NONE:
        default:
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, 0, "bad H5T_NATIVE_INT endianness order")
    } /* end switch */

    /* copy filter parameters to local variables */
    d_nelmts     = cd_values[H5Z_SCALEOFFSET_PARM_NELMTS];
    dtype_class  = cd_values[H5Z_SCALEOFFSET_PARM_CLASS];
    dtype_sign   = cd_values[H5Z_SCALEOFFSET_PARM_SIGN];
    filavail     = cd_values[H5Z_SCALEOFFSET_PARM_FILAVAIL];
    scale_factor = (int)cd_values[H5Z_SCALEOFFSET_PARM_SCALEFACTOR];
    scale_type   = (H5Z_SO_scale_type_t)cd_values[H5Z_SCALEOFFSET_PARM_SCALETYPE];

    /* check and assign proper values set by user to related parameters
     * scale type can be H5Z_SO_FLOAT_DSCALE (0), H5Z_SO_FLOAT_ESCALE (1) or H5Z_SO_INT (other)
     * H5Z_SO_FLOAT_DSCALE : floating-point type, variable-minimum-bits method,
     *                      scale factor is decimal scale factor
     * H5Z_SO_FLOAT_ESCALE : floating-point type, fixed-minimum-bits method,
     *                      scale factor is the fixed minimum number of bits
     * H5Z_SO_INT          : integer type, scale_factor is minimum number of bits
     */
    if(dtype_class==H5Z_SCALEOFFSET_CLS_FLOAT) { /* floating-point type */
        if(scale_type!=H5Z_SO_FLOAT_DSCALE && scale_type!=H5Z_SO_FLOAT_ESCALE)
            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, 0, "invalid scale type")
    }

    if(dtype_class==H5Z_SCALEOFFSET_CLS_INTEGER) { /* integer type */
        if(scale_type!=H5Z_SO_INT)
            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, 0, "invalid scale type")

        /* if scale_factor is less than 0 for integer, library will reset it to 0
         * in this case, library will calculate the minimum-bits
         */
	if(scale_factor < 0) scale_factor = 0;
    }

    /* fixed-minimum-bits method is not implemented and is forbidden */
    if(scale_type==H5Z_SO_FLOAT_ESCALE)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, 0, "E-scaling method not supported")

    if(scale_type==H5Z_SO_FLOAT_DSCALE) { /* floating-point type, variable-minimum-bits */
        D_val = (double)scale_factor;
    } else { /* integer type, or floating-point type with fixed-minimum-bits method */
        if(scale_factor > (int)(cd_values[H5Z_SCALEOFFSET_PARM_SIZE] * 8))
            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, 0, "minimum number of bits exceeds maximum")

        /* no need to process data */
        if(scale_factor == (int)(cd_values[H5Z_SCALEOFFSET_PARM_SIZE] * 8)) {
            ret_value = *buf_size;
            goto done;
        }
        minbits = (uint32_t)scale_factor;
    }

    /* prepare paramters to pass to compress/decompress functions */
    p.size = cd_values[H5Z_SCALEOFFSET_PARM_SIZE];
    p.mem_order = H5T_native_order_g;

    /* input; decompress */
    if (flags & H5Z_FLAG_REVERSE) {
        /* retrieve values of minbits and minval from input compressed buffer
         * retrieve them corresponding to how they are stored during compression
         */
        uint32_t minbits_mask = 0;
        unsigned long long minval_mask = 0;
        unsigned minval_size = 0;

        minbits = 0;
        for(i = 0; i < 4; i++) {
            minbits_mask = ((unsigned char *)*buf)[i];
            minbits_mask <<= i*8;
            minbits |= minbits_mask;
        }

        /* retrieval of minval takes into consideration situation where sizeof
         * unsigned long long (datatype of minval) may change from compression
         * to decompression, only smaller size is used
         */
        minval_size = sizeof(unsigned long long) <= ((unsigned char *)*buf)[4] ?
                      sizeof(unsigned long long) : ((unsigned char *)*buf)[4];
        minval = 0;
        for(i = 0; i < minval_size; i++) {
            minval_mask = ((unsigned char *)*buf)[5+i];
            minval_mask <<= i*8;
            minval |= minval_mask;
        }

        HDassert(minbits <= p.size * 8);
        p.minbits = minbits;

        /* calculate size of output buffer after decompression */
        size_out = d_nelmts * p.size;

