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Re: Endian-ness [message #29233]

Fri, 08 February 2002 13:18

Liam E. Gumley
Messages: 378
Registered: January 2000

Senior Member

Jonathan Joseph wrote:
> Is there a system variable that gives the endian-ness of the current
> hardware? I am reading a file which tells me the endian-ness of the
> data, and I'd like to swap_endian if it is different from the current
> hardware. In lieu of finding a system variable to compare to, I have
> done this:
>
> test_int = 1
> byteorder,test_int,/ntohs
> big_endian = test_int eq 1
>
> "network" byte order is big-endian, so I convert a 1 to the host
> byte-order and see if it's still a 1.
>
> This way works fine, but it seems as thought I'm missing something.
> Is there a better way? Using the byteorder routine to convert the data
> is not an option (unless it's been improved for 5.5).

;---
FUNCTION BIG_ENDIAN

;- Returns true (1B) if the host platform is big endian
;- (most significant byte first)

return, 1B - byte(1L, 0L)

END
;---
FUNCTION LITTLE_ENDIAN

;- Returns true (1B) if the host platform is little endian
;- (least significant byte first)

return, byte(1L, 0L)

END
;---

IDL Version 5.3 (IRIX mipseb). (c) 1999, Research Systems, Inc.
IDL> print, big_endian(), little_endian()
1 0

IDL Version 5.3 (Win32 x86). (c) 1999, Research Systems, Inc.
IDL> print, big_endian(), little_endian()
0 1

Cheers,
Liam.
Practical IDL Programming
http://www.gumley.com/

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[Message index]

		Re: Endian-ness By: Liam E. Gumley on Fri, 08 February 2002 13:18
		Re: Endian-ness By: David Fanning on Fri, 08 February 2002 13:14
		Re: Endian-ness By: Jonathan Joseph on Mon, 11 February 2002 07:16
		Re: Endian-ness By: george.mccabe on Wed, 20 February 2002 11:48

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