oskit/oskit-20020317/unix/pit.c

86 lines
2.4 KiB
C
Executable File

/*
* Copyright (c) 1997-2000 University of Utah and the Flux Group.
* All rights reserved.
*
* This file is part of the Flux OSKit. The OSKit is free software, also known
* as "open source;" you can redistribute it and/or modify it under the terms
* of the GNU General Public License (GPL), version 2, as published by the Free
* Software Foundation (FSF). To explore alternate licensing terms, contact
* the University of Utah at csl-dist@cs.utah.edu or +1-801-585-3271.
*
* The OSKit is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GPL for more details. You should have
* received a copy of the GPL along with the OSKit; see the file COPYING. If
* not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
*/
/*
* This selectivly overrides half of the default implementation of
* osenv_timer
*/
#include <oskit/dev/dev.h>
#include "native.h"
#include "support.h"
int
osenv_timer_pit_read()
{
return 0;
}
#ifdef OSKIT_ARM32
#define osenv_timer_pit_init oskit_timer_rtc_init
#define osenv_timer_pit_shutdown oskit_timer_rtc_shutdown
#endif
int
osenv_timer_pit_init(int freq, void (*timer_intr)())
{
struct itimerval it;
memset(&it, 0, sizeof it);
it.it_value.tv_usec = it.it_interval.tv_usec = 1000000/freq;
NATIVEOS(setitimer)(ITIMER_VIRTUAL, &it, 0);
oskitunix_set_signal_handler(SIGVTALRM,
(void (*)(int,int,struct sigcontext*))timer_intr);
return 0;
}
void
osenv_timer_pit_shutdown()
{
struct itimerval it;
memset(&it, 0, sizeof it);
NATIVEOS(setitimer)(ITIMER_VIRTUAL, &it, 0);
}
/*
* Helper function for pthreads. Delay by calling select, which avoids
* cpu spin in the idle loop. If the select timeout, generate a signal
* initiate a clock tick.
*
* N.B. we are operating at the resolution of the underlying unix clock
* here (10ms) so we have no choice but to sleep for a full ITIMER_VIRTUAL
* clock tick even though we may be partially or mostly through the current
* tick. As a result, you can experience up to 2:1 inflation of virtual to
* real time in OSKit unix applications that are mostly idle.
*/
void
pthread_delay(void)
{
struct timeval timeout = { 0, 10000 };
if (NATIVEOS(select)(0, 0, 0, 0, &timeout) == 0) {
/*
* Timed out. Simulate a clock tick
*/
osenv_intr_disable();
NATIVEOS(kill)(NATIVEOS(getpid)(), SIGVTALRM);
osenv_intr_enable();
}
}