[svn-r10028] Purpose:

     New feature.

Description:
    Source code for the scaleoffset internal filter. For debugging purpose.

Solution:

Platforms tested:
    heping, copper, arabica

Misc. update:

1 files changed, 813 insertions, 0 deletions

diff --git a/src/H5Zscaleoffset.c b/src/H5Zscaleoffset.c
new file mode 100644
index 0000000..21bb3f5
--- /dev/null
+++ b/src/H5Zscaleoffset.c
@@ -0,0 +1,813 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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 files COPYING and Copyright.html.  COPYING can be found at the root   *
+ * of the source code distribution tree; Copyright.html can be found at the  *
+ * root level of an installed copy of the electronic HDF5 document set and   *
+ * is linked from the top-level documents page.  It can also be found at     *
+ * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html.  If you do not have     *
+ * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/* currently this filter only handles integer datatype 
+ * does not consider fill value
+ */
+
+#define H5Z_PACKAGE		/*suppress error about including H5Zpkg	  */
+
+#include "H5private.h"		/* Generic Functions			*/
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5MMprivate.h"	/* Memory management			*/
+#include "H5Ppublic.h"		/* Property lists			*/
+#include "H5Oprivate.h"         /* Object headers                       */
+#include "H5Tpublic.h"		/* Datatype functions			*/
+#include "H5Zpkg.h"		/* Data filters				*/
+
+#ifdef H5_HAVE_FILTER_SCALEOFFSET
+
+/* Struct of parameters needed for compressing/decompressing one atomic datatype */ 
+typedef struct {
+   size_t size;
+   unsigned order;
+   unsigned minbits;
+} parms_atomic; 
+
+/* Local function prototypes */
+static herr_t H5Z_can_apply_scaleoffset(hid_t dcpl_id, hid_t type_id, hid_t space_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);
+void H5Z_scaleoffset_precompress(void *data, unsigned d_nelmts, unsigned type, unsigned filavail,
+                                 unsigned *minbits, unsigned long_long *minval);
+void H5Z_scaleoffset_postdecompress(void *data, unsigned d_nelmts, unsigned type, unsigned filavail,
+                                    unsigned long_long minval);
+void H5Z_scaleoffset_next_byte(size_t *j, int *buf_len);
+void H5Z_scaleoffset_decompress_one_byte(void *data, size_t data_offset, int k, int begin_i,
+                             unsigned char *buffer, size_t *j, int *buf_len, parms_atomic p);
+void H5Z_scaleoffset_compress_one_byte(void *data, size_t data_offset, int k, int begin_i,
+                           unsigned char *buffer, size_t *j, int *buf_len, parms_atomic p);
+void H5Z_scaleoffset_decompress_one_atomic(void *data, size_t data_offset, unsigned char *buffer,
+                                           size_t *j, int *buf_len, parms_atomic p);
+void H5Z_scaleoffset_compress_one_atomic(void *data, size_t data_offset, unsigned char *buffer,
+                                         size_t *j, int *buf_len, parms_atomic p);
+void H5Z_scaleoffset_decompress(void *data, unsigned d_nelmts, unsigned char *buffer,
+                                parms_atomic p);
+void H5Z_scaleoffset_compress(void *data, unsigned d_nelmts, unsigned char *buffer,
+                              size_t buffer_size, parms_atomic p);
+
+/* This message derives from H5Z */
+H5Z_class_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_USER_NPARMS     1    /* Number of parameters that users can set */
+#define H5Z_SCALEOFFSET_TOTAL_NPARMS    7    /* Total number of parameters for filter */
+#define H5Z_SCALEOFFSET_PARM_MINBITS    0    /* "User" parameter for minimum number of bits */
+#define H5Z_SCALEOFFSET_PARM_NELMTS     1    /* "Local" parameter for number of elements in the chunk */
+#define H5Z_SCALEOFFSET_PARM_CLASS      2    /* "Local" parameter for datatype class */
+#define H5Z_SCALEOFFSET_PARM_SIZE       3    /* "Local" parameter for datatype size */
+#define H5Z_SCALEOFFSET_PARM_TYPE       4    /* "Local" parameter for integer types */
+#define H5Z_SCALEOFFSET_PARM_ORDER      5    /* "Local" parameter for datatype byte order */
+#define H5Z_SCALEOFFSET_PARM_FILAVAIL   6    /* "Local" parameter for dataset fill value existence */
+
+#define H5Z_SCALEOFFSET_CLS_INTEGER     0    /* Integer (datatype class) */
+#define H5Z_SCALEOFFSET_CLS_FLOAT       1    /* Floating point (datatype class) */
+
+#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 */
+
+/* Local variables */
+/* can not use pfill_val now
+ * pfill_val: pointer to buffer containing fill value of dataset fill value if is defined
+ */
+static void *pfill_val;
+
+enum H5Z_scaleoffset_type {t_uchar, t_ushort, t_uint, t_ulong, t_ulong_long,
+                           t_schar, t_short, t_int, t_long, t_long_long};
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Z_can_apply_scaleoffset
+ *
+ * Purpose:	Check the parameters for scaleoffset compression for 
+ *              validity and whether they fit a particular dataset.
