path: root/users/flokli/ipu6-softisp/libcamera/0010-libcamera-software_isp-Add-DebayerCpu-class.patch

From 7eb7164ed7d90ea4cf9ec7e4f35fa8efa25f35e9 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Mon, 11 Dec 2023 17:00:17 +0100
Subject: [PATCH 10/25] libcamera: software_isp: Add DebayerCpu class

Add CPU based debayering implementation. This initial implementation
only supports debayering packed 10 bits per pixel bayer data in
the 4 standard bayer orders.

Doxygen documentation by Dennis Bonke.

Co-authored-by: Dennis Bonke <admin@dennisbonke.com>
Signed-off-by: Dennis Bonke <admin@dennisbonke.com>
Co-authored-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Co-authored-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> # sc8280xp Lenovo x13s
Tested-by: Pavel Machek <pavel@ucw.cz>
---
 .../internal/software_isp/debayer_cpu.h       | 131 +++++
 .../internal/software_isp/meson.build         |   1 +
 src/libcamera/software_isp/debayer_cpu.cpp    | 528 ++++++++++++++++++
 src/libcamera/software_isp/meson.build        |   1 +
 4 files changed, 661 insertions(+)
 create mode 100644 include/libcamera/internal/software_isp/debayer_cpu.h
 create mode 100644 src/libcamera/software_isp/debayer_cpu.cpp

diff --git a/include/libcamera/internal/software_isp/debayer_cpu.h b/include/libcamera/internal/software_isp/debayer_cpu.h
new file mode 100644
index 00000000..78573f44
--- /dev/null
+++ b/include/libcamera/internal/software_isp/debayer_cpu.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2023, Linaro Ltd
+ * Copyright (C) 2023, Red Hat Inc.
+ *
+ * Authors:
+ * Hans de Goede <hdegoede@redhat.com> 
+ *
+ * debayer_cpu.h - CPU based debayering header
+ */
+
+#pragma once
+
+#include <memory>
+#include <stdint.h>
+#include <vector>
+
+#include <libcamera/base/object.h>
+
+#include "libcamera/internal/software_isp/swstats_cpu.h"
+#include "libcamera/internal/software_isp/debayer.h"
+
+namespace libcamera {
+
+/**
+ * \class DebayerCpu
+ * \brief Class for debayering on the CPU
+ *
+ * Implementation for CPU based debayering
+ */
+class DebayerCpu : public Debayer, public Object
+{
+public:
+	/*
+	  * FIXME this should be a plain (implementation independent)  SwStats
+	  * this can be fixed once getStats() is dropped.
+	  */
+	/**
+	 * \brief Constructs a DebayerCpu object.
+	 * \param[in] stats Pointer to the stats object to use.
+	 */
+	DebayerCpu(std::unique_ptr<SwStatsCpu> stats);
+	~DebayerCpu();
+
+	/*
+	 * Setup the Debayer object according to the passed in parameters.
+	 * Return 0 on success, a negative errno value on failure
+	 * (unsupported parameters).
+	 */
+	int configure(const StreamConfiguration &inputCfg,
+		      const std::vector<std::reference_wrapper<StreamConfiguration>> &outputCfgs);
+
+	/*
+	 * Get width and height at which the bayer-pattern repeats.
+	 * Return pattern-size or an empty Size for an unsupported inputFormat.
+	 */
+	Size patternSize(PixelFormat inputFormat);
+
+	std::vector<PixelFormat> formats(PixelFormat input);
+	std::tuple<unsigned int, unsigned int>
+		strideAndFrameSize(const PixelFormat &outputFormat, const Size &size);
+
+	void process(FrameBuffer *input, FrameBuffer *output, DebayerParams params);
+
+	/**
+	 * \brief Get the file descriptor for the statistics.
+	 *
+	 * \return the file descriptor pointing to the statistics.
+	 */
+	const SharedFD &getStatsFD() { return stats_->getStatsFD(); }
+
+	/**
+	 * \brief Get the output frame size.
+	 *
+	 * \return The output frame size.