        /* allocate memory space for decompressed buffer */
        if(NULL == (outbuf = (unsigned char *)H5MM_malloc(size_out)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "memory allocation failed for scaleoffset decompression")

        /* special case: minbits equal to full precision */
        if(minbits == p.size * 8) {
            HDmemcpy(outbuf, (unsigned char*)(*buf)+buf_offset, size_out);

            /* convert to dataset datatype endianness order if needed */
            if(need_convert)
                H5Z_scaleoffset_convert(outbuf, d_nelmts, p.size);

            *buf = outbuf;
            outbuf = NULL;
            *buf_size = size_out;
            ret_value = size_out;
            goto done;
        }

        /* decompress the buffer if minbits not equal to zero */
        if(minbits != 0)
            H5Z_scaleoffset_decompress(outbuf, d_nelmts, (unsigned char*)(*buf)+buf_offset, p);
        else {
            /* fill value is not defined and all data elements have the same value */
            for(i = 0; i < size_out; i++) outbuf[i] = 0;
        }

        /* before postprocess, get memory type */
        if((type = H5Z_scaleoffset_get_type(dtype_class, (unsigned)p.size, dtype_sign)) == 0)
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, 0, "cannot use C integer datatype for cast")

        /* postprocess after decompression */
        if(dtype_class==H5Z_SCALEOFFSET_CLS_INTEGER)
            H5Z_scaleoffset_postdecompress_i(outbuf, d_nelmts, type, filavail,
                                             cd_values, minbits, minval);

        if(dtype_class==H5Z_SCALEOFFSET_CLS_FLOAT)
            if(scale_type==0) { /* variable-minimum-bits method */
                if(H5Z_scaleoffset_postdecompress_fd(outbuf, d_nelmts, type, filavail,
                        cd_values, minbits, minval, D_val)==FAIL)
                    HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, 0, "post-decompression failed")
            }

        /* after postprocess, convert to dataset datatype endianness order if needed */
        if(need_convert)
            H5Z_scaleoffset_convert(outbuf, d_nelmts, p.size);
    }
    /* output; compress */
    else {
        HDassert(nbytes == d_nelmts * p.size);

        /* before preprocess, convert to memory endianness order if needed */
        if(need_convert)
            H5Z_scaleoffset_convert(*buf, d_nelmts, p.size);

        /* before preprocess, get memory type */
        if((type = H5Z_scaleoffset_get_type(dtype_class, (unsigned)p.size, dtype_sign))==0)
            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, 0, "cannot use C integer datatype for cast")

        /* preprocess before compression */
        if(dtype_class==H5Z_SCALEOFFSET_CLS_INTEGER)
            H5Z_scaleoffset_precompress_i(*buf, d_nelmts, type, filavail,
                                          cd_values, &minbits, &minval);

        if(dtype_class==H5Z_SCALEOFFSET_CLS_FLOAT)
            if(scale_type==0) { /* variable-minimum-bits method */
                if(H5Z_scaleoffset_precompress_fd(*buf, d_nelmts, type, filavail,
                        cd_values, &minbits, &minval, D_val)==FAIL)
                    HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, 0, "pre-compression failed")
            }

        HDassert(minbits <= p.size * 8);

        /* calculate buffer size after compression
         * minbits and minval are stored in the front of the compressed buffer
         */
        p.minbits = minbits;
        size_out = buf_offset + nbytes * p.minbits / (p.size * 8) + 1; /* may be 1 larger */

        /* allocate memory space for compressed buffer */
        if(NULL == (outbuf = (unsigned char *)H5MM_malloc(size_out)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "memory allocation failed for scaleoffset compression")

        /* store minbits and minval in the front of output compressed buffer
         * store byte by byte from least significant byte to most significant byte
         * constant buffer size (21 bytes) is left for these two parameters
         * 4 bytes for minbits, 1 byte for size of minval, 16 bytes for minval
         */
        for(i = 0; i < 4; i++)
            ((unsigned char *)outbuf)[i] = (unsigned char)((minbits & ((uint32_t)0xff << i*8)) >> i*8);

        ((unsigned char *)outbuf)[4] = sizeof(unsigned long long);

        for(i = 0; i < sizeof(unsigned long long); i++)
            ((unsigned char *)outbuf)[5+i] = (unsigned char)((minval & ((unsigned long long)0xff << i*8)) >> i*8);

