[libcamera-devel] [PATCH 3/4] libcamera: controls: Store array control size in Control class
Jacopo Mondi
jacopo at jmondi.org
Wed Aug 10 10:50:32 CEST 2022
Hi Laurent
On Wed, Aug 10, 2022 at 03:29:05AM +0300, Laurent Pinchart via libcamera-devel wrote:
> Baside just identifying a control, the Control class enables usage of
> the control type for metaprogramming. This is mainly used by the
> ControlList get() and set() functions to type-check and cast the control
> value automatically at compilation time.
>
> Extend this with a new Size template argument for the Control class that
> specifies the size of array controls. Use it already in the
> ControlList::set() overload that takes an std::initializer list to
> construct the Span with an explicit size, enabling usage of the function
> for fixed-size array controls.
>
> A possible future extension would be to pass the size to the ControlId
> constructor and store it internally, enabling access to the size at
> runtime, for instance to perform validity checks.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> include/libcamera/controls.h | 20 +++++++++++--------
> src/libcamera/controls.cpp | 37 +++++++++++++++++++++++++++---------
> utils/gen-controls.py | 24 +++++++++++++++++++++--
> 3 files changed, 62 insertions(+), 19 deletions(-)
>
> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> index ebc168fc28b7..dd474a807d68 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -8,6 +8,7 @@
> #pragma once
>
> #include <assert.h>
> +#include <limits>
> #include <optional>
> #include <set>
> #include <stdint.h>
> @@ -213,6 +214,8 @@ private:
> class ControlId
> {
> public:
> + static constexpr size_t dynamic_size = std::numeric_limits<std::size_t>::max();
nit: should this be kDynamicSize (the notion we use for constants) ?
> +
> ControlId(unsigned int id, const std::string &name, ControlType type)
> : id_(id), name_(name), type_(type)
> {
> @@ -250,11 +253,12 @@ static inline bool operator!=(const ControlId &lhs, unsigned int rhs)
> return !(lhs == rhs);
> }
>
> -template<typename T>
> +template<typename T, size_t Size = 0>
this bothers me a bit. Non-array controls are of size 0 for real ? or
should they be of size 1 ?
I don't see implications in this patch in having fixed size controls
with size set to 1, have I missed them ?
> class Control : public ControlId
> {
> public:
> using type = T;
> + static constexpr size_t size = Size;
>
> Control(unsigned int id, const char *name)
> : ControlId(id, name, details::control_type<std::remove_cv_t<T>>::value)
> @@ -372,8 +376,8 @@ public:
>
> bool contains(unsigned int id) const;
>
> - template<typename T>
> - std::optional<T> get(const Control<T> &ctrl) const
> + template<typename T, size_t Size>
> + std::optional<T> get(const Control<T, Size> &ctrl) const
> {
> const auto entry = controls_.find(ctrl.id());
> if (entry == controls_.end())
> @@ -383,8 +387,8 @@ public:
> return val.get<T>();
> }
>
> - template<typename T, typename V>
> - void set(const Control<T> &ctrl, const V &value)
> + template<typename T, typename V, size_t Size>
> + void set(const Control<T, Size> &ctrl, const V &value)
> {
> ControlValue *val = find(ctrl.id());
> if (!val)
> @@ -393,14 +397,14 @@ public:
> val->set<T>(value);
> }
>
> - template<typename T, typename V>
> - void set(const Control<T> &ctrl, const std::initializer_list<V> &value)
> + template<typename T, typename V, size_t Size>
> + void set(const Control<T, Size> &ctrl, const std::initializer_list<V> &value)
> {
> ControlValue *val = find(ctrl.id());
> if (!val)
> return;
>
> - val->set<T>(Span<const typename std::remove_cv_t<V>>{ value.begin(), value.size() });
> + val->set<T>(Span<const typename std::remove_cv_t<V>, Size>{ value.begin(), value.size() });
> }
>
> const ControlValue &get(unsigned int id) const;
> diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> index bc3db4f69388..24c836382f10 100644
> --- a/src/libcamera/controls.cpp
> +++ b/src/libcamera/controls.cpp
> @@ -384,6 +384,11 @@ void ControlValue::reserve(ControlType type, bool isArray, std::size_t numElemen
> * Control class for more information.
> */
>
> +/**
> + * \var ControlId::dynamic_size
> + * \brief Size value for dynamic array controls
> + */
> +
> /**
> * \fn ControlId::ControlId(unsigned int id, const std::string &name, ControlType type)
> * \brief Construct a ControlId instance
> @@ -431,12 +436,17 @@ void ControlValue::reserve(ControlType type, bool isArray, std::size_t numElemen
> /**
> * \class Control
> * \brief Describe a control and its intrinsic properties
> + * \tparam T The control data type
> + * \tparam Size The number of elements (for array controls only)
> *
> - * The Control class models a control exposed by an object. Its template type
> - * name T refers to the control data type, and allows functions that operate on
> - * control values to be defined as template functions using the same type T for
> - * the control value. See for instance how the ControlList::get() function
> - * returns a value corresponding to the type of the requested control.