+ *
+ * Note:        
+ *              
+ * Return:	Success: Non-negative
+ *		Failure: Negative
+ *
+ * Programmer:  Xiaowen Wu
+ *              Friday, February 4, 2005
+ *
+ * Modifications: 
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5Z_can_apply_scaleoffset(hid_t UNUSED dcpl_id, hid_t type_id, hid_t UNUSED space_id)
+{
+    H5T_class_t dtype_class;            /* Datatype's class */
+    unsigned dtype_size;                /* Datatype's size (in bytes) */
+    H5T_order_t dtype_order;            /* Datatype's endianness order */
+    herr_t ret_value=TRUE;              /* Return value */
+
+    FUNC_ENTER_NOAPI(H5Z_can_apply_scaleoffset, FAIL)
+
+    /* Get datatype's class, for checking the "datatype class" */
+    if((dtype_class = H5Tget_class(type_id)) == H5T_NO_CLASS )
+	HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype class")
+
+    /* Get datatype's size, for checking the "datatype size" */
+    if((dtype_size = H5Tget_size(type_id)) == 0)
+	HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype size")
+
+    /* Codes below apply to integer or floating point datatype */
+    if(dtype_class == H5T_INTEGER || dtype_class == H5T_FLOAT) {
+        /* Get datatype's endianness order */
+        if((dtype_order = H5Tget_order(type_id)) == H5T_ORDER_ERROR)
+	    HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "can't retrieve datatype endianness order")
+
+        /* Range check datatype's endianness order */
+        /* (Note: this may not handle non-atomic datatypes well) */
+        if(dtype_order != H5T_ORDER_LE && dtype_order != H5T_ORDER_BE)
+            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype endianness order")
+    } else
+        HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "datatype class not supported by scaleoffset")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5Z_can_apply_scaleoffset() */
+
+
+/*-------------------------------------------------------------------------
+ * 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)
+{
+    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_type type; /* Integer type */
+    H5D_fill_value_t status;        /* Status of fill value in property list */
+    herr_t ret_value=SUCCEED;       /* Return value */
+
+    FUNC_ENTER_NOAPI(H5Z_set_local_scaleoffset, FAIL)
+
+    /* Get the filter's current parameters */
+#ifdef H5_WANT_H5_V1_6_COMPAT
+    if(H5Pget_filter_by_id(dcpl_id,H5Z_FILTER_SCALEOFFSET,&flags,&cd_nelmts,cd_values,0,NULL)<0)
+#else
+    if(H5Pget_filter_by_id(dcpl_id,H5Z_FILTER_SCALEOFFSET,&flags,&cd_nelmts,cd_values,0,NULL,NULL)<0)
+#endif
+	HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "can't get scaleoffset parameters")
+
+    /* Get total number of elements in the chunk */
+    if ((npoints=H5Sget_simple_extent_npoints(space_id))<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_ASSIGN_OVERFLOW(cd_values[H5Z_SCALEOFFSET_PARM_NELMTS],npoints,hssize_t,unsigned);
+
+    /* Get datatype's class */
+    if((dtype_class=H5Tget_class(type_id))==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;
+        default:
+            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "datatype class not supported by scaleoffset")
+    } /* end switch */
+
+    /* Get datatype's size */
+    if((dtype_size=H5Tget_size(type_id))==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;
+
+    /* Get datatype's sign */
+    if((dtype_sign=H5Tget_sign(type_id))==H5T_SGN_ERROR)
+        HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype sign")
+
+    if(dtype_class==H5T_INTEGER) {
+        if(dtype_sign==H5T_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, FAIL, "integer size not matched")
+        }
+
+        if(dtype_sign==H5T_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, FAIL, "integer size not matched")
+        }
+
+        /* Set "local" parameter for integer types */
+        cd_values[H5Z_SCALEOFFSET_PARM_TYPE] = type;
+    }
+    
+    /* Get datatype's endianness order */
+    if((dtype_order=H5Tget_order(type_id))==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;
+        default:
+            HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad datatype endianness order")
+    } /* end switch */
+
