From 8daf20485b90af2065e3db0e3fd0cd5b72fd7ac4 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Fri, 28 Feb 2020 17:01:43 +0200 Subject: libcamera: controls: Add zero-copy set API for ControlValue Extend the ControlValue class with a reserve() function to set the value without actually copying data, and a non-const data() function that allows writing data directly to the ControlValue storage. This allows allocating memory directly in ControlValue, potentially removing a data copy. Note that this change was implemented before ByteStreamBuffer gained the zero-copy read() variant, and doesn't actually save a copy in the control serializer. It however still simplifies ControlSerializer::loadControlValue(). Signed-off-by: Laurent Pinchart Reviewed-by: Jacopo Mondi --- include/libcamera/controls.h | 4 ++ src/libcamera/control_serializer.cpp | 61 ++---------------------------- src/libcamera/controls.cpp | 54 ++++++++++++++++++++------ src/libcamera/include/control_serializer.h | 3 -- 4 files changed, 50 insertions(+), 72 deletions(-) diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h index 2a665712..4b2e7e9c 100644 --- a/include/libcamera/controls.h +++ b/include/libcamera/controls.h @@ -115,6 +115,7 @@ public: bool isArray() const { return isArray_; } std::size_t numElements() const { return numElements_; } Span data() const; + Span data(); std::string toString() const; @@ -174,6 +175,9 @@ public: value.data(), value.size(), sizeof(typename T::value_type)); } + void reserve(ControlType type, bool isArray = false, + std::size_t numElements = 1); + private: ControlType type_ : 8; bool isArray_; diff --git a/src/libcamera/control_serializer.cpp b/src/libcamera/control_serializer.cpp index 808419f2..fcff5e56 100644 --- a/src/libcamera/control_serializer.cpp +++ b/src/libcamera/control_serializer.cpp @@ -295,70 +295,17 @@ int ControlSerializer::serialize(const ControlList &list, return 0; } -template -ControlValue ControlSerializer::loadControlValue(ByteStreamBuffer &buffer, - bool isArray, - unsigned int count) -{ - ControlValue value; - - const T *data = buffer.read(count); - if (!data) - return value; - - if (isArray) - value.set(Span{ data, count }); - else - value.set(*data); - - return value; -} - -template<> -ControlValue ControlSerializer::loadControlValue(ByteStreamBuffer &buffer, - bool isArray, - unsigned int count) -{ - ControlValue value; - - const char *data = buffer.read(count); - if (!data) - return value; - - value.set(std::string{ data, count }); - - return value; -} - ControlValue ControlSerializer::loadControlValue(ControlType type, ByteStreamBuffer &buffer, bool isArray, unsigned int count) { - switch (type) { - case ControlTypeBool: - return loadControlValue(buffer, isArray, count); - - case ControlTypeByte: - return loadControlValue(buffer, isArray, count); - - case ControlTypeInteger32: - return loadControlValue(buffer, isArray, count); - - case ControlTypeInteger64: - return loadControlValue(buffer, isArray, count); - - case ControlTypeFloat: - return loadControlValue(buffer, isArray, count); - - case ControlTypeString: - return loadControlValue(buffer, isArray, count); + ControlValue value; - case ControlTypeNone: - return ControlValue(); - } + value.reserve(type, isArray, count); + buffer.read(value.data()); - return ControlValue(); + return value; } ControlInfo ControlSerializer::loadControlInfo(ControlType type, diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp index 25684474..540cc026 100644 --- a/src/libcamera/controls.cpp +++ b/src/libcamera/controls.cpp @@ -189,6 +189,15 @@ Span ControlValue::data() const return { data, size }; } +/** + * \copydoc ControlValue::data() const + */ +Span ControlValue::data() +{ + Span data = const_cast(this)->data(); + return { const_cast(data.data()), data.size() }; +} + /** * \brief Assemble and return a string describing the value * \return A string describing the ControlValue @@ -312,23 +321,44 @@ void ControlValue::set(ControlType type, bool isArray, const void *data, { ASSERT(elementSize == ControlValueSize[type]); - release(); + reserve(type, isArray, numElements); + + Span storage = ControlValue::data(); + memcpy(storage.data(), data, storage.size()); +} + +/** + * \brief Set the control type and reserve memory + * \param[in] type The control type + * \param[in] isArray True to make the value an array + * \param[in] numElements The number of elements + * + * This function sets the type of the control value to \a type, and reserves + * memory to store the control value. If \a isArray is true, the instance + * becomes an array control and storage for \a numElements is reserved. + * Otherwise the instance becomes a simple control, numElements is ignored, and + * storage for the single element is reserved. + */ +void ControlValue::reserve(ControlType type, bool isArray, std::size_t numElements) +{ + if (!isArray) + numElements = 1; + + std::size_t oldSize = numElements_ * ControlValueSize[type_]; + std::size_t newSize = numElements * ControlValueSize[type]; + + if (oldSize != newSize) + release(); type_ = type; - numElements_ = numElements; isArray_ = isArray; + numElements_ = numElements; - std::size_t size = elementSize * numElements; - void *storage; - - if (size > sizeof(value_)) { - storage_ = reinterpret_cast(new uint8_t[size]); - storage = storage_; - } else { - storage = reinterpret_cast(&value_); - } + if (oldSize == newSize) + return; - memcpy(storage, data, size); + if (newSize > sizeof(value_)) + storage_ = reinterpret_cast(new uint8_t[newSize]); } /** diff --git a/src/libcamera/include/control_serializer.h b/src/libcamera/include/control_serializer.h index 70aa28fd..99bacd92 100644 --- a/src/libcamera/include/control_serializer.h +++ b/src/libcamera/include/control_serializer.h @@ -40,9 +40,6 @@ private: static void store(const ControlValue &value, ByteStreamBuffer &buffer); static void store(const ControlInfo &info, ByteStreamBuffer &buffer); - template - ControlValue loadControlValue(ByteStreamBuffer &buffer, bool isArray, - unsigned int count); ControlValue loadControlValue(ControlType type, ByteStreamBuffer &buffer, bool isArray = false, unsigned int count = 1); ControlInfo loadControlInfo(ControlType type, ByteStreamBuffer &buffer); -- cgit v1.2.1