Function xiProcGetParam 

pub unsafe extern "C" fn xiProcGetParam(
    processing_handle: xiProcessingHandle_t,
    prm: *const c_char,
    val: *mut c_void,
    size: DWORD,
    type_: Type,
) -> XI_RETURN

xiGetProcParam Gets the selected parameter from processing @param[in] processing_handle Handle for processing @param[in] prm parameter name string. @param[in] val pointer to parameter set value. @param[in] size size of val. @param[in] type val data type. @return XI_OK on success, error value otherwise.