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Tue, 20 Jun 2023 12:45:04 +0100 X-MC-Unique: CwR9mL0JPti0FE6q9jlz4w-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Tue, 20 Jun 2023 12:45:02 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Tue, 20 Jun 2023 12:45:02 +0100 From: David Laight To: 'Herve Codina' , Liam Girdwood , Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jonathan Cameron , Lars-Peter Clausen , Jaroslav Kysela , Takashi Iwai , "Kuninori Morimoto" , Andy Shevchenko CC: "alsa-devel@alsa-project.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-iio@vger.kernel.org" , Christophe Leroy , Thomas Petazzoni Subject: RE: [PATCH v5 07/13] minmax: Introduce {min,max}_array() Thread-Topic: [PATCH v5 07/13] minmax: Introduce {min,max}_array() Thread-Index: AQHZn535xpz9i2gsDE6nNaGlDsvHDa+TlXFw Date: Tue, 20 Jun 2023 11:45:01 +0000 Message-ID: <70697b976107473b8779eea7d6c8a189@AcuMS.aculab.com> References: <20230615152631.224529-1-herve.codina@bootlin.com> <20230615152631.224529-8-herve.codina@bootlin.com> In-Reply-To: <20230615152631.224529-8-herve.codina@bootlin.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Message-ID-Hash: 5AKB3WRTWAG4BHIHL27ZZ27JNV4JTGMX X-Message-ID-Hash: 5AKB3WRTWAG4BHIHL27ZZ27JNV4JTGMX X-MailFrom: david.laight@aculab.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: From: Herve Codina > Sent: 15 June 2023 16:26 >=20 > Introduce min_array() (resp max_array()) in order to get the > minimal (resp maximum) of values present in an array. >=20 > Signed-off-by: Herve Codina > Reviewed-by: Andy Shevchenko > --- > include/linux/minmax.h | 64 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 64 insertions(+) >=20 > diff --git a/include/linux/minmax.h b/include/linux/minmax.h > index 396df1121bff..1672985b02a3 100644 > --- a/include/linux/minmax.h > +++ b/include/linux/minmax.h > @@ -133,6 +133,70 @@ > */ > #define max_t(type, x, y)=09__careful_cmp((type)(x), (type)(y), >) >=20 > +/* > + * Remove a const qualifier from integer types > + * _Generic(foo, type-name: association, ..., default: association) perf= orms a > + * comparison against the foo type (not the qualified type). > + * Do not use the const keyword in the type-name as it will not match th= e > + * unqualified type of foo. > + */ > +#define __unconst_integer_type_cases(type)=09\ > +=09unsigned type: (unsigned type)0,=09\ > +=09signed type: (signed type)0 > + > +#define __unconst_integer_typeof(x) typeof(=09=09=09\ > +=09_Generic((x),=09=09=09=09=09=09\ > +=09=09char: (char)0,=09=09=09=09=09\ > +=09=09__unconst_integer_type_cases(char),=09=09\ > +=09=09__unconst_integer_type_cases(short),=09=09\ > +=09=09__unconst_integer_type_cases(int),=09=09\ > +=09=09__unconst_integer_type_cases(long),=09=09\ > +=09=09__unconst_integer_type_cases(long long),=09\ > +=09=09default: (x))) Those are probably more generally useful and belong elsewhere. > + > +/* > + * Do not check the array parameter using __must_be_array(). > + * In the following legit use-case where the "array" passed is a simple = pointer, > + * __must_be_array() will return a failure. > + * --- 8< --- > + * int *buff > + * ... > + * min =3D min_array(buff, nb_items); > + * --- 8< --- Is that needed in the .h file? > + * > + * The first typeof(&(array)[0]) is needed in order to support arrays of= both > + * 'int *buff' and 'int buf[N]' types. > + * > + * The array can be an array of const items. > + * typeof() keeps the const qualifier. Use __unconst_typeof() in order t= o > + * discard the const qualifier for the __element variable. > + */ > +#define __minmax_array(op, array, len) ({=09=09=09=09\ > +=09typeof(&(array)[0]) __array =3D (array);=09=09=09=09\ > +=09typeof(len) __len =3D (len);=09=09=09=09=09\ > +=09__unconst_integer_typeof(__array[0]) __element =3D __array[--__len]; = \ s/__element/__bound/ > +=09while (__len--)=09=09=09=09=09=09=09\ > +=09=09__element =3D op(__element, __array[__len]);=09=09\ > +=09__element; }) I'm not all sure that all the shenanigans required to use min() is really needed here. It would also be generally better to process the array forwards. So something like: =09typeof (&array[0]) __ptr =3D array, __limit =3D array + len; =09typeof (array[0] + 0) __element, __bound =3D *__ptr++; =09while (ptr < __limit) { =09=09__element =3D *__ptr++; =09=09if (__element > __bound) =09=09=09__bound =3D __element; =09} =09(typeof (array[0]))__bound; }) seems fine to me. The final cast is there to convert 'int' back to un/signed char|short. Not really needed and might generate worse code. But if you insist on using min/max ignore this bit. =09David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales)