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authorTavian Barnes <tavianator@gmail.com>2009-09-18 19:47:51 +0000
committerTavian Barnes <tavianator@gmail.com>2009-09-18 19:47:51 +0000
commite2fa7956b87c23a8229926f39a3863ecd4d4752a (patch)
tree89008fd214693cf8b5df22b9b492fcd3f394e0cb /src
parent25052f0997c75f91846511041cf4eeb20959ae96 (diff)
downloadlibsandglass-e2fa7956b87c23a8229926f39a3863ecd4d4752a.tar.xz
Add timespec helper routines.
Diffstat (limited to 'src')
-rw-r--r--src/Makefile.am6
-rw-r--r--src/sandglass_impl.h6
-rw-r--r--src/timespec.c109
-rw-r--r--src/tsc.c34
4 files changed, 124 insertions, 31 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index d1a0109..a91e2b6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -24,7 +24,11 @@ nobase_include_HEADERS = sandglass.h
libsandglass_la_SOURCES = sandglass.h \
sandglass_impl.h \
sandglass.c \
- tsc.c
+ timespec.c
+
+if TSC
+ libsandglass_la_SOURCES += tsc.c
+endif
if X86
libsandglass_la_SOURCES += x86/tsc-x86.s
diff --git a/src/sandglass_impl.h b/src/sandglass_impl.h
index cea95c3..07a3616 100644
--- a/src/sandglass_impl.h
+++ b/src/sandglass_impl.h
@@ -37,4 +37,10 @@ double sandglass_tsc_resolution();
unsigned int sandglass_tsc_loops();
#endif
+void sandglass_get_currtime(struct timespec *ts);
+void sandglass_timespec_add(struct timespec *ts, const struct timespec *d);
+void sandglass_timespec_sub(struct timespec *ts, const struct timespec *d);
+int sandglass_timespec_cmp(const struct timespec *a, const struct timespec *b);
+void sandglass_spin(struct timespec *ts);
+
#endif /* SANDGLASS_IMPL_H_INCLUDED */ \ No newline at end of file
diff --git a/src/timespec.c b/src/timespec.c
new file mode 100644
index 0000000..f8ab791
--- /dev/null
+++ b/src/timespec.c
@@ -0,0 +1,109 @@
+/*************************************************************************
+ * Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com> *
+ * *
+ * This file is part of The Sandglass Library. *
+ * *
+ * The Sandglass Library 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 *
+ * 3 of the License, or (at your option) any later version. *
+ * *
+ * The Sandglass Library 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 this program. If not, see *
+ * <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+#include "sandglass_impl.h"
+#include "sandglass.h"
+#include <time.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+void
+sandglass_get_currtime(struct timespec *ts)
+{
+ static int monotonic = 0;
+ if (!monotonic) {
+ monotonic = sysconf(_SC_MONOTONIC_CLOCK);
+ }
+
+ if (monotonic > 0) {
+ if (clock_gettime(CLOCK_MONOTONIC, ts) != 0) {
+ fprintf(stderr,
+ "libsandglass: couldn't get value of clock CLOCK_MONOTONIC\n");
+ exit(EXIT_FAILURE);
+ }
+ } else {
+ if (clock_gettime(CLOCK_REALTIME, ts) != 0) {
+ fprintf(stderr,
+ "libsandglass: couldn't get value of clock CLOCK_REALTIME\n");
+ exit(EXIT_FAILURE);
+ }
+ }
+}
+
+void
+sandglass_timespec_add(struct timespec *ts, const struct timespec *d)
+{
+ if (d->tv_nsec >= 1000000000L - ts->tv_nsec) {
+ ts->tv_nsec += d->tv_nsec - 1000000000L;
+ ++ts->tv_sec;
+ } else {
+ ts->tv_nsec += d->tv_nsec;
+ }
+ ts->tv_sec += d->tv_sec;
+}
+
+void
+sandglass_timespec_sub(struct timespec *ts, const struct timespec *d)
+{
+ if (d->tv_nsec > ts->tv_nsec) {
+ ts->tv_nsec -= d->tv_nsec - 1000000000L;
+ --ts->tv_sec;
+ } else {
+ ts->tv_nsec -= d->tv_nsec;
+ }
+ ts->tv_sec -= d->tv_sec;
+}
+
+int
+sandglass_timespec_cmp(const struct timespec *a, const struct timespec *b)
+{
+ if (a->tv_sec > b->tv_sec)
+ return 1;
+ else if (a->tv_sec == b->tv_sec) {
+ if (a->tv_nsec > b->tv_nsec)
+ return 1;
+ else if (a->tv_nsec == b->tv_nsec)
+ return 0;
+ else
+ return -1;
+ }
+ else
+ return -1;
+}
+
+/* Spins for the time interval specified by ts */
+void
+sandglass_spin(struct timespec *ts)
+{
+ struct timespec curr, until;
+ sandglass_get_currtime(&curr);
+ until = curr;
+ sandglass_timespec_add(&until, ts);
+
+ /* Spin */
+ do {
+ sandglass_get_currtime(&curr);
+ } while (sandglass_timespec_cmp(&curr, &until) < 0);
+
+ /* Adjust ts to the time actually waited */
+ sandglass_timespec_sub(&curr, &until);
+ sandglass_timespec_add(ts, &curr);
+}
diff --git a/src/tsc.c b/src/tsc.c
index 28066a4..554a6d8 100644
--- a/src/tsc.c
+++ b/src/tsc.c
@@ -27,40 +27,14 @@
double
sandglass_tsc_resolution()
{
- static long tsc = 0, grains1, grains2;
-
- int monotonic;
- struct timespec ts;
+ static long tsc = 0;
+ static struct timespec ts = { .tv_sec = 0, .tv_nsec = 10000000L };
if (tsc == 0) {
- monotonic = sysconf(_SC_MONOTONIC_CLOCK) > 0;
- if (monotonic) {
- if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
- return 0.0/0.0;
- } else {
- if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
- return 0.0/0.0;
- }
tsc = sandglass_get_tsc();
- grains1 = sandglass_timespec_grains(&ts);
- grains2 = grains1;
-
- while (((grains2 >= grains1) ? grains2 - grains1
- : 1000000000L + (grains2 - grains1))
- < 10000000L)
- {
- if (monotonic) {
- if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
- return 0.0/0.0;
- } else {
- if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
- return 0.0/0.0;
- }
- grains2 = ts.tv_nsec;
- }
-
+ sandglass_spin(&ts);
tsc = sandglass_get_tsc() - tsc;
}
- return tsc*1.0e9/(grains2 - grains1);
+ return tsc*1.0e9/ts.tv_nsec;
}