+	 */
+	unsigned int frameSize() { return outputConfig_.frameSize; }
+private:
+	void initLinePointers(const uint8_t *linePointers[], const uint8_t *src);
+	void shiftLinePointers(const uint8_t *linePointers[], const uint8_t *src);
+	void process2(const uint8_t *src, uint8_t *dst);
+	void process4(const uint8_t *src, uint8_t *dst);
+	/* CSI-2 packed 10-bit raw bayer format (all the 4 orders) */
+	void debayer10P_BGBG_BGR888(uint8_t *dst, const uint8_t *src[]);
+	void debayer10P_GRGR_BGR888(uint8_t *dst, const uint8_t *src[]);
+	void debayer10P_GBGB_BGR888(uint8_t *dst, const uint8_t *src[]);
+	void debayer10P_RGRG_BGR888(uint8_t *dst, const uint8_t *src[]);
+
+	typedef void (DebayerCpu::*debayerFn)(uint8_t *dst, const uint8_t *src[]);
+
+	struct DebayerInputConfig {
+		Size patternSize;
+		unsigned int bpp; /* Memory used per pixel, not precision */
+		unsigned int stride;
+		std::vector<PixelFormat> outputFormats;
+	};
+
+	struct DebayerOutputConfig {
+		unsigned int bpp; /* Memory used per pixel, not precision */
+		unsigned int stride;
+		unsigned int frameSize;
+	};
+
+	int getInputConfig(PixelFormat inputFormat, DebayerInputConfig &config);
+	int getOutputConfig(PixelFormat outputFormat, DebayerOutputConfig &config);
+	int setDebayerFunctions(PixelFormat inputFormat, PixelFormat outputFormat);
+
+	uint8_t gamma_[1024];
+	uint8_t red_[256];
+	uint8_t green_[256];
+	uint8_t blue_[256];
+	debayerFn debayer0_;
+	debayerFn debayer1_;
+	debayerFn debayer2_;
+	debayerFn debayer3_;
+	Rectangle window_;
+	DebayerInputConfig inputConfig_;
+	DebayerOutputConfig outputConfig_;
+	std::unique_ptr<SwStatsCpu> stats_;
+	uint8_t *lineBuffers_[5];
+	unsigned int lineBufferIndex_;
+	bool enableInputMemcpy_;
+	float gamma_correction_;
+	int measuredFrames_;
+	int64_t frameProcessTime_;
+	/* Skip 30 frames for things to stabilize then measure 30 frames */
+	static const int framesToSkip = 30;
+	static const int framesToMeasure = 60;
+};
+
+} /* namespace libcamera */
diff --git a/include/libcamera/internal/software_isp/meson.build b/include/libcamera/internal/software_isp/meson.build
index 7e40925e..b5a0d737 100644
--- a/include/libcamera/internal/software_isp/meson.build
+++ b/include/libcamera/internal/software_isp/meson.build
@@ -2,6 +2,7 @@
 
 libcamera_internal_headers += files([
     'debayer.h',
+    'debayer_cpu.h',
     'debayer_params.h',
     'swisp_stats.h',
     'swstats.h',
diff --git a/src/libcamera/software_isp/debayer_cpu.cpp b/src/libcamera/software_isp/debayer_cpu.cpp
new file mode 100644
index 00000000..e0c3c658
--- /dev/null
+++ b/src/libcamera/software_isp/debayer_cpu.cpp
@@ -0,0 +1,528 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2023, Linaro Ltd
+ * Copyright (C) 2023, Red Hat Inc.