#ifdef H5_CLEAR_MEMORY
        /* Zero out remaining, unused bytes */
        /* (Looks like an error in the original determination of how many
         *      bytes would be needed for parameters. - QAK, 2010/08/19)
         */
        HDmemset(outbuf + 13, 0, (size_t)8);
#endif /* H5_CLEAR_MEMORY */

        /* special case: minbits equal to full precision */
        if(minbits == p.size * 8) {
            HDmemcpy(outbuf + buf_offset, *buf, nbytes);
            *buf = outbuf;
            outbuf = NULL;
            *buf_size = size_out;
            ret_value = buf_offset + nbytes;
            goto done;
        }

        /* compress the buffer if minbits not equal to zero
         * minbits equal to zero only when fill value is not defined and
         * all data elements have the same value
         */
        if(minbits != 0)
            H5Z_scaleoffset_compress((unsigned char *)*buf, d_nelmts, outbuf + buf_offset, size_out - buf_offset, p);
    }

    /* free the input buffer */
    H5MM_xfree(*buf);

    /* set return values */
    *buf = outbuf;
    outbuf = NULL;
    *buf_size = size_out;
    ret_value = size_out;

done:
    if(outbuf)
        H5MM_xfree(outbuf);
    FUNC_LEAVE_NOAPI(ret_value)
}

/* ============ Scaleoffset Algorithm ===============================================
 * assume one byte has 8 bit
 * assume padding bit is 0
 * assume size of unsigned char is one byte
 * assume one data item of certain datatype is stored continously in bytes
 * atomic datatype is treated on byte basis
 */


/* change byte order of input buffer either from little-endian to big-endian
 * or from big-endian to little-endian  2/21/2005
 */
static void
H5Z_scaleoffset_convert(void *buf, unsigned d_nelmts, size_t dtype_size)
{
   if(dtype_size > 1) {
       unsigned i, j;
       unsigned char *buffer, temp;

       buffer = (unsigned char *)buf;
       for(i = 0; i < d_nelmts * dtype_size; i += dtype_size)
          for(j = 0; j < dtype_size / 2; j++) {
             /* swap pair of bytes */
             temp = buffer[i + j];
             buffer[i + j] = buffer[i + dtype_size - 1 - j];
             buffer[i + dtype_size - 1 - j] = temp;
          } /* end for */
    } /* end if */
} /* end H5Z_scaleoffset_convert() */

/* Round a floating-point value to the nearest integer value 4/19/05 */
/* rounding to the bigger absolute value if val is in the middle,
 0.5 -> 1, -0.5 ->-1
5/9/05, KY */
static double
H5Z_scaleoffset_rnd(double val)
{
    double u_val, l_val;

    u_val = HDceil(val);
    l_val = HDfloor(val);

    if(val > 0) {
        if((u_val - val) <= (val - l_val))
            return u_val;
        else
            return l_val;
    } /* end if */
    else {
        if((val - l_val) <= (u_val - val))
            return l_val;
        else
            return u_val;
    }
} /* H5Z_scaleoffset_rnd() */

/* return ceiling of floating-point log2 function
 * receive unsigned integer as argument 3/10/2005
 */
static unsigned
H5Z_scaleoffset_log2(unsigned long long num)
{
   unsigned v = 0;
   unsigned long long lower_bound = 1; /* is power of 2, largest value <= num */
   unsigned long long val = num;

   while(val >>= 1) {
       v++;
       lower_bound <<= 1;
   }

   if(num == lower_bound)
       return v;
   else
       return v + 1;
}

/* precompress for integer type */
static void
H5Z_scaleoffset_precompress_i(void *data, unsigned d_nelmts, enum H5Z_scaleoffset_t type,
    unsigned filavail, const unsigned cd_values[], uint32_t *minbits, unsigned long long *minval)
{
    if(type ==  t_uchar)
        H5Z_scaleoffset_precompress_1(unsigned char, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_ushort)
        H5Z_scaleoffset_precompress_1(unsigned short, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_uint)
        H5Z_scaleoffset_precompress_1(unsigned int, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_ulong)
        H5Z_scaleoffset_precompress_1(unsigned long, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_ulong_long)
        H5Z_scaleoffset_precompress_1(unsigned long long, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_schar) {
        signed char *buf = (signed char *)data, min = 0, max = 0, filval = 0;
        unsigned char span;
        unsigned i;

