Re: [Amforth] bset and bclr

[Matthias T. <mt...@we...>]

Hi,

> I whas reading the German "das Fort magazin, vierte Dimension" and
> find two interesting commands for manupulating on a simple way
> individual bits with bset and bclr.
> 
> Why are these not implemented in amForth?. Is thebsource for these
> two available?

Within the core/words directory you can find three files:
bm_set.asm bm_clear.asm and bm_toggle.asm which should do,
what you expect (and they are compatible with the bitname.frt
structures and are implemented in assembly for speed reasons).

bm-set will set all bits at the specified RAM Address that
are set in the bitmask. bm-clear will clear all thoses bit
positions and bm-toggle, well you'll guess yourself ;)

I prefer the bitmask over a bitnumber simply because it
can deal with more bits in one operation. Expanding the
bitmask to more than 8bits is a little bit dangerous since
both the pure action of reading/writing and the order of
the read/write operations may be important in some cases.

The bclr and bset commands Michael mentioned are basically the
same, but we could not (yet) agree on a common name....

HTH
Matthias