I believe the correct interpretation is 0 and -1. Not keen on re-interpreting this as 0 and 1. I am ok with a schema definition error. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: Steve Hanson/UK/IBM@IBMGB, Cc: dfdl-wg@ogf.org Date: 11/12/2012 16:45 Subject: Re: [DFDL-WG] needed: signed bit fields Doesn't seem to say what happens if type is signed, but length in bits is 1. Can we make this an SDE please, since it can't be interpreted as a twos-complement integer? Alternatively, can we clarify that if the length is 1, the bit is interpreted as if there was a sign bit of 0? When people write: <element name="myBit" type="xs:int" dfdl:length="1"/> I am pretty sure they aren't expecting values of 0 or -1. They're expecting 0 or 1. ...mikeb On Tue, Dec 11, 2012 at 3:46 AM, Steve Hanson <smh@uk.ibm.com> wrote: Errata 2.90. Sections 12.3, 12.3.7.2. Additionally allow lengthUnits 'bits' to apply to binary signed integer types, to support the modeling of signed integer bit fields in the C language. The physical bits are interpreted as a two's complement integer. Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: dfdl-wg@ogf.org, Date: 10/12/2012 21:42 Subject: [DFDL-WG] needed: signed bit fields Sent by: dfdl-wg-bounces@ogf.org current DFDL v1.0 spec says bit fields are all unsigned integers up to length 64. I am modeling data that uses lots of twos-complement 24-bit long and other length signed integers on various bit-boundaries. Was there a reason to leave signed twos-complement out for bit fields (other than perhaps just we thought we might get away with it?) The only corner case I can think of is if you make a 1-bit wide signed bit field. This should be a Schema Defintion Error I believe, because twos-complement isn't defined unless you have at one sign bit, and at least 1 mantissa bit. ...mikeb -- Mike Beckerle | OGF DFDL WG Co-Chair | Tresys Technologies Tel: 781-330-0412 -- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg 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 -- Mike Beckerle | OGF DFDL WG Co-Chair | Tresys Technologies Tel: 781-330-0412 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