That might be frought with other issues...
For example, what does this mean?
A EQU32 1
B EQU64 2
C EQU32 (A + B)
Is the addition of A+B conducted as a 64-bit addition or a 32-bit one?
What is the result type of that addition? If the result type is 64-bit
what is the meaning of assigning the 64-bit value to a 32-bit value?
In this example, with the values "1" and "2" - it might not matter
too much, but what about this:
A EQU32 X'7FFFFFFF'
B EQU64 1
C EQU32 (A + B)
what is the value in C? And, what would be the value of this:
D EQU64 (A + B)
And... then, what is the value of this:
E EQU32 1
...
E EQU64 1
My point being that in the introduction of a type system,
you have to be careful to define semantics of operations on those
types.
Typically - a type system includes:
1) A way to create data of the type.
2) Operations on those types.
3) A way to destroy data of the type.
Doing only #1 doesn't really solve the problem... I don't think.
However - if you did do a type on LCL and GBL, then you are
declaring data of the type (#1) and since the definition of LCL and GBL
define when the data is destroyed, you have solved #2. All we
need to do is define #3... some simple rules might suffice (along
the lines of something similar to C's default promotion rules???)
Something like - if either operand is 64-bits, the result is 64-bits,
otherwise the result is 32-bits. 32-bit values are sign-extended
to become 64-bit values.
The storage of a 64-bit value to a 32-bit value simply truncates,
the storage of a 32-bit value does sign-extension to the 64-value.
Just some thoughts....
- Dave Rivers -
>
> That's just what I was considering for HLASM, but we ran out of time etc.
> John Ehrman
> (------------------ Referenced Note Follows --------------------)
> Date: Sun, 6 Jul 2014 01:14:03 -0400
> From: Tony Harminc <[email protected]>
> Subject: Re: HLASM doubleword set-symbol arithmetic
>
> On 5 July 2014 11:55, Paul Gilmartin
> <[email protected]> wrote:
> > A less 'easy' alternative would be to introduce types, and associated
> > instructions: GBLA32, GBLA64, SETA32, SETA64, EQU32, EQU64, ...
>
> If someone for some reason decided to do it this way, I'd expect GBLG,
> SETG, and so on...
>
> Tony H.
>
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