Date: Fri, 4 Apr 2003 23:14:43 +0300 From: Ruslan Ermilov <ru@FreeBSD.org> To: Nate Lawson <nate@root.org> Cc: Mike Barcroft <mike@FreeBSD.org> Subject: Re: cvs commit: src/sys/sys endian.h src/share/man/man9 byteorder.9 Message-ID: <20030404201443.GA82587@sunbay.com> In-Reply-To: <Pine.BSF.4.21.0304041150530.17052-100000@root.org> References: <20030404085200.GA1765@sunbay.com> <Pine.BSF.4.21.0304041150530.17052-100000@root.org>
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On Fri, Apr 04, 2003 at 11:54:07AM -0800, Nate Lawson wrote:
> On Fri, 4 Apr 2003, Ruslan Ermilov wrote:
> > > > On Thu, 3 Apr 2003, Poul-Henning Kamp wrote:
> > > > > Modified files:
> > > > > sys/sys endian.h=20
> > > > > share/man/man9 byteorder.9=20
> > > > > Log:
> > > > > Add inline functions {be,le}{16,32,64}{enc,dec}() for encoding =
decoding
> > > > > into byte strings of unknown alignment.
> >=20
> > /*
> > + * General byte order swapping macros.
> > + */
> > +#define BSWAP16(x) (uint16_t) \
> > + (((x) >> 8) | ((x) << 8))
> > +
> > +#define BSWAP32(x) (uint32_t) \
> > + (((x) >> 24) | (((x) >> 8) & 0xff00) | \
> > + (((x) << 8) & 0xff0000) | ((x) << 24))
> > +
> > +#define BSWAP64(x) (uint64_t) \
> > + (((x) >> 56) | (((x) >> 40) & 0xff00) | (((x) >> 24) & 0xff0000) | \
> > + (((x) >> 8) & 0xff000000) | (((x) << 8) & ((uint64_t)0xff << 32)) | \
> > + (((x) << 24) & ((uint64_t)0xff << 40)) | \
> > + (((x) << 40) & ((uint64_t)0xff << 48)) | (((x) << 56)))
> > +
> > +/*
> > * Host to big endian, host to little endian, big endian to host, and =
little
> > * endian to host byte order functions as detailed in byteorder(9).
> > */
> > #if _BYTE_ORDER =3D=3D _LITTLE_ENDIAN
> > #define htobe16(x) bswap16((x))
> > +#define HTOBE16(x) BSWAP16((x))
>=20
> I don't mind the addition of the macros but I don't like the
> implementation. Too many unnecessary casts and overly complicated.
>=20
I've borrowed them from sys/sparc64/include/endian.h.
The type casts are necessary, otherwise you'll get
``warning: left shift count >=3D width of type'', and
it should be trivial to test with this program:
#include <sys/types.h>
#include <sys/endian.h>
#include <stdio.h>
int
main(void)
{
uint64_t i =3D 0xefcdab8967452301;
printf("%jx\n", i);
i =3D BSWAP64(i);
printf("%jx\n", i);
return (0);
}
Cheers,
--=20
Ruslan Ermilov Sysadmin and DBA,
ru@sunbay.com Sunbay Software AG,
ru@FreeBSD.org FreeBSD committer,
+380.652.512.251 Simferopol, Ukraine
http://www.FreeBSD.org The Power To Serve
http://www.oracle.com Enabling The Information Age
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