[libcamera-devel] [PATCH 03/11] libcamera: controls: Add support for string controls

Jacopo Mondi jacopo at jmondi.org
Fri Mar 20 13:08:44 CET 2020


Hi Laurent,

On Mon, Mar 09, 2020 at 05:24:06PM +0100, Jacopo Mondi wrote:
> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>
> String controls are stored internally as an array of char, but the
> ControlValue constructor, get() and set() functions operate on an
> std::string for convenience. Array of strings are thus not supported.
>
> Unlike for other control types, the ControlInfo range reports the
> minimum and maximum allowed lengths of the string (the minimum will
> usually be 0), not the minimum and maximum value of each element.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  include/libcamera/controls.h         | 30 +++++++++++++++++++-----
>  src/libcamera/control_serializer.cpp | 22 +++++++++++++++++
>  src/libcamera/controls.cpp           | 35 ++++++++++++++++++++++++----
>  src/libcamera/gen-controls.py        | 18 +++++++-------
>  4 files changed, 87 insertions(+), 18 deletions(-)
>
> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> index 9c6cbffb88b5..5cf6280e612b 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -26,6 +26,7 @@ enum ControlType {
>  	ControlTypeInteger32,
>  	ControlTypeInteger64,
>  	ControlTypeFloat,
> +	ControlTypeString,
>  };
>
>  namespace details {
> @@ -64,6 +65,11 @@ struct control_type<float> {
>  	static constexpr ControlType value = ControlTypeFloat;
>  };
>
> +template<>
> +struct control_type<std::string> {
> +	static constexpr ControlType value = ControlTypeString;
> +};
> +
>  template<typename T, std::size_t N>
>  struct control_type<Span<T, N>> : public control_type<std::remove_cv_t<T>> {
>  };
> @@ -76,7 +82,9 @@ public:
>  	ControlValue();
>
>  #ifndef __DOXYGEN__
> -	template<typename T, typename std::enable_if_t<!details::is_span<T>::value, std::nullptr_t> = nullptr>
> +	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
> +						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
> +						       std::nullptr_t> = nullptr>
>  	ControlValue(const T &value)
>  		: type_(ControlTypeNone), numElements_(0)
>  	{
> @@ -84,7 +92,9 @@ public:
>  		    &value, 1, sizeof(T));
>  	}
>
> -	template<typename T, typename std::enable_if_t<details::is_span<T>::value, std::nullptr_t> = nullptr>
> +	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> +						       std::is_same<std::string, std::remove_cv_t<T>>::value,
> +						       std::nullptr_t> = nullptr>
>  #else
>  	template<typename T>
>  #endif
> @@ -115,7 +125,9 @@ public:
>  	}
>
>  #ifndef __DOXYGEN__
> -	template<typename T, typename std::enable_if_t<!details::is_span<T>::value, std::nullptr_t> = nullptr>
> +	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
> +						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
> +						       std::nullptr_t> = nullptr>
>  	T get() const
>  	{
>  		assert(type_ == details::control_type<std::remove_cv_t<T>>::value);
> @@ -124,7 +136,9 @@ public:
>  		return *reinterpret_cast<const T *>(data().data());
>  	}
>
> -	template<typename T, typename std::enable_if_t<details::is_span<T>::value, std::nullptr_t> = nullptr>
> +	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> +						       std::is_same<std::string, std::remove_cv_t<T>>::value,
> +						       std::nullptr_t> = nullptr>
>  #else
>  	template<typename T>
>  #endif
> @@ -139,14 +153,18 @@ public:
>  	}
>
>  #ifndef __DOXYGEN__
> -	template<typename T, typename std::enable_if_t<!details::is_span<T>::value, std::nullptr_t> = nullptr>
> +	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
> +						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
> +						       std::nullptr_t> = nullptr>
>  	void set(const T &value)
>  	{
>  		set(details::control_type<std::remove_cv_t<T>>::value, false,
>  		    reinterpret_cast<const void *>(&value), 1, sizeof(T));
>  	}
>
> -	template<typename T, typename std::enable_if_t<details::is_span<T>::value, std::nullptr_t> = nullptr>
> +	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> +						       std::is_same<std::string, std::remove_cv_t<T>>::value,
> +						       std::nullptr_t> = nullptr>
>  #else
>  	template<typename T>
>  #endif
> diff --git a/src/libcamera/control_serializer.cpp b/src/libcamera/control_serializer.cpp
> index eef875f4d96c..808419f246c0 100644
> --- a/src/libcamera/control_serializer.cpp
> +++ b/src/libcamera/control_serializer.cpp
> @@ -314,6 +314,22 @@ ControlValue ControlSerializer::loadControlValue(ByteStreamBuffer &buffer,
>  	return value;
>  }
>
> +template<>
> +ControlValue ControlSerializer::loadControlValue<std::string>(ByteStreamBuffer &buffer,
> +						 bool isArray,
> +						 unsigned int count)

