{"id":19935,"url":"https://patchwork.libcamera.org/api/patches/19935/?format=json","web_url":"https://patchwork.libcamera.org/patch/19935/","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":"<20240424074409.1275425-1-paul.elder@ideasonboard.com>","date":"2024-04-24T07:44:09","name":"[v2] libcamera: utils: Add a helper to convert floating-point to fixed-point","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"faa2cbfe6418274f71de00e3d6d1521f1fc40430","submitter":{"id":17,"url":"https://patchwork.libcamera.org/api/people/17/?format=json","name":"Paul Elder","email":"paul.elder@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/19935/mbox/","series":[{"id":4269,"url":"https://patchwork.libcamera.org/api/series/4269/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=4269","date":"2024-04-24T07:44:09","name":"[v2] libcamera: utils: Add a helper to convert floating-point to fixed-point","version":2,"mbox":"https://patchwork.libcamera.org/series/4269/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/19935/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/19935/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 91916C3200\n\tfor ;\n\tWed, 24 Apr 2024 07:44:36 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 6EA5C633ED;\n\tWed, 24 Apr 2024 09:44:35 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id E855E61B14\n\tfor ;\n\tWed, 24 Apr 2024 09:44:33 +0200 (CEST)","from pyrite.hamster-moth.ts.net (h175-177-049-156.catv02.itscom.jp\n\t[175.177.49.156])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id EC7F9B1;\n\tWed, 24 Apr 2024 09:43:40 +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=\"G9FTynnY\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1713944622;\n\tbh=r8eS9lDyLCVKJ7GtzSqXzFLJ+nXVadwK6EuA6mBSp6I=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=G9FTynnYjGew/3xymZHQWdHXWHIIKT+xsjhl2KFTMECsZNCyx6dy2JIKtyAOIcyrm\n\twRzLmzHhdNIM2oeDpNVEfjbxwqLzLMzlMWdVNwHS4KqMI/QRTnWGuN6wTLt1ax3oqQ\n\tXEzzSZkfjepmmxI1CAtdm93LJUs0III0zakaHHZc=","From":"Paul Elder ","To":"libcamera-devel@lists.libcamera.org","Cc":"Paul Elder ","Subject":"[PATCH v2] libcamera: utils: Add a helper to convert floating-point\n\tto fixed-point","Date":"Wed, 24 Apr 2024 16:44:09 +0900","Message-Id":"<20240424074409.1275425-1-paul.elder@ideasonboard.com>","X-Mailer":"git-send-email 2.39.2","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":"Add helper functions for converting between floating point and fixed\npoint numbers. Also add tests for them.\n\nSigned-off-by: Paul Elder \n---\nChanges in v2:\n- added the reverse conversion function (fixed -> floating)\n- added tests\n- make the conversion code cleaner\n---\n include/libcamera/base/utils.h | 37 +++++++++++++++++++++++++\n src/libcamera/base/utils.cpp | 20 ++++++++++++++\n test/utils.cpp | 49 ++++++++++++++++++++++++++++++++++\n 3 files changed, 106 insertions(+)","diff":"diff --git a/include/libcamera/base/utils.h b/include/libcamera/base/utils.h\nindex 37d9af60..da0767e3 100644\n--- a/include/libcamera/base/utils.h\n+++ b/include/libcamera/base/utils.h\n@@ -9,6 +9,7 @@\n \n #include \n #include \n+#include \n #include \n #include \n #include \n@@ -369,6 +370,42 @@ decltype(auto) abs_diff(const T &a, const T &b)\n \n double strtod(const char *__restrict nptr, char **__restrict endptr);\n \n+#ifndef __DOXYGEN__\n+template &&\n+\t\t\t std::is_floating_point_v> * = nullptr>\n+#else\n+template\n+#endif\n+constexpr R floatingToFixedPoint(T number)\n+{\n+\tstatic_assert(I + F <= sizeof(R) * 