Date: Tue, 30 Jun 2020 09:30:06 +0200 From: Hans Petter Selasky <hps@selasky.org> To: Ian Lepore <ian@freebsd.org>, Warner Losh <imp@bsdimp.com>, Ravi Pokala <rpokala@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r362781 - head/sys/compat/linuxkpi/common/include/linux Message-ID: <5516059a-0168-f1cd-742e-bb7d7a108f67@selasky.org> In-Reply-To: <24a300c54e94be8e6915c588a25a641ca0620200.camel@freebsd.org> References: <202006291308.05TD8eTP014019@repo.freebsd.org> <E675DB44-963F-498A-97D4-DC326DB3A0EA@panasas.com> <CANCZdfob=Ri%2B1v1QPg-m9O_%2BqXjD88NcjFQtdSkjGh%2B3GG5SZw@mail.gmail.com> <24a300c54e94be8e6915c588a25a641ca0620200.camel@freebsd.org>
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On 2020-06-29 22:32, Ian Lepore wrote: > On Mon, 2020-06-29 at 14:26 -0600, Warner Losh wrote: >> On Mon, Jun 29, 2020, 2:15 PM Ravi Pokala <rpokala@freebsd.org> >> wrote: >> >>> -----Original Message----- >>> From: <owner-src-committers@freebsd.org> on behalf of Hans Petter >>> Selasky >>> <hselasky@FreeBSD.org> >>> Date: 2020-06-29, Monday at 06:08 >>> To: <src-committers@freebsd.org>, <svn-src-all@freebsd.org>, < >>> svn-src-head@freebsd.org> >>> Subject: svn commit: r362781 - >>> head/sys/compat/linuxkpi/common/include/linux >>> >>> Author: hselasky >>> Date: Mon Jun 29 13:08:40 2020 >>> New Revision: 362781 >>> URL: https://svnweb.freebsd.org/changeset/base/362781 >>> >>> Log: >>> Implement is_signed(), type_max() and type_min() function >>> macros in >>> the >>> LinuxKPI. >>> >>> MFC after: 1 week >>> Sponsored by: Mellanox Technologies >>> >>> Modified: >>> head/sys/compat/linuxkpi/common/include/linux/kernel.h >>> >>> Modified: >>> head/sys/compat/linuxkpi/common/include/linux/kernel.h >>> >>> =================================================================== >>> =========== >>> --- head/sys/compat/linuxkpi/common/include/linux/kernel.h Mon >>> Jun 29 >>> 12:59:09 2020 (r362780) >>> +++ head/sys/compat/linuxkpi/common/include/linux/kernel.h Mon >>> Jun 29 >>> 13:08:40 2020 (r362781) >>> @@ -564,4 +564,20 @@ linux_ratelimited(linux_ratelimit_t *rl) >>> #define __is_constexpr(x) \ >>> __builtin_constant_p(x) >>> >>> Hi Hans, >>> >>> +#define is_signed(x) (((x)-1 / (x)2) == (x)0) >>> >>> It took me several reads to understand this, until I figured out >>> that 'x' >>> is not a variable, it's the name of a *type*. >>> >>> If 'x' is a variable, then '(x)-1' is subtraction, but '(x)2' and >>> '(x)0' >>> are nonsensical. >>> >>> If 'x' is a *type*, then '(x)-1' is typecasting '-1', and similarly >>> for >>> '(x)2' and '(x)0'. >>> >>> So, perhaps a comment, or a better name for 'x'? >>> >> >> I had similar thoughts. Maybe 't' instead? >> > > Or maybe since there's no one-character restriction on macro variable > names, something actually descriptive like 'datatype'. > > -- Ian > >> Warner >> >> Thanks, >>> >>> Ravi (rpokala@) >>> Thanks for the feedback. I'll have a look at using a more descriptive name there for the macro argument. --HPS
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