huwan · May 14, 2020 02:50 · May 14, 2020 · May 14, 2020 · Apr 14, 2019
diff --git a/benchmark_time.c b/benchmark_time.c
@@ -52,8 +52,10 @@ void
 benchmark_time_diff(benchmark_time_t *d, benchmark_time_t *t1,
                     benchmark_time_t *t2)
 {
+#ifdef DEBUG
     print_timespec(t1, "t1");
     print_timespec(t2, "t2");
+#endif
     long long nsecs = (t2->tv_sec - t1->tv_sec) * NSECPSEC + t2->tv_nsec -
                       t1->tv_nsec;
     assert(nsecs >= 0);
@@ -137,13 +139,10 @@ benchmark_get_avg_get_time(void)
     return avg;
 }
 
-/* average time required to get a current time from the system */
-unsigned long long Get_time_avg;
-
-
 int main()
 {
+    unsigned long long Get_time_avg;
     Get_time_avg = benchmark_get_avg_get_time();
-    printf("%llu\n", Get_time_avg);
+    printf("Average time required to get the current time from the system: %llu nanoseconds\n", Get_time_avg);
     return 0;
 }
diff --git a/benchmark_time.c b/benchmark_time.c
@@ -118,12 +118,13 @@ benchmark_time_set(benchmark_time_t *time, unsigned long long nsecs)
 unsigned long long
 benchmark_get_avg_get_time(void)
 {
+    size_t i;
     benchmark_time_t time;
     benchmark_time_t start;
     benchmark_time_t stop;
 
     benchmark_time_get(&start);
-    for (size_t i = 0; i < N_PROBES_GET_TIME; i++) {
+    for (i = 0; i < N_PROBES_GET_TIME; i++) {
         benchmark_time_get(&time);
     }
     benchmark_time_get(&stop);

diff --git a/benchmark_time.c b/benchmark_time.c
@@ -0,0 +1,148 @@
+#include <stdio.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#define NSECPSEC 1000000000
+
+/*
+ * benchmark_time.c -- benchmark_time module definitions
+ */
+
+typedef struct timespec benchmark_time_t;
+
+void benchmark_time_get(benchmark_time_t *time);
+void benchmark_time_diff(benchmark_time_t *d, benchmark_time_t *t1,
+                         benchmark_time_t *t2);
+double benchmark_time_get_secs(benchmark_time_t *t);
+unsigned long long benchmark_time_get_nsecs(benchmark_time_t *t);
+int benchmark_time_compare(const benchmark_time_t *t1,
+                           const benchmark_time_t *t2);
+void benchmark_time_set(benchmark_time_t *time, unsigned long long nsecs);
+unsigned long long benchmark_get_avg_get_time(void);
+
+/*
+ * os_clock_gettime -- clock_gettime abstraction layer
+ */
+static int
+os_clock_gettime(int id, struct timespec *ts)
+{
+    return clock_gettime(id, ts);
+}
+
+static void print_timespec(benchmark_time_t *diff, const char *name)
+{
+    printf("%s.tv_sec=%ld  %s.tv_nsec=%ld\n", name, diff->tv_sec, name, diff->tv_nsec);
+}
+
+/*
+ * benchmark_time_get -- get timestamp from clock source
+ */
+void
+benchmark_time_get(benchmark_time_t *time)
+{
+    os_clock_gettime(CLOCK_MONOTONIC, time);
+}
+
+/*
+ * benchmark_time_diff -- get time interval
+ */
+void
+benchmark_time_diff(benchmark_time_t *d, benchmark_time_t *t1,
+                    benchmark_time_t *t2)
+{
+    print_timespec(t1, "t1");
+    print_timespec(t2, "t2");
+    long long nsecs = (t2->tv_sec - t1->tv_sec) * NSECPSEC + t2->tv_nsec -
+                      t1->tv_nsec;
+    assert(nsecs >= 0);
+    d->tv_sec = nsecs / NSECPSEC;
+    d->tv_nsec = nsecs % NSECPSEC;
+}
+
+/*
+ * benchmark_time_get_secs -- get total number of seconds
+ */
+double
+benchmark_time_get_secs(benchmark_time_t *t)
+{
+    return (double)t->tv_sec + (double)t->tv_nsec / NSECPSEC;
+}
+
+/*
+ * benchmark_time_get_nsecs -- get total number of nanoseconds
+ */
+unsigned long long
+benchmark_time_get_nsecs(benchmark_time_t *t)
+{
+    unsigned long long ret = t->tv_nsec;
+
+    ret += t->tv_sec * NSECPSEC;
+
+    return ret;
+}
+
+/*
+ * benchmark_time_compare -- compare two moments in time
+ */
+int
+benchmark_time_compare(const benchmark_time_t *t1, const benchmark_time_t *t2)
+{
+    if (t1->tv_sec == t2->tv_sec)
+        return (int)((long long)t1->tv_nsec - (long long)t2->tv_nsec);
+    else
+        return (int)((long long)t1->tv_sec - (long long)t2->tv_sec);
+}
+
+/*
+ * benchmark_time_set -- set time using number of nanoseconds
+ */
+void
+benchmark_time_set(benchmark_time_t *time, unsigned long long nsecs)
+{
+    time->tv_sec = nsecs / NSECPSEC;
+    time->tv_nsec = nsecs % NSECPSEC;
+}
+
+/*
+ * number of samples used to calculate average time required to get a current
+ * time from the system
+ */
+#define N_PROBES_GET_TIME 10000000UL
+
+/*
+ * benchmark_get_avg_get_time -- calculates average time required to get the
+ * current time from the system in nanoseconds
+ */
+unsigned long long
+benchmark_get_avg_get_time(void)
+{
+    benchmark_time_t time;
+    benchmark_time_t start;
+    benchmark_time_t stop;
+
+    benchmark_time_get(&start);
+    for (size_t i = 0; i < N_PROBES_GET_TIME; i++) {
+        benchmark_time_get(&time);
+    }
+    benchmark_time_get(&stop);
+
+    benchmark_time_diff(&time, &start, &stop);
+
+    unsigned long long avg =
+        benchmark_time_get_nsecs(&time) / N_PROBES_GET_TIME;
+
+    return avg;
+}
+
+/* average time required to get a current time from the system */
+unsigned long long Get_time_avg;
+
+
+int main()
+{
+    Get_time_avg = benchmark_get_avg_get_time();
+    printf("%llu\n", Get_time_avg);
+    return 0;
+}
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