+    /* Check whether fill value is defined for dataset */
+    if(H5Pfill_value_defined(dcpl_id, &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 {
+        cd_values[H5Z_SCALEOFFSET_PARM_FILAVAIL] = H5Z_SCALEOFFSET_FILL_DEFINED;
+#if 0
+        /* Get dataset fill value */
+        if(H5Pget_fill_value(dcpl_id, type_id, pfill_val)<0)
+            HGOTO_ERROR(H5E_PLINE, H5E_CANTGET, FAIL, "unable to get fill value")
+#endif
+    }
+
+    /* Modify the filter's parameters for this dataset */
+    if(H5Pmodify_filter(dcpl_id, H5Z_FILTER_SCALEOFFSET, flags, 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/float
+ *              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 minbits = 0;          /* minimum number of bits to store values */
+    unsigned long_long minval= 0;  /* minimum value of input buffer */
+    unsigned char *outbuf = NULL;  /* pointer to new output buffer */
+    parms_atomic p;                /* paramters needed for compress/decompress functions */
+    unsigned buf_offset;        /* buffer offset because of parameters stored in file */
+ 	
+    FUNC_ENTER_NOAPI(H5Z_filter_scaleoffset, 0)
+
+    /* check arguments */
+    if (cd_nelmts!=H5Z_SCALEOFFSET_TOTAL_NPARMS)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, 0, "invalid scaleoffset number of paramters")
+
+    /* copy a filter parameter to d_nelmts */
+    d_nelmts = cd_values[H5Z_SCALEOFFSET_PARM_NELMTS];
+
+    /* check and assign value to minimum number of bits if set by user */
+    if(cd_values[H5Z_SCALEOFFSET_PARM_MINBITS]!=0) { 
+        if(cd_values[H5Z_SCALEOFFSET_PARM_MINBITS]>cd_values[H5Z_SCALEOFFSET_PARM_SIZE]*8)
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, 0, "invalid scaleoffset minimum number of bits")
+        minbits = cd_values[H5Z_SCALEOFFSET_PARM_MINBITS];
+    }
+
+    /* prepare paramters to pass to compress/decompress functions */
+    p.size = cd_values[H5Z_SCALEOFFSET_PARM_SIZE];
+    p.order = cd_values[H5Z_SCALEOFFSET_PARM_ORDER];
+
+    /* input; decompress */
+    if (flags & H5Z_FLAG_REVERSE) {
+        /* get values of minbits and minval from input buffer */
+        HDmemcpy(&minbits, *buf, sizeof(unsigned));
+        HDmemcpy(&minval, (unsigned char*)(*buf)+sizeof(unsigned), sizeof(unsigned long_long));
+
+        assert(minbits < p.size * 8);
+
+        /* no need to process the data */
+        if(minbits == cd_values[H5Z_SCALEOFFSET_PARM_SIZE] * 8) { 
+            ret_value = *buf_size;
+            goto done;
+        }
+
+        size_out = d_nelmts * p.size;
+
+        /* allocate memory space for decompressed buffer */
+        if(NULL==(outbuf = H5MM_malloc(size_out)))
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "memory allocation failed for scaleoffset decompression")
+  
+#if 0
+        /* the data buffer all have same value */
+        if(minbits == 0) {
+        }
+#endif
+
+        p.minbits = minbits;
+
+        /* decompress the buffer */
+        buf_offset = sizeof(unsigned) + sizeof(unsigned long_long);
+        H5Z_scaleoffset_decompress(outbuf, d_nelmts, (unsigned char*)(*buf)+buf_offset, p);   
+
+        /* postprocess after decompress */
+        H5Z_scaleoffset_postdecompress(outbuf, d_nelmts, cd_values[H5Z_SCALEOFFSET_PARM_TYPE], 
+                                       cd_values[H5Z_SCALEOFFSET_PARM_FILAVAIL], minval);
+    }
+    /* output; compress */
+    else { 
+        /* preprocess before compress */
+        H5Z_scaleoffset_precompress(*buf, d_nelmts, cd_values[H5Z_SCALEOFFSET_PARM_TYPE], 
+                             cd_values[H5Z_SCALEOFFSET_PARM_FILAVAIL], &minbits, &minval);
+        
+        assert(minbits < p.size * 8);
+
+        /* no need to process the data */
+        if(minbits == p.size * 8) { 
+            ret_value = *buf_size;
+            goto done;
+        }
+#if 0
+        /* the data buffer all have same value */
+        if(minbits == 0) {
+            *buf_size = 0;
+            ret_value = 0;
+            goto done;
+        }
+#endif
+        p.minbits = minbits;
+
+        /* calculate buffer size after compression, may be 1 bigger 
+         * minbits and minval are stored in the front of the compressed buffer
+         */
+        size_out = nbytes * p.minbits / (p.size * 8) + 1 + 
