program for testing volatiles

1 files changed, 32 insertions, 0 deletions

diff --git a/test/monniaux/volatile/volatile.c b/test/monniaux/volatile/volatile.c
new file mode 100644
index 00000000..75f8ce3b
--- /dev/null
+++ b/test/monniaux/volatile/volatile.c
@@ -0,0 +1,32 @@
+#include <pthread.h>
+#include <stdio.h>
+#include <time.h>
+
+#define VOLATILE volatile
+
+typedef unsigned data;
+
+static data powm(data x, unsigned e, data m) {
+  data y = 1;
+  for(unsigned i=0; i<e; i++) {
+    y = (y * x) % m;
+  }
+  return y;
+}
+
+void* second_thread_entry(void *ptr) {
+  *((data*) ptr) = powm(3, 65536, 65537);
+  return NULL;
+}
+
+int main() {
+  pthread_t second_thread_id;
+  VOLATILE data value;
+  pthread_create(&second_thread_id, NULL,
+                 second_thread_entry, (void*) &value);
+  value = 0;
+  data correct = powm(3, 65536*4, 65537);;
+  data read = value;
+  pthread_join(second_thread_id, NULL);
+  printf("%u %u\n", correct, read);
+}