[DFDL-WG] DFDL Expressions and hex literal constants

[Steve Hanson]

So I think DFDL needs to add such functions to its list of functions in 
23.5.3.

Regards

Steve Hanson
Architect, IBM Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848



From:   Tim Kimber/UK/IBM at IBMGB
To:     dfdl-wg at ogf.org, 
Date:   13/06/2013 11:27
Subject:        Re: [DFDL-WG] DFDL Expressions and hex literal constants
Sent by:        dfdl-wg-bounces at ogf.org



XPath uses XML schema lexical formats for all simple types. The XML Schema 
lexical format for an integer does not allow a hexadecimal option. 
The standard solution is to create a pair of custom XPath functions that 
convert between hex and decimal lexical formats. But that's not a viable 
solution for a DFDL modeller because they cannot define custom XPath 
functions. 

regards,

Tim Kimber, DFDL Team,
Hursley, UK
Internet:  kimbert at uk.ibm.com
Tel. 01962-816742 
Internal tel. 37246742




From:        Steve Hanson/UK/IBM at IBMGB 
To:        Mike Beckerle <mbeckerle.dfdl at gmail.com>, 
Cc:        dfdl-wg at ogf.org, dfdl-wg-bounces at ogf.org 
Date:        13/06/2013 10:39 
Subject:        Re: [DFDL-WG] DFDL Expressions and hex literal constants 
Sent by:        dfdl-wg-bounces at ogf.org 



Mike 

I think there might be a wider problem in specifying any hex in XPath 
expressions.  Tim's been looking into this as part of an IBM DFDL defect. 

Regards

Steve Hanson
Architect, IBM Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848 



From:        Mike Beckerle <mbeckerle.dfdl at gmail.com> 
To:        dfdl-wg at ogf.org, 
Date:        13/06/2013 00:24 
Subject:        [DFDL-WG] DFDL Expressions and hex literal constants 
Sent by:        dfdl-wg-bounces at ogf.org 




I haven't found a way in XPath to specify a hexadecimal integer number.

E.g., I want to write expressions like 
{ if (../magicNum eq 0xa1b2c3d4) then 'bigEndian' 
 else if (.../magicNum eq 0xd4c3b2a1) then 'littleEndian'
   else error()
}

But it rejects the 0x notation. Do I really have to write decimal 
everywhere? When dealing with binary data this is a bit of a nightmare.

I think the above code is clear to anyone, but if I convert those numbers 
to decimal it becomes completely obscure. 

...mike

-- 
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | 
www.tresys.com
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Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
--
  dfdl-wg mailing list
  dfdl-wg at ogf.org
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741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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