reduce software cursor flickering

the software cursor starts flickering and reacts bumby if a process
spends most of its time with drawlock acquired because the timer interrupt
thats supposed to redraw the cursor fails to acquire the lock at the time
the timer fires.

instead of trying to draw the cursor on the screen from a timer interrupt
30 times per second, devmouse now creates a process calling cursoron() and
cursoroff() when the cursor needs to be redrawn. this allows the swcursor
to schedule a redraw while holding the drawlock in swcursoravoid() and
cursoron()/cursoroff() are now able to wait for a qlock (drawlock) because
they get called from process context.

the overall responsiveness is also improved with this change as the cursor
redraw rate isnt limited to 30 times a second anymore.

1 files changed, 10 insertions, 2 deletions

diff --git a/sys/src/9/bcm/screen.h b/sys/src/9/bcm/screen.h
index 8703796a9..9c45e3a2f 100644
--- a/sys/src/9/bcm/screen.h
+++ b/sys/src/9/bcm/screen.h
@@ -21,16 +21,24 @@ extern Cursor arrow;
 /* mouse.c */
 extern void mousectl(Cmdbuf*);
 extern void mouseresize(void);
+extern void mouseredraw(void);
 
 /* screen.c */
 extern void	blankscreen(int);
 extern void	flushmemscreen(Rectangle);
 extern uchar*	attachscreen(Rectangle*, ulong*, int*, int*, int*);
-extern int	cursoron(int);
-extern void	cursoroff(int);
+extern void	cursoron(void);
+extern void	cursoroff(void);
 extern void	setcursor(Cursor*);
 
 /* devdraw.c */
 extern QLock	drawlock;
 
 #define ishwimage(i)	1		/* for ../port/devdraw.c */
+
+/* swcursor.c */
+void		swcursorhide(void);
+void		swcursoravoid(Rectangle);
+void		swcursordraw(Point);
+void		swcursorload(Cursor *);
+void		swcursorinit(void);