+ *
+ * Authors:
+ * Hans de Goede <hdegoede@redhat.com> 
+ *
+ * debayer_cpu.cpp - CPU based debayering class
+ */
+
+#include "libcamera/internal/software_isp/debayer_cpu.h"
+
+#include <math.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include <libcamera/formats.h>
+
+#include "libcamera/internal/bayer_format.h"
+#include "libcamera/internal/framebuffer.h"
+#include "libcamera/internal/mapped_framebuffer.h"
+
+namespace libcamera {
+
+DebayerCpu::DebayerCpu(std::unique_ptr<SwStatsCpu> stats)
+	: stats_(std::move(stats)), gamma_correction_(1.0)
+{
+#ifdef __x86_64__
+	enableInputMemcpy_ = false;
+#else
+	enableInputMemcpy_ = true;
+#endif
+	/* Initialize gamma to 1.0 curve */
+	for (int i = 0; i < 1024; i++)
+		gamma_[i] = i / 4;
+
+	for (int i = 0; i < 5; i++)
+		lineBuffers_[i] = NULL;
+}
+
+DebayerCpu::~DebayerCpu()
+{
+	for (int i = 0; i < 5; i++)
+		free(lineBuffers_[i]);
+}
+
+// RGR
+// GBG
+// RGR
+#define BGGR_BGR888(p, n, div)                                                                \
+	*dst++ = blue_[curr[x] / (div)];                                                      \
+	*dst++ = green_[(prev[x] + curr[x - p] + curr[x + n] + next[x]) / (4 * (div))];       \
+	*dst++ = red_[(prev[x - p] + prev[x + n] + next[x - p] + next[x + n]) / (4 * (div))]; \
+	x++;
+
+// GBG
+// RGR
+// GBG
+#define GRBG_BGR888(p, n, div)                                    \
+	*dst++ = blue_[(prev[x] + next[x]) / (2 * (div))];        \
+	*dst++ = green_[curr[x] / (div)];                         \
+	*dst++ = red_[(curr[x - p] + curr[x + n]) / (2 * (div))]; \
+	x++;
+
+// GRG
+// BGB
+// GRG
+#define GBRG_BGR888(p, n, div)                                     \
+	*dst++ = blue_[(curr[x - p] + curr[x + n]) / (2 * (div))]; \
+	*dst++ = green_[curr[x] / (div)];                          \
+	*dst++ = red_[(prev[x] + next[x]) / (2 * (div))];          \
+	x++;
+
+// BGB
+// GRG
+// BGB
+#define RGGB_BGR888(p, n, div)                                                                 \
+	*dst++ = blue_[(prev[x - p] + prev[x + n] + next[x - p] + next[x + n]) / (4 * (div))]; \
+	*dst++ = green_[(prev[x] + curr[x - p] + curr[x + n] + next[x]) / (4 * (div))];        \
+	*dst++ = red_[curr[x] / (div)];                                                        \
+	x++;
+
+void DebayerCpu::debayer10P_BGBG_BGR888(uint8_t *dst, const uint8_t *src[])
+{
+	const int width_in_bytes = window_.width * 5 / 4;
+	const uint8_t *prev = (const uint8_t *)src[0];
+	const uint8_t *curr = (const uint8_t *)src[1];
+	const uint8_t *next = (const uint8_t *)src[2];
+
+	/*
+	 * For the first pixel getting a pixel from the previous column uses
+	 * x - 2 to skip the 5th byte with least-significant bits for 4 pixels.
+	 * Same for last pixel (uses x + 2) and looking at the next column.
+	 * x++ in the for-loop skips the 5th byte with 4 x 2 lsb-s for 10bit packed.
+	 */
+	for (int x = 0; x < width_in_bytes; x++) {
+		/* Even pixel */
+		BGGR_BGR888(2, 1, 1)
+		/* Odd pixel BGGR -> GBRG */
+		GBRG_BGR888(1, 1, 1)
+		/* Same thing for next 2 pixels */
+		BGGR_BGR888(1, 1, 1)
+		GBRG_BGR888(1, 2, 1)
+	}
+}
+
+void DebayerCpu::debayer10P_GRGR_BGR888(uint8_t *dst, const uint8_t *src[])
+{
+	const int width_in_bytes = window_.width * 5 / 4;
+	const uint8_t *prev = (const uint8_t *)src[0];
