Date: Fri, 4 Oct 2019 16:35:45 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: Andriy Gapon <avg@freebsd.org> Cc: freebsd-arch@freebsd.org Subject: Re: atomic_cmpset_64 vs atomic_cas_64 Message-ID: <CAGudoHGx0yK4RD7fcBnsmtr3K%2BHGbxeBnBofG_f=QF-O8EwCHQ@mail.gmail.com> In-Reply-To: <0a330e4a-9b8b-7678-cb54-a379f1e4b0bc@FreeBSD.org> References: <0a330e4a-9b8b-7678-cb54-a379f1e4b0bc@FreeBSD.org>
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On 10/4/19, Andriy Gapon <avg@freebsd.org> wrote:
>
> I see that almost all 64-bit platforms provide atomic_cmpset_64, but
> sparc64
> provides atomic_cas_64 (instead?).
> I think that the meanings of "cas" and "cmpset" are really the same, but I
> am
> not sure if there are any differences in that the functions do.
> Could anyone who knows that stuff (sparc64 assembly) please shed some
> light?
> Thanks!
>
> #define atomic_cas_64(p, e, s) casxa((p), (e), (s), __ASI_ATOMIC)
>
cas returns the found value, while cmpset throws it away.
static __inline int \
atomic_cmpset_ ## name(volatile ptype p, vtype e, vtype s) \
{ \
return (((vtype)atomic_cas((p), (e), (s), sz)) == (e)); \
}
Just use fcmpset instead.
--
Mateusz Guzik <mjguzik gmail.com>
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