ipa: raspberrypi: Make sensor embedded data parser use Span class

Improve MdParser::Parse() by taking a Span, pointing to const data
that it should not change, as its input buffer.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/ipa/raspberrypi/cam_helper_imx219.cpp

@@ -29,7 +29,7 @@ class MdParserImx219 : public MdParserSmia
 {
 public:
 	MdParserImx219();
-	Status Parse(void *data) override;
+	Status Parse(libcamera::Span<const uint8_t> buffer) override;
 	Status GetExposureLines(unsigned int &lines) override;
 	Status GetGainCode(unsigned int &gain_code) override;
 private:
@@ -118,7 +118,7 @@ MdParserImx219::MdParserImx219()
 	reg_offsets_[0] = reg_offsets_[1] = reg_offsets_[2] = -1;
 }
 
-MdParser::Status MdParserImx219::Parse(void *data)
+MdParser::Status MdParserImx219::Parse(libcamera::Span<const uint8_t> buffer)
 {
 	bool try_again = false;
 
@@ -132,7 +132,7 @@ MdParser::Status MdParserImx219::Parse(void *data)
 		/* Need to be ordered */
 		uint32_t regs[3] = { GAIN_REG, EXPHI_REG, EXPLO_REG };
 		reg_offsets_[0] = reg_offsets_[1] = reg_offsets_[2] = -1;
-		int ret = static_cast<int>(findRegs(static_cast<uint8_t *>(data),
+		int ret = static_cast<int>(findRegs(buffer,
 						    regs, reg_offsets_, 3));
 		/*
 		 * > 0 means "worked partially but parse again next time",
@@ -148,7 +148,7 @@ MdParser::Status MdParserImx219::Parse(void *data)
 		if (reg_offsets_[i] == -1)
 			continue;
 
-		reg_values_[i] = static_cast<uint8_t *>(data)[reg_offsets_[i]];
+		reg_values_[i] = buffer[reg_offsets_[i]];
 	}
 
 	/* Re-parse next time if we were unhappy in some way. */

src/ipa/raspberrypi/cam_helper_imx477.cpp

@@ -21,7 +21,7 @@ class MdParserImx477 : public MdParserSmia
 {
 public:
 	MdParserImx477();
-	Status Parse(void *data) override;
+	Status Parse(libcamera::Span<const uint8_t> buffer) override;
 	Status GetExposureLines(unsigned int &lines) override;
 	Status GetGainCode(unsigned int &gain_code) override;
 private:
@@ -107,7 +107,7 @@ MdParserImx477::MdParserImx477()
 	reg_offsets_[0] = reg_offsets_[1] = reg_offsets_[2] = reg_offsets_[3] = -1;
 }
 
-MdParser::Status MdParserImx477::Parse(void *data)
+MdParser::Status MdParserImx477::Parse(libcamera::Span<const uint8_t> buffer)
 {
 	bool try_again = false;
 
@@ -126,7 +126,7 @@ MdParser::Status MdParserImx477::Parse(void *data)
 			GAINLO_REG
 		};
 		reg_offsets_[0] = reg_offsets_[1] = reg_offsets_[2] = reg_offsets_[3] = -1;
-		int ret = static_cast<int>(findRegs(static_cast<uint8_t *>(data),
+		int ret = static_cast<int>(findRegs(buffer,
 						    regs, reg_offsets_, 4));
 		/*
 		 * > 0 means "worked partially but parse again next time",
@@ -142,7 +142,7 @@ MdParser::Status MdParserImx477::Parse(void *data)
 		if (reg_offsets_[i] == -1)
 			continue;
 
-		reg_values_[i] = static_cast<uint8_t *>(data)[reg_offsets_[i]];
+		reg_values_[i] = buffer[reg_offsets_[i]];
 	}
 
 	/* Re-parse next time if we were unhappy in some way. */

src/ipa/raspberrypi/md_parser.cpp

@@ -27,12 +27,13 @@ using namespace RPiController;
 #define REG_VALUE 0x5a
 #define REG_SKIP 0x55
 
