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WDI TLV generator interface overview

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C++ overloaded function model

In this model, there is only one function call to generate a TLV byte array from your data structure.

WDI_INDICATION_BSS_ENTRY_LIST_PARAMETERS BssEntryList = ...;
BYTE* pOutput = NULL;
ULONG length = 0;
NDIS_STATUS ndisStatus = NDIS_STATUS_SUCCESS;

ndisStatus = Generate(
    &BssEntryList,
    cbHeaderLength,
    &Context,
    &length,
    &pOutput);

The second parameter can be very helpful. Sometimes, the TLV buffer is packed into a bigger data structure, and this parameter allows you to pre-reserve space at the beginning of the buffer for that header. The correct value for cbHeaderLength is often sizeof(WDI_MESSAGE_HEADER).

For messages that have no associated data, there are still overloaded Generate APIs, but the first parameter is optional and may simply be passed in as (EmptyMessageStructureType*)NULL.

When you are done with the TLV data contained in pOutput, you must call back into the library to release the buffer.

    FreeGenerated(pOutput);
    pOutput = NULL;

C-style function model

In this model, there is a specific Generate routine for each top-level message or structure because C does not support overloaded functions. Otherwise, it behaves the same as the C++ model.

ndisStatus = GenerateWdiGetAdapterCapabilities(
    &adapterCapabilities,
    (ULONG)sizeof(WFC_COMMAND_HEADER),
    &Context,
    &length,
    &pOutput);

When you are done with the TLV byte array, call back to release the memory in the same way as the C++ model.

    FreeGenerated(pOutput);
    pOutput = NULL;