Re: Fw: BCD-lib
On 14 Apr 2002, at 9:36, petelomax at blueyonder.co.uk wrote:
>
> On Sat, 13 Apr 2002 21:15:59 -0500, Kat <gertie at PELL.NET> wrote:
>
> > The question is how will
> >Eu store the BCD bytes for us?
>
> Off the top of my head, a "short" BCD could be held in an integer,
> which is 31 bits. The natural scheme would be sign+ 7 nibbles
> (therefore seven significant digits), using 29 bits, leaving space for
> a 2-bit mantissa (therefore between 0 and 3 decimal places). That
> could accurately hold 0.001 or 9,999,999. The largest money value it
> could hold would be 99,999.99. Longer BCD values could be held as a
> sequence of n integers, with up to 7*n significant digits and 3*n
> decimal places.
>
> Alternatively, you explicitly specify how many decimal places you need
> at the start of the program and the routines return the shortest
> possible sequence which will hold the calculated result.
I prefer this, rather than locking the user to a limited number of digits on
either side of decimal. If someone really needs to measure the distance to
Alpha Centuri in angstroms, i'd let them. 
What i was worried about was that every nibble would take a 32bit integer in
Eu, making a large data store in memory impossible, like with storing strings
in sequences now.
Kat
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