Issue 2117:  telecom/98-10-05, IDL spec of SFP v1.0 (avstreams-rtf)
Source:  (, )
Nature:  Uncategorized Issue
Severity: 
Summary: Summary: the definition of struct fragment of module flowProtocol implies
 a waste of 4 bytes
 

Resolution: 
Revised Text: 
Actions taken:
October 21, 1998: received issue
Discussion: 
 received issue
End of Annotations:=====
Return-Path: <kath@informatik.hu-berlin.de>
Sender: kath@informatik.hu-berlin.de
Date: Wed, 21 Oct 1998 15:23:12 +0200
From: Olaf Kath <kath@informatik.hu-berlin.de>
Organization: HUB Comp Science; Research Dep Systems Analysis
To: avstreams-rtf@omg.org, issues@omg.org, juergen@omg.org
Subject: Issue with A/V Streams standard - waste of 4 bytes in struct
fragment

issue: the definition of struct fragment of module flowProtocol
implies
a waste of 4 bytes

In document number telecom/98-10-05,
IDL spec of SFP v1.0,
the struct fragment is defined as
    struct fragment
        {
        char magic_number [4];         // for  'F' 'R' 'A' 'G'
        octet flags;
        unsigned_long frag_number;
        ...
where magic_number and frag_number are aligned. That implies, that
after flags 3 bytes have to be included for alignment of frag_number.
Therefore, these 3 bytes are wasted. (Background: If one want to map
a SFP Fragment onto exectly one ATM cell payload, 3, better 4 bytes
are
quite a lot)

Proposed Solution:
Change the definition of fragment to
    struct fragment
        {
        char magic_number [3]    // for 'F' 'R' 'A'
        octet flags;
        unsigned long frag_number;
        ...
and one saves exactly 4 bytes.

--
 Olaf Kath
 Tel: +49 30 2093 3116  Fax: +49 30 2093 3112
 kath@informatik.hu-berlin.de
 http://www.informatik.hu-berlin.de/~kath