From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3899EEB64DB for ; Tue, 20 Jun 2023 11:45:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232515AbjFTLpK convert rfc822-to-8bit (ORCPT ); Tue, 20 Jun 2023 07:45:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231913AbjFTLpJ (ORCPT ); Tue, 20 Jun 2023 07:45:09 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95F00132 for ; Tue, 20 Jun 2023 04:45:07 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-183-CwR9mL0JPti0FE6q9jlz4w-1; 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: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Herve Codina > Sent: 15 June 2023 16:26 > > Introduce min_array() (resp max_array()) in order to get the > minimal (resp maximum) of values present in an array. > > Signed-off-by: Herve Codina > Reviewed-by: Andy Shevchenko > --- > include/linux/minmax.h | 64 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 64 insertions(+) > > 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) __careful_cmp((type)(x), (type)(y), >) > > +/* > + * Remove a const qualifier from integer types > + * _Generic(foo, type-name: association, ..., default: association) performs 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 the > + * unqualified type of foo. > + */ > +#define __unconst_integer_type_cases(type) \ > + unsigned type: (unsigned type)0, \ > + signed type: (signed type)0 > + > +#define __unconst_integer_typeof(x) typeof( \ > + _Generic((x), \ > + char: (char)0, \ > + __unconst_integer_type_cases(char), \ > + __unconst_integer_type_cases(short), \ > + __unconst_integer_type_cases(int), \ > + __unconst_integer_type_cases(long), \ > + __unconst_integer_type_cases(long long), \ > + default: (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 = 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 to > + * discard the const qualifier for the __element variable. > + */ > +#define __minmax_array(op, array, len) ({ \ > + typeof(&(array)[0]) __array = (array); \ > + typeof(len) __len = (len); \ > + __unconst_integer_typeof(__array[0]) __element = __array[--__len]; \ s/__element/__bound/ > + while (__len--) \ > + __element = op(__element, __array[__len]); \ > + __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: typeof (&array[0]) __ptr = array, __limit = array + len; typeof (array[0] + 0) __element, __bound = *__ptr++; while (ptr < __limit) { __element = *__ptr++; if (__element > __bound) __bound = __element; } (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. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)