User`s guide

Contents xiii
Windows Calls
The WinHLLAPI( ) call requires you to specify four parameters in every call and has the following
format:
extern VOID FAR PASCAL WinHLLAPI( )
LPWORD lpwFunction, /* Function name */
LPBYTE lpbyString, /* String pointer */
LPWORD lpwLength, /* String (data) length */
LPWORD lpwReturnCode ); /* Return code */
The parameters used in the WinHLLAPI function calls are:
Parameter Description
lpwFunction A pointer to the defined function name of the WinHLLAPI
function call. It has a corresponding constant which you can find
in WHLLAPI.H. To avoid additional complexity, the function
prototype definitions for each function will list the constant instead
of correctly listing a pointer to a word containing the function
number.
lpbyString A pointer to the Data String used by most Windows HLLAPI
functions. Not all functions require a Data String. Some functions
only use the Data String on the call (to pass data to
WinHLLAPI), some only on the return (passing data back to
your Windows HLLAPI application), and some on both the call
and return.
lpwLength This is a pointer to the Data Length, or it is the length of the Data
String, depending on the particular Windows HLLAPI function
call. Not all functions require a Data Length. Some functions only
use the Data Length on the call (to pass a value to WinHLLAPI),
some only on the return (passing a value back to your Windows
HLLAPI application).
lpwReturnCode A pointer to the return code. It indicates the status of the function
request and is passed on the return from the function. Some
functions, however, use this parameter on the call to indicate a
position in the Host session presentation space. In this situation,
the same parameter is referred to as “PS Position” on the call and
“Return Code” on the return.
Call Parameter
Definitions