C Sharp help on pointers unmanaged code

Hi all,

i am working on a C DLL which takes all inputs as pointer values...unmanaged code

[DllImport("Ziee_Mask.dll")]
unsafe public static extern void IQ_Data_to_Spectrum(double* Spec, double* Real, double* Img, Int32 len);

where the inputs are real and img values should be read from a excel sheet and provided as input around 65536 values ...len is 65536(length) ..

output is a array of data in "spec" ...

i need to store the input data from excel sheet and pass to function and take output from spec and store it

i tried some of the ways which ends up in hanging of forms ...I am new to c sharp....Somebody please help me...