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Re: Modifying an array while conserving memory [message #30970 is a reply to message #30875]

Fri, 24 May 2002 04:45

Randall Skelton
Messages: 169
Registered: October 2000

Senior Member

On 23 May 2002, Craig Markwardt wrote:

> At one time I devised a set of functions called ARRINSERT and
> ARRDELETE, in which I tried to do insertion and deletion operations as
> efficiently as I thought possible.
>
> I don't think I was able to get around your concern of necessarily
> allocating at least as much storage as the original data. What is
> really needed at the IDL internal level, is the ability to **augment**
> the storage of an existing array efficiently. I tend to do that alot,
> say when I'm building a list element by element.

It seems this will be my 3rd feature request of the week as my long-shot
attempts at using realloc on an IDL passed array have failed miserably :(

Cheers,
Randall

--
void IDL_CDECL am_resize(int argc, IDL_VPTR argv[], char *argk) {

/* Local */
float *A;
long n, l;

/* IDL inputs: Ensure we get a float array from IDL */
IDL_ENSURE_ARRAY(argv[0]);

if (argv[0]->value.arr->n_dim != 1) {
IDL_Message(IDL_M_NAMED_GENERIC, IDL_MSG_LONGJMP,
"Passed array must only contain one dimension");
}

if (argv[0]->type != IDL_TYP_FLOAT) {
IDL_Message(IDL_M_NAMED_GENERIC, IDL_MSG_LONGJMP,
"Passed array must be of float precision");
}

/* Get a local pointer to the passed array */
A = (float *) argv[0]->value.arr->data;

/* Get number of elements */
n = (long) argv[0]->value.arr->n_elts;

/* IDL inputs: Ensure we get a scalar from IDL */
IDL_ENSURE_SCALAR(argv[1]);

/* Handle different precisions for new length */
switch (argv[1]->type) {
case IDL_TYP_FLOAT: l = (long) argv[1]->value.f;
break;
case IDL_TYP_DOUBLE: l = (long) argv[1]->value.l;
break;
case IDL_TYP_INT: l = (long) argv[1]->value.i;
break;
case IDL_TYP_LONG: l = (long) argv[1]->value.l;
break;
default: IDL_Message(IDL_M_NAMED_GENERIC, IDL_MSG_LONGJMP,
"Type of passed length not recognized");
}

/* printf("Got: %li elemnts. New length: %li.", n, l); */

/* Watch me Seg fault... */
if (realloc(A, 0) == NULL) {
IDL_Message(IDL_M_NAMED_GENERIC, IDL_MSG_LONGJMP,
"Cannot allocate memory");
}

/* Reset the number of elements in the IDL variable structure */
/* argv[0]->value.arr->n_elts = (IDL_MEMINT) l; */

}

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[Message index]

		Re: Modifying an array while conserving memory By: R.Bauer on Fri, 24 May 2002 02:49
		Re: Modifying an array while conserving memory By: Randall Skelton on Fri, 24 May 2002 02:06
		Re: Modifying an array while conserving memory By: R.Bauer on Thu, 23 May 2002 23:44
		Re: Modifying an array while conserving memory By: Craig Markwardt on Thu, 23 May 2002 20:03
		Re: Modifying an array while conserving memory By: David Fanning on Thu, 23 May 2002 19:58
		Re: Modifying an array while conserving memory By: Pavel A. Romashkin on Fri, 24 May 2002 09:33
		Re: Modifying an array while conserving memory By: Randall Skelton on Fri, 24 May 2002 04:45

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