[Info-vax] Kednos PL/I

[Arne Vajhøj]

On 9/13/2023 4:53 PM, gah4 wrote:
> On Wednesday, September 13, 2023 at 12:28:45 PM UTC-7, Arne Vajhøj wrote:
> (snip, I wrote)
>>> Does Alpha have 64 bit multiply and divide?
> 
>> In instruction set?
> 
>> Multiply: yes.
> 
> With 128 bit product?

No.

>> Division: no. But obviously you can divide two 64 bit integers in your
>> favorite HLL.
> 
> But PL/I allows for a scaling factor for FIXED BIN values.
> That often requires a shift before the divide, so you really want a double
> length dividend and product for divide and multiply instructions.
> 
>>> I even forget now, does x86-64 hardware have multiply and divide with 128 bit
>>> product and dividend?
> 
>> I don't think so.
> 
> It has been usual for a long time, for hardware to have multiply and divide with
> double length product and dividend.  Many algorithms depend on that, though few
> HLLs have a way to do it.  (Other than call an assembly language routine.)
> 
> It seems that 64 bit processors don't all do it.

Big integers in software is pretty standard today. You can get
128 or 245 or 512 or 1024 bit integers or whatever if you want to.
In software. And on todays hardware it will be pretty fast anyway.

Arne