Kenwood HP 9000 manual Shlget and shlgetr Routines, 226

Shared Library Management Routines

The shl_load Shared Library Management Routines

shl_t	load_lib(int argc, char * argv[]);
main(int argc,
{	char * argv[])
shl_t lib_handle;		/* handle of	shared library	*/
int	(*gopen)(void);	/* opens the	graphics device	*/
int	(*gclose)(void);	/* closes the graphics device		*/
int	(*move2d)(int, int);	/* moves to specified x,y location */
int	(*draw2d)(int, int);	/* draw line	to specified x,y location*/
int	*maxX;	/* maximum X	pixel on device	*/
int	*maxY;	/* maximum Y	pixel on device	*/

lib_handle = load_lib(argc, argv); /* load required shared library */ /*

*Get addresses of all functions and data that will be used:

*/

if (shl_findsym(&lib_handle,	GOPEN, TYPE_PROCEDURE, (void *) &gopen))
perror(“shl_findsym: error	finding function gopen”), exit(1);
if (shl_findsym(&lib_handle,	GCLOSE, TYPE_PROCEDURE, (void *) &gclose))
perror(“shl_findsym: error	finding function gclose”), exit(1);
if (shl_findsym(&lib_handle,	MOVE2D, TYPE_PROCEDURE, (void *) &move2d))
perror(“shl_findsym: error	finding function move2d”), exit(1);
if (shl_findsym(&lib_handle,	DRAW2D, TYPE_PROCEDURE, (void *) &draw2d))
perror(“shl_findsym: error	finding function draw2d”), exit(1);
if (shl_findsym(&lib_handle,	MAXX, TYPE_DATA, (void *) &maxX))
perror(“shl_findsym: error	finding data maxX”), exit(1);
if (shl_findsym(&lib_handle,	MAXY, TYPE_DATA, (void *) &maxY))

perror(“shl_findsym: error finding data maxY”), exit(1);

/*

*Using the routines, draw a line from (0,0) to (maxX,maxY):

*/

(*gopen)();	/* open the graphics device				*/
(*move2d)(0,0);	/* move		to pixel 0,0		*/
(*draw2d)(*maxX,*maxY);	/*	draw	line	to maxX,maxY pixel	*/
(*gclose)();	/*	close the		graphics device	*/

}

Shown below is the compile line for this program, along with the commands to set SHLPATH appropriately before running the program. SHLPATH is declared and used by load_lib(), defined in“The shl_load and cxxshl_load Routines” example. Notice that load_lib() is compiled here along with this program. Finally, this example assumes you have created a graphics library, libgrphdd.sl:

$ cc -Aa -o drawline shl_findsym.c load_lib.c -ldld $ SHLPATH=/usr/lib/libgrphdd.sl

$ export SHLPATH $ drawline

The shl_get and shl_get_r Routines

Obtains information on the currently loaded libraries.

226 Chapter 6