+	const uint8_t *curr = (const uint8_t *)src[1];
+	const uint8_t *next = (const uint8_t *)src[2];
+
+	for (int x = 0; x < width_in_bytes; x++) {
+		/* Even pixel */
+		GRBG_BGR888(2, 1, 1)
+		/* Odd pixel GRBG -> RGGB */
+		RGGB_BGR888(1, 1, 1)
+		/* Same thing for next 2 pixels */
+		GRBG_BGR888(1, 1, 1)
+		RGGB_BGR888(1, 2, 1)
+	}
+}
+
+void DebayerCpu::debayer10P_GBGB_BGR888(uint8_t *dst, const uint8_t *src[])
+{
+	const int width_in_bytes = window_.width * 5 / 4;
+	const uint8_t *prev = (const uint8_t *)src[0];
+	const uint8_t *curr = (const uint8_t *)src[1];
+	const uint8_t *next = (const uint8_t *)src[2];
+
+	for (int x = 0; x < width_in_bytes; x++) {
+		/* Even pixel */
+		GBRG_BGR888(2, 1, 1)
+		/* Odd pixel GBGR -> BGGR */
+		BGGR_BGR888(1, 1, 1)
+		/* Same thing for next 2 pixels */
+		GBRG_BGR888(1, 1, 1)
+		BGGR_BGR888(1, 2, 1)
+	}
+}
+
+void DebayerCpu::debayer10P_RGRG_BGR888(uint8_t *dst, const uint8_t *src[])
+{
+	const int width_in_bytes = window_.width * 5 / 4;
+	const uint8_t *prev = (const uint8_t *)src[0];
+	const uint8_t *curr = (const uint8_t *)src[1];
+	const uint8_t *next = (const uint8_t *)src[2];
+
+	for (int x = 0; x < width_in_bytes; x++) {
+		/* Even pixel */
+		RGGB_BGR888(2, 1, 1)
+		/* Odd pixel RGGB -> GRBG*/
+		GRBG_BGR888(1, 1, 1)
+		/* Same thing for next 2 pixels */
+		RGGB_BGR888(1, 1, 1)
+		GRBG_BGR888(1, 2, 1)
+	}
+}
+
+static bool isStandardBayerOrder(BayerFormat::Order order)
+{
+	return order == BayerFormat::BGGR || order == BayerFormat::GBRG ||
+	       order == BayerFormat::GRBG || order == BayerFormat::RGGB;
+}
+
+int DebayerCpu::getInputConfig(PixelFormat inputFormat, DebayerInputConfig &config)
+{
+	BayerFormat bayerFormat =
+		BayerFormat::fromPixelFormat(inputFormat);
+
+	if (bayerFormat.bitDepth == 10 &&
+	    bayerFormat.packing == BayerFormat::Packing::CSI2 &&
+	    isStandardBayerOrder(bayerFormat.order)) {
+		config.bpp = 10;
+		config.patternSize.width = 4; /* 5 bytes per *4* pixels */
+		config.patternSize.height = 2;
+		config.outputFormats = std::vector<PixelFormat>({ formats::RGB888 });
+		return 0;
+	}
+
+	LOG(Debayer, Info)
+		<< "Unsupported input format " << inputFormat.toString();
+	return -EINVAL;
+}
+
+int DebayerCpu::getOutputConfig(PixelFormat outputFormat, DebayerOutputConfig &config)
+{
+	if (outputFormat == formats::RGB888) {
+		config.bpp = 24;
+		return 0;
+	}
+
+	LOG(Debayer, Info)
+		<< "Unsupported output format " << outputFormat.toString();
+	return -EINVAL;
+}
+
+/* TODO: this ignores outputFormat since there is only 1 supported outputFormat for now */
+int DebayerCpu::setDebayerFunctions(PixelFormat inputFormat, [[maybe_unused]] PixelFormat outputFormat)
+{
+	BayerFormat bayerFormat =
+		BayerFormat::fromPixelFormat(inputFormat);
+
+	if (bayerFormat.bitDepth == 10 &&
+	    bayerFormat.packing == BayerFormat::Packing::CSI2) {
+		switch (bayerFormat.order) {
+		case BayerFormat::BGGR:
+			debayer0_ = &DebayerCpu::debayer10P_BGBG_BGR888;
+			debayer1_ = &DebayerCpu::debayer10P_GRGR_BGR888;
+			return 0;
+		case BayerFormat::GBRG:
+			debayer0_ = &DebayerCpu::debayer10P_GBGB_BGR888;
+			debayer1_ = &DebayerCpu::debayer10P_RGRG_BGR888;
+			return 0;
+		case BayerFormat::GRBG:
+			debayer0_ = &DebayerCpu::debayer10P_GRGR_BGR888;
+			debayer1_ = &DebayerCpu::debayer10P_BGBG_BGR888;
+			return 0;
