{"id":25800,"url":"https://patchwork.libcamera.org/api/1.1/patches/25800/?format=json","web_url":"https://patchwork.libcamera.org/patch/25800/","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":"<20260114173918.1744023-5-kieran.bingham@ideasonboard.com>","date":"2026-01-14T17:39:04","name":"[v5,04/16] ipa: libipa: Provide fixed point quantized traits","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"941a694c9af28f6b1ee97e6d31e190d01c26ce40","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/1.1/people/4/?format=json","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/25800/mbox/","series":[{"id":5708,"url":"https://patchwork.libcamera.org/api/1.1/series/5708/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5708","date":"2026-01-14T17:39:00","name":"libipa: Introduce a Quantized type","version":5,"mbox":"https://patchwork.libcamera.org/series/5708/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/25800/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/25800/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 C7739C3284\n\tfor ;\n\tWed, 14 Jan 2026 17:39:34 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 7CD6361FC5;\n\tWed, 14 Jan 2026 18:39:28 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 8C59D61FBF\n\tfor ;\n\tWed, 14 Jan 2026 18:39:23 +0100 (CET)","from Monstersaurus.infra.iob\n\t(cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id A879D1F16;\n\tWed, 14 Jan 2026 18:38:56 +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=\"t7YQaSDZ\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1768412336;\n\tbh=6AWHoe1C/ACRuMNYY21QXcRal1P9jzdXPX6+MHKvNec=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=t7YQaSDZpq8H3XJu5PoBtP8qwtT7TR8XeaJlueMo8wsPFVYcfpHeSiDIC6lPHO0V9\n\tNXwllSlF/8W8bbUYsKOJF8p7U2tR0hGPXz1O7HGv0tISX0zrTjOC37CLiPNSp+pwBH\n\tZh/Kfjk7LbdYnkgte8CQNU/4n6dkOSFULZymmoaw=","From":"Kieran Bingham ","To":"libcamera devel ","Cc":"Kieran Bingham ,\n\tIsaac Scott ","Subject":"[PATCH v5 04/16] ipa: libipa: Provide fixed point quantized traits","Date":"Wed, 14 Jan 2026 17:39:04 +0000","Message-ID":"<20260114173918.1744023-5-kieran.bingham@ideasonboard.com>","X-Mailer":"git-send-email 2.52.0","In-Reply-To":"<20260114173918.1744023-1-kieran.bingham@ideasonboard.com>","References":"<20260114173918.1744023-1-kieran.bingham@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":"Extend the new Quantized type infrastructure by providing a\nFixedPointQTraits template.\n\nThis allows construction of fixed point types with a Quantized storage\nthat allows easy reading of both the underlying quantized type value and\na floating point representation of that same value.\n\nReviewed-by: Isaac Scott \nSigned-off-by: Kieran Bingham \n\n---\nv4:\n- Assert that the given type has enough bits for the usage\n- Use unsigned types for calculating qmin/qmax\n- Reorder toFloat/fromFloat and min/max for future inlining\n- Make toFloat and fromFloat constexpr\n\nv5:\n- Make UT, Bits and Bitmask private (and remove doxygen)\n- Remove constexpr from fromFloat which uses std::round (only constexpr\n in C++23)\n- static_assert that minqMin qmax->qMax Bits->bits BitMask->bitMask\n- Remove typedefs for Q1_7 etc\n\nSigned-off-by: Kieran Bingham \n---\n src/ipa/libipa/fixedpoint.cpp | 89 +++++++++++++++++++++++++++++++++++\n src/ipa/libipa/fixedpoint.h | 69 +++++++++++++++++++++++++++\n 2 files changed, 158 insertions(+)","diff":"diff --git a/src/ipa/libipa/fixedpoint.cpp b/src/ipa/libipa/fixedpoint.cpp\nindex 6b698fc5d680..43d76f745d8a 100644\n--- a/src/ipa/libipa/fixedpoint.cpp\n+++ b/src/ipa/libipa/fixedpoint.cpp\n@@ -37,6 +37,95 @@ namespace ipa {\n * \\return The converted value\n */\n \n+/**\n+ * \\struct libcamera::ipa::FixedPointQTraits\n+ * \\brief Traits type implementing fixed-point quantisation conversions\n+ *\n+ * The FixedPointQTraits structure defines a policy for mapping floating-point\n+ * values to and from fixed-point integer representations. It is parameterised\n+ * by the number of integer bits \\a I, fractional bits \\a F, and the integral\n+ * storage type \\a T. The traits are used with Quantized to create a\n+ * quantised type that stores both the fixed-point representation and the\n+ * corresponding floating-point value.\n+ *\n+ * The trait exposes compile-time constants describing the bit layout, limits,\n+ * and scaling factors used in the fixed-point representation.