Date: Thu, 5 Apr 2018 17:07:35 +0100 From: Roger Pau =?utf-8?B?TW9ubsOp?= <royger@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: Ian Lepore <ian@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r332072 - head/sys/sys Message-ID: <20180405160735.wkpsqqiyoyh7ewuk@MacBook-Pro-de-Roger.local> In-Reply-To: <CANCZdfputnwHg-gChVKfvZdHn1nHcHXpE0WVLfejHUZfeC8jLg@mail.gmail.com> References: <201804051431.w35EVtg4047897@repo.freebsd.org> <1522942377.49673.245.camel@freebsd.org> <20180405154619.q3blip266qa3z5ut@MacBook-Pro-de-Roger.local> <CANCZdfputnwHg-gChVKfvZdHn1nHcHXpE0WVLfejHUZfeC8jLg@mail.gmail.com>
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On Thu, Apr 05, 2018 at 09:58:36AM -0600, Warner Losh wrote: > On Thu, Apr 5, 2018 at 9:46 AM, Roger Pau Monné <royger@freebsd.org> wrote: > > > On Thu, Apr 05, 2018 at 09:32:57AM -0600, Ian Lepore wrote: > > > On Thu, 2018-04-05 at 14:31 +0000, Roger Pau Monné wrote: > > > > Author: royger > > > > Date: Thu Apr 5 14:31:54 2018 > > > > New Revision: 332072 > > > > URL: https://svnweb.freebsd.org/changeset/base/332072 > > > > > > > > Log: > > > > introduce GiB and MiB macros > > > > > > > > This macros convert from GiB or MiB into bytes. > > > > > > > > Sponsored by: Citrix Systems R&D > > > > > > > > Modified: > > > > head/sys/sys/param.h > > > > > > > > Modified: head/sys/sys/param.h > > > > ============================================================ > > ================== > > > > --- head/sys/sys/param.h Thu Apr 5 14:25:39 2018 (r332071) > > > > +++ head/sys/sys/param.h Thu Apr 5 14:31:54 2018 (r332072) > > > > @@ -362,4 +362,8 @@ __END_DECLS > > > > */ > > > > #define __PAST_END(array, offset) (((__typeof__(*(array)) > > *)(array))[offset]) > > > > > > > > +/* Unit conversion macros. */ > > > > +#define GiB(v) (v ## ULL << 30) > > > > +#define MiB(v) (v ## ULL << 20) > > > > + > > > > #endif /* _SYS_PARAM_H_ */ > > > > > > > > > > These names don't make it clear whether the conversion is bytes->GiB or > > > GiB->bytes. The names seem way too generic for a public namespace in a > > > file as heavily included behind your back as param.h is. > > > > > > Also, this completely reasonable usage won't work, likely with > > > confusing compile error messages: > > > > > > int bytes, gibytes; > > > ... > > > bytes = GiB(gibytes); > > > > I find those helpful for their specific usage. I could introduce > > static inline functions like: > > > > size_t gb_to_bytes(size_t)... > > > > But I assume this is also going to cause further discussion. > > > > Yea, traditional macro names would be "gibtob" and "btogib" but I didn't > just reply to bikeshed a name: > > But you don't need to specify a type, consider the current btodb macro: > #define btodb(bytes) /* calculates (bytes / DEV_BSIZE) > */ \ > (sizeof (bytes) > sizeof(long) \ > ? (daddr_t)((unsigned long long)(bytes) >> DEV_BSHIFT) \ > : (daddr_t)((unsigned long)(bytes) >> DEV_BSHIFT)) > > which shows how to do this in a macro, which is orthogonal to any name you > may choose. I can also bikeshed function vs macro :) I was just going to remove those from here and place them in the files where I use them, but I can also change them to: #define gibtob(gib) ((unsigned long long)(gib) << 30) #define mibtob(mib) ((unsigned long long)(mib) << 20) If it's not going to start a bikeshed. Thanks, Roger.
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