{"id":26201,"url":"https://patchwork.libcamera.org/api/patches/26201/?format=json","web_url":"https://patchwork.libcamera.org/patch/26201/","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":"<20260219-kbingham-quantizers-v8-4-2b6ff68ead26@ideasonboard.com>","date":"2026-02-19T15:05:05","name":"[v8,04/15] ipa: libipa: Provide fixed point quantized traits","commit_ref":"5b4c0c5b8b5bcf39a149c69487098e58fd48d666","pull_url":null,"state":"accepted","archived":false,"hash":"8f0efd3e633389fc100571df22bac8183330828b","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/?format=json","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/26201/mbox/","series":[{"id":5802,"url":"https://patchwork.libcamera.org/api/series/5802/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5802","date":"2026-02-19T15:05:01","name":"libipa: Introduce a Quantized type","version":8,"mbox":"https://patchwork.libcamera.org/series/5802/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/26201/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/26201/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 AB882C0DA4\n\tfor ;\n\tThu, 19 Feb 2026 15:05:22 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 26DF662268;\n\tThu, 19 Feb 2026 16:05:16 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 84C8262255\n\tfor ;\n\tThu, 19 Feb 2026 16:05:09 +0100 (CET)","from ping.linuxembedded.co.uk\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 549F11023;\n\tThu, 19 Feb 2026 16:04:16 +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=\"syVmGh7b\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1771513456;\n\tbh=OLNJoiHLmmmIIuIvF7pWFX26DPsb+CGOkVU0InYRLUE=;\n\th=From:Date:Subject:References:In-Reply-To:To:Cc:From;\n\tb=syVmGh7bAO4VBh2bm9/ogXKXIymshZLCHYQ1KhzyJmeupy/zK3U+BCKFRZ8Uewxxr\n\tJiv1J8VIMJTVsKsce/L/T3AdnThyhzCzG5H5Es3T/k7pSw3fr0cVPywOo1q39V32uA\n\tBHjOj751vh4b3XFYZuVjBEdAGKNjOoABF3o+3wuk=","From":"Kieran Bingham ","Date":"Thu, 19 Feb 2026 15:05:05 +0000","Subject":"[PATCH v8 04/15] ipa: libipa: Provide fixed point quantized traits","MIME-Version":"1.0","Content-Type":"text/plain; charset=\"utf-8\"","Content-Transfer-Encoding":"7bit","Message-Id":"<20260219-kbingham-quantizers-v8-4-2b6ff68ead26@ideasonboard.com>","References":"<20260219-kbingham-quantizers-v8-0-2b6ff68ead26@ideasonboard.com>","In-Reply-To":"<20260219-kbingham-quantizers-v8-0-2b6ff68ead26@ideasonboard.com>","To":"libcamera-devel@lists.libcamera.org","Cc":"Kieran Bingham , \n\tIsaac Scott , \n\tPaul Elder , \n\tStefan Klug ","X-Mailer":"b4 0.14.3","X-Developer-Signature":"v=1; a=ed25519-sha256; t=1771513507; l=7570;\n\ti=kieran.bingham@ideasonboard.com; s=20260207;\n\th=from:subject:message-id; \n\tbh=OLNJoiHLmmmIIuIvF7pWFX26DPsb+CGOkVU0InYRLUE=;\n\tb=a4oNA3kjlrp/bvUyt+hSgxgRYBddct6pV9AXOi37QMxp9Df6cHFC8QIJVNxy7RGM28XCbYkeS\n\tBq1fOO3ViBxB/Hk3HfUOkkwrkZRcoiBnbbcOvd8m7jlL4ymZfIfGnfI","X-Developer-Key":"i=kieran.bingham@ideasonboard.com; a=ed25519;\n\tpk=FVXKN7YuwHc6UtbRUeTMAmranfsQomA+vnilfglWdaY=","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 \nReviewed-by: Paul Elder \nReviewed-by: Stefan Klug \nSigned-off-by: Kieran Bingham \n---\n src/ipa/libipa/fixedpoint.cpp | 98 +++++++++++++++++++++++++++++++++++++++++++\n src/ipa/libipa/fixedpoint.h | 74 ++++++++++++++++++++++++++++++++\n 2 files changed, 172 insertions(+)","diff":"diff --git a/src/ipa/libipa/fixedpoint.cpp b/src/ipa/libipa/fixedpoint.cpp\nindex 6b698fc5d680..b581ca8453ef 100644\n--- a/src/ipa/libipa/fixedpoint.cpp\n+++ b/src/ipa/libipa/fixedpoint.cpp\n@@ -37,6 +37,104 @@ namespace ipa {\n * \\return The converted value\n */\n \n+/**\n+ * \\struct libcamera::ipa::FixedPointQTraits\n+ * \\brief Traits type implementing fixed-point quantization conversions\n+ *\n+ * The FixedPointQTraits structure defines a policy for mapping floating-point\n+ * values to and from fixed-point 2's complement integer representations. It is\n+ * parameterised by the number of integer bits \\a I, fractional bits \\a F, and\n+ * the integral storage type \\a T. The traits are used with Quantized to\n+ * create a quantized type that stores both the fixed-point representation and\n+ * the corresponding floating-point value.\n+ *\n+ * The signedness of the type is determined by the signedness of \\a T. For\n+ * signed types, the number of integer bits in \\a I includes the sign bit.\n+ *\n+ * Storage is determined by the total number of bits \\a (I + F) and is\n+ * automatically selected, but the internal storage type is always an unsigned\n+ * integer to guarantee against sign extension when storing quantized values\n+ * in registers.\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 quantized 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 quantized 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 quantized 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 quantized fixed-point integer representation\n+ *\n+ * The conversion first clamps the floating-point input \\a v to the range [min,\n+ * max] and then rounds it to the nearest fixed-point value according to the\n+ * 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 quantized 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 quantized 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 quantized 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 quantized 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 aeb9bce3269b..df685e852bff 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 +65,78 @@ 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(UT) * 8, \"FixedPointQTraits: too many bits for type UT\");\n+\n+\t/*\n+\t * If fixed point storage is required with more than 24 bits, consider\n+\t * updating this implementation to use double-precision floating point.\n+\t */\n+\tstatic_assert(bits <= 24, \"Floating point precision may be insufficient for more than 24 bits\");\n+\n+\tstatic constexpr UT bitMask = bits < sizeof(UT) * 8\n+\t\t\t\t ? (UT{ 1 } << bits) - 1\n+\t\t\t\t : ~UT{ 0 };\n+\n+public:\n+\tusing QuantizedType = UT;\n+\n+\tstatic constexpr UT qMin = std::is_signed_v\n+\t\t\t\t ? -(UT{ 1 } << (bits - 1))\n+\t\t\t\t : 0;\n+\n+\tstatic constexpr UT qMax = std::is_signed_v\n+\t\t\t\t ? (UT{ 1 } << (bits - 1)) - 1\n+\t\t\t\t : bitMask;\n+\n+\tstatic constexpr float toFloat(QuantizedType q)\n+\t{\n+\t\treturn fixedToFloatingPoint(q);\n+\t}\n+\n+\tstatic constexpr float min = fixedToFloatingPoint(static_cast(qMin));\n+\tstatic constexpr float max = fixedToFloatingPoint(static_cast(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 <= 32,\n+\t\t \"Unsupported number of bits for quantized type\");\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+}\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":["v8","04/15"]}