| Re: C Alignment/IDL structures [message #43159 is a reply to message #43098] |
Mon, 21 March 2005 08:56   |
joey
Messages: 5
Registered: March 2005
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Junior Member |
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Randall Skelton <randall.skelton@gmail.com> wrote:
> I'm not sure I completely understand what you are doing... can you post
> a snipit of code? I trust that you are passing back an unnamed
Here's my code that does the IDL/C interaction. I have a vector (_dataIDL)
which has all the values I want into IDL within it as a malloc'ed sets of
memory.
// Copy the real data
unsigned long pos = 0;
unsigned char *myStructureThatLooksLikeTags = malloc (_totalSpaceNeeded
* _dataIDL.size ());
for (unsigned int i = 0; i < _dataIDL.size (); i++) {
memcpy (&(myStructureThatLooksLikeTags [pos]), _dataIDL [i],
_totalSpaceNeeded);
pos += _totalSpaceNeeded;
}
char idl_struct_name [100];
sprintf (idl_struct_name, "%s_K%ld_V%d", dbVirtualName (data_key),
data_key, version);
void *idl_struct = IDL_MakeStruct (idl_struct_name, tags);
IDL_LONG dims;
dims = _dataIDL.size (); // number of elment in the array of structures
IDL_VPTR ivReturn = IDL_ImportArray (1, &dims, IDL_TYP_STRUCT,
myStructureThatLooksLikeTags,
cleanUpIDL, idl_struct);
> In general, when I have to pass C structures from existing code back to
> IDL I do it by creating a shadow structure (in C) that uses all the
> defined IDL types and copying the data. You really cannot rely on
> generic C variables having the same size as thier IDL counterparts
> (take a look at the definition of IDL_ALLTYPES in idl_export.h).
Ok, this probably answers my question. I was hoping I could create an array
of structs, but this is maybe not so memory efficient so I might try to
create one structure with multiple arrays.
Joey
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