comp.lang.idl-pvwave archive: archive » Re: call

Home » Public Forums » archive » Re: call_external for file I/O

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: call_external for file I/O [message #13219 is a reply to message #13213]

Thu, 22 October 1998 00:00

rivers
Messages: 228
Registered: March 1991

Senior Member

In article <70ldu6$i60@hacgate2.hac.com>, "Charlie Solomon" <crsolomon@west.raytheon.com> writes:
> Hello experts,
>
> Is anyone out there using call_external to read image files into a variable
> on the Windows NT platform? I have used a c routine on the Solaris platform
> called map_file, which bypasses the standard I/O layer and maps data
> directly into/from memory, making data access very fast compared to using
> IDL's built in file I/O utils. I did not write map_file, but my
> understanding is that it utilizes features in unix which allow this sort of
> memory mapping without going through the stdio layer. I would love to get
> the same speed on my NT machine. Any ideas?

I am not sure what you mean. Is the data actually in a disk file or is it in
memory? If it is in a disk file then some process needs to do the disk I/O.
If it is in memory then call_external can be used to get it into IDL.

Note that IDL's disk I/O on NT is quite fast. >5MB/sec is not hard to achieve
using writeu and readu.

____________________________________________________________
Mark Rivers (773) 702-2279 (office)
CARS (773) 702-9951 (secretary)
Univ. of Chicago (773) 702-5454 (FAX)
5640 S. Ellis Ave. (708) 922-0499 (home)
Chicago, IL 60637 rivers@cars.uchicago.edu (e-mail)

or:
Argonne National Laboratory (630) 252-0422 (office)
Building 434A (630) 252-0405 (lab)
9700 South Cass Avenue (630) 252-1713 (beamline)
Argonne, IL 60439 (630) 252-0443 (FAX)

Report message to a moderator

[Message index]

		Re: call_external for file I/O By: Charlie Solomon on Mon, 26 October 1998 00:00
		Re: call_external for file I/O By: David Foster on Mon, 26 October 1998 00:00
		Re: call_external for file I/O By: Charlie Solomon on Thu, 22 October 1998 00:00
		Re: call_external for file I/O By: rivers on Thu, 22 October 1998 00:00

Previous Topic:	Re: Finding "objects" in images
Next Topic:	Re: Anybody !!! Help me !!! About IDL!!! And ...

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sun Oct 12 09:38:01 PDT 2025

Total time taken to generate the page: 1.76203 seconds