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([2001:470:1f05:79e:2d98:a12:ce0e:c3e3]) by smtp.gmail.com with ESMTPSA id t19sm1365323pfg.38.2021.04.21.02.23.44 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Apr 2021 02:23:44 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (1.0) Subject: Re: [PATCH 8/8] v4l2-utils: turn prefixes to a constexpr array From: Rosen Penev X-Mailer: iPhone Mail (16G201) In-Reply-To: <566ba9fe-509c-26b4-19a3-845a45093ba1@xs4all.nl> Date: Wed, 21 Apr 2021 02:23:44 -0700 Cc: linux-media@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: <21827EC0-E8B2-46F2-B943-A09A2D31EA45@gmail.com> References: <20210421072035.4188497-1-rosenp@gmail.com> <20210421072035.4188497-8-rosenp@gmail.com> <566ba9fe-509c-26b4-19a3-845a45093ba1@xs4all.nl> To: Hans Verkuil Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org > On Apr 21, 2021, at 01:06, Hans Verkuil wrote: >=20 >> On 21/04/2021 09:20, Rosen Penev wrote: >> Allows usage of a single any_of instead of a raw loop. >>=20 >> Signed-off-by: Rosen Penev >> --- >> utils/v4l2-ctl/v4l2-ctl-common.cpp | 24 +++++------------------- >> 1 file changed, 5 insertions(+), 19 deletions(-) >>=20 >> diff --git a/utils/v4l2-ctl/v4l2-ctl-common.cpp b/utils/v4l2-ctl/v4l2-ctl= -common.cpp >> index 17ad488dd..2b6dd6d13 100644 >> --- a/utils/v4l2-ctl/v4l2-ctl-common.cpp >> +++ b/utils/v4l2-ctl/v4l2-ctl-common.cpp >> @@ -116,28 +116,14 @@ void common_usage() >> ); >> } >>=20 >> -static const char *prefixes[] =3D { >> - "video", >> - "radio", >> - "vbi", >> - "swradio", >> - "v4l-subdev", >> - "v4l-touch", >> - "media", >> - nullptr >> +static constexpr std::array prefixes{ >> + "video", "radio", "vbi", "swradio", "v4l-subdev", "v4l-touch", "medi= a", >> }; >>=20 >> static bool is_v4l_dev(const char *name) >> { >> - for (unsigned i =3D 0; prefixes[i]; i++) { >> - unsigned l =3D strlen(prefixes[i]); >> - >> - if (!memcmp(name, prefixes[i], l)) { >> - if (isdigit(name[l])) >> - return true; >> - } >> - } >> - return false; >> + return std::any_of(prefixes.begin(), prefixes.end(), >> + [=3D](const char *prefix) { return !strcmp(name, prefix) &= & isdigit(name[strlen(prefix)]); }); >=20 > Yuck. Besides, it is wrong AFAIKS since strcmp is not the same as memcmp. True. C++17 would make this better with std::string_view with its size membe= r function which also happens to be constexpr. strlen IIRC is slow. >=20 > I like the original code, easier to understand than the replacement. So su= e me :-) I=E2=80=99ll convert to range loop. >=20 > Regards, >=20 > Hans >=20 >> } >>=20 >> static int calc_node_val(const char *s) >> @@ -146,7 +132,7 @@ static int calc_node_val(const char *s) >>=20 >> s =3D std::strrchr(s, '/') + 1; >>=20 >> - for (unsigned i =3D 0; prefixes[i]; i++) { >> + for (size_t i =3D 0; i < prefixes.size(); i++) { >> unsigned l =3D strlen(prefixes[i]); >>=20 >> if (!memcmp(s, prefixes[i], l)) { >>=20 >=20