[boost] Re: Fixed-Point Decimal Formal Review

From: Dirk Schreib (Dirk.Schreib_at_[hidden])
Date: 2003-07-25 01:50:03

Hello Mike,

I completly agree with your your statement.

> The IEEE 754 revision committee has added decimal formats (32, 64,
> and 128 bits) to the proposed new Floating-point standard, along
> with full DFP arithmetic.

> May I suggest that the class be changed to implement the proposed IEEE
> 754 arithmetic?  This would be a tremendous contribution, and it could
> even use the existing representation (perhaps expanded to 128 bits), or
> it could use the proposed IEEE 754 layouts.  The latter offers the
> possibility of changing the class later to take advantage of the
> hardware DFP when that becomes available.

We used the proposed IEEE754 layouts for our own number class
with some minor changes. The proposed format seems to be ideal
for hardware but was a little bit to slow for a pure software
implementation.

For every feature in the specification we asked "Is there a performance
penalty even if I don't use this feature" and removed it if necessary.
The resulting class is quite fast (not as fast as a fixed point decimal
class).

Dirk