Not may way around this specialization I gueess..
I see std::string being defined as std::basic_string<char> and I was
wondering if we could reuse the <char>  template argument, but I don't
see a clear way to do so

Anyway, ControlTypeFloat documentation removal apart
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
  j

> +{
> +	ControlValue value;
> +
> +	const char *data = buffer.read<char>(count);
> +	if (!data)
> +		return value;
> +
> +	value.set(std::string{ data, count });
> +
> +	return value;
> +}
> +
>  ControlValue ControlSerializer::loadControlValue(ControlType type,
>  						 ByteStreamBuffer &buffer,
>  						 bool isArray,
> @@ -335,6 +351,9 @@ ControlValue ControlSerializer::loadControlValue(ControlType type,
>  	case ControlTypeFloat:
>  		return loadControlValue<float>(buffer, isArray, count);
>
> +	case ControlTypeString:
> +		return loadControlValue<std::string>(buffer, isArray, count);
> +
>  	case ControlTypeNone:
>  		return ControlValue();
>  	}
> @@ -345,6 +364,9 @@ ControlValue ControlSerializer::loadControlValue(ControlType type,
>  ControlInfo ControlSerializer::loadControlInfo(ControlType type,
>  					       ByteStreamBuffer &b)
>  {
> +	if (type == ControlTypeString)
> +		type = ControlTypeInteger32;
> +
>  	ControlValue min = loadControlValue(type, b);
>  	ControlValue max = loadControlValue(type, b);
>
> diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> index 53649fe897db..68d040db4daa 100644
> --- a/src/libcamera/controls.cpp
> +++ b/src/libcamera/controls.cpp
> @@ -57,6 +57,7 @@ static constexpr size_t ControlValueSize[] = {
>  	[ControlTypeInteger32]		= sizeof(int32_t),
>  	[ControlTypeInteger64]		= sizeof(int64_t),
>  	[ControlTypeFloat]		= sizeof(float),
> +	[ControlTypeString]		= sizeof(char),
>  };
>
>  } /* namespace */
> @@ -74,8 +75,8 @@ static constexpr size_t ControlValueSize[] = {
>   * The control stores a 32-bit integer value
>   * \var ControlTypeInteger64
>   * The control stores a 64-bit integer value
> - * \var ControlTypeFloat
> - * The control stores a 32-bit floating point value

