1.1.4.5.3 DRV_WM8904_BufferAddWriteRead Function
void DRV_WM8904_BufferAddWriteRead ( const DRV_HANDLE handle, DRV_WM8904_BUFFER_HANDLE *bufferHandle, void *transmitBuffer, void *receiveBuffer, size_t size )
Summary
Schedule a non-blocking driver write-read operation.
Description
This function schedules a non-blocking write-read operation. The function returns with a valid buffer handle in the bufferHandle argument if the write-read request was scheduled successfully. The function adds the request to the hardware instance queue and returns immediately. While the request is in the queue, the application buffer is owned by the driver and should not be modified. The function returns DRV_WM8904_BUFFER_EVENT_COMPLETE:
if a buffer could not be allocated to the request
if the input buffer pointer is NULL
if the client opened the driver for read only or write only
if the buffer size is 0
if the queue is full or the queue depth is insufficient
If the requesting client registered an event callback with the driver, the driver will issue a DRV_WM8904_BUFFER_EVENT_COMPLETE event if the buffer was processed successfully of DRV_WM8904_BUFFER_EVENT_ERROR event if the buffer was not processed successfully.
Preconditions
The DRV_WM8904_Initialize routine must have been called for the specified WM8904 device instance and the DRV_WM8904_Status must have returned SYS_STATUS_READY.
DRV_WM8904_Open must have been called to obtain a valid opened device handle.
DRV_IO_INTENT_READWRITE must have been specified in the DRV_WM8904_Open call.
Parameters
| Parameters | Description |
|---|---|
| handle | Handle of the WM8904 instance as returned by the DRV_WM8904_Open function |
| bufferHandle | Pointer to an argument that will contain the return buffer handle |
| transmitBuffer | The buffer where the transmit data will be stored |
| receiveBuffer | The buffer where the received data will be stored |
| size | Buffer size in bytes |
Returns
The bufferHandle parameter will contain the return buffer handle. This will be DRV_WM8904_BUFFER_HANDLE_INVALID if the function was not successful.
Remarks
This function is thread safe in a RTOS application. It can be called from within the WM8904 Driver Buffer Event Handler that is registered by this client. It should not be called in the event handler associated with another WM8904 driver instance. It should not otherwise be called directly in an ISR.
This function is useful when there is valid read expected for every WM8904 write. The transmit and receive size must be same.
Example
MY_APP_OBJ myAppObj; uint8_t mybufferTx[MY_BUFFER_SIZE]; uint8_t mybufferRx[MY_BUFFER_SIZE]; DRV_WM8904_BUFFER_HANDLE bufferHandle;
_// mywm8904Handle is the handle returned // by the DRV_WM8904_Open function._
_// Client registers an event handler with driver_
DRV_WM8904_BufferEventHandlerSet(mywm8904Handle, APP_WM8904BufferEventHandler, (uintptr_t)&myAppObj);
DRV_WM8904_BufferAddWriteRead(mywm8904handle, &bufferHandle,
mybufferTx,mybufferRx,MY_BUFFER_SIZE);
if(DRV_WM8904_BUFFER_HANDLE_INVALID == bufferHandle) { _// Error handling here_
}
_// Event is received when // the buffer is processed._ void APP_WM8904BufferEventHandler(DRV_WM8904_BUFFER_EVENT event, DRV_WM8904_BUFFER_HANDLE bufferHandle, uintptr_t contextHandle)
{ _// contextHandle points to myAppObj._ switch(event) { case DRV_WM8904_BUFFER_EVENT_COMPLETE: _// This means the data was transferred._ break; case DRV_WM8904_BUFFER_EVENT_ERROR: _// Error handling here._ break; default: break; }
}C
void DRV_WM8904_BufferAddWriteRead(const DRV_HANDLE handle, DRV_WM8904_BUFFER_HANDLE * bufferHandle, void * transmitBuffer, void * receiveBuffer, size_t size);