+                   sizeof(unsigned) + sizeof(unsigned long_long);
+
+        /* allocate memory space for compressed buffer */
+        if(NULL==(outbuf = H5MM_malloc(size_out)))
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "memory allocation failed for scaleoffset compression")
+
+        /* first store minbits and minval in output buffer */
+        HDmemcpy(outbuf, &minbits, sizeof(unsigned));
+        HDmemcpy(outbuf+sizeof(unsigned), &minval, sizeof(unsigned long_long));
+
+        /* compress the buffer */
+        buf_offset = sizeof(unsigned) + sizeof(unsigned long_long);
+        H5Z_scaleoffset_compress(*buf, d_nelmts, outbuf+buf_offset, size_out-buf_offset, p);
+#if 0
+        printf("After compress:\n");
+        for(i = 0; i < size_out; i++) { 
+           printf("%02x  ", ((unsigned char *)(outbuf))[i]);
+           if((i+1)%4==0) printf("\n");
+        }
+#endif
+    }
+
+    /* 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 
+ */
+
+void H5Z_scaleoffset_precompress(void *data, unsigned d_nelmts, unsigned type, unsigned filavail,
+                                 unsigned *minbits, unsigned long_long *minval)
+{
+   unsigned i;
+   unsigned long_long span; /* span of values of input buffer data */
+   enum H5Z_scaleoffset_type t; /* integer type */
+
+   t = type;
+   if(type ==  t_uchar) {
+      unsigned char *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min; 
+   } 
+   else if(type == t_ushort) {
+      unsigned short *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   }
+   else if(type == t_uint) {
+      unsigned int *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   }
+   else if(type == t_ulong) {
+      unsigned long *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   } 
+   else if(type == t_ulong_long) {
+      unsigned long_long *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   } 
+   else if(type == t_schar) {
+      signed char *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   } 
+   else if(type == t_short) {
+      short *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   } 
+   else if(type == t_int) {
+      int *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min; 
+   } else if(type == t_long) {
+      long *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   } 
+   else if(type == t_long_long) {
+      long_long *buf, min, max;
+      buf = data; min = max = buf[0];
+      for(i = 0; i < d_nelmts; i++) { /* find maximum and minimum values */
+         if(buf[i] > max) max = buf[i];
+         if(buf[i] < min) min = buf[i];
+      }
+      span = max - min + 1; *minval = min;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] -= min;
+   }
+#if 0
+   /* if minbits not set by application, calculate minbits */
+   if(*minbits == 0) {
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         *minbits = HDceil(log(span)*M_LOG2E);
+      else
+         *minbits = HDceil(log(span+1)*M_LOG2E);
+   }
+#endif
+}
+
+void H5Z_scaleoffset_postdecompress(void *data, unsigned d_nelmts, unsigned type, unsigned filavail,
+                                    unsigned long_long minval)
+{
+   unsigned i;
+   long_long sminval = *(long_long*)&minval; /* for signed integer types */
+   enum H5Z_scaleoffset_type t; /* integer type */
+
+   t = type;
+   if(type == t_uchar) {
+      unsigned char *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += minval;
+   }
+   else if(type == t_ushort) {
+      unsigned short *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += minval;
+   }
+   else if(type == t_uint) {
+      unsigned int *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += minval;
+   }
+   else if(type == t_ulong) {
+      unsigned long *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += minval;
+   }
+   else if(type == t_ulong_long) {
+      unsigned long_long *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += minval;
+   }
+   else if(type == t_schar) {
+      signed char *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += sminval;
+   } 
+   else if(type == t_short) {
+      short *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += sminval;
+   }
+   else if(type == t_int) {
+      int *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += sminval;
+   }
