Add timespec helper routines.

6 files changed, 141 insertions, 46 deletions

diff --git a/configure.ac b/configure.ac
index deea2b8..c767daa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,19 +41,22 @@ AC_CANONICAL_HOST
 
 if echo $host_cpu | grep '86$' 2>&1 >/dev/null
 then
-  arch_x86="true"
-  AC_DEFINE([SANDGLASS_TSC])
+  arch_x86=1
+  tsc=1
 fi
 
 if echo $host_cpu | grep 'x86_64$' 2>&1 >/dev/null
 then
-  arch_x86_64="true"
-  AC_DEFINE([SANDGLASS_TSC])
+  arch_x86_64=1
+  tsc=1
 fi
 
 AM_CONDITIONAL([X86], [test "$arch_x86"])
 AM_CONDITIONAL([X86_64], [test "$arch_x86_64"])
 
+AC_DEFINE([SANDGLASS_TSC], ["$tsc"])
+AM_CONDITIONAL([TSC], [test "$tsc"])
+
 dnl Generate Makefiles
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_FILES([Makefile
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;
 }
diff --git a/tests/introspective-system.c b/tests/introspective-system.c
index 8366623..21ffa4c 100644
--- a/tests/introspective-system.c
+++ b/tests/introspective-system.c
@@ -18,7 +18,8 @@
  * <http://www.gnu.org/licenses/>.                                       *
  *************************************************************************/
 
-#include <sandglass.h>
+#include "../src/sandglass_impl.h"
+#include "../src/sandglass.h"
 #include <unistd.h>
 #include <time.h>
 #include <stdlib.h>
@@ -29,22 +30,20 @@ main()
 {
   sandglass_t sandglass;
   sandglass_attributes_t attr = { SANDGLASS_INTROSPECTIVE, SANDGLASS_SYSTEM };
-  struct timespec tosleep = { .tv_sec = 0, .tv_nsec = 100000000 };
+  struct timespec tosleep;
 
   if (sandglass_create(&sandglass, &attr, &attr) != 0) {
     perror("sandglass_create()");
     return EXIT_FAILURE;
   }
 
-  if (sandglass_begin(&sandglass) != 0) {
-    perror("sandglass_begin()");
-    return EXIT_FAILURE;
-  }
-  while (nanosleep(&tosleep, &tosleep) != 0);
-  if (sandglass_elapse(&sandglass) != 0) {
-    perror("sandglass_elapse()");
-    return EXIT_FAILURE;
-  }
+  sandglass_bench(&sandglass, {
+    tosleep.tv_sec = 0;
+    tosleep.tv_nsec = 100000000L;
+    sandglass_spin(&tosleep);
+  });
+
+  printf("%g\n", sandglass.grains/sandglass.resolution);
 
   return EXIT_SUCCESS;
 }