Function cusparseSpMM_bufferSize 

pub unsafe fn cusparseSpMM_bufferSize(
    handle: cusparseHandle_t,
    opA: cusparseOperation_t,
    opB: cusparseOperation_t,
    alpha: *const c_void,
    matA: cusparseConstSpMatDescr_t,
    matB: cusparseConstDnMatDescr_t,
    beta: *const c_void,
    matC: cusparseDnMatDescr_t,
    computeType: cudaDataType,
    alg: cusparseSpMMAlg_t,
    bufferSize: *mut usize,
) -> cusparseStatus_t