{"id":25635,"url":"https://patchwork.libcamera.org/api/1.1/patches/25635/?format=json","web_url":"https://patchwork.libcamera.org/patch/25635/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/1.1/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":"<20260106165754.1759831-6-barnabas.pocze@ideasonboard.com>","date":"2026-01-06T16:57:37","name":"[v4,05/22] libcamera: base: cxx20: Add `has_single_bit()`","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"cf573de55999ae9aeab89592ed1f3ad655624383","submitter":{"id":216,"url":"https://patchwork.libcamera.org/api/1.1/people/216/?format=json","name":"Barnabás Pőcze","email":"barnabas.pocze@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/25635/mbox/","series":[{"id":5688,"url":"https://patchwork.libcamera.org/api/1.1/series/5688/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5688","date":"2026-01-06T16:57:32","name":"libcamera: Add `MetadataList`","version":4,"mbox":"https://patchwork.libcamera.org/series/5688/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/25635/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/25635/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 19FB8BDCBF\n\tfor ;\n\tTue, 6 Jan 2026 16:58:13 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id A71D261FD6;\n\tTue, 6 Jan 2026 17:58:04 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 393FC61F9F\n\tfor ;\n\tTue, 6 Jan 2026 17:57:59 +0100 (CET)","from pb-laptop.local (185.221.143.114.nat.pool.zt.hu\n\t[185.221.143.114])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 2DCDD16CD;\n\tTue, 6 Jan 2026 17:57:38 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"ngl+TCMg\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1767718658;\n\tbh=mkcW4kOYD2jP66GKK3ji8SaLitSezNm7hJvxYbBYpC0=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=ngl+TCMgutPonxKXPhXK/PTSS1GuqGqmSESqTEg4MGyDlqtPfVmvnLh+UjEySgqtP\n\t2cJVJnFPgoi6gZuW8i3kE5uqJC277NQka5oj6+23quUs1tXEFUJ6X1b7NzH+B1GTbW\n\tYo5k5I5CBQni4Z8uyolLHK8G4XC7H/xTNuYGG5/M=","From":"=?utf-8?q?Barnab=C3=A1s_P=C5=91cze?= ","To":"libcamera-devel@lists.libcamera.org","Cc":"Paul Elder ,\n\tKieran Bingham ","Subject":"[PATCH v4 05/22] libcamera: base: cxx20: Add `has_single_bit()`","Date":"Tue, 6 Jan 2026 17:57:37 +0100","Message-ID":"<20260106165754.1759831-6-barnabas.pocze@ideasonboard.com>","X-Mailer":"git-send-email 2.52.0","In-Reply-To":"<20260106165754.1759831-1-barnabas.pocze@ideasonboard.com>","References":"<20260106165754.1759831-1-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 \nReviewed-by: Paul Elder \nReviewed-by: Kieran Bingham \n---\n include/libcamera/base/internal/cxx20.h | 16 ++++++++++++++++\n 1 file changed, 16 insertions(+)","diff":"diff --git a/include/libcamera/base/internal/cxx20.h b/include/libcamera/base/internal/cxx20.h\nindex 1f4caf56f..d47168a70 100644\n--- a/include/libcamera/base/internal/cxx20.h\n+++ b/include/libcamera/base/internal/cxx20.h\n@@ -7,6 +7,8 @@\n \n #pragma once\n \n+#include \n+\n /**\n * \\internal\n * \\file cxx20.h\n@@ -39,4 +41,18 @@ template struct type_identity {\n */\n template using type_identity_t = typename type_identity::type;\n \n+/**\n+ * \\internal\n+ * \\brief std::has_single_bit()\n+ *\n+ * Implementation of std::has_single_bit() for C++17.\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::internal::cxx20 */\n","prefixes":["v4","05/22"]}