8);\n+\n+\tR maskI = (1 << I) - 1;\n+\tR whole = (static_cast(number) & maskI) << F;\n+\n+\tR maskF = (1 << F) - 1;\n+\tR frac = static_cast(std::round(number * (1 << F))) & maskF;\n+\n+\treturn whole | frac;\n+}\n+\n+#ifndef __DOXYGEN__\n+template &&\n+\t\t\t std::is_integral_v> * = nullptr>\n+#else\n+template\n+#endif\n+constexpr R fixedToFloatingPoint(T number)\n+{\n+\tstatic_assert(I + F <= sizeof(T) * 8);\n+\n+\tint coeff = number >> (I + F - 1) ? -1 : 1;\n+\n+\treturn coeff * static_cast(number) / static_cast(1 << F);\n+}\n+\n } /* namespace utils */\n \n #ifndef __DOXYGEN__\ndiff --git a/src/libcamera/base/utils.cpp b/src/libcamera/base/utils.cpp\nindex 3b73b442..ba36026d 100644\n--- a/src/libcamera/base/utils.cpp\n+++ b/src/libcamera/base/utils.cpp\n@@ -521,6 +521,26 @@ double strtod(const char *__restrict nptr, char **__restrict endptr)\n #endif\n }\n \n+/**\n+ * \\fn R floatingToFixedPoint(T number)\n+ * \\brief Convert a floating point number to a fixed-point representation\n+ * \\tparam I Bit width of the integer part of the fixed-point\n+ * \\tparam F Bit width of the fractional part of the fixed-point\n+ * \\tparam R Return type of the fixed-point representation\n+ * \\tparam T Input type of the floating point representation\n+ * \\return The converted value\n+ */\n+\n+/**\n+ * \\fn R fixedToFloatingPoint(T number)\n+ * \\brief Convert a fixed-point number to a floating point representation\n+ * \\tparam I Bit width of the integer part of the fixed-point\n+ * \\tparam F Bit width of the fractional part of the fixed-point\n+ * \\tparam R Return type of the floating point representation\n+ * \\tparam T Input type of the fixed-point representation\n+ * \\return The converted value\n+ */\n+\n } /* namespace utils */\n \n #ifndef __DOXYGEN__\ndiff --git a/test/utils.cpp b/test/utils.cpp\nindex fc56e14e..f1805207 100644\n--- a/test/utils.cpp\n+++ b/test/utils.cpp\n@@ -170,6 +170,51 @@ protected:\n \t\treturn TestPass;\n \t}\n \n+\ttemplate\n+\tint testSingleFixedPoint(double input, T expected)\n+\t{\n+\t\tT ret = utils::floatingToFixedPoint(input);\n+\t\tif (ret != expected) {\n+\t\t\tcerr << \"Expected \" << input << \" to convert to \"\n+\t\t\t << expected << \", got \" << ret << std::endl;\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\t/*\n+\t\t * The precision check is fairly arbitrary but is based on what\n+\t\t * the rkisp1 is capable of in the crosstalk module.\n+\t\t */\n+\t\tdouble f = utils::fixedToFloatingPoint(ret);\n+\t\tif (std::abs(f - input) > 0.001) {\n+\t\t\tcerr << \"Reverse conversion expected \" << ret\n+\t\t\t << \" to convert to \" << input\n+\t\t\t << \", got \" << f << std::endl;\n+\t\t\treturn TestFail;\n+\t\t}\n+\n+\t\treturn TestPass;\n+\t}\n+\n+\tint testFixedPoint()\n+\t{\n+\t\t/* These are the only cases that we know for certain */\n+\t\tstd::map testCases = {\n+\t\t\t{ 7.992, 0x3FF },\n+\t\t\t{ -8, 0x400 },\n+\t\t\t{ 0, 0 },\n+\t\t};\n+\n+\t\tint ret;\n+\t\tfor (const auto &testCase : testCases) {\n+\t\t\tret = testSingleFixedPoint<4, 7, uint16_t>(testCase.first,\n+\t\t\t\t\t\t\t\t testCase.second);\n+\t\t\tif (ret != TestPass)\n+\t\t\t\treturn ret;\n+\t\t}\n+\n+\t\treturn TestPass;\n+\t}\n+\n \tint run()\n \t{\n \t\t/* utils::hex() test. */\n@@ -290,6 +335,10 @@ protected:\n \t\tif (testDuration() != TestPass)\n \t\t\treturn TestFail;\n \n+\t\t/* fixed point conversion test */\n+\t\tif (testFixedPoint() != TestPass)\n+\t\t\treturn TestFail;\n+\n \t\treturn TestPass;\n \t}\n };\n","prefixes":["v2"]}