CC2640R2F: proper allocation/de-allocation function use

Patrik Bachan

Part Number: CC2640R2F

I need to use function:

bStatus_t GATT_ReliableWrites ( uint16 connHandle,
    attPrepareWriteReq_t * pReqs,
    uint8 numReqs,
    uint8 flags,
    uint8 taskId
)

So I am allocating pReqs using GATT_bm_alloc(connection.connHandle, ATT_PREPARE_WRITE_REQ, sizeof(attPrepareWriteReq_t), NULL)

Q1: is ATT_PREPARE_WRITE_REQ correct argument?

Now I have allocated structure with name req.

This structure stores pointer to data (pValue), so I have to allocate it too.

Q2: should I use GATT_bm_alloc again (with some/different opcode?) or rather BM_alloc?

Q3: How should be de-allocation handled in case of GATT_ReliableWrites fail? Which free function to use? Do I have to free both allocated resources manually or would GATT_bm_free also handle freeing of pValue buffer?

Preferred answers would be pointers to documentation explaining proper use. Next time, I'd like to be able to answer such question by myself...

over 3 years ago

0 Jan over 3 years ago

TI__Mastermind 43900 points

Hi,

Thank you for reaching out. We will look into your provided queries and respond soon. In the meantime, could you provide some additional information that may help us resolve this issue as efficiently as possible? Could you specify the SDK you are using? Which example are you implementing the function in?

Best Regards,

Jan

0 Patrik Bachan over 3 years ago in reply to Jan

Prodigy 50 points

Hi,

Sure, SDK is: simplelink cc2640r2 sdk 5.30.00.03

My application is based on simple central ble5 example.

Example with use of function GATT_ReliableWrites would be perfect, but I couldn't find one.

0 Clément over 3 years ago in reply to Patrik Bachan

TI__Guru** 101490 points

Hi Patrik,

Per your request, I'll try to point you to the docs in order to help you to find this information on your own next time. I have highlighted the short answers in case other readers are interested.

GATT_ReliableWrites is a GATT procedure. You should then follow the recommended way to allocate memory for GATT procedures.

Q1- From the documentation of GATT_ReliableWrites, the first argument is a pointer on a attPrepareWriteReq_t structure. When it comes to the opcode to pass to the function, look at the list of available opcode. As you can notice, the opcode depends on the type to allocate. Here, the required type is attPrepareWriteReq_t, so

==> attPrepareWriteReq_t can be allocated using GATT_bm_alloc() with ATT_PREPARE_WRITE_REQ opcode

Q2 & Q3- GATT_ReliableWrites is a GATT procedure. You should then follow the recommended way to allocate memory for GATT procedures.

==> Allocation should be done using GATT_bm_alloc(), and free should be done with GATT_bm_free().

==> ATT_PREPARE_WRITE_REQ should be used as opcode.

When it comes to the memory freeing, you can refer to the documentation of GATT_bm_free(). It states that the first argument is the "pointer to GATT message containing the memory to free". It does not not mention additional free, or the possibility of freeing memory in a non consecutive memory region.

==> GATT_bm_free only free the attPrepareWriteReq_t structure. Additionally allocated resources should be freed on their own.

I hope this will help,

Best regards,

0 Patrik Bachan over 3 years ago in reply to Clément

Prodigy 50 points

Thank you for reply. I already saw documentation you are linking, but it does not answer all my questions.

About Q2 and Q3....

It's still not clear to me, how I should allocate, and if necessary free, data buffer pointed by pValue in attPrepareWriteReq_t.

If using GATT_bm_alloc() is correct way, what opcode should I use? ATT_PREPARE_WRITE_REQ does not sound right as it is used for attPrepareWriteReq_t allocation.

If BM_alloc/free is the right way, should I also manually handle pValue buffer freeing when GATT_ReliableWrites fails?

+1 Clément over 3 years ago in reply to Patrik Bachan

TI__Guru** 101490 points

Hi,

The data buffer pointed by pValue in attPrepareWriteReq_t can be allocated using GATT_bm_alloc() with ATT_WRITE_REQ opcode. This is because the GATT_ReliableWrites "sub-procedure has two phases, the first phase prepares the characteristic values to be written. Once this is complete, the second phase performs the execution of all of the prepared characteristic value writes on the server from this client. In the first phase, ATT_PrepareWriteReq is used. In the second phase, ATT_ExecuteWriteReq is used."

Yes, the application is responsible to free the pValue buffer whenever GATT_ReliableWrites fails.

I hope this will help,

Best regards,

Bluetooth®︎

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CC2640R2F: proper allocation/de-allocation function use