[PATCH v2 07/18] libcamera: software_isp: Add SwStats base class

[Milan Zamazal]

Hans de Goede <hdegoede at redhat.com> writes:

> Add a virtual base class for CPU based software statistics gathering
> implementations.
>
> The idea is for the implementations to offer a configure function +
> functions to gather statistics on a line by line basis. This allows
> CPU based software debayering to call into interlace debayering and
> statistics gathering on a line by line bases while the input data
> is still hot in the cache.
>
> This base class also allows the user of an implementation to specify
> a window over which to gather statistics instead of processing the
> whole frame; and it allows the implementation to choose to only
> process 1/2, 1/4th, etc. of the lines instead of processing all
> lines (in the window) by setting y_skip_mask_ from configure().
> Skipping columns is left up the line-processing functions provided
> by the implementation.
>
> Doxygen documentation by Dennis Bonke.
>
> Co-authored-by: Dennis Bonke <admin at dennisbonke.com>
> Signed-off-by: Dennis Bonke <admin at dennisbonke.com>
> Co-authored-by: Andrey Konovalov <andrey.konovalov at linaro.org>
> Signed-off-by: Andrey Konovalov <andrey.konovalov at linaro.org>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> Tested-by: Bryan O'Donoghue <bryan.odonoghue at linaro.org> # sc8280xp Lenovo x13s
> Tested-by: Pavel Machek <pavel at ucw.cz>
> ---
>  include/libcamera/internal/meson.build        |   1 +
>  .../internal/software_isp/meson.build         |   6 +
>  .../internal/software_isp/swisp_stats.h       |  34 +++
>  .../libcamera/internal/software_isp/swstats.h | 215 ++++++++++++++++++
>  src/libcamera/meson.build                     |   1 +
>  src/libcamera/software_isp/meson.build        |   5 +
>  src/libcamera/software_isp/swstats.cpp        |  22 ++
>  7 files changed, 284 insertions(+)
>  create mode 100644 include/libcamera/internal/software_isp/meson.build
>  create mode 100644 include/libcamera/internal/software_isp/swisp_stats.h
>  create mode 100644 include/libcamera/internal/software_isp/swstats.h
>  create mode 100644 src/libcamera/software_isp/meson.build
>  create mode 100644 src/libcamera/software_isp/swstats.cpp
>
> diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
> index 1325941d..caa533c4 100644
> --- a/include/libcamera/internal/meson.build
> +++ b/include/libcamera/internal/meson.build
> @@ -51,3 +51,4 @@ libcamera_internal_headers = files([
>  ])
>  
>  subdir('converter')
> +subdir('software_isp')
> diff --git a/include/libcamera/internal/software_isp/meson.build b/include/libcamera/internal/software_isp/meson.build
> new file mode 100644
> index 00000000..1c43acc4
> --- /dev/null
> +++ b/include/libcamera/internal/software_isp/meson.build
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: CC0-1.0
> +
> +libcamera_internal_headers += files([
> +    'swisp_stats.h',
> +    'swstats.h',
> +])
> diff --git a/include/libcamera/internal/software_isp/swisp_stats.h b/include/libcamera/internal/software_isp/swisp_stats.h
> new file mode 100644
> index 00000000..07ba7d6a
> --- /dev/null
> +++ b/include/libcamera/internal/software_isp/swisp_stats.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2023, Linaro Ltd
> + *
> + * swisp_stats.h - Statistics data format used by the software ISP and software IPA
> + */
> +
> +#pragma once
> +
> +namespace libcamera {
> +
> +/**
> + * \brief Struct that holds the statistics for the Software ISP.
> + */
> +struct SwIspStats {
> +	/**
> +	 * \brief Holds the sum of all sampled red pixels.
> +	 */
> +	unsigned long sumR_;
> +	/**
> +	 * \brief Holds the sum of all sampled green pixels.
> +	 */
> +	unsigned long sumG_;
> +	/**
> +	 * \brief Holds the sum of all sampled blue pixels.
> +	 */
> +	unsigned long sumB_;
> +	/**
> +	 * \brief A histogram of luminance values.
> +	 */
> +	unsigned int y_histogram[16];
> +};
> +
> +} /* namespace libcamera */
> diff --git a/include/libcamera/internal/software_isp/swstats.h b/include/libcamera/internal/software_isp/swstats.h
> new file mode 100644
> index 00000000..dcac7064
> --- /dev/null
