> On 31-Jan-01 Matthew Emmerton wrote:
> > Hi all,
> >
> > I've taken a look around for an implementation of atomic bit operations
in
> > FreeBSD (similar to Linux' asm/bitopt.h, which include clear_bit() and
> > test_and_set_bit()) but haven't found any. The only thing I've found
are
> > the atomic clear/set/add/sub routines in machine/atomic.h.
> >
> > Do we have an implementation of atomic bit operations, and if we don't,
> > would we like some?
>
> Erm, atomic_set() sets's bits, and atomic_clear() clear's bits. Anything
else
> you might need can be done with atomic_cmpset() anyways.
Where are these functions implemented? /usr/include/machine/atomic.h just
has atomic_set_XXX and clear_XXX primitives, which work on char/short/longs,
but not individual bits.
I presume that I could wrap the char operations with something that takes
0x01 and bit-shifts it appropriately so that atomic_set/clear could be used.
However, certain other primitives are missing, such as an atomic
test-and-set operation. Under the current scheme this would have to be done
by two independent operations, which is not useful when atomicitiy is
required.
--
Matt Emmerton
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