        if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */
            H5Z_scaleoffset_get_filval_1(signed char, cd_values, filval);
            if(*minbits == H5Z_SO_INT_MINBITS_DEFAULT) { /* minbits not set yet, calculate max, min, and minbits */
                H5Z_scaleoffset_max_min_1(i, d_nelmts, buf, filval, max, min)
                if((unsigned char)(max - min) > (unsigned char)(~(unsigned char)0 - 2)) {
                    *minbits = sizeof(signed char)*8;
                    return;
                }
                span = (unsigned char)(max - min + 1);
                *minbits = H5Z_scaleoffset_log2((unsigned long long)(span+1));
            } else /* minbits already set, only calculate min */
                H5Z_scaleoffset_min_1(i, d_nelmts, buf, filval, min)
            if(*minbits != sizeof(signed char)*8) /* change values if minbits != full precision */
                for(i = 0; i < d_nelmts; i++)
                    buf[i] = (signed char)((buf[i] == filval) ? (((unsigned char)1 << *minbits) - 1) : (buf[i] - min));
        } else { /* fill value undefined */
            if(*minbits == H5Z_SO_INT_MINBITS_DEFAULT) { /* minbits not set yet, calculate max, min, and minbits */
                H5Z_scaleoffset_max_min_2(i, d_nelmts, buf, max, min)
                if((unsigned char)(max - min) > (unsigned char)(~(unsigned char)0 - 2)) {
                    *minbits = sizeof(signed char)*8;
                    *minval = (unsigned long long)min;
                    return;
                }
                span = (unsigned char)(max - min + 1);
                *minbits = H5Z_scaleoffset_log2((unsigned long long)span);
            } else /* minbits already set, only calculate min */
                H5Z_scaleoffset_min_2(i, d_nelmts, buf, min)
            if(*minbits != sizeof(signed char) * 8) /* change values if minbits != full precision */
                for(i = 0; i < d_nelmts; i++)
                    buf[i] = (signed char)(buf[i] - min);
        }
        *minval = (unsigned long long)min;
    }
    else if(type == t_short)
        H5Z_scaleoffset_precompress_2(short, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_int)
        H5Z_scaleoffset_precompress_2(int, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_long)
        H5Z_scaleoffset_precompress_2(long, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
    else if(type == t_long_long)
        H5Z_scaleoffset_precompress_2(long long, data, d_nelmts,
                                    filavail, cd_values, minbits, minval)
}

/* postdecompress for integer type */
static void
H5Z_scaleoffset_postdecompress_i(void *data, unsigned d_nelmts, enum H5Z_scaleoffset_t type,
    unsigned filavail, const unsigned cd_values[], uint32_t minbits, unsigned long long minval)
{
   long long sminval = *(long long*)&minval; /* for signed integer types */

   if(type == t_uchar)
      H5Z_scaleoffset_postdecompress_1(unsigned char, data, d_nelmts, filavail,
                                       cd_values, minbits, minval)
   else if(type == t_ushort)
      H5Z_scaleoffset_postdecompress_1(unsigned short, data, d_nelmts, filavail,
                                       cd_values, minbits, minval)
   else if(type == t_uint)
      H5Z_scaleoffset_postdecompress_1(unsigned int, data, d_nelmts, filavail,
                                       cd_values, minbits, minval)
   else if(type == t_ulong)
      H5Z_scaleoffset_postdecompress_1(unsigned long, data, d_nelmts, filavail,
                                       cd_values, minbits, minval)
   else if(type == t_ulong_long)
      H5Z_scaleoffset_postdecompress_1(unsigned long long, data, d_nelmts, filavail,
                                       cd_values, minbits, minval)
   else if(type == t_schar) {
      signed char *buf = (signed char *)data, filval = 0;
      unsigned i;

      if(filavail == H5Z_SCALEOFFSET_FILL_DEFINED) { /* fill value defined */
         H5Z_scaleoffset_get_filval_1(signed char, cd_values, filval)
         for(i = 0; i < d_nelmts; i++)
            buf[i] = (signed char)((buf[i] == (((unsigned char)1 << minbits) - 1)) ? filval : (buf[i] + sminval));
      } else /* fill value undefined */
         for(i = 0; i < d_nelmts; i++)
             buf[i] = (signed char)(buf[i] + sminval);
   }
   else if(type == t_short)
      H5Z_scaleoffset_postdecompress_2(short, data, d_nelmts, filavail,
                                       cd_values, minbits, sminval)
   else if(type == t_int)
      H5Z_scaleoffset_postdecompress_2(int, data, d_nelmts, filavail,
                                       cd_values, minbits, sminval)
   else if(type == t_long)
      H5Z_scaleoffset_postdecompress_2(long, data, d_nelmts, filavail,
                                       cd_values, minbits, sminval)
   else if(type == t_long_long)
      H5Z_scaleoffset_postdecompress_2(long long, data, d_nelmts, filavail,
                                       cd_values, minbits, sminval)
}

