Create benchmarking library

benchmarks/benchmarking.c

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) Camden Dixie O'Brien
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+#include "benchmarking.h"
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+
+#define SWAP(x, y) \
+	do { \
+		const double tmp = x; \
+		x = y; \
+		y = tmp; \
+	} while (0)
+
+clock_t benchmark_start, benchmark_end;
+
+static void sort(double *xs, int n)
+{
+	if (n <= 0)
+		return;
+
+	const double pivot = xs[(n - 1) / 2];
+	int lt = 0;
+	int eq = 0;
+	int gt = n - 1;
+	while (eq <= gt) {
+		if (xs[eq] < pivot) {
+			SWAP(xs[eq], xs[lt]);
+			++lt;
+			++eq;
+		} else if (xs[eq] > pivot) {
+			SWAP(xs[eq], xs[gt]);
+			--gt;
+		} else {
+			++eq;
+		}
+	}
+
+	sort(xs, lt);
+	sort(xs + gt + 1, n - (gt + 1));
+}
+
+void benchmark_summarise(double *res, int reps, benchmark_summary_t *out)
+{
+	assert(reps > 0);
+
+	sort(res, reps);
+	const double median = res[reps / 2];
+
+	double sum = 0;
+	for (int i = 0; i < reps; ++i)
+		sum += res[i];
+	const double mean = sum / reps;
+
+	double diff_sum = 0;
+	for (int i = 0; i < reps; ++i)
+		diff_sum += pow(res[i] - mean, 2);
+	const double variance = diff_sum / (reps - 1);
+
+	out->reps = reps;
+	out->total = sum;
+	out->median = median;
+	out->mean = mean;
+	out->min = res[0];
+	out->max = res[reps - 1];
+	out->stddev = sqrt(variance);
+}
+
+void benchmark_print_header(void)
+{
+	printf(
+	    "%-12s %13s %13s %13s %13s %12s\n", "benchmark", "median (µs)",
+	    "mean (µs)", "min (µs)", "max (µs)", "stddev");
+}
+
+void benchmark_print(const char *name, const benchmark_summary_t *s)
+{
+	printf(
+	    "%-12s %12.2f %12.2f %12.2f %12.2f %12.2f\n", name, s->median,
+	    s->mean, s->min, s->max, s->stddev);
+}