+   else if(type == t_long) {
+      long *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += sminval;
+   }
+   else if(type == t_long_long) {
+      long_long *buf = data;
+      if(filavail == H5Z_SCALEOFFSET_FILL_UNDEFINED)
+         for(i = 0; i < d_nelmts; i++) buf[i] += sminval;
+   } 
+}
+
+void H5Z_scaleoffset_next_byte(size_t *j, int *buf_len)
+{
+   ++(*j); 
+   *buf_len = 8 * sizeof(unsigned char);
+}
+
+void H5Z_scaleoffset_decompress_one_byte(void *data, size_t data_offset, int k, int begin_i, 
+unsigned char *buffer, size_t *j, int *buf_len, parms_atomic p)
+{
+   int 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 = p.minbits % 8;
+   else 
+      dat_len = 8;
+
+   if(*buf_len > dat_len) { 
+      ((unsigned char *)data)[data_offset + k] =
+      ((val >> (*buf_len - dat_len)) & ~(~0 << dat_len));
+      *buf_len -= dat_len;
+   } else {
+      ((unsigned char *)data)[data_offset + k] =
+      ((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];
+      ((unsigned char *)data)[data_offset + k] |=
+      ((val >> (*buf_len - dat_len)) & ~(~0 << dat_len));
+      *buf_len -= dat_len; 
+   }
+}
+
+void H5Z_scaleoffset_decompress_one_atomic(void *data, size_t data_offset, unsigned char *buffer, 
+                                           size_t *j, int *buf_len, parms_atomic p) 
+{
+   /* begin_i: the index of byte having first significant bit */
+   int k, begin_i, dtype_len;
+
+   assert(p.minbits > 0);
+
+   dtype_len = p.size * 8;
+
+   if(p.order == H5Z_SCALEOFFSET_ORDER_LE) { /* little endian */
+      begin_i = p.size - 1 - (dtype_len - p.minbits) / 8;
+
+      for(k = begin_i; k >= 0; k--) 
+         H5Z_scaleoffset_decompress_one_byte(data, data_offset, k, begin_i, 
+                                             buffer, j, buf_len, p);
+   }
+
+   if(p.order == H5Z_SCALEOFFSET_ORDER_BE) { /* big endian */
+      begin_i = (dtype_len - p.minbits) / 8;
+
+      for(k = begin_i; k <= p.size - 1; k++) 
+         H5Z_scaleoffset_decompress_one_byte(data, data_offset, k, begin_i,  
+                                             buffer, j, buf_len, p);
+   } 
+}
+
+void H5Z_scaleoffset_decompress(void *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;
+   int buf_len; 
+
+   /* may not have to initialize to zeros */  
+   for(i = 0; i < d_nelmts*p.size; i++)  
+      ((unsigned char *)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);
+}
+
+void H5Z_scaleoffset_compress_one_byte(void *data, size_t data_offset, int k, int begin_i, 
+unsigned char *buffer, size_t *j, int *buf_len, parms_atomic p)
+{
+   int 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 = ((unsigned char *)data)[data_offset + k];
+
+   if(k == begin_i) 
+      dat_len = p.minbits % 8;
+   else
+      dat_len = 8;
+
+   if(*buf_len > dat_len) { 
+      buffer[*j] |= (val & ~(~0 << dat_len)) << (*buf_len - dat_len);
+      *buf_len -= dat_len;
+   } else {
+      buffer[*j] |= (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] = (val & ~(~0 << dat_len)) << (*buf_len - dat_len);
+      *buf_len -= dat_len; 
+   }
+}
+
+void H5Z_scaleoffset_compress_one_atomic(void *data, size_t data_offset, unsigned char *buffer, 
+                                         size_t *j, int *buf_len, parms_atomic p) 
+{
+   /* begin_i: the index of byte having first significant bit */
+   int k, begin_i, dtype_len;
+
+   assert(p.minbits > 0);
+
+   dtype_len = p.size * 8;
+
+   if(p.order == H5Z_SCALEOFFSET_ORDER_LE) { /* little endian */
+      begin_i = p.size - 1 - (dtype_len - p.minbits) / 8;
+
+      for(k = begin_i; k >= 0; k--) 
+         H5Z_scaleoffset_compress_one_byte(data, data_offset, k, begin_i,  
+                                           buffer, j, buf_len, p);
+   }
+
+   if(p.order == H5Z_SCALEOFFSET_ORDER_BE) { /* big endian */
+      begin_i = (dtype_len - p.minbits) / 8;
+
+      for(k = begin_i; k <= p.size - 1; k++) 
+         H5Z_scaleoffset_compress_one_byte(data, data_offset, k, begin_i,  
+                                           buffer, j, buf_len, p);
+   }    
+}
+
+void H5Z_scaleoffset_compress(void *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;
+   int 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);
+}
+#endif /* H5_HAVE_FILTER_SCALEOFFSET */