Re: [f-cpu] pointer add & sub

[cedric <cedric.bail@free.fr>]

> >> (you know, Whygee, you told me if I do "add 8,sp,sp",
> >> sp would no longer be considered as a pointer).
>
> I don't understand why, by the way.
>
> You could have the following :
>
> - add r3,r2,r1 => r1.pointer = r2.pointer XOR r3.pointer
> - sub r3,r2,r1 => r1.pointer = r3.pointer AND NOT r2.pointer
>
> (as for immediates, the obvious convention is imm8.pointer = false)
>
> So, unless there are useful exceptions to the above,
> you can get rid of special "memory pointer" operations.

In fact a pointer imply a TLB check, so it complicate really a lot the normal 
adder. In F-CPU it's more logical to add a new instruction that only with 
memory.

Cedric
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