+		case BayerFormat::RGGB:
+			debayer0_ = &DebayerCpu::debayer10P_RGRG_BGR888;
+			debayer1_ = &DebayerCpu::debayer10P_GBGB_BGR888;
+			return 0;
+		default:
+			break;
+		}
+	}
+
+	LOG(Debayer, Error) << "Unsupported input output format combination";
+	return -EINVAL;
+}
+
+int DebayerCpu::configure(const StreamConfiguration &inputCfg,
+			  const std::vector<std::reference_wrapper<StreamConfiguration>> &outputCfgs)
+{
+	if (getInputConfig(inputCfg.pixelFormat, inputConfig_) != 0)
+		return -EINVAL;
+
+	if (stats_->configure(inputCfg) != 0)
+		return -EINVAL;
+
+	const Size &stats_pattern_size = stats_->patternSize();
+	if (inputConfig_.patternSize.width != stats_pattern_size.width ||
+	    inputConfig_.patternSize.height != stats_pattern_size.height) {
+		LOG(Debayer, Error)
+			<< "mismatching stats and debayer pattern sizes for "
+			<< inputCfg.pixelFormat.toString();
+		return -EINVAL;
+	}
+
+	inputConfig_.stride = inputCfg.stride;
+
+	if (outputCfgs.size() != 1) {
+		LOG(Debayer, Error)
+			<< "Unsupported number of output streams: "
+			<< outputCfgs.size();
+		return -EINVAL;
+	}
+
+	const StreamConfiguration &outputCfg = outputCfgs[0];
+	SizeRange outSizeRange = sizes(inputCfg.pixelFormat, inputCfg.size);
+	std::tie(outputConfig_.stride, outputConfig_.frameSize) =
+		strideAndFrameSize(outputCfg.pixelFormat, outputCfg.size);
+
+	if (!outSizeRange.contains(outputCfg.size) || outputConfig_.stride != outputCfg.stride) {
+		LOG(Debayer, Error)
+			<< "Invalid output size/stride: "
+			<< "\n  " << outputCfg.size << " (" << outSizeRange << ")"
+			<< "\n  " << outputCfg.stride << " (" << outputConfig_.stride << ")";
+		return -EINVAL;
+	}
+
+	if (setDebayerFunctions(inputCfg.pixelFormat, outputCfg.pixelFormat) != 0)
+		return -EINVAL;
+
+	window_.x = ((inputCfg.size.width - outputCfg.size.width) / 2) &
+		    ~(inputConfig_.patternSize.width - 1);
+	window_.y = ((inputCfg.size.height - outputCfg.size.height) / 2) &
+		    ~(inputConfig_.patternSize.height - 1);
+	window_.width = outputCfg.size.width;
+	window_.height = outputCfg.size.height;
+
+	/* Don't pass x,y since process() already adjusts src before passing it */
+	stats_->setWindow(Rectangle(window_.size()));
+
+	for (unsigned int i = 0;
+	     i < (inputConfig_.patternSize.height + 1) && enableInputMemcpy_;
+	     i++) {
+		/* pad with patternSize.Width on both left and right side */
+		size_t lineLength = (window_.width + 2 * inputConfig_.patternSize.width) *
+				    inputConfig_.bpp / 8;
+
+		free(lineBuffers_[i]);
+		lineBuffers_[i] = (uint8_t *)malloc(lineLength);
+		if (!lineBuffers_[i])
+			return -ENOMEM;
+	}
+
+	measuredFrames_ = 0;
+	frameProcessTime_ = 0;
+
+	return 0;
+}
+
+Size DebayerCpu::patternSize(PixelFormat inputFormat)
+{
+	DebayerCpu::DebayerInputConfig config;
+
+	if (getInputConfig(inputFormat, config) != 0)
+		return {};
+
+	return config.patternSize;
+}
+
+std::vector<PixelFormat> DebayerCpu::formats(PixelFormat inputFormat)
+{
+	DebayerCpu::DebayerInputConfig config;
+
+	if (getInputConfig(inputFormat, config) != 0)
+		return std::vector<PixelFormat>();
+
+	return config.outputFormats;
+}
+
+std::tuple<unsigned int, unsigned int>
+DebayerCpu::strideAndFrameSize(const PixelFormat &outputFormat, const Size &size)
+{
+	DebayerCpu::DebayerOutputConfig config;
+
