Re: Calculate and set Parity

[Jeffrey Carter <jrcarter@acm.org>]

Sebastian wrote:
> I need a subroutine that calculates the parity of a record type with the
> size of 16 bits. Is there some nice way
> to do this? I currently have a solution were I use Unchecked_Conversion to
> convert my variable to an
> array booleans, then I calculate every true etc. Is there some way to do
> this without using Unchecked_Conversion.

Well, you could always try

* using a machine code insertion
* using an imported C subprogram
* passing an address and size

but it you want it to be safe and readable, unchecked conversion to an 
array of Boolean seems like a good way to go. You then simply add up the 
Boolean'Pos of each element and determine if the result is even or odd 
("rem 2"). You could do an unchecked conversion to a 16-bit modular type 
and use shifts and masks to isolate the individual bits, but using 
Booleans seems simpler.

-- 
Jeff Carter
"Oh Lord, bless this thy hand grenade, that with it thou
mayst blow thine enemies to tiny bits, in thy mercy."
Monty Python and the Holy Grail