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[RFC][PATCH] Prototype for extended printf hooks
- From: "Ryan S. Arnold" <rsa at us dot ibm dot com>
- To: libc-help <libc-help at sourceware dot org>, Jakub Jelinek <jakub at redhat dot com>
- Cc: Ulrich Weigand <Ulrich dot Weigand at de dot ibm dot com>, Stewart Katherine-ra4863 <K dot Stewart at freescale dot com>, "H.J. Lu" <hjl at lucon dot org>, Steven Munroe <munroesj at us dot ibm dot com>, Andreas Krebbel1 <Andreas dot Krebbel at de dot ibm dot com>
- Date: Fri, 22 Aug 2008 16:45:10 -0500
- Subject: [RFC][PATCH] Prototype for extended printf hooks
- Organization: IBM
- Reply-to: rsa at us dot ibm dot com
Jakub, libc-help, et al.
The linked patch (a GLIBC bugzilla attachment) is a prototype patch
which adds fully featured printf hooks to GLIBC to support the C-spec
Draft extension data types: DFP, Altivec/VMX, and VSX.
http://sourceware.org/bugzilla/attachment.cgi?id=2922&action=view
The highlights of this patch are the callback functions which allow
recognition of overridden format specification characters and the va_arg
callback function that allows an override to use va_arg to peel an
overridden data type off of the printf argument list.
I'm guiding development of these hooks in the GLIBC bugzilla where I've
also presented a discussion of some of the criteria and challenges:
http://sourceware.org/bugzilla/show_bug.cgi?id=6846
Included in the bugzilla are some samples of how I use this code to
achieve printf support in the decimal floating point library.
Please realize that this is prototype code that I'm using a proof of
concept. It is quite crude in place but I just wanted to demonstrate an
effective direction that these hooks can go.
Any comments on my implementation can take place in this email thread or
in the bugzilla.
Ryan S. Arnold
IBM Linux Technology Center
Linux Toolchain Development