On 09/03/2011 06:11 AM, Philipp Klaus Krause wrote:
> Would you be interested in seeing support for some so-called
> undocumented Z80 instructions in sdcc? This would be available via a
> command-line switch, that would allow sdcc to generate the following:
>
> adc a, ir
> add a, ir
> and a, ir
> cp a, ir
> inc ir
> ld ir, ir'
> ld ir, n
> ld ir, r
> ld r, ir
> or a, ir
> sbc a, ir
> sub a, ir
> xor a, ir
>
> Where ir/ir' is iyh or iyl, and r is a, b, c, d or e, and n is an 8-bit
> immediate.
>
> For targets that support them this could result in slightly smaller and
> faster code since it allows more flexible use of iy.
>
> AFAIK most softcore implementation of the Z80 officially support them,
> and they just work on most other implementations as well, even where
> this is not documented.
I would say definitely yes, but control their use with a compiler option.
When the Z80 was considered a mainstream processor for
general-purpose computing, in the CP/M era, lots of software, both
commercial and otherwise, used the undocumented instructions. Just sayin'..
-Dave
--
Dave McGuire
Port Charlotte, FL
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