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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: Bit operators
Date: 2000/02/13
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Date: 2000-02-13T00:00:00+00:00
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In article <884o85$jjv$1@news.fsu.edu>,
  grant@cs.fsu.edu (Joshua Grant) wrote:
> I was recently assigned a project for one of my classes that
gave us the
> option of implementing a simplified MIPS assempler in any
preferred higher
> level language.  I have choosen ADA, but I am running into a
problem with
> the bit operators.  I can't find them!  In case someone isn't
sure of my
> question.  In C++ if you perform an 'and' operation with the
'&'
> operator like...

All the answers you got were inappropriate (a not uncommon
occurrence around here :-) :-)

You approached the problem with a "how-do-I-write-C-in-Ada"
viewpoint, and three people answered you to tell you how :-)

But the proper answer is to use the features of Ada that allow
this to be done nicely without such nasty low level gizmos.

MIPS assembly instructions have a very regular format, there
are only a very few instruction formats.

For each of these define a record type, with nicely typed fields
and then use a record representation clause to lay out the
record in a manner that matches the MIPS layouts (you may have
to worry about endian considerations here, but the same is
true using the low level C approach anyway).

Now you assign to the fields of this record with full type
checking, e.g. if you try to put an immediate value in a
register field, you will get a compile time error.

There is no point in writing C in Ada, if you want to write
C, write C in C, it is less trouble :-)


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