Trying to get closer to the original OS/161 sources.

kern/test/lib.c

@@ -0,0 +1,27 @@
+#include <types.h>
+#include <thread.h>
+#include <test.h>
+
+/*
+ * Helper functions used by testing and problem driver code
+ * to establish better mixtures of threads.
+ */
+
+void
+random_yielder(uint32_t max_yield_count)
+{
+	uint32_t i;
+	for (i = 0; i < random() % max_yield_count; i++) {
+		thread_yield();
+	}
+}
+
+void
+random_spinner(uint32_t max_spin_count)
+{
+	uint32_t i;
+	volatile int spin;
+	for (i = 0; i < random() % max_spin_count; i++) {
+		spin += i;
+	}
+}