/* precompress for floating-point type, variable-minimum-bits method
   success: non-negative, failure: negative 4/15/05 */
static herr_t
H5Z_scaleoffset_precompress_fd(void *data, unsigned d_nelmts, enum H5Z_scaleoffset_t type,
    unsigned filavail, const unsigned cd_values[], uint32_t *minbits,
    unsigned long long *minval, double D_val)
{
   herr_t ret_value=SUCCEED; /* Return value */

   FUNC_ENTER_NOAPI_NOINIT

   if(type == t_float)
      H5Z_scaleoffset_precompress_3(float, data, d_nelmts,
                                    filavail, cd_values, minbits, minval, D_val)
   else if(type == t_double)
      H5Z_scaleoffset_precompress_3(double, data, d_nelmts,
                                    filavail, cd_values, minbits, minval, D_val)

done:
   FUNC_LEAVE_NOAPI(ret_value)
}

/* postdecompress for floating-point type, variable-minimum-bits method
   success: non-negative, failure: negative 4/15/05 */
static herr_t
H5Z_scaleoffset_postdecompress_fd(void *data, unsigned d_nelmts, enum H5Z_scaleoffset_t type,
    unsigned filavail, const unsigned cd_values[], uint32_t minbits,
    unsigned long long minval, double D_val)
{
   long long sminval = (long long)minval;    /* for signed integer types */
   herr_t ret_value=SUCCEED;                 /* Return value */

   FUNC_ENTER_NOAPI_NOINIT

   if(type == t_float)
      H5Z_scaleoffset_postdecompress_3(float, data, d_nelmts, filavail,
                                       cd_values, minbits, sminval, D_val)
   else if(type == t_double)
      H5Z_scaleoffset_postdecompress_3(double, data, d_nelmts, filavail,
                                       cd_values, minbits, sminval, D_val)

done:
   FUNC_LEAVE_NOAPI(ret_value)
}

static void
H5Z_scaleoffset_next_byte(size_t *j, unsigned *buf_len)
{
   ++(*j);
   *buf_len = 8 * sizeof(unsigned char);
}

static void
H5Z_scaleoffset_decompress_one_byte(unsigned char *data, size_t data_offset,
    unsigned k, unsigned begin_i, unsigned char *buffer, size_t *j, unsigned *buf_len,
    parms_atomic p, unsigned dtype_len)
{
   unsigned dat_len;    /* dat_len is the number of bits to be copied in each data byte */
   unsigned char val;   /* value to be copied in each data byte */

   /* initialize value and bits of unsigned char to be copied */
   val = buffer[*j];
   if(k == begin_i)
      dat_len = 8 - (dtype_len - p.minbits) % 8;
   else
      dat_len = 8;

   if(*buf_len > dat_len) {
      data[data_offset + k] = (unsigned char)((val >> (*buf_len - dat_len)) & ~(~0 << dat_len));
      *buf_len -= dat_len;
   } /* end if */
   else {
      data[data_offset + k] = (unsigned char)((val & ~(~0 << *buf_len)) << (dat_len - *buf_len));
      dat_len -= *buf_len;
      H5Z_scaleoffset_next_byte(j, buf_len);
      if(dat_len == 0)
          return;

      val = buffer[*j];
      data[data_offset + k] |= (unsigned char)((val >> (*buf_len - dat_len)) & ~(~0 << dat_len));
      *buf_len -= dat_len;
   } /* end else */
}

static void
H5Z_scaleoffset_decompress_one_atomic(unsigned char *data, size_t data_offset,
    unsigned char *buffer, size_t *j, unsigned *buf_len, parms_atomic p)
{
   /* begin_i: the index of byte having first significant bit */
   unsigned begin_i;
   unsigned dtype_len;
   int k;

