[{"id":17486,"web_url":"https://patchwork.libcamera.org/comment/17486/","msgid":"","date":"2021-06-08T20:57:22","subject":"Re: [libcamera-devel] [PATCH v6 1/4] libcamera: utils: Add helper\n\tclass for std::chrono::duration","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Naush,\n\nThank you for the patch.\n\nOn Tue, Jun 08, 2021 at 12:03:32PM +0100, Naushir Patuck wrote:\n> A new utils::Duration class is defined to represent a std::chrono::duration type\n> with double precision nanosecond timebase. Using a double minimises the loss of\n> precision when converting timebases. This helper class may be used by IPAs to\n> represent variables such as frame durations and exposure times.\n> \n> An operator << overload is defined to help with displaying utils::Duration value\n> in stream objects. Currently, this will display the duration value in\n> microseconds.\n> \n> Signed-off-by: Naushir Patuck \n> Reviewed-by: David Plowman \n> Reviewed-by: Jacopo Mondi \n> Reviewed-by: Laurent Pinchart \n> ---\n> include/libcamera/internal/utils.h | 32 +++++++++++++++++\n> src/libcamera/utils.cpp | 58 ++++++++++++++++++++++++++++++\n> test/utils.cpp | 45 +++++++++++++++++++++++\n> 3 files changed, 135 insertions(+)\n> \n> diff --git a/include/libcamera/internal/utils.h b/include/libcamera/internal/utils.h\n> index 83dada7cc16c..15beb0f44172 100644\n> --- a/include/libcamera/internal/utils.h\n> +++ b/include/libcamera/internal/utils.h\n> @@ -316,8 +316,40 @@ auto enumerate(T (&iterable)[N]) -> details::enumerate_adapter\n> }\n> #endif\n> \n> +class Duration : public std::chrono::duration\n> +{\n> +\tusing BaseDuration = std::chrono::duration;\n> +\n> +public:\n> +\tDuration() = default;\n> +\n> +\ttemplate\n> +\tconstexpr Duration(const std::chrono::duration &d)\n> +\t\t: BaseDuration(d)\n> +\t{\n> +\t}\n> +\n> +\ttemplate\n> +\tdouble get() const\n> +\t{\n> +\t\tauto const c = std::chrono::duration_cast>(*this);\n> +\t\treturn c.count();\n> +\t}\n> +\n> +\texplicit constexpr operator bool() const\n> +\t{\n> +\t\treturn *this != BaseDuration::zero();\n> +\t}\n> +};\n> +\n> } /* namespace utils */\n> \n> +#ifndef __DOXYGEN__\n> +template\n> +std::basic_ostream &operator<<(std::basic_ostream &os,\n> +\t\t\t\t\t const utils::Duration &d);\n> +#endif\n> +\n> } /* namespace libcamera */\n> \n> #endif /* __LIBCAMERA_INTERNAL_UTILS_H__ */\n> diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp\n> index 826144d3c837..2e7d35fb1173 100644\n> --- a/src/libcamera/utils.cpp\n> +++ b/src/libcamera/utils.cpp\n> @@ -506,6 +506,64 @@ std::string libcameraSourcePath()\n> * loop, iterates over an indexed view of the \\a iterable\n> */\n> \n> +/**\n> + * \\class Duration\n> + * \\brief Helper class from std::chrono::duration that represents a time\n> + * duration in nanoseconds with double precision\n> + */\n> +\n> +/**\n> + * \\fn Duration::Duration(const std::chrono::duration &d)\n> + * \\brief Construct a Duration by converting an arbitrary std::chrono::duration\n> + * \\param[in] d The std::chrono::duration object to convert from\n> + *\n> + * The constructed \\a Duration object is internally represented in double\n> + * precision with nanoseconds ticks.