{"id":23118,"url":"https://patchwork.libcamera.org/api/patches/23118/?format=json","web_url":"https://patchwork.libcamera.org/patch/23118/","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":"<20250403154925.382973-3-stefan.klug@ideasonboard.com>","date":"2025-04-03T15:49:07","name":"[v3,02/16] libcamera: matrix: Make most functions constexpr","commit_ref":null,"pull_url":null,"state":"accepted","archived":false,"hash":"cf5110c9ca99479c544fa1c61f85cf62efe6654c","submitter":{"id":184,"url":"https://patchwork.libcamera.org/api/people/184/?format=json","name":"Stefan Klug","email":"stefan.klug@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/23118/mbox/","series":[{"id":5111,"url":"https://patchwork.libcamera.org/api/series/5111/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5111","date":"2025-04-03T15:49:05","name":"Some rkisp1 awb improvements","version":3,"mbox":"https://patchwork.libcamera.org/series/5111/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/23118/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/23118/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 E0CB0C327D\n\tfor ;\n\tThu, 3 Apr 2025 15:49:42 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 97C9B689A8;\n\tThu, 3 Apr 2025 17:49:42 +0200 (CEST)","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 EB826689A4\n\tfor ;\n\tThu, 3 Apr 2025 17:49:40 +0200 (CEST)","from ideasonboard.com (unknown\n\t[IPv6:2a00:6020:448c:6c00:6d9d:9854:3fc1:4bb2])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 458AB8FA;\n\tThu, 3 Apr 2025 17:47:47 +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=\"UjaJQHE2\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1743695267;\n\tbh=/lShqxVKPC83P8c7ZF16LUmZo5jxREkUBIJoqFx7/k0=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=UjaJQHE2eskJNvLGNEU0NJZCJdv+SG4T6z9XdcV6/hEIkE+/MHGnPfAJaB9hM696u\n\tNF+sQmGnD7ZTlb4zt3tJZO5v1qvqzCu8jLwE+lyfEGOmnYFzj9slydyMEi+1H8KQN3\n\tCq9gOEtQhGsKSZGEO63tJf+zPgY38KneMV2N7RfA=","From":"Stefan Klug ","To":"libcamera-devel@lists.libcamera.org","Cc":"Stefan Klug ,\n\tLaurent Pinchart ","Subject":"[PATCH v3 02/16] libcamera: matrix: Make most functions constexpr","Date":"Thu, 3 Apr 2025 17:49:07 +0200","Message-ID":"<20250403154925.382973-3-stefan.klug@ideasonboard.com>","X-Mailer":"git-send-email 2.43.0","In-Reply-To":"<20250403154925.382973-1-stefan.klug@ideasonboard.com>","References":"<20250403154925.382973-1-stefan.klug@ideasonboard.com>","MIME-Version":"1.0","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":"By zero-initializing the data_ member we can make most functions\nconstexpr which will come in handy in upcoming patches. Note that this\nis due to C++17. In C++20 we will be able to leave data_ uninitialized\nfor constexpr. The Matrix(std::array) version of the constructor can\nnot be constexpr because std::copy only became constexpr in C++20.\n\nSigned-off-by: Stefan Klug \nReviewed-by: Laurent Pinchart \n\n---\n\nChanges in v2:\n- Added this patch\n\nChanges in v3:\n- Added comment on data_ initializer\n---\n include/libcamera/internal/matrix.h | 20 ++++++++++++--------\n 1 file changed, 12 insertions(+), 8 deletions(-)","diff":"diff --git a/include/libcamera/internal/matrix.h b/include/libcamera/internal/matrix.h\nindex b9c3d41ef855..512c1162c3bc 100644\n--- a/include/libcamera/internal/matrix.h\n+++ b/include/libcamera/internal/matrix.h\n@@ -25,9 +25,8 @@ class Matrix\n \tstatic_assert(std::is_arithmetic_v, \"Matrix type must be arithmetic\");\n \n public:\n-\tMatrix()\n+\tconstexpr Matrix()\n \t{\n-\t\tdata_.fill(static_cast(0));\n \t}\n \n \tMatrix(const std::array &data)\n@@ -35,7 +34,7 @@ public:\n \t\tstd::copy(data.begin(), data.end(), data_.begin());\n \t}\n \n-\tstatic Matrix identity()\n+\tstatic constexpr Matrix identity()\n \t{\n \t\tMatrix ret;\n \t\tfor (size_t i = 0; i < std::min(Rows, Cols); i++)\n@@ -63,14 +62,14 @@ public:\n \t\treturn out.str();\n \t}\n \n-\tSpan data() const { return data_; }\n+\tconstexpr Span data() const { return data_; }\n \n-\tSpan operator[](size_t i) const\n+\tconstexpr Span operator[](size_t i) const\n \t{\n \t\treturn Span{ &data_.data()[i * Cols], Cols };\n \t}\n \n-\tSpan operator[](size_t i)\n+\tconstexpr Span operator[](size_t i)\n \t{\n \t\treturn Span{ &data_.data()[i * Cols], Cols };\n \t}\n@@ -88,7 +87,12 @@ public:\n \t}\n \n private:\n-\tstd::array data_;\n+\t/*\n+\t * \\todo The initializer is only necessary for the constructor to be\n+\t * constexpr in C++17. Remove the initializer as soon as we are on\n+\t * C++20.\n+\t */\n+\tstd::array data_ = {};\n };\n \n #ifndef __DOXYGEN__\n@@ -141,7 +145,7 @@ constexpr Matrix operator*(const Matrix &m1, const Matrix<\n }\n \n template\n-Matrix operator+(const Matrix &m1, const Matrix &m2)\n+constexpr Matrix operator+(const Matrix &m1, const Matrix &m2)\n {\n \tMatrix result;\n \n","prefixes":["v3","02/16"]}