MaxMessageSize.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
//
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//
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// agreements granting a non-assignable, non-transferable and non-exclusive license
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// in the Agreement.
//
// Except as otherwise granted within the terms of the Agreement, copying or
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#pragma once

#include <OnixS/CME/iLink3/ABI.h>
#include <OnixS/CME/iLink3/Compiler.h>

#include <OnixS/CME/iLink3/messaging/Fields.h>
#include <OnixS/CME/iLink3/messaging/Composites.h>
#include <OnixS/CME/iLink3/messaging/SimpleOpenFramingHeader.h>

#include <OnixS/CME/iLink3/messaging/MessageSizeTraits.h>

ONIXS_ILINK3_MESSAGING_NAMESPACE_BEGIN

/// Maximum supported message size.
ONIXS_ILINK3_CONST_OR_CONSTEXPR UInt16 MaxILink3MessageSize = 65535 - sizeof(SimpleOpenFramingHeader);

#if defined(ONIXS_ILINK3_CXX11)

/// \private
template <typename Message>
struct MaxMessageSizeTraits
{
    static constexpr bool UseCustomValue = false;
};

/// Calculates the buffer size for a message with the given number of repeating group items.
template<typename Message>
constexpr
MessageSize calculateMaxMessageSize(UInt8 maxGroupItems)
{
    return
        ONIXS_ILINK3_ASSERT(Message::getMaxMessageSize(maxGroupItems) <= MaxILink3MessageSize),
        static_cast<MessageSize>(Message::getMaxMessageSize(maxGroupItems));
}

/// Calculates the buffer size for a message with the given number of repeating group items.
template<typename Message>
constexpr
typename std::enable_if<MaxMessageSizeTraits<Message>::UseCustomValue, MessageSize>::type
getMaxMessageSize(UInt8)
{
    return
        MaxMessageSizeTraits<Message>::calculateMaxMessageSize();
}

/// Calculates the buffer size for a message with the given number of repeating group items.
template<typename Message>
constexpr
typename std::enable_if<!MaxMessageSizeTraits<Message>::UseCustomValue, MessageSize>::type
getMaxMessageSize(UInt8 maxGroupItems)
{
    return calculateMaxMessageSize<Message>(maxGroupItems);
}

/// \private
template<typename Message, UInt8 MaxGroupItems>
struct GetMaxMessageSize
{
    enum {Size = getMaxMessageSize<Message>(MaxGroupItems)};
};

/// \private
template<typename Message>
constexpr
UInt16 getMinMessageSize()
{
    return
        Message::blockLength(Message::Schema::Version)
        + MessageHeader::Size
        + Message::getMinimalVariableFieldsSize(Message::Schema::Version);
}

/// \private
template<typename Message>
struct GetMinMessageSize
{
    enum {Size = getMinMessageSize<Message>()};
};

#else

/// \private
template<typename Message, UInt8>
struct GetMaxMessageSize
{
    enum {Size = MaxILink3MessageSize};
};

/// \private
template<typename Message>
struct GetMinMessageSize
{
    enum {Size = sizeof(SimpleOpenFramingHeader) + sizeof(MessageHeader) + 1};
};

#endif

ONIXS_ILINK3_MESSAGING_NAMESPACE_END