\n> + */\n> +\n> +/**\n> + * \\fn Duration::get()\n> + * \\brief Retrieve the tick count, converted to the timebase provided by the\n> + * template argument Period of type \\a std::ratio\n> + *\n> + * A typical usage example is given below:\n> + *\n> + * \\code{.cpp}\n> + * utils::Duration d = 5s;\n> + * double d_in_ms = d.get();\n> + * \\endcode\n> + *\n> + * \\return The tick count of the Duration expressed in \\a Period\n> + */\n> +\n> +/**\n> + * \\fn Duration::operator bool()\n> + * \\brief Boolean operator to test if a \\a Duration holds a non-zero time value\n> + *\n> + * \\return True if \\a Duration is a non-zero time value, False otherwise\n> + */\n> +\n> } /* namespace utils */\n> \n> +#ifndef __DOXYGEN__\n> +template\n> +std::basic_ostream &operator<<(std::basic_ostream &os,\n> +\t\t\t\t\t const utils::Duration &d)\n> +{\n> +\tstd::basic_ostringstream s;\n> +\n> +\ts.flags(os.flags());\n> +\ts.imbue(os.getloc());\n> +\ts.setf(std::ios_base::fixed, std::ios_base::floatfield);\n> +\ts.precision(2);\n> +\ts << d.get() << \"us\";\n> +\treturn os << s.str();\n> +}\n> +\n> +template\n> +std::basic_ostream> &\n> +operator<< >(std::basic_ostream> &os,\n> +\t\t\t\t\t const utils::Duration &d);\n> +#endif\n> +\n> } /* namespace libcamera */\n> diff --git a/test/utils.cpp b/test/utils.cpp\n> index 7e24c71e4775..f170ae4c2f35 100644\n> --- a/test/utils.cpp\n> +++ b/test/utils.cpp\n> @@ -20,6 +20,7 @@\n> \n> using namespace std;\n> using namespace libcamera;\n> +using namespace std::literals::chrono_literals;\n> \n> class UtilsTest : public Test\n> {\n> @@ -128,6 +129,46 @@ protected:\n> \t\treturn TestPass;\n> \t}\n> \n> +\tint testDuration()\n> +\t{\n> +\t\tstd::ostringstream os;\n> +\t\tutils::Duration exposure;\n> +\t\tdouble ratio;\n> +\n> +\t\texposure = 25ms + 25ms;\n> +\t\tif (exposure.get() != 50000.0) {\n> +\t\t\tcerr << \"utils::Duration failed to return microsecond count\";\n> +\t\t\treturn TestFail;\n> +\t\t}\n> +\n> +\t\texposure = 1.0s / 4;\n> +\t\tif (exposure != 250ms) {\n> +\t\t\tcerr << \"utils::Duration failed scalar divide test\";\n> +\t\t\treturn TestFail;\n> +\t\t}\n> +\n> +\t\texposure = 5000.5us;\n> +\t\tif (!exposure) {\n> +\t\t\tcerr << \"utils::Duration failed boolean test\";\n> +\t\t\treturn TestFail;\n> +\t\t}\n> +\n> +\t\tos << exposure;\n> +\t\tif (os.str() != \"5000.50us\") {\n> +\t\t\tcerr << \"utils::Duration operator << failed\";\n\nI'll s/operator < +\t\t\treturn TestFail;\n> +\t\t}\n> +\n> +\t\texposure = 100ms;\n> +\t\tratio = exposure / 25ms;\n> +\t\tif (ratio != 4.0) {\n> +\t\t\tcerr << \"utils::Duration failed ratio test\";\n> +\t\t\treturn TestFail;\n> +\t\t}\n> +\n> +\t\treturn TestPass;\n> +\t}\n> +\n> \tint run()\n> \t{\n> \t\t/* utils::hex() test. */\n> @@ -236,6 +277,10 @@ protected:\n> \t\tif (testEnumerate() != TestPass)\n> \t\t\treturn TestFail;\n> \n> +\t\t/* utils::Duration test. */\n> +\t\tif (testDuration() != TestPass)\n> +\t\t\treturn TestFail;\n> +\n> \t\treturn TestPass;\n> \t}\n> };","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 AADE2BD22E\n\tfor ;\n\tTue, 8 Jun 2021 20:57:39 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 2F5D66892C;\n\tTue, 8 Jun 2021 22:57:39 +0200 (CEST)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby 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Pinchart ","To":"Naushir Patuck ","Message-ID":"","References":"<20210608110335.4078551-1-naush@raspberrypi.com>\n\t<20210608110335.4078551-2-naush@raspberrypi.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<20210608110335.4078551-2-naush@raspberrypi.com>","Subject":"Re: [libcamera-devel] [PATCH v6 1/4] libcamera: utils: Add helper\n\tclass for std::chrono::duration","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","Cc":"libcamera-devel@lists.libcamera.org","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]