> +++ b/include/libcamera/internal/software_isp/swstats.h
> @@ -0,0 +1,215 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2023, Linaro Ltd
> + * Copyright (C) 2023, Red Hat Inc.
> + *
> + * Authors:
> + * Hans de Goede <hdegoede at redhat.com> 
> + *
> + * swstats.h - software statistics base class
> + */
> +
> +#pragma once
> +
> +#include <stdint.h>
> +
> +#include <libcamera/base/log.h>
> +#include <libcamera/base/signal.h>
> +
> +#include <libcamera/geometry.h>
> +
> +namespace libcamera {
> +
> +class PixelFormat;
> +struct SharedFD;
> +struct StreamConfiguration;
> +
> +LOG_DECLARE_CATEGORY(SwStats)
> +
> +/**
> + * \class SwStats
> + * \brief Base class for the software ISP statistics.
> + *
> + * Base class for the software ISP statistics.
> + */
> +class SwStats
> +{
> +public:
> +	virtual ~SwStats() = 0;
> +
> +	/**
> +	 * \brief Gets wether the statistics object is valid.
> +	 * 
> +	 * \return true if it's valid, false otherwise.
> +	 */
> +	virtual bool isValid() const = 0;
> +
> +	/**
> +	 * \brief Configure the statistics object for the passed in input format.
> +	 * \param[in] inputCfg The input format
> +	 *
> +	 * \return 0 on success, a negative errno value on failure.
> +	 */
> +	virtual int configure(const StreamConfiguration &inputCfg) = 0;
> +
> +	/**
> +	 * \brief Get the file descriptor for the statistics.
> +	 *
> +	 * \return the file descriptor
> +	 */
> +	virtual const SharedFD &getStatsFD() = 0;
> +
> +protected:
> +	/**
> +	 * \brief Called when there is data to get statistics from.
> +	 * \param[in] src The input data
> +	 */
> +	typedef void (SwStats::*statsProcessFn)(const uint8_t *src[]);
> +	/**
> +	 * \brief Called when the statistics gathering is done or when a new frame starts.
> +	 */
> +	typedef void (SwStats::*statsVoidFn)();
> +
> +	/* Variables set by configure(), used every line */
> +	/**
> +	 * \brief The function called when a line is ready for statistics processing.
> +	 *
> +	 * Used for line 0 and 1, repeating if there isn't a 3rd and a 4th line in the bayer order.
> +	 */
> +	statsProcessFn stats0_;
> +	/**
> +	 * \brief The function called when a line is ready for statistics processing.
> +	 *
> +	 * Used for line 3 and 4, only needed if the bayer order has 4 different lines.
> +	 */
> +	statsProcessFn stats2_;
> +
> +	/**
> +	 * \brief The memory used per pixel in bits.
> +	 */
> +	unsigned int bpp_;
> +	/**
> +	 * \brief Skip lines where this bitmask is set in y.
> +	 */
> +	unsigned int y_skip_mask_;
> +
> +	/**
> +	 * \brief Statistics window, set by setWindow(), used ever line.
> +	 */
> +	Rectangle window_;
> +
> +	/**
> +	 * \brief The function called at the start of a frame.
> +	 */
> +	statsVoidFn startFrame_;
> +	/**
> +	 * \brief The function called at the end of a frame.
> +	 */
> +	statsVoidFn finishFrame_;
> +	/**
> +	 * \brief The size of the bayer pattern.
> +	 */
> +	Size patternSize_;
> +	/**
> +	 * \brief The offset of x, applied to window_.x for bayer variants.
> +	 *
> +	 * This can either be 0 or 1.
> +	 */
> +	unsigned int x_shift_;
> +
> +public:
> +	/**
> +	 * \brief Get the pattern size.
> +	 *
> +	 * For some input-formats, e.g. Bayer data, processing is done multiple lines
> +	 * and/or columns at a time. Get width and height at which the (bayer) pattern
> +	 * repeats. Window values are rounded down to a multiple of this and the height
> +	 * also indicates if processLine2() should be called or not.
> +	 * This may only be called after a successful configure() call.
> +	 *
> +	 * \return the pattern size.
> +	 */
> +	const Size &patternSize() { return patternSize_; }
> +
> +	/**
> +	 * \brief Specify window coordinates over which to gather statistics.
> +	 * \param[in] window The window object.
> +	 */
> +	void setWindow(Rectangle window)
> +	{
> +		window_ = window;
> +
> +		window_.x &= ~(patternSize_.width - 1);
> +		window_.x += x_shift_;
> +		window_.y &= ~(patternSize_.height - 1);
> +
> +		/* width_ - x_shift_ to make sure the window fits */
> +		window_.width -= x_shift_;
> +		window_.width &= ~(patternSize_.width - 1);
> +		window_.height &= ~(patternSize_.height - 1);

