lib: Add a tiny utility function to compute averages

The master plan would be to get a bit more stats in it, at least the
standard deviation and confidence interval. Just need the average for
now.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/lib/igt_stats.c b/lib/igt_stats.c
new file mode 100644
index 00000000..fcf7abe1
--- /dev/null
+++ b/lib/igt_stats.c
@@ -0,0 +1,56 @@
+/*
+ * Copyright © 2015 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include "igt_core.h"
+#include "igt_stats.h"
+
+void igt_stats_init(igt_stats_t *stats, unsigned int capacity)
+{
+	stats->values = calloc(capacity, sizeof(*stats->values));
+	igt_assert(stats->values);
+	stats->capacity = capacity;
+	stats->n_values = 0;
+}
+
+void igt_stats_fini(igt_stats_t *stats)
+{
+	free(stats->values);
+}
+
+void igt_stats_push(igt_stats_t *stats, uint64_t value)
+{
+	igt_assert(stats->n_values < stats->capacity);
+	stats->values[stats->n_values++] = value;
+}
+
+double igt_stats_get_average(igt_stats_t *stats)
+{
+	unsigned int i;
+	double a = 0.0;
+
+	for (i = 0; i < stats->n_values; i++)
+		a += (double)stats->values[i] / stats->n_values;
+
+	return a;
+}