Anyone familiar with VData tables in HDF? (fwd)

[msolomon1]

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Subject: Anyone familiar with VData tables in HDF?

We're having a problem with some old software that attempts to set up a
Vdata table using HDF functions VSsetfields(), VSsetname() and
Vinsert(). If anyone happens to be familiar with the process of
initializing VData tables, please send me some email, as you could probably
save us a great deal of time diagnosing this!
RE




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[jjohnson1]

> Subject: Anyone familiar with VData tables in HDF?
>
> We're having a problem with some old software that attempts to set up a
> Vdata table using HDF functions VSsetfields(), VSsetname() and
> Vinsert(). If anyone happens to be familiar with the process of
> initializing VData tables, please send me some email, as you could probably
> save us a great deal of time diagnosing this!
> RE
>

First, Vinsert is for Vgroups, not Vdata. You should use VSwrite to (obviously)
write a Vdata. Here is a sample:

#include "hdf.h"

main(int argc, char *argv[])
{
intn status;
int32 Hid, VSid;
uint8 *buffer;

/* Open and create file (0 = default number of data descriports per block) */
Hid = Hopen(argv[1], DFACC_CREATE, 0);

/* Initialize the V interface */
status = Vstart(Hid);

/* Initialize the VS interface, index -1 (create new) for Vdata */
VSid = VSattach(Hid, -1, "w");

/* Set name for this Vdata */
status = VSsetname(VSid, "Vset_1");

/* Define and set the field names for this Vdata */
status = VSfdefine(VSid, "Field_1", DFNT_FLOAT32, 1);
status = VSfdefine(VSid, "Field_2", DFNT_INT16, 5);
status = VSfdefine(VSid, "Field_3", DFNT_FLOAT64, 1);
status = VSfdefine(VSid, "Field_4", DFNT_UINT8, 20);
status = VSsetfields(VSid, "Field_1,Field_2,Field_3,Field_4");

/* Optionally, you could define some field level and/or Vdata table level
* attributes with VSsetattr
*/

/* Allocate memory for the Vdata */
buffer = calloc(10, 1*sizeof(float32) + 5*sizeof(int16) +
1*sizeof(float64) + 20*sizeof(uint8));

/* Write out the Vdata */
status = VSwrite(VSid, buffer, 10, FULL_INTERLACE);

free(buffer);

/* Detach from the Vdata */
status = VSdetach(VSid);

/* Shut down the V interface */
status = Vend(Hid);

/* Finally, close the file */
status = Hclose(Hid);

exit(0);
}

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