1 files changed, 149 insertions, 0 deletions
diff --git a/src/ipa/raspberrypi/md_parser_smia.cpp b/src/ipa/raspberrypi/md_parser_smia.cpp
new file mode 100644
index 00000000..ea5eac41
--- /dev/null
+++ b/src/ipa/raspberrypi/md_parser_smia.cpp
@@ -0,0 +1,149 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019-2021, Raspberry Pi (Trading) Limited
+ *
+ * md_parser_smia.cpp - SMIA specification based embedded data parser
+ */
+
+#include <libcamera/base/log.h>
+#include "md_parser.hpp"
+
+using namespace RPiController;
+using namespace libcamera;
+
+/*
+ * This function goes through the embedded data to find the offsets (not
+ * values!), in the data block, where the values of the given registers can
+ * subsequently be found.
+ *
+ * Embedded data tag bytes, from Sony IMX219 datasheet but general to all SMIA
+ * sensors, I think.
+ */
+
+constexpr unsigned int LINE_START = 0x0a;
+constexpr unsigned int LINE_END_TAG = 0x07;
+constexpr unsigned int REG_HI_BITS = 0xaa;
+constexpr unsigned int REG_LOW_BITS = 0xa5;
+constexpr unsigned int REG_VALUE = 0x5a;
+constexpr unsigned int REG_SKIP = 0x55;
+
+MdParserSmia::MdParserSmia(std::initializer_list<uint32_t> registerList)
+{
+	for (auto r : registerList)
+		offsets_[r] = {};
+}
+
+MdParser::Status MdParserSmia::Parse(libcamera::Span<const uint8_t> buffer,
+				     RegisterMap &registers)
+{
+	if (reset_) {
+		/*
+		 * Search again through the metadata for all the registers
+		 * requested.
+		 */
+		ASSERT(bits_per_pixel_);
+
+		for (const auto &kv : offsets_)
+			offsets_[kv.first] = {};
+
+		ParseStatus ret = findRegs(buffer);
+		/*
+		 * > 0 means "worked partially but parse again next time",
+		 * < 0 means "hard error".
+		 *
+		 * In either case, we retry parsing on the next frame.
+		 */
+		if (ret != PARSE_OK)
+			return ERROR;
+
+		reset_ = false;
+	}
+
+	/* Populate the register values requested. */
+	registers.clear();
+	for (const auto &[reg, offset] : offsets_) {
+		if (!offset) {
+			reset_ = true;
+			return NOTFOUND;
+		}
+		registers[reg] = buffer[offset.value()];
+	}
+
+	return OK;
+}
+
+MdParserSmia::ParseStatus MdParserSmia::findRegs(libcamera::Span<const uint8_t> buffer)
+{
+	ASSERT(offsets_.size());
+
+	if (buffer[0] != LINE_START)
+		return NO_LINE_START;
+
+	unsigned int current_offset = 1; /* after the LINE_START */
+	unsigned int current_line_start = 0, current_line = 0;
+	unsigned int reg_num = 0, regs_done = 0;
+
+	while (1) {
+		int tag = buffer[current_offset++];
+
+		if ((bits_per_pixel_ == 10 &&
+		     (current_offset + 1 - current_line_start) % 5 == 0) ||
+		    (bits_per_pixel_ == 12 &&
+		     (current_offset + 1 - current_line_start) % 3 == 0)) {
+			if (buffer[current_offset++] != REG_SKIP)
+				return BAD_DUMMY;
+		}
+
+		int data_byte = buffer[current_offset++];
+
+		if (tag == LINE_END_TAG) {
+			if (data_byte != LINE_END_TAG)
+				return BAD_LINE_END;
+
+			if (num_lines_ && ++current_line == num_lines_)
+				return MISSING_REGS;
+
+			if (line_length_bytes_) {
+				current_offset = current_line_start + line_length_bytes_;
+
+				/* Require whole line to be in the buffer (if buffer size set). */
+				if (buffer.size() &&
+				    current_offset + line_length_bytes_ > buffer.size())
+					return MISSING_REGS;
+
+				if (buffer[current_offset] != LINE_START)
+					return NO_LINE_START;
+			} else {
+				/* allow a zero line length to mean "hunt for the next line" */
+				while (current_offset < buffer.size() &&
+				       buffer[current_offset] != LINE_START)
+					current_offset++;
+
+				if (current_offset == buffer.size())
+					return NO_LINE_START;
+			}
+
+			/* inc current_offset to after LINE_START */
+			current_line_start = current_offset++;
+		} else {
+			if (tag == REG_HI_BITS)
+				reg_num = (reg_num & 0xff) | (data_byte << 8);
+			else if (tag == REG_LOW_BITS)
+				reg_num = (reg_num & 0xff00) | data_byte;
+			else if (tag == REG_SKIP)
+				reg_num++;
+			else if (tag == REG_VALUE) {
+				auto reg = offsets_.find(reg_num);
+
+				if (reg != offsets_.end()) {
+					offsets_[reg_num] = current_offset - 1;
+
+					if (++regs_done == offsets_.size())
+						return PARSE_OK;
+				}
+				reg_num++;
+			} else
+				return ILLEGAL_TAG;
+		}
+	}
+}