| Re: Returning a struct containing variable-length arrays [message #62528 is a reply to message #62527] |
Tue, 16 September 2008 14:11   |
franzpx125
Messages: 6
Registered: September 2008
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Junior Member |
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On 16 Set, 15:37, Mike <Michael.Mill...@gmail.com> wrote:
> On Sep 15, 6:28 pm, franzpx125 <franzpx...@gmail.com> wrote:
>
>> Hi!
>
>> Within my DLM, I need to return a struct containing two arrays but the
>> length of the arrays is known only at run-time. Which is the correct
>> way to write the DLM code?
>
> You can put avariable lengtharray into a structure by putting a
> pointer to the array in the structure:
>
> result = { x: x, y: y, ptr: ptr_new()}
> ...
> result.ptr = ptr_new(data)
> return, result
>
> I don't know if there are any DLM issues that will affect this, but it
> works well forvariable lengtharrays in objects and other structures.
>
Thanks for your reply. I don't know if it's the correct way to perform
this task, anyway I've tried the following workaround and it works.
I'll post the code if you're interested in:
IDL_VPTR idl_out_struct;
unsigned int* rev_x;
double* rev_y;
unsigned int num_el;
void* s;
IDL_LONG tmp_dims[IDL_MAX_ARRAY_DIM];
IDL_MEMINT offset;
double* y_ptr;
unsigned int* x_ptr;
char* s_data;
int i;
/* .... omitted code .... */
// Format struct for IDL output:
REV_tags_dims[0] = 1;
REV_tags_dims[1] = num_el;
s = IDL_MakeStruct("REV", REV_tags);
tmp_dims[0] = 1;
s_data = (char *)IDL_MakeTempStruct(s, 1, tmp_dims,
&idl_out_struct, 0);
// Get the field of the structure:
offset = IDL_StructTagInfoByName(s, "Y", IDL_MSG_LONGJMP, NULL);
// Get a pointer to that location:
y_ptr = (double *)(s_data + offset);
// Store values into array:
for ( i = 0; i < num_el; i++)
*(y_ptr++) = rev_y[i];
// Get the field of the structure:
offset = IDL_StructTagInfoByName(s, "X", IDL_MSG_LONGJMP, NULL);
// Get a pointer to that location:
x_ptr = (unsigned int*)(s_data + offset);
// Store values into array:
for ( i = 0; i < num_el; i++)
*(x_ptr++) = rev_x[i];
// Return output in IDL Format:
return idl_out_struct;
Any criticism is well accepted.
Regards,
Brun Francesco
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