How is my C ++ driver application call interface?

I have the driver source code and understand it. I am writing an application in user mode. I want to call driver functions. How should I do it?

some driver header code:

...
BYTE ReadRegister(DEVICE_CONTEXT *pDevice, BYTE SlavAddr, BYTE SlavMode, WORD RegAddr, BYTE* pData, BYTE DataCont);

BYTE WriteRegister(DEVICE_CONTEXT *pDevice, BYTE SlavAddr, BYTE SlavMode, WORD RegAddr, BYTE* pData, BYTE DataCont);
...

snippets of cpp driver code:

BYTE ReadRegister(DEVICE_CONTEXT *pDevice, BYTE SlavAddr, BYTE SlavMode, WORD RegAddr, BYTE* pData, BYTE DataCont)
{
.....
}

//-----------------------------------------------------------------------------
BYTE WriteRegister(DEVICE_CONTEXT *pDevice, BYTE SlavAddr, BYTE SlavMode, WORD RegAddr, BYTE* pData, BYTE DataCont)
{
....
}