Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atnf.csiro.au/computing/software/gipsy/sub/events.dc3 Дата изменения: Wed Aug 4 15:41:20 1999 Дата индексирования: Fri Jan 16 01:21:30 2009 Кодировка:

Document: events

Purpose: Describes routines for event-driven programs.

Category: SYSTEM

File: events.src

Author: J.P. Terlouw

Description: The eventhandler routines allow a program to specify ("schedule")
one or more functions to be called when a specified event
occurs. An event can be one of the following:
- data can be read from a specified file descriptor;
- data can be written to a specified file descriptor;
- a specified period of time has elapsed.

The following elementary routines are available:

ScheduleRead - Schedule function for reading.
ScheduleWrite - Schedule function for writing.
ScheduleTimer - Schedule function to be called periodically.
Deschedule - Deschedule function.
DescheduleAll - Deschedule all scheduled functions.
MainLoop - Wait for events and call scheduled functions.
BreakMainLoop - Terminate current MainLoop invocation.

The following function is related to the X toolkit:

AttachXt - Required when program uses the X toolkit.

Each routine is described in the appropriate document.

Example: The following program writes every second a dash to the screen.
It does this 10 times. During the same time it also reads
characters from the keyboard and writes these to the screen.
When a dot has been typed, it stops looking for more characters.

#include "stddef.h"
#include "stdio.h"
#include
#include
#include "events.h"

void timefun(ident id, void *arg)
{
static int count=10;

write(1,(char*)arg,1);
count--;
if (!count) Deschedule(&id); /* deschedule after 10 dashes */
}

void readfun(ident id, int fd, void *arg)
{
char c;

read(0,&c,1);
if (c=='.') Deschedule(&id); /* deschedule when dot seen */
write(1,&c,1); /* echo character read */
}

void main(void)
{
struct sgttyb tt;

ioctl(0,TIOCGETP,&tt);
tt.sg_flags |= RAW;
tt.sg_flags &= ~ECHO;
ioctl(0,TIOCSETP,&tt); /* set modes for keyboard input */

(void)ScheduleRead(readfun, 0, NULL); /* read from stdin */
(void)ScheduleTimer(timefun, 1000, "-"); /* every 1000 ms */
MainLoop(); /* handle events */
write(1,"\n",1); /* all functions descheduled - MainLoop returns */
}

Related Docs: ScheduleRead.dc3, ScheduleWrite.dc3, ScheduleTimer.dc3,
Deschedule.dc3, DescheduleAll.dc3, MainLoop.dc2
BreakMainLoop.dc2, AttachXt.dc2, ScheduleX.dc2

Still to do: This software would also be a logical place to handle signals
and exceptional conditions on file descriptors.

Updates: Apr 8, 1997: JPT, Document created.
Apr 22, 1997: JPT, ScheduleX added.
Aug 4, 1999: JPT, BreakMainLoop added.