What did the poor Float type do to you ? :(

> + * \var ControlTypeString
> + * The control stores a string value as an array of char
>   */
>
>  /**
> @@ -164,7 +165,8 @@ ControlValue &ControlValue::operator=(const ControlValue &other)
>   * \brief Retrieve the number of elements stored in the ControlValue
>   *
>   * For instances storing an array, this function returns the number of elements
> - * in the array. Otherwise, it returns 1.
> + * in the array. For instances storing a string, it returns the length of the
> + * string, not counting the terminating '\0'. Otherwise, it returns 1.
>   *
>   * \return The number of elements stored in the ControlValue
>   */
> @@ -192,6 +194,11 @@ std::string ControlValue::toString() const
>  		return "<ValueType Error>";
>
>  	const uint8_t *data = ControlValue::data().data();
> +
> +	if (type_ == ControlTypeString)
> +		return std::string(reinterpret_cast<const char *>(data),
> +				   numElements_);
> +
>  	std::string str(isArray_ ? "[ " : "");
>
>  	for (unsigned int i = 0; i < numElements_; ++i) {
> @@ -222,6 +229,7 @@ std::string ControlValue::toString() const
>  			break;
>  		}
>  		case ControlTypeNone:
> +		case ControlTypeString:
>  			break;
>  		}
>
> @@ -439,12 +447,22 @@ ControlInfo::ControlInfo(const ControlValue &min,
>  /**
>   * \fn ControlInfo::min()
>   * \brief Retrieve the minimum value of the control
> + *
> + * For string controls, this is the minimum length of the string, not counting
> + * the terminating '\0'. For all other control types, this is the minimum value
> + * of each element.
> + *
>   * \return A ControlValue with the minimum value for the control
>   */
>
>  /**
>   * \fn ControlInfo::max()
>   * \brief Retrieve the maximum value of the control
> + *
> + * For string controls, this is the maximum length of the string, not counting
> + * the terminating '\0'. For all other control types, this is the maximum value
> + * of each element.
> + *
>   * \return A ControlValue with the maximum value for the control
>   */
>
> @@ -653,7 +671,16 @@ void ControlInfoMap::generateIdmap()
>  	idmap_.clear();
>
>  	for (const auto &ctrl : *this) {
> -		if (ctrl.first->type() != ctrl.second.min().type()) {
> +		/*
> +		 * For string controls, min and max define the valid
> +		 * range for the string size, not for the individual
> +		 * values.
> +		 */
> +		ControlType rangeType = ctrl.first->type() == ControlTypeString
> +				      ? ControlTypeInteger32 : ctrl.first->type();
> +		const ControlInfo &info = ctrl.second;
> +
> +		if (info.min().type() != rangeType) {
>  			LOG(Controls, Error)
>  				<< "Control " << utils::hex(ctrl.first->id())
>  				<< " type and info type mismatch";
> diff --git a/src/libcamera/gen-controls.py b/src/libcamera/gen-controls.py
> index ff8bda6b16c1..87c3d52ada6d 100755
> --- a/src/libcamera/gen-controls.py
> +++ b/src/libcamera/gen-controls.py
> @@ -42,10 +42,11 @@ ${description}
>          name, ctrl = ctrl.popitem()
>          id_name = snake_case(name).upper()
>
> -        if ctrl.get('size'):
> -            ctrl_type = 'Span<const %s>' % ctrl['type']
> -        else:
> -            ctrl_type = ctrl['type']
> +        ctrl_type = ctrl['type']
> +        if ctrl_type == 'string':
> +            ctrl_type = 'std::string'
> +        elif ctrl.get('size'):
> +            ctrl_type = 'Span<const %s>' % ctrl_type
>
>          info = {
>              'name': name,
> @@ -97,10 +98,11 @@ def generate_h(controls):
>
>          ids.append('\t' + id_name + ' = ' + str(id_value) + ',')
>
> -        if ctrl.get('size'):
> -            ctrl_type = 'Span<const %s>' % ctrl['type']
> -        else:
> -            ctrl_type = ctrl['type']
> +        ctrl_type = ctrl['type']
> +        if ctrl_type == 'string':
> +            ctrl_type = 'std::string'
> +        elif ctrl.get('size'):
> +            ctrl_type = 'Span<const %s>' % ctrl_type
>
>          info = {
>              'name': name,
> --
> 2.25.0
>
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