> + * The Control class models a control exposed by an object. Its template
> + * paramter \a T refers to the control data type, and allows functions that
> + * operate on control values to be defined as template functions using the same
> + * type T for the control value. See for instance how the ControlList::get()
> + * function returns a value corresponding to the type of the requested control.
> + *
> + * Similarly, for array controls the template parameter \a Size indicates the
> + * number of elements in the array.
> *
> * While this class is the main means to refer to a control, the control
> * identifying information is stored in the non-template base ControlId class.
> @@ -469,6 +479,15 @@ void ControlValue::reserve(ControlType type, bool isArray, std::size_t numElemen
> * \brief The Control template type T
> */
>
> +/**
> + * \var Control::size
> + * \brief The number of elements for array controls
> + *
> + * The \a size reports the number of elements stored by an array Control. It is
> + * equal to 0 for non-array controls, and to ControlId::dynamic_size for
> + * variable-size controls.
> + */
> +
> /**
> * \class ControlInfo
> * \brief Describe the limits of valid values for a Control
> @@ -943,7 +962,7 @@ bool ControlList::contains(unsigned int id) const
> }
>
> /**
> - * \fn ControlList::get(const Control<T> &ctrl) const
> + * \fn ControlList::get(const Control<T, Size> &ctrl) const
> * \brief Get the value of control \a ctrl
> * \param[in] ctrl The control
> *
> @@ -956,7 +975,7 @@ bool ControlList::contains(unsigned int id) const
> */
>
> /**
> - * \fn ControlList::set(const Control<T> &ctrl, const V &value)
> + * \fn ControlList::set(const Control<T, Size> &ctrl, const V &value)
> * \brief Set the control \a ctrl value to \a value
> * \param[in] ctrl The control
> * \param[in] value The control value
> @@ -970,8 +989,8 @@ bool ControlList::contains(unsigned int id) const
> */
>
> /**
> - * \fn ControlList::set(const Control<T> &ctrl, const std::initializer_list<V> &value)
> - * \copydoc ControlList::set(const Control<T> &ctrl, const V &value)
> + * \fn ControlList::set(const Control<T, Size> &ctrl, const std::initializer_list<V> &value)
> + * \copydoc ControlList::set(const Control<T, Size> &ctrl, const V &value)
> */
>
> /**
> diff --git a/utils/gen-controls.py b/utils/gen-controls.py
> index bcfbeb7f9f17..a3b9c58beec6 100755
> --- a/utils/gen-controls.py
> +++ b/utils/gen-controls.py
> @@ -100,6 +100,10 @@ class Control(object):
> ns = 'draft::' if self.is_draft else ''
> return ns + self.__name
>
> + @property
> + def size(self):
> + return self.__size
> +
> @property
> def type(self):
> typ = self.__data.get('type')
> @@ -137,7 +141,7 @@ ${description}''')
> * \\var ${name}
> ${description}
> */''')
> - def_template = string.Template('extern const Control<${type}> ${name}(${id_name}, "${name}");')
> + def_template = string.Template('extern const Control<${type}${size}> ${name}(${id_name}, "${name}");')
> enum_values_doc = string.Template('''/**
> * \\var ${name}Values
> * \\brief List of all $name supported values
> @@ -154,9 +158,17 @@ ${description}
> for ctrl in controls:
> id_name = snake_case(ctrl.name).upper()
>
> + if ctrl.size is None:
> + size = ''
> + elif ctrl.size == 0:
> + size = ', ControlId::dynamic_size'
> + else:
> + size = f', {ctrl.size}'
> +
> info = {
> 'name': ctrl.name,
> 'type': ctrl.type,
> + 'size': size,
> 'description': format_description(ctrl.description),
> 'id_name': id_name,
> }
> @@ -216,7 +228,7 @@ def generate_h(controls):
> enum_template_start = string.Template('''enum ${name}Enum {''')
> enum_value_template = string.Template('''\t${name} = ${value},''')
> enum_values_template = string.Template('''extern const std::array<const ControlValue, ${size}> ${name}Values;''')
> - template = string.Template('''extern const Control<${type}> ${name};''')
> + template = string.Template('''extern const Control<${type}${size}> ${name};''')
>
> ctrls = []
> draft_ctrls = []
> @@ -228,9 +240,17 @@ def generate_h(controls):
>
> ids.append('\t' + id_name + ' = ' + str(id_value) + ',')
>
> + if ctrl.size is None:
> + size = ''
> + elif ctrl.size == 0:
> + size = ', ControlId::dynamic_size'
> + else:
> + size = f', {ctrl.size}'
> +
> info = {
> 'name': ctrl.name,
> 'type': ctrl.type,
> + 'size': size,
> }
>
> target_ctrls = ctrls
> --
> Regards,
>
> Laurent Pinchart
>
More information about the libcamera-devel
mailing list