add monotonic clock abstraction pa_rtclock

git-svn-id: file:///home/lennart/svn/public/pulseaudio/branches/lennart@1687 fefdeb5f-60dc-0310-8127-8f9354f1896f

src/pulsecore/rtclock.c

@@ -0,0 +1,153 @@
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2004-2006 Lennart Poettering
+  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio 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 GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stddef.h>
+#include <sys/time.h>
+
+#include <pulse/timeval.h>
+#include <pulsecore/macro.h>
+
+#include "rtclock.h"
+
+struct timespec *pa_timespec_store(struct timespec *a, pa_usec_t u) {
+    pa_assert(a);
+
+    a->tv_sec = u / PA_USEC_PER_SEC;
+
+    u -= (pa_usec_t) a->tv_sec * PA_USEC_PER_SEC;
+    
+    a->tv_nsec = u * 1000;
+
+    return a;
+}
+
+pa_usec_t pa_timespec_load(struct timespec *ts) {
+    pa_assert(ts);
+    
+    return (pa_usec_t) ts->tv_sec * PA_USEC_PER_SEC + (pa_usec_t) (ts->tv_nsec / 1000);
+}
+
+pa_usec_t pa_timespec_diff(const struct timespec *a, const struct timespec *b) {
+    pa_usec_t r;
+    
+    pa_assert(a);
+    pa_assert(b);
+
+    /* Check which whan is the earlier time and swap the two arguments if required. */
+    if (pa_timespec_cmp(a, b) < 0) {
+        const struct timespec *c;
+        c = a;
+        a = b;
+        b = c;
+    }
+
+    /* Calculate the second difference*/
+    r = ((pa_usec_t) a->tv_sec - b->tv_sec) * PA_USEC_PER_SEC;
+
+    /* Calculate the microsecond difference */
+    if (a->tv_nsec > b->tv_nsec)
+        r += (pa_usec_t) ((a->tv_nsec - b->tv_nsec) / 1000);
+    else if (a->tv_nsec < b->tv_nsec)
+        r -= (pa_usec_t) ((b->tv_nsec - a->tv_nsec) / 1000);
+
+    return r;
+}
+
+int pa_timespec_cmp(const struct timespec *a, const struct timespec *b) {
+    pa_assert(a);
+    pa_assert(b);
+
+    if (a->tv_sec < b->tv_sec)
+        return -1;
+
+    if (a->tv_sec > b->tv_sec)
+        return 1;
+
+    if (a->tv_nsec < b->tv_nsec)
+        return -1;
+
+    if (a->tv_nsec > b->tv_nsec)
+        return 1;
+
+    return 0;
+}
+
+struct timespec* pa_timespec_add(struct timespec *ts, pa_usec_t v) {
+    unsigned long secs;
+    pa_assert(ts);
+
+    secs = (unsigned long) (v/PA_USEC_PER_SEC);
+    ts->tv_sec += secs;
+    v -= ((pa_usec_t) secs) * PA_USEC_PER_SEC;
+
+    ts->tv_nsec += (long) (v*1000);
+
+    /* Normalize */
+    while (ts->tv_nsec >= PA_NSEC_PER_SEC) {
+        ts->tv_sec++;
+        ts->tv_nsec -= PA_NSEC_PER_SEC;
+    }
+
+    return ts;
+}
+
+pa_usec_t pa_rtclock_age(const struct timespec *ts) {
+    struct timespec now;
+    pa_assert(ts);
+
+    return pa_timespec_diff(pa_rtclock_get(&now), ts);
+}
+
+struct timespec *pa_rtclock_get(struct timespec *ts) {
+    static int no_monotonic = 0;
+
+    /* No locking or atomic ops for no_monotonic here */
+    
+    pa_assert(ts);
+
+    if (!no_monotonic) {
+        if (clock_gettime(CLOCK_MONOTONIC, ts) >= 0)
+            return ts;
+        
+        no_monotonic = 1;
+    }
+
+    pa_assert_se(clock_gettime(CLOCK_REALTIME, ts) == 0);
+    return ts;
+}
+
+int pa_rtclock_hrtimer(void) {
+    struct timespec ts;
+    
+    if (clock_getres(CLOCK_MONOTONIC, &ts) >= 0)
+        return ts.tv_sec == 0 && ts.tv_nsec <= PA_HRTIMER_THRESHOLD_USEC*1000;
+
+    pa_assert_se(clock_getres(CLOCK_REALTIME, &ts) == 0);
+    return ts.tv_sec == 0 && ts.tv_nsec <= PA_HRTIMER_THRESHOLD_USEC*1000;
+}
+

src/pulsecore/rtclock.h

@@ -0,0 +1,48 @@
+#ifndef foopulsertclockhfoo
+#define foopulsertclockhfoo
+
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2004-2006 Lennart Poettering
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio 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 GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#include <sys/types.h>
+#include <time.h>
+
+#include <pulse/sample.h>
+
+/* Something like pulse/timeval.h but based on CLOCK_MONOTONIC and
+ * timespec instead of timeval */
+
+struct timespec *pa_rtclock_get(struct timespec *ts);
+pa_usec_t pa_rtclock_age(const struct timespec *tv);
+int pa_rtclock_hrtimer(void);
+
+struct timespec *pa_timespec_store(struct timespec *a, pa_usec_t u);
+pa_usec_t pa_timespec_load(struct timespec *tv);
+struct timespec *pa_timespec_add(struct timespec *tv, pa_usec_t t);
+pa_usec_t pa_timespec_diff(const struct timespec *a, const struct timespec *b);
+int pa_timespec_cmp(const struct timespec *a, const struct timespec *b);
+
+/* timer with a resolution better than this are considered high-resolution */
+#define PA_HRTIMER_THRESHOLD_USEC 10
+
+#endif