RE: Bytes Swapping in iSeries

["John Brandt Sr." <pgmr@xxxxxxxxxxxxxxx>]

Lakshmi,
As Scott said, the problem is not on your end. Modifying your program will
damage the ability to use this interface with any other Non-PC client. The
problem is that the PC is not a Big-Endian machine and the transform does
nothing because the system is already in network order.

******************************
Big-endian
The adjectives big-endian and little-endian refer to which bytes are most
significant in multi-byte data types and describe the order in which a
sequence of bytes is stored in a computer's memory.
In a big-endian system, the most significant value in the sequence is stored
at the lowest storage address (i.e., first). In a little-endian system, the
least significant value in the sequence is stored first. For example,
consider the number 1025 (2 to the tenth power plus one) stored in a 4-byte
integer:

00000000 00000000 00000100 00000001
Address Big-Endian representation of 1025       Little-Endian representation
of 1025
00            00000000                            00000000 
01          00000100                            00000001
02          00000001                            00000100
03          00000000                            00000000

Many mainframe computers, particularly IBM mainframes, use a big-endian
architecture. Most modern computers, including PCs, use the little-endian
system. 

Taken from:
http://www.webopedia.com/TERM/b/big_endian.html

John Brandt
iStudio400.com


-----Original Message-----
From: srilaxmi@xxxxxxx [mailto:srilaxmi@xxxxxxx]
Sent: Monday, February 09, 2004 9:59 PM
To: RPG programming on the AS400 / iSeries
Cc: RPG programming on the AS400 / iSeries;
rpg400-l-bounces@xxxxxxxxxxxx
Subject: Re: Bytes Swapping in iSeries



Hi Scott,

I understood what you are saying. My problem is the third party(PC) they do
not want to do the bytes swapping, so my end (On AS/400) need to do the
swapping and send.Is there any other way to do the bytes swapping on
AS/400.

Thanks
Lakshmi



 

                    Scott Klement

                    <klemscot@klements.        To:     RPG programming on
the AS400 / iSeries    
                    com>                       <rpg400-l@xxxxxxxxxxxx>

                    Sent by:                   cc:

                    rpg400-l-bounces@mi        Subject:     Re: Bytes
Swapping in iSeries        
                    drange.com

 

 

                    10/02/2004 11:35 AM

                    Please respond to

                    RPG programming on

                    the AS400 / iSeries

 

 






I already explained this to you off-list, but I'll explain it again here:

   htons converts from host byte-order to network byte-order.
   ntohs converts from network to host.

The byte order used by the iSeries is the SAME as the byte order used by
the network -- therefore htons and ntohs are NO-OPs.  They do nothing.

It's the PC that uses a different byte order from the network.  It's the
PC program that needs to call htons, not your RPG program.


On Tue, 10 Feb 2004 srilaxmi@xxxxxxx wrote:
>
> I have a ILERPG Socket program, that sends data in the form of data
> structures to the third party API (written in delphi). The data is
> transmitting fine, but reaching in different format.
>
> Example :
>
> Input:
> Field A = 0         200
>           1st Byte       2nd Byte
>
> Where the Field A is declared as Unsigned 5 U 0 in RPG Pgm.
> When it transmit over a socket, the bytes are swapping and becoming 200
0.
>
> Result:
> Field A = 200       0
>           1st Byte       2nd Byte
>
> This is the problem I am getting. To do the bytes swapping, Can I use
htons
> () in RPG Pgm. If yes, please explain with examples.
>
> Thanks & Regards
> Lakshmi
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