[Info-vax] Kednos PL/I

[Johnny Billquist]

On 2023-09-14 13:18, Andreas Gruhl wrote:
> Arne Vajhøj schrieb am Donnerstag, 14. September 2023 um 02:53:20 UTC+2:
>> 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.
> Sorry Arne, but I would prefer to say yes.
> Since Alpha can only deliver 64 bits per instruction, you have to use two of them:
> MULQ for the lower 64 bits and then UMULQ for the upper 64 bits.
> Andreas

It's UMULH, but I agree. The Alpha was definitely designed for getting a 
128 bit result from 64 bit multiply. But it is done via two 
instructions. MULQ;UMULH. If you want a signed MUL, you then need a 
couple of more steps to adjust the result. But it's a simple thing.

   Johnny