\n+ *\n+ * \\tparam I Number of integer bits\n+ * \\tparam F Number of fractional bits\n+ * \\tparam T Integral type used to store the quantised value\n+ */\n+\n+/**\n+ * \\typedef FixedPointQTraits::QuantizedType\n+ * \\brief The integral storage type used for the fixed-point representation\n+ */\n+\n+/**\n+ * \\var FixedPointQTraits::qMin\n+ * \\brief Minimum representable quantised integer value\n+ *\n+ * This corresponds to the most negative value for signed formats or zero for\n+ * unsigned formats.\n+ */\n+\n+/**\n+ * \\var FixedPointQTraits::qMax\n+ * \\brief Maximum representable quantised integer value\n+ */\n+\n+/**\n+ * \\var FixedPointQTraits::min\n+ * \\brief Minimum representable floating-point value corresponding to qMin\n+ */\n+\n+/**\n+ * \\var FixedPointQTraits::max\n+ * \\brief Maximum representable floating-point value corresponding to qMax\n+ */\n+\n+/**\n+ * \\fn FixedPointQTraits::fromFloat(float v)\n+ * \\brief Convert a floating-point value to a fixed-point integer\n+ * \\param[in] v The floating-point value to be converted\n+ * \\return The quantised fixed-point integer representation\n+ *\n+ * The conversion rounds the floating-point input \\a v to the nearest integer\n+ * according to the scaling factor defined by the number of fractional bits F.\n+ */\n+\n+/**\n+ * \\fn FixedPointQTraits::toFloat(QuantizedType q)\n+ * \\brief Convert a fixed-point integer to a floating-point value\n+ * \\param[in] q The fixed-point integer value to be converted\n+ * \\return The corresponding floating-point value\n+ *\n+ * The conversion sign-extends the integer value if required and divides by the\n+ * scaling factor defined by the number of fractional bits F.\n+ */\n+\n+/**\n+ * \\typedef Q\n+ * \\brief Define a signed fixed-point quantised type with automatic storage width\n+ * \\tparam I The number of integer bits\n+ * \\tparam F The number of fractional bits\n+ *\n+ * This alias defines a signed fixed-point quantised type using the\n+ * \\ref FixedPointQTraits trait and a suitable signed integer storage type\n+ * automatically selected based on the total number of bits \\a (I + F).\n+ */\n+\n+/**\n+ * \\typedef UQ\n+ * \\brief Define an unsigned fixed-point quantised type with automatic storage width\n+ * \\tparam I The number of integer bits\n+ * \\tparam F The number of fractional bits\n+ *\n+ * This alias defines an unsigned fixed-point quantised type using the\n+ * \\ref FixedPointQTraits trait and a suitable unsigned integer storage type\n+ * automatically selected based on the total number of bits \\a (I + F).\n+ */\n+\n } /* namespace ipa */\n \n } /* namespace libcamera */\ndiff --git a/src/ipa/libipa/fixedpoint.h b/src/ipa/libipa/fixedpoint.h\nindex b4a7fa5e0ecd..4f6ee081604b 100644\n--- a/src/ipa/libipa/fixedpoint.h\n+++ b/src/ipa/libipa/fixedpoint.h\n@@ -10,6 +10,8 @@\n #include \n #include \n \n+#include \"quantized.h\"\n+\n namespace libcamera {\n \n namespace ipa {\n@@ -63,6 +65,73 @@ constexpr R fixedToFloatingPoint(T number)\n \treturn static_cast(t) / static_cast(1 << F);\n }\n \n+template\n+struct FixedPointQTraits {\n+private:\n+\tstatic_assert(std::is_integral_v, \"FixedPointQTraits: T must be integral\");\n+\tusing UT = std::make_unsigned_t;\n+\n+\tstatic constexpr unsigned int bits = I + F;\n+\tstatic_assert(bits <= sizeof(T) * 8, \"FixedPointQTraits: too many bits for type T\");\n+\n+\tstatic constexpr T bitMask = (bits < sizeof(T) * 8)\n+\t\t\t\t ? static_cast((UT{1} << bits) - 1)\n+\t\t\t\t : static_cast(~UT{0});\n+\n+public:\n+\tusing QuantizedType = T;\n+\n+\tstatic constexpr T qMin = std::is_signed_v\n+\t\t\t\t? static_cast(-(UT{1} << (bits - 1)))\n+\t\t\t\t: static_cast(0);\n+\n+\tstatic constexpr T qMax = std::is_signed_v\n+\t\t\t\t? static_cast((UT{1} << (bits - 1)) - 1)\n+\t\t\t\t: static_cast((UT{1} << bits) - 1);\n+\n+\tstatic constexpr float toFloat(QuantizedType q)\n+\t{\n+\t\treturn fixedToFloatingPoint(q);\n+\t}\n+\n+\tstatic constexpr float min = fixedToFloatingPoint(qMin);\n+\tstatic constexpr float max = fixedToFloatingPoint(qMax);\n+\n+\tstatic_assert(min < max, \"FixedPointQTraits: Minimum must be less than maximum\");\n+\n+\t/* Conversion functions required by Quantized */\n+\tstatic QuantizedType fromFloat(float v)\n+\t{\n+\t\tv = std::clamp(v, min, max);\n+\t\treturn floatingToFixedPoint(v);\n+\t}\n+};\n+\n+namespace details {\n+\n+template\n+constexpr auto qtype()\n+{\n+\tstatic_assert(Bits <= 64);\n+\n+\tif constexpr (Bits <= 8)\n+\t\treturn int8_t();\n+\telse if constexpr (Bits <= 16)\n+\t\treturn int16_t();\n+\telse if constexpr (Bits <= 32)\n+\t\treturn int32_t();\n+\telse if constexpr (Bits <= 64)\n+\t\treturn int64_t();\n+}\n+\n+} /* namespace details */\n+\n+template\n+using Q = Quantized())>>;\n+\n+template\n+using UQ = Quantized())>>>;\n+\n } /* namespace ipa */\n \n } /* namespace libcamera */\n","prefixes":["v5","04/16"]}