{"id":23486,"url":"https://patchwork.libcamera.org/api/patches/23486/?format=json","web_url":"https://patchwork.libcamera.org/patch/23486/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20250606164156.1442682-6-barnabas.pocze@ideasonboard.com>","date":"2025-06-06T16:41:38","name":"[RFC,v1,05/23] libcamera: base: cxx20: Add `has_single_bit()`","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"afbfc4e7a00b1ec6f9d8513cf786f83d35f04f59","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/people/216/?format=json","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/23486/mbox/","series":[{"id":5210,"url":"https://patchwork.libcamera.org/api/series/5210/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5210","date":"2025-06-06T16:41:33","name":"libcamera: Add `MetadataList`","version":1,"mbox":"https://patchwork.libcamera.org/series/5210/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/23486/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/23486/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id E179CC3325\n\tfor ;\n\tFri, 6 Jun 2025 16:42:35 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 2D9C668DF2;\n\tFri, 6 Jun 2025 18:42:33 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 5A04668DBD\n\tfor ;\n\tFri, 6 Jun 2025 18:42:16 +0200 (CEST)","from pb-laptop.local (185.182.215.79.nat.pool.zt.hu\n\t[185.182.215.79])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id DD3126DC\n\tfor ;\n\tFri, 6 Jun 2025 18:42:11 +0200 (CEST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"GYQzkkxQ\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1749228132;\n\tbh=I154HYs0GO304Y6yaX6MDVD3TR7uKqgqftaAYmVUJcU=;\n\th=From:To:Subject:Date:In-Reply-To:References:From;\n\tb=GYQzkkxQG1OTmKCdnb8xQqivNQFrBboJN8Ho59lXcDFr8Nvfu0l37lf8eHQPZRk/R\n\tBOxEro7jrIJlixO92EJ3sRgKBmkbfApZkDb3KsniojfDEMEAj2T9HyNVbxvXeZyISZ\n\tAR1481VjoFpcoxvIf78c0XwyNX/KEuXPo9iEBpoY=","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","To":"libcamera-devel@lists.libcamera.org","Subject":"[RFC PATCH v1 05/23] libcamera: base: cxx20: Add `has_single_bit()`","Date":"Fri, 6 Jun 2025 18:41:38 +0200","Message-ID":"<20250606164156.1442682-6-barnabas.pocze@ideasonboard.com>","X-Mailer":"git-send-email 2.49.0","In-Reply-To":"<20250606164156.1442682-1-barnabas.pocze@ideasonboard.com>","References":"<20250606164156.1442682-1-barnabas.pocze@ideasonboard.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"`has_single_bit()` checks if the given unsigned integer has a single\nbit set, that is, whether the number is a power of two or not.\n\nNot all requirements of the C++20 standard are implemented.\n\nSee https://en.cppreference.com/w/cpp/numeric/has_single_bit\n\nSigned-off-by: Barnabás Pőcze \n---\n include/libcamera/base/details/cxx20.h | 10 ++++++++++\n 1 file changed, 10 insertions(+)","diff":"diff --git a/include/libcamera/base/details/cxx20.h b/include/libcamera/base/details/cxx20.h\nindex 2d26db53e..8bf45ff11 100644\n--- a/include/libcamera/base/details/cxx20.h\n+++ b/include/libcamera/base/details/cxx20.h\n@@ -7,9 +7,19 @@\n \n #pragma once\n \n+#include \n+\n namespace libcamera::details::cxx20 {\n \n template struct type_identity { using type = T; };\n template using type_identity_t = typename type_identity::type;\n \n+template\n+constexpr bool has_single_bit(T x) noexcept\n+{\n+\tstatic_assert(std::is_unsigned_v);\n+\n+\treturn x != 0 && (x & (x - 1)) == 0;\n+}\n+\n } /* namespace libcamera::details::cxx20 */\n","prefixes":["RFC","v1","05/23"]}