On Thu, Mar 08, 2001 at 04:28:48PM -0500, Dan Sugalski wrote:
> At 08:43 PM 3/8/2001 +0000, Nicholas Clark wrote:
> I think most processors that do 32x32 multiply provide a way to get the
> 64-bit result. Whether *we* can is another matter, of course, but if
> platform folks want to drop to assembly I'm fine with that.
Yeah. Cool. :-)
Much code to maintain :-(
> The potential vagaries of platform math is why I was thinking of 31-bit
> things, because then all you need do is:
>
> int overflow = 0x80000000 & (c = a + b)
>
> which isn't quite so clever, but still not too bad. :)
Do we need to settle on 31 or 32 at this point?
Do we need to settle on anything - can it vary by platform so that 64 bit
platforms can use 64 bit, in which case the 32/31 choice could even be by
platform (or always 32 if we find it works well)
Nicholas Clark
