Frank Hofmann <[EMAIL PROTECTED]> wrote:
> I'm looking for a generic opinion on the use of "#pragma pack" for writing
> Solaris code. I know it's useful for device register sets, or data structures
> that don't follow ABI layout rules.
Do you know ot hardware that needs registers to be read/written in chunks > one
byte?
> We use #pragma pack(4) at a few places in Solaris (for example, the SVM
> on-disk
> layout data structures on Solaris/x86).
>
> Should such a use be allowed or discouraged for new code ? I.e. if I have a
> data structure that is packed (no padding, contains misaligned multibyte
> entities), should I better write a convertor function or were it ok to use
> #pragma pack(1) ?
The clean and portable way is to have character arrays in structures and to use
converting macros. Sparc processors cannot access unaligned data > one byte.
I know of only one case where obscure packing is needed and in this case even
#pragma pack(1) does not work:
It seems that gcc needs "__attribute__((packed))" past some structure
definitions
in order to avoid post structure padding for ARM processors.
Jörg
--
EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni)
[EMAIL PROTECTED] (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily
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