add hash, plist, etc (untested)

c/include/likely.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*  taken from Kernel's <linux/compiler.h
+ */
+#ifndef __LIKELY_H
+#define __LIKELY_H
+
+/* See https://kernelnewbies.org/FAQ/LikelyUnlikely
+ *
+ * In 2 words:
+ * "You should use it [likely() and unlikely()] only in cases when the likeliest
+ *  branch is very very very likely, or when the unlikeliest branch is very very
+ *  very unlikely."
+ */
+# define likely(x)      __builtin_expect(!!(x), 1)
+# define unlikely(x)    __builtin_expect(!!(x), 0)
+
+#endif /* __LIKELY_H */