   HDassert(p.minbits > 0);

   dtype_len = p.size * 8;

   if(p.mem_order == H5Z_SCALEOFFSET_ORDER_LE) { /* little endian */
      begin_i = p.size - 1 - (dtype_len - p.minbits) / 8;

      for(k = (int)begin_i; k >= 0; k--)
         H5Z_scaleoffset_decompress_one_byte(data, data_offset, (unsigned)k, begin_i,
                                             buffer, j, buf_len, p, dtype_len);
   }
   else { /* big endian */
      HDassert(p.mem_order == H5Z_SCALEOFFSET_ORDER_BE);

      begin_i = (dtype_len - p.minbits) / 8;

      for(k = (int)begin_i; k <= (int)(p.size - 1); k++)
         H5Z_scaleoffset_decompress_one_byte(data, data_offset, (unsigned)k, begin_i,
                                             buffer, j, buf_len, p, dtype_len);
   }
}

static void
H5Z_scaleoffset_decompress(unsigned char *data, unsigned d_nelmts,
    unsigned char *buffer, parms_atomic p)
{
    /* i: index of data, j: index of buffer,
       buf_len: number of bits to be filled in current byte */
    size_t i, j;
    unsigned buf_len;

    /* must initialize to zeros */
    for(i = 0; i < d_nelmts*p.size; i++)
        data[i] = 0;

    /* initialization before the loop */
    j = 0;
    buf_len = sizeof(unsigned char) * 8;

    /* decompress */
    for(i = 0; i < d_nelmts; i++)
        H5Z_scaleoffset_decompress_one_atomic(data, i * p.size, buffer, &j, &buf_len, p);
}

static void
H5Z_scaleoffset_compress_one_byte(unsigned char *data, size_t data_offset,
    unsigned k, unsigned begin_i, unsigned char *buffer, size_t *j, unsigned *buf_len,
    parms_atomic p, unsigned dtype_len)
{
   unsigned dat_len;    /* dat_len is the number of bits to be copied in each data byte */
   unsigned char val;   /* value to be copied in each data byte */

   /* initialize value and bits of unsigned char to be copied */
   val = data[data_offset + k];
   if(k == begin_i)
      dat_len = 8 - (dtype_len - p.minbits) % 8;
   else
      dat_len = 8;

   if(*buf_len > dat_len) {
      buffer[*j] |= (unsigned char)((val & ~(~0 << dat_len)) << (*buf_len - dat_len));
      *buf_len -= dat_len;
   } else {
      buffer[*j] |= (unsigned char)((val >> (dat_len - *buf_len)) & ~(~0 << *buf_len));
      dat_len -= *buf_len;
      H5Z_scaleoffset_next_byte(j, buf_len);
      if(dat_len == 0)
          return;

      buffer[*j] = (unsigned char)((val & ~(~0 << dat_len)) << (*buf_len - dat_len));
      *buf_len -= dat_len;
   } /* end else */
}

static void
H5Z_scaleoffset_compress_one_atomic(unsigned char *data, size_t data_offset,
    unsigned char *buffer, size_t *j, unsigned *buf_len, parms_atomic p)
{
   /* begin_i: the index of byte having first significant bit */
   unsigned begin_i;
   unsigned dtype_len;
   int k;

   HDassert(p.minbits > 0);

   dtype_len = p.size * 8;

   if(p.mem_order == H5Z_SCALEOFFSET_ORDER_LE) { /* little endian */
      begin_i = p.size - 1 - (dtype_len - p.minbits) / 8;

      for(k = (int)begin_i; k >= 0; k--)
         H5Z_scaleoffset_compress_one_byte(data, data_offset, (unsigned)k, begin_i,
                                           buffer, j, buf_len, p, dtype_len);
   }
   else { /* big endian */
      HDassert(p.mem_order == H5Z_SCALEOFFSET_ORDER_BE);
      begin_i = (dtype_len - p.minbits) / 8;

      for(k = (int)begin_i; k <= (int)(p.size - 1); k++)
         H5Z_scaleoffset_compress_one_byte(data, data_offset, (unsigned)k, begin_i,
                                           buffer, j, buf_len, p, dtype_len);
   }
}

static void
H5Z_scaleoffset_compress(unsigned char *data, unsigned d_nelmts,
    unsigned char *buffer, size_t buffer_size, parms_atomic p)
{
   /* i: index of data, j: index of buffer,
      buf_len: number of bits to be filled in current byte */
   size_t i, j;
   unsigned buf_len;

   /* must initialize buffer to be zeros */
   for(j = 0; j < buffer_size; j++)
      buffer[j] = 0;

   /* initialization before the loop */
   j = 0;
   buf_len = sizeof(unsigned char) * 8;

   /* compress */
   for(i = 0; i < d_nelmts; i++)
       H5Z_scaleoffset_compress_one_atomic(data, i * p.size, buffer, &j, &buf_len, p);
}