I've come to like pthread_cond_wait, although I admit that I found it
disgusting until recently -- when I wrote some applications where it
was quite pleasant.
On Sat, Apr 14, 2001 at 02:43:03AM +0200, Bernhard Kuhn wrote:
> David Schleef schrieb:
>
> > It can be duplicated using something similar to the attached
> > file.
>
> select() is not bad, but you can't guarantee a stable
> period (means a delay is propagated to the following
> periods).
>
> For this reason, i prefer pthread_cond_timedwait()
> (see file attached).
> Suspending can be done by using pthread_cond_wait().
>
> Bernhard
> // gcc -Wall -O2 -I/usr/src/rtai/include -D__KERNEL__ -DMODULE -c rt_thread.c
>
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/version.h>
> #include <asm/io.h>
>
> #include <rtai.h>
> #include <rtai_sched.h>
> #include <rtai_pthread.h>
>
> #define PORT 0x378
>
> pthread_t thread_data;
>
> pthread_mutex_t wait_mutex = PTHREAD_MUTEX_INITIALIZER;
> pthread_cond_t wait_cond = PTHREAD_COND_INITIALIZER;
>
> volatile int kill=0;
>
> int position=0;
> MODULE_PARM(position,"i");
>
>
> void add_ns(struct timespec *time,long ns) {
> time->tv_nsec+=ns;
> time->tv_sec += time->tv_nsec/(1000000000LL);
> time->tv_nsec = time->tv_nsec%(1000000000LL);
> };
>
>
> void thread_code(int arg) {
>
> struct timespec time;
> clock_gettime(CLOCK_REALTIME,&time);
>
> while(!kill) {
>
> outb(0xff,PORT);
> add_ns(&time,1000000+position);
> pthread_mutex_lock(&wait_mutex);
> pthread_cond_timedwait(&wait_cond,&wait_mutex,&time);
> pthread_mutex_unlock(&wait_mutex);
>
> outb(0x00,PORT);
> add_ns(&time,19000000-position);
> pthread_mutex_lock(&wait_mutex);
> pthread_cond_timedwait(&wait_cond,&wait_mutex,&time);
> pthread_mutex_unlock(&wait_mutex);
>
> };
>
> kill=2;
> pthread_exit(0);
>
> };
>
>
> int init_module(void) {
> printk("rt_task: started, position=%i\n",position);
> rt_set_oneshot_mode();
> start_rt_timer(0);
> pthread_create(&thread_data,0,(void*)thread_code,0);
> return 0;
> };
>
>
> void cleanup_module(void) {
> kill=1;
> while(kill!=2);
>
> pthread_cond_destroy(&wait_cond);
> pthread_mutex_destroy(&wait_mutex);
>
> stop_rt_timer();
> printk("rt_task: stopped, position=%i\n",position);
> };
--
---------------------------------------------------------
Victor Yodaiken
Finite State Machine Labs: The RTLinux Company.
www.fsmlabs.com www.rtlinux.com
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