L (was Re: D)

[Steve Smith]

On Tue, Jun 25, 2019 at 10:20 PM glen herrmannsfeldt 
wrote:

> Someone wrote:
>
> > Thought it was a double word
>
> > As in DS D
>
> It is a doubleword, specifically a long (64 bit)  floating point type.
>
> And yes,
>
>  DS  D
>
> and
>
>   DS 0D
>
> are commonly used when floating point is not intended.
>
> And as Fortran programmers would know, E is the short (32 bit) floating
> point type.
>
> Now that I think about it, I don’t remember the assembler notation for 128
> bit
> (extended precision) floating point constants, though am pretty sure that
> it
> isn’t the Q that IBM and DEC  Fortran uses.
>
> I suppose I don’t see anything wrong with 0D for doubleword alignment,
> even when
> not for floating point data.  Probably better not to use D or 2D or
> others, though.
>
> D would be the one that needed doubleword alignment for OS/360, and so its
> use
> goes back that far.  One could use FL8 for fixed point data, but I suspect
> without
> doubleword alignment.



-- 
sas

D

[glen herrmannsfeldt]

Someone wrote:

> Thought it was a double word 

> As in DS D

It is a doubleword, specifically a long (64 bit)  floating point type.

And yes,

     DS  D
 
and 

  DS 0D

are commonly used when floating point is not intended. 

And as Fortran programmers would know, E is the short (32 bit) floating point 
type.

Now that I think about it, I don’t remember the assembler notation for 128 bit
(extended precision) floating point constants, though am pretty sure that it
isn’t the Q that IBM and DEC  Fortran uses.

I suppose I don’t see anything wrong with 0D for doubleword alignment, even when
not for floating point data.  Probably better not to use D or 2D or others, 
though.

D would be the one that needed doubleword alignment for OS/360, and so its use
goes back that far.  One could use FL8 for fixed point data, but I suspect 
without
doubleword alignment.