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diff --git a/src/ipa/rpi/cam_helper/md_parser.h b/src/ipa/rpi/cam_helper/md_parser.h
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+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi Ltd
+ *
+ * md_parser.h - image sensor metadata parser interface
+ */
+#pragma once
+
+#include <initializer_list>
+#include <map>
+#include <optional>
+#include <stdint.h>
+
+#include <libcamera/base/span.h>
+
+/*
+ * Camera metadata parser class. Usage as shown below.
+ *
+ * Setup:
+ *
+ * Usually the metadata parser will be made as part of the CamHelper class so
+ * application code doesn't have to worry which kind to instantiate. But for
+ * the sake of example let's suppose we're parsing imx219 metadata.
+ *
+ * MdParser *parser = new MdParserSmia({ expHiReg, expLoReg, gainReg });
+ * parser->SetBitsPerPixel(bpp);
+ * parser->SetLineLengthBytes(pitch);
+ * parser->SetNumLines(2);
+ *
+ * Note 1: if you don't know how many lines there are, the size of the input
+ * buffer is used as a limit instead.
+ *
+ * Note 2: if you don't know the line length, you can leave the line length unset
+ * (or set to zero) and the parser will hunt for the line start instead.
+ *
+ * Then on every frame:
+ *
+ * RegisterMap registers;
+ * if (parser->Parse(buffer, registers) != MdParser::OK)
+ *     much badness;
+ * Metadata metadata;
+ * CamHelper::PopulateMetadata(registers, metadata);
+ *
+ * (Note that the CamHelper class converts to/from exposure lines and time,
+ * and gain_code / actual gain.)
+ *
+ * If you suspect your embedded data may have changed its layout, change any line
+ * lengths, number of lines, bits per pixel etc. that are different, and
+ * then:
+ *
+ * parser->Reset();
+ *
+ * before calling Parse again.
+ */
+
+namespace RPiController {
+
+/* Abstract base class from which other metadata parsers are derived. */
+
+class MdParser
+{
+public:
+	using RegisterMap = std::map<uint32_t, uint32_t>;
+
+	/*
+	 * Parser status codes:
+	 * OK       - success
+	 * NOTFOUND - value such as exposure or gain was not found
+	 * ERROR    - all other errors
+	 */
+	enum Status {
+		OK = 0,
+		NOTFOUND = 1,
+		ERROR = 2
+	};
+
+	MdParser()
+		: reset_(true), bitsPerPixel_(0), numLines_(0), lineLengthBytes_(0)
+	{
+	}
+
+	virtual ~MdParser() = default;
+
+	void reset()
+	{
+		reset_ = true;
+	}
+
+	void setBitsPerPixel(int bpp)
+	{
+		bitsPerPixel_ = bpp;
+	}
+
+	void setNumLines(unsigned int numLines)
+	{
+		numLines_ = numLines;
+	}
+
+	void setLineLengthBytes(unsigned int numBytes)
+	{
+		lineLengthBytes_ = numBytes;
+	}
+
+	virtual Status parse(libcamera::Span<const uint8_t> buffer,
+			     RegisterMap &registers) = 0;
+
+protected:
+	bool reset_;
+	int bitsPerPixel_;
+	unsigned int numLines_;
+	unsigned int lineLengthBytes_;
+};
+
+/*
+ * This isn't a full implementation of a metadata parser for SMIA sensors,
+ * however, it does provide the findRegs function which will prove useful and
+ * make it easier to implement parsers for other SMIA-like sensors (see
+ * md_parser_imx219.cpp for an example).
+ */
+
+class MdParserSmia final : public MdParser
+{
+public:
+	MdParserSmia(std::initializer_list<uint32_t> registerList);
+
+	MdParser::Status parse(libcamera::Span<const uint8_t> buffer,
+			       RegisterMap &registers) override;
+
+private:
+	/* Maps register address to offset in the buffer. */
+	using OffsetMap = std::map<uint32_t, std::optional<uint32_t>>;
+
+	/*
+	 * Note that error codes > 0 are regarded as non-fatal; codes < 0
+	 * indicate a bad data buffer. Status codes are:
+	 * ParseOk     - found all registers, much happiness
+	 * MissingRegs - some registers found; should this be a hard error?
+	 * The remaining codes are all hard errors.
+	 */
+	enum ParseStatus {
+		ParseOk      =  0,
+		MissingRegs  =  1,
+		NoLineStart  = -1,
+		IllegalTag   = -2,
+		BadDummy     = -3,
+		BadLineEnd   = -4,
+		BadPadding   = -5
+	};
+
+	ParseStatus findRegs(libcamera::Span<const uint8_t> buffer);
+
+	OffsetMap offsets_;
+};
+
+} /* namespace RPi */