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From: dce@smsc.sony.com (David Elliott)
Newsgroups: comp.sys.mac.programmer
Subject: Question: Putting structs in resources
Message-ID: <1990Sep5.145717.13291@smsc.sony.com>
Date: 5 Sep 90 14:57:17 GMT
Sender: dce@smsc.sony.com (David Elliott)
Organization: Sony Microsystems Corp, San Jose, CA
Lines: 28

As a Unix programmer, I've learned that it is usually a bad idea
to write the contents of a struct to a file, since there is no
way to know if every machine can read it back correctly.

As you may already know, data written on a big-endian machine,
such as a 680x0, will have a different format than on a little-endian
machine, such as a Vax or a DEC MIPS-based machine.

In addition, machines may have different alignment rules.  For example,
a Sun 3 (68020) allows a long (32 bit integer) to be aligned on
half-word (16-bit) boundaries, whereas the SPARC-based machines require
full-word alignment.  As a result, a struct written on a Sun 3 may have
to be handled specially when read back on a Sun 4 (a typical method is
to define the struct as containing shorts and then convert the shorts
to longs by copying).

Is it common practice to read and write structs as resources on the
Mac?  If so, is there any worry that these resources will not be
compatible if Apple were to go to a platform with different alignment
restrictions (I assume byte order isn't an issue)?  If not, what
is the recommended procedure for putting lots of data into a resource
and getting it back easily?

-- 
...David Elliott
...dce@smsc.sony.com | ...!{uunet,mips}!sonyusa!dce
...(408)944-4073
...Krusty says: Give a hoot, read a book!