These operations work correctly only if width & height are powers of 2, right?
Maybe this is satisfied for all Bayer patterns but I think such implicit
assumptions should be either not introduced or sufficiently visibly documented.

> +	}
> +
> +	/**
> +	 * \brief Reset state to start statistics gathering for a new frame.
> +	 * 
> +	 * This may only be called after a successful setWindow() call.
> +	 */
> +	void startFrame()
> +	{
> +		(this->*startFrame_)();
> +	}
> +
> +	/**
> +	 * \brief Process line 0.
> +	 * \param[in] y The y coordinate.
> +	 * \param[in] src The input data.
> +	 *
> +	 * This function processes line 0 for input formats with patternSize height == 1.
> +	 * It'll process line 0 and 1 for input formats with patternSize height >= 2.
> +	 * This function may only be called after a successful setWindow() call.
> +	 */
> +	void processLine0(unsigned int y, const uint8_t *src[])
> +	{
> +		if ((y & y_skip_mask_) || y < (unsigned int)window_.y ||
> +		    y >= (window_.y + window_.height))
> +			return;
> +
> +		(this->*stats0_)(src);
> +	}
> +
> +	/**
> +	 * \brief Process line 2 and 3.
> +	 * \param[in] y The y coordinate.
> +	 * \param[in] src The input data.
> +	 *
> +	 * This function processes line 2 and 3 for input formats with patternSize height == 4.
> +	 * This function may only be called after a successful setWindow() call.
> +	 */
> +	void processLine2(unsigned int y, const uint8_t *src[])
> +	{
> +		if ((y & y_skip_mask_) || y < (unsigned int)window_.y ||
> +		    y >= (window_.y + window_.height))
> +			return;
> +
> +		(this->*stats2_)(src);
> +	}
> +
> +	/**
> +	 * \brief Finish statistics calculation for the current frame.
> +	 * 
> +	 * This may only be called after a successful setWindow() call.
> +	 */
> +	void finishFrame()
> +	{
> +		(this->*finishFrame_)();
> +	}
> +
> +	/**
> +	 * \brief Signals that the statistics are ready.
> +	 *
> +	 * The int parameter isn't actually used.
> +	 */
> +	Signal<int> statsReady;
> +};
> +
> +} /* namespace libcamera */
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index 86494663..3d63e8a2 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -71,6 +71,7 @@ subdir('converter')
>  subdir('ipa')
>  subdir('pipeline')
>  subdir('proxy')
> +subdir('software_isp')
>  
>  null_dep = dependency('', required : false)
>  
> diff --git a/src/libcamera/software_isp/meson.build b/src/libcamera/software_isp/meson.build
> new file mode 100644
> index 00000000..9359075d
> --- /dev/null
> +++ b/src/libcamera/software_isp/meson.build
> @@ -0,0 +1,5 @@
> +# SPDX-License-Identifier: CC0-1.0
> +
> +libcamera_sources += files([
> +	'swstats.cpp',
> +])
> diff --git a/src/libcamera/software_isp/swstats.cpp b/src/libcamera/software_isp/swstats.cpp
> new file mode 100644
> index 00000000..e65a7ada
> --- /dev/null
> +++ b/src/libcamera/software_isp/swstats.cpp
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2023, Linaro Ltd
> + * Copyright (C) 2023, Red Hat Inc.
> + *
> + * Authors:
> + * Hans de Goede <hdegoede at redhat.com> 
> + *
> + * swstats.cpp - software statistics base class
> + */
> +
> +#include "libcamera/internal/software_isp/swstats.h"
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(SwStats)
> +
> +SwStats::~SwStats()
> +{
> +}
> +
> +} /* namespace libcamera */