+	if (getOutputConfig(outputFormat, config) != 0)
+		return std::make_tuple(0, 0);
+
+	/* round up to multiple of 8 for 64 bits alignment */
+	unsigned int stride = (size.width * config.bpp / 8 + 7) & ~7;
+
+	return std::make_tuple(stride, stride * size.height);
+}
+
+void DebayerCpu::initLinePointers(const uint8_t *linePointers[], const uint8_t *src)
+{
+	const int patternHeight = inputConfig_.patternSize.height;
+
+	for (int i = 0; i < patternHeight; i++)
+		linePointers[i + 1] = src +
+				      (-patternHeight / 2 + i) * (int)inputConfig_.stride;
+
+	if (!enableInputMemcpy_)
+		return;
+
+	for (int i = 0; i < patternHeight; i++) {
+		/* pad with patternSize.Width on both left and right side */
+		size_t lineLength = (window_.width + 2 * inputConfig_.patternSize.width) *
+				    inputConfig_.bpp / 8;
+		int padding = inputConfig_.patternSize.width * inputConfig_.bpp / 8;
+
+		memcpy(lineBuffers_[i], linePointers[i + 1] - padding, lineLength);
+		linePointers[i + 1] = lineBuffers_[i] + padding;
+	}
+
+	/* Point lineBufferIndex_ to first unused lineBuffer */
+	lineBufferIndex_ = patternHeight;
+}
+
+void DebayerCpu::shiftLinePointers(const uint8_t *linePointers[], const uint8_t *src)
+{
+	const int patternHeight = inputConfig_.patternSize.height;
+
+	for (int i = 0; i < patternHeight; i++)
+		linePointers[i] = linePointers[i + 1];
+
+	linePointers[patternHeight] = src +
+				      (patternHeight / 2) * (int)inputConfig_.stride;
+
+	if (!enableInputMemcpy_)
+		return;
+
+	size_t lineLength = (window_.width + 2 * inputConfig_.patternSize.width) *
+			    inputConfig_.bpp / 8;
+	int padding = inputConfig_.patternSize.width * inputConfig_.bpp / 8;
+	memcpy(lineBuffers_[lineBufferIndex_], linePointers[patternHeight] - padding, lineLength);
+	linePointers[patternHeight] = lineBuffers_[lineBufferIndex_] + padding;
+
+	lineBufferIndex_ = (lineBufferIndex_ + 1) % (patternHeight + 1);
+}
+
+void DebayerCpu::process2(const uint8_t *src, uint8_t *dst)
+{
+	const unsigned int y_end = window_.y + window_.height;
+	const uint8_t *linePointers[3];
+
+	/* Adjust src to top left corner of the window */
+	src += window_.y * inputConfig_.stride + window_.x * inputConfig_.bpp / 8;
+
+	initLinePointers(linePointers, src);
+
+	for (unsigned int y = window_.y; y < y_end; y += 2) {
+		shiftLinePointers(linePointers, src);
+		stats_->processLine0(y, linePointers);
+		(this->*debayer0_)(dst, linePointers);
+		src += inputConfig_.stride;
+		dst += outputConfig_.stride;
+
+		shiftLinePointers(linePointers, src);
+		(this->*debayer1_)(dst, linePointers);
+		src += inputConfig_.stride;
+		dst += outputConfig_.stride;
+	}
+}
+
+void DebayerCpu::process4(const uint8_t *src, uint8_t *dst)
+{
+	const unsigned int y_end = window_.y + window_.height;
+	const uint8_t *linePointers[5];
+
+	/* Adjust src to top left corner of the window */
+	src += window_.y * inputConfig_.stride + window_.x * inputConfig_.bpp / 8;
+
+	initLinePointers(linePointers, src);
+
+	for (unsigned int y = window_.y; y < y_end; y += 4) {
+		shiftLinePointers(linePointers, src);
+		stats_->processLine0(y, linePointers);
+		(this->*debayer0_)(dst, linePointers);
+		src += inputConfig_.stride;
+		dst += outputConfig_.stride;
+
+		shiftLinePointers(linePointers, src);
+		(this->*debayer1_)(dst, linePointers);
+		src += inputConfig_.stride;