-MdParserSmia::ParseStatus MdParserSmia::findRegs(unsigned char *data,
+MdParserSmia::ParseStatus MdParserSmia::findRegs(libcamera::Span<const uint8_t> buffer,
 						 uint32_t regs[], int offsets[],
 						 unsigned int num_regs)
 {
 	assert(num_regs > 0);
-	if (data[0] != LINE_START)
+
+	if (buffer[0] != LINE_START)
 		return NO_LINE_START;
 
 	unsigned int current_offset = 1; // after the LINE_START
@@ -40,15 +41,15 @@ MdParserSmia::ParseStatus MdParserSmia::findRegs(unsigned char *data,
 	unsigned int reg_num = 0, first_reg = 0;
 	ParseStatus retcode = PARSE_OK;
 	while (1) {
-		int tag = data[current_offset++];
+		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 (data[current_offset++] != REG_SKIP)
+			if (buffer[current_offset++] != REG_SKIP)
 				return BAD_DUMMY;
 		}
-		int data_byte = data[current_offset++];
+		int data_byte = buffer[current_offset++];
 		//printf("Offset %u, tag 0x%02x data_byte 0x%02x\n", current_offset-1, tag, data_byte);
 		if (tag == LINE_END_TAG) {
 			if (data_byte != LINE_END_TAG)
@@ -59,18 +60,18 @@ MdParserSmia::ParseStatus MdParserSmia::findRegs(unsigned char *data,
 				current_offset =
 					current_line_start + line_length_bytes_;
 				// Require whole line to be in the buffer (if buffer size set).
-				if (buffer_size_bytes_ &&
+				if (buffer.size() &&
 				    current_offset + line_length_bytes_ >
-					    buffer_size_bytes_)
+					    buffer.size())
 					return MISSING_REGS;
-				if (data[current_offset] != LINE_START)
+				if (buffer[current_offset] != LINE_START)
 					return NO_LINE_START;
 			} else {
 				// allow a zero line length to mean "hunt for the next line"
-				while (data[current_offset] != LINE_START &&
+				while (buffer[current_offset] != LINE_START &&
-				       current_offset < buffer_size_bytes_)
+				       current_offset < buffer.size())
 					current_offset++;
-				if (current_offset == buffer_size_bytes_)
+				if (current_offset == buffer.size())
 					return NO_LINE_START;
 			}
 			// inc current_offset to after LINE_START

src/ipa/raspberrypi/md_parser.hpp

@@ -8,6 +8,8 @@
 
 #include <stdint.h>
 
+#include <libcamera/span.h>
+
 /* Camera metadata parser class. Usage as shown below.
 
 Setup:
@@ -21,17 +23,15 @@ parser->SetBitsPerPixel(bpp);
 parser->SetLineLengthBytes(pitch);
 parser->SetNumLines(2);
 
-Note 1: if you don't know how many lines there are, you can use SetBufferSize
+Note 1: if you don't know how many lines there are, the size of the input
-instead to limit the total buffer size.
+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. In this
+(or set to zero) and the parser will hunt for the line start instead.
-case SetBufferSize *must* be used so that the parser won't run off the end of
-the buffer.
 
 Then on every frame:
 
-if (parser->Parse(data) != MdParser::OK)
+if (parser->Parse(buffer) != MdParser::OK)
     much badness;
 unsigned int exposure_lines, gain_code
 if (parser->GetExposureLines(exposure_lines) != MdParser::OK)
@@ -75,11 +75,7 @@ public:
 	{
 		line_length_bytes_ = num_bytes;
 	}
-	void SetBufferSize(unsigned int num_bytes)
+	virtual Status Parse(libcamera::Span<const uint8_t> buffer) = 0;
-	{
-		buffer_size_bytes_ = num_bytes;
-	}
-	virtual Status Parse(void *data) = 0;
 	virtual Status GetExposureLines(unsigned int &lines) = 0;
 	virtual Status GetGainCode(unsigned int &gain_code) = 0;
 
@@ -116,7 +112,7 @@ protected:
 		BAD_LINE_END  = -4,
 		BAD_PADDING   = -5
 	};
-	ParseStatus findRegs(unsigned char *data, uint32_t regs[],
+	ParseStatus findRegs(libcamera::Span<const uint8_t> buffer, uint32_t regs[],
 			     int offsets[], unsigned int num_regs);
 };