note on cycles

1 files changed, 37 insertions, 0 deletions

diff --git a/test/monniaux/loop/fill_buffer.c b/test/monniaux/loop/fill_buffer.c
new file mode 100644
index 00000000..9d89a2d1
--- /dev/null
+++ b/test/monniaux/loop/fill_buffer.c
@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "../clock.h"
+
+typedef unsigned char data;
+
+/* 8 cycles / iteration */
+void fill_buffer(data x, unsigned n, data *buf) {
+  for(unsigned i=0; i<n; i++) buf[i] = x;
+}
+
+/* 7 cycles / iteration */
+void fill_buffer2(data x, unsigned n, data *buf) {
+  unsigned i=0;
+  if (i<n) {
+    do {
+       buf[i] = x;
+      i++;
+    } while (i<n);
+  }
+}
+
+void fill_buffer10(data x, data *buf) {
+  for(unsigned i=0; i<10; i++) buf[i] = x;
+}
+
+int main() {
+  const size_t n = 10000;
+  data *buf = malloc(n * sizeof(data));
+  clock_prepare();
+  clock_start();
+  fill_buffer(42, n, buf);
+  clock_stop();
+  free(buf);
+  print_total_clock();
+  return 0;
+}