+		dst += outputConfig_.stride;
+
+		shiftLinePointers(linePointers, src);
+		stats_->processLine2(y, linePointers);
+		(this->*debayer2_)(dst, linePointers);
+		src += inputConfig_.stride;
+		dst += outputConfig_.stride;
+
+		shiftLinePointers(linePointers, src);
+		(this->*debayer3_)(dst, linePointers);
+		src += inputConfig_.stride;
+		dst += outputConfig_.stride;
+	}
+}
+
+static inline int64_t timeDiff(timespec &after, timespec &before)
+{
+	return (after.tv_sec - before.tv_sec) * 1000000000LL +
+	       (int64_t)after.tv_nsec - (int64_t)before.tv_nsec;
+}
+
+void DebayerCpu::process(FrameBuffer *input, FrameBuffer *output, DebayerParams params)
+{
+	timespec frameStartTime;
+
+	if (measuredFrames_ < DebayerCpu::framesToMeasure) {
+		frameStartTime = {};
+		clock_gettime(CLOCK_MONOTONIC_RAW, &frameStartTime);
+	}
+
+	/* Apply DebayerParams */
+	if (params.gamma != gamma_correction_) {
+		for (int i = 0; i < 1024; i++)
+			gamma_[i] = 255 * powf(i / 1023.0, params.gamma);
+
+		gamma_correction_ = params.gamma;
+	}
+
+	for (int i = 0; i < 256; i++) {
+		int idx;
+
+		/* Apply gamma after gain! */
+		idx = std::min({ i * params.gainR / 64U, 1023U });
+		red_[i] = gamma_[idx];
+
+		idx = std::min({ i * params.gainG / 64U, 1023U });
+		green_[i] = gamma_[idx];
+
+		idx = std::min({ i * params.gainB / 64U, 1023U });
+		blue_[i] = gamma_[idx];
+	}
+
+	/* Copy metadata from the input buffer */
+	FrameMetadata &metadata = output->_d()->metadata();
+	metadata.status = input->metadata().status;
+	metadata.sequence = input->metadata().sequence;
+	metadata.timestamp = input->metadata().timestamp;
+
+	MappedFrameBuffer in(input, MappedFrameBuffer::MapFlag::Read);
+	MappedFrameBuffer out(output, MappedFrameBuffer::MapFlag::Write);
+	if (!in.isValid() || !out.isValid()) {
+		LOG(Debayer, Error) << "mmap-ing buffer(s) failed";
+		metadata.status = FrameMetadata::FrameError;
+		return;
+	}
+
+	stats_->startFrame();
+
+	if (inputConfig_.patternSize.height == 2)
+		process2(in.planes()[0].data(), out.planes()[0].data());
+	else
+		process4(in.planes()[0].data(), out.planes()[0].data());
+
+	metadata.planes()[0].bytesused = out.planes()[0].size();
+
+	/* Measure before emitting signals */
+	if (measuredFrames_ < DebayerCpu::framesToMeasure &&
+	    ++measuredFrames_ > DebayerCpu::framesToSkip) {
+		timespec frameEndTime = {};
+		clock_gettime(CLOCK_MONOTONIC_RAW, &frameEndTime);
+		frameProcessTime_ += timeDiff(frameEndTime, frameStartTime);
+		if (measuredFrames_ == DebayerCpu::framesToMeasure) {
+			const int measuredFrames = DebayerCpu::framesToMeasure -
+						   DebayerCpu::framesToSkip;
+			LOG(Debayer, Info)
+				<< "Processed " << measuredFrames
+				<< " frames in " << frameProcessTime_ / 1000 << "us, "
+				<< frameProcessTime_ / (1000 * measuredFrames)
+				<< " us/frame";
+		}
+	}
+
+	stats_->finishFrame();
+	outputBufferReady.emit(output);
+	inputBufferReady.emit(input);
+}
+
+} /* namespace libcamera */
diff --git a/src/libcamera/software_isp/meson.build b/src/libcamera/software_isp/meson.build
index d4ae5ac7..6d7a44d7 100644
--- a/src/libcamera/software_isp/meson.build
+++ b/src/libcamera/software_isp/meson.build
@@ -2,6 +2,7 @@
 
 libcamera_sources += files([
 	'debayer.cpp',
+	'debayer_cpu.cpp',
 	'swstats.cpp',
 	'swstats_cpu.cpp',
 ])
-- 
2.43.0