Re: [f-cpu] (!) a few noteworthy things

[Ben Franchuk <bfranchuk@jetnet.ab.ca>]

Yann Guidon wrote:
 
> personal notes :
>  a) is possible but a bit complex.
>  b) is simpler but still requires a mux (so a) would be the same)
>  c) is a bit like b but the sign must be propagated :
>      more complex because we must choose between at least
>     3 sign bits (corresponding to a 8, 16 and 32-bit result)
>  d) is plain simple and would be a choice except that it would confuse compilers
>  e) is a "failsafe" solution that would allow the implementor to choose between
>     a), b), c) and d) on a case-per case basis. This is some more pressure on the
>     compiler but i guess it's still manageable.

But would selection of what happens depends on just what is meant 
by a byte and just what you are doing? Unless you are packing bytes
for something like byteswap why is a internal representation of
bytes needed on a modern machine? The 8008 had load H,# and load L,#
and load a,(HL) because the machine could only process bytes? 
No wait this is a RISC machine age !! You can't have 32,64?? bit
immediate
constant in the next word! Other than stupid Immediate packing because
of a brain dead achitecure design all data should be converted to 32
or 64 bit  internal format upon loading and not adjusted in the register
bypass.

-- 
Ben Franchuk - Dawn * 12/24 bit cpu *
www.jetnet.ab.ca/users/bfranchuk/index.html
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