project for a (works on my devices) demo

threading.h

@@ -0,0 +1,17 @@
+#pragma once
+
+/* https://stackoverflow.com/questions/61647896/unknown-type-name-pthread-barrier-t */
+/*
+-std=c99 is bad for this, 
+use
+-std=gnu99
+
+or if keeping -std=c99
+use either
+#define _XOPEN_SOURCE 600
+or
+#define _POSIX_C_SOURCE 200112L
+*/
+#define _POSIX_C_SOURCE 200112L /* Or higher */
+
+#include <pthread.h>