On 2012-02-28 20:39, Tijl Coosemans wrote: > Author: tijl > Date: Tue Feb 28 19:39:54 2012 > New Revision: 232266 > URL: http://svn.freebsd.org/changeset/base/232266 > > Log: > Copy amd64 endian.h to x86 and merge with i386 endian.h. Replace > amd64/i386/pc98 endian.h with stubs. > > In __bswap64_const(x) the conflict between 0xffUL and 0xffULL has been > resolved by reimplementing the macro in terms of __bswap32(x). As a side > effect __bswap64_var(x) is now implemented using two bswap instructions on > i386 and should be much faster. __bswap32_const(x) has been reimplemented > in terms of __bswap16(x) for consistency. ... > +#define __bswap32_const(_x) \ > + (((__uint32_t)__bswap16(_x) << 16) | __bswap16((_x) >> 16)) > + > +#define __bswap32(_x) \ > + (__builtin_constant_p(_x) ? \ > + __bswap32_const((__uint32_t)(_x)) : __bswap32_var(_x)) > + > +#define __bswap64_const(_x) \ > + (((__uint64_t)__bswap32(_x) << 32) | __bswap32((_x) >> 32))
Hmm, shouldn't __bswap32_const() be implemented in terms of __bswap16_const(), and similarly for __bswap64_const(), which should be implemented in terms of __bswap32_const()? The whole reason for the difficult dance with __builtin_constant_p is to allow for compile-time resolving of bswap'd constants. Invoking the regular __bswap() macros doesn't gain you anything here. _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
