Re: [Sdcc-user] Z80 --std-c99 and _Bool results in larger code size and slow speed

[Philipp K. K. <pk...@sp...>]

Am 07.12.2010 16:16, schrieb Lin Rongrong:
> Just tested rev #6078, with TestBoolean function, the compiled size are the 
> same now, and "_Bool" is 4ms faster than "unsigned char".

On an original Z80 _Bool should be exactly three clock cycles faster per
loop iteration in your example. In terms of speed this is the main
advantage of _Bool over unsigned char: saving three clock cycles each
time we use it as a condition, be it in the ternary operator, an if/else
or some other control mechanism.

> Really a fast fix.
> But I am still uncomfortable with "_Bool", as my overall code size is still 
> a little larger with "_Bool".

Well there probably are still some places where sdcc generates
unnecessary casts for _Bool, this will improve over time (and the
improvmeent will be faster when users report the issue on this list (as
you did) or as a feature request (which has the advantage of not being
forgotten as easily)).

Philipp