Re: how to do bit-wise operation on none modular types?

[dennison@telepath.com]

In article <7bjjck$25t7@news1.newsguy.com>,
  Samuel Mize <smize@imagin.net> wrote:
> Bill,
>
> If your status is a positive number, Tucker's answer is good.  (Of course.)
>
> If not -- for instance, if it's a bitmap of status values and the sign
> bit is used -- you'll have to use unchecked conversion.  Make sure the
> unsigned type and the signed type are the same size, and use an instance
> of Unchecked_Conversion to convert the signed type to the modular type.

If this value comes directly from a "pragma import"ed routine, you have
another option. Just change the type of the parameter to a type that would
work better for you (modular integer, packed array of boolean, whatever).
Just make sure the type is the same size as C's "int". Putting a 'size clause
on the type's declaration will enforce this by causing a compilation error
when it won't fit.

> Some people prefer to convert to a packed array of booleans if they're
> working with a boolean bitmap, as they feel it makes the rest of the
> code clearer.

I'm definitely one of those. I just showed a developer here how to do that
this morning. Being an old Fortran guy, he liked it better than how C had him
do it, because it resembled the "btest" call he used to make in Fortran.

T.E.D.

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