comms::frame Namespace Reference

Namespace that contains definition of layers that can be used to wrap message data with transport data. More...

Detailed Description

Namespace that contains definition of layers that can be used to wrap message data with transport data.

Namespaces
namespace	checksum
	Namespace that contains definition of checksum calculator classes which can be used with comms::frame::ChecksumLayer transport layer class.

Classes
class	ChecksumLayer
	Protocol layer that is responsible to calculate checksum on the data written by all the wrapped internal layers and append it to the end of the written data. When reading, this layer is responsible to verify the checksum reported at the end of the read data. More...
class	ChecksumPrefixLayer
	Protocol layer that is responsible to calculate checksum on the data written by all the wrapped internal layers and prepend it before the written data. When reading, this layer is responsible to verify the checksum reported at the beginning of the read data. More...
class	FrameLayerBase
	Base class for all the middle (non MsgDataLayer) protocol transport layers. More...
class	MsgDataLayer
	Message data layer. More...
class	MsgIdLayer
	Protocol layer that uses uses message ID field as a prefix to all the subsequent data written by other (next) layers. More...
class	MsgSizeLayer
	Protocol layer that uses size field as a prefix to all the subsequent data written by other (next) layers. More...
class	SyncPrefixLayer
	Protocol layer that uses "sync" field as a prefix to all the subsequent data written by other (next) layers. More...
class	TransportValueLayer
	Protocol layer that reads a value from transport wrapping and reassigns it to appropriate "extra transport" data member of the created message object. More...

Functions
details::MissingSizeRetriever	missingSize (std::size_t &val)
	Add "missing size" output parameter to frame's "read" operation.
template<typename TId >
details::MsgIdRetriever< TId >	msgId (TId &val)
	Add "message ID" output parameter to frame's "read" operation.
details::MsgIndexRetriever	msgIndex (std::size_t &val)
	Add "message index" output parameter to frame's "read" operation.
template<typename TIter >
details::MsgPayloadRetriever< TIter >	msgPayload (TIter &iter, std::size_t &len)
	Add "payload start" and "payload size" output parameters to frame's "read" operation.
template<typename TField , typename TNextLayer , typename TDerived , typename... TOptions>
constexpr const FrameLayerBase< TField, TNextLayer, TDerived, TOptions... > &	toFrameLayerBase (const FrameLayerBase< TField, TNextLayer, TDerived, TOptions... > &layer)
	Upcast protocol layer in order to have access to its internal types.
template<typename TField , typename TNextLayer , typename TDerived , typename... TOptions>
FrameLayerBase< TField, TNextLayer, TDerived, TOptions... > &	toFrameLayerBase (FrameLayerBase< TField, TNextLayer, TDerived, TOptions... > &layer)
	Upcast protocol layer in order to have access to its internal types.

Function Documentation

missingSize()

details::MissingSizeRetriever comms::frame::missingSize

(

std::size_t &

val

)

Add "missing size" output parameter to frame's "read" operation.

Can be passed as variadic parameters to "read" functions of frame (see comms::frame::FrameLayerBase::read() and comms::frame::FrameLayerBase::readFieldsCached()). It can be used to retrieve missing length information in case "read" of frame operation returns comms::ErrorStatus::NotEnoughData.

using Frame = ...
Frame frame;
Frame::MsgPtr msg;
std::size_t missingSize = 0U;
auto es = frame.read(msg, readIter, size, comms::frame::missingSize(missingSize));
if (es == comms::ErrorStatus::NotEnoughData) {
    ... // missingSize will hold a minimal number of bytes that are required to be yet read
}

Parameters

[out]

val

Missing size value to be returned.

Returns

Implementation dependent object accepted by "read" functions.

See also

comms::frame::FrameLayerBase::read()

comms::frame::FrameLayerBase::readFieldsCached()

msgId()

template<typename TId >

details::MsgIdRetriever< TId > comms::frame::msgId

(

TId &

val

)

Add "message ID" output parameter to frame's "read" operation.

Can be passed as variadic parameters to "read" functions of frame (see comms::frame::FrameLayerBase::read() and comms::frame::FrameLayerBase::readFieldsCached()). It can be used to retrieve numeric message ID value.

using Frame = ...
Frame frame;
Frame::MsgPtr msg;
my_prot::MsgId msgId = my_prot::MsgId();
auto es = frame.read(msg, readIter, size, comms::frame::msgId(msgId));
if (es == comms::ErrorStatus::Success) {
    assert(msg); // Message object must be created
    ... // use msgId value
}

Parameters

[out]

val

Numeric message ID value to be returned.

Returns

Implementation dependent object accepted by "read" functions.

See also

comms::frame::FrameLayerBase::read()

comms::frame::FrameLayerBase::readFieldsCached()

msgIndex()

details::MsgIndexRetriever comms::frame::msgIndex

(

std::size_t &

val

)

Add "message index" output parameter to frame's "read" operation.

In case the expected input message types tuple contains multiple different message classes but having the same numeric ID, it may be beneficial to know the reletive index (starting from the first message type having the same ID) of the detected message. This function can be used to retrieve such information. Can be passed as variadic parameters to "read" functions of frame (see comms::frame::FrameLayerBase::read() and comms::frame::FrameLayerBase::readFieldsCached()).

using Frame = ...
Frame frame;
Frame::MsgPtr msg;
my_prot::MsgId msgId = my_prot::MsgId();
std::size_t msgIndex = 0U;
auto es =
   frame.read(
       msg,
       readIter,
       size,
       comms::frame::msgId(msgId),
       comms::frame::msgIndex(msgIndex));
if (es == comms::ErrorStatus::Success) {
    assert(msg); // Message object must be created
    ... // use msgId and msgIndex values
}

Parameters

[out]

val

Message index value to be returned.

Returns

Implementation dependent object accepted by "read" functions.

See also

comms::frame::FrameLayerBase::read()

comms::frame::FrameLayerBase::readFieldsCached()

msgPayload()

template<typename TIter >

details::MsgPayloadRetriever< TIter > comms::frame::msgPayload	(	TIter &	iter,
		std::size_t &	len
	)

Add "payload start" and "payload size" output parameters to frame's "read" operation.

Can be passed as variadic parameters to "read" functions of frame (see comms::frame::FrameLayerBase::read() and comms::frame::FrameLayerBase::readFieldsCached()). It can be used to retrieve information on payload start location as well as its size.

using Frame = ...
Frame frame;
Frame::MsgPtr msg;
decltype(readIter) payloadIter;
std::size_t payloadSize = 0U;
auto es = frame.read(msg, readIter, size, comms::frame::msgPayload(payloadIter, payloadSize));
... // use payload location and size information

Parameters

[out]	iter	Iterator pointing to the begining of the message payload in the input buffer.
[out]	len	Number of bytes in the detected payload.

Returns

Implementation dependent object accepted by "read" functions.

See also

comms::frame::FrameLayerBase::read()

comms::frame::FrameLayerBase::readFieldsCached()