macros: add BIT(n) and BIT_SIZE(t) macros

include/macros.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <limits.h>
+
 #define min(x, y) ((x < y) ? (x) : (y))
 #define max(x, y) ((x > y) ? (x) : (y))
 
@@ -12,3 +14,7 @@
 #define IS_ROUND(x, k) (!((x) & ((k) - 1)))
 #define ROUND_DOWN(x, k) ((x) & ~((k) - 1))
 #define ROUND_UP(x, k) (((x) + (k) - 1) & ~((k) - 1))
+
+/* Bit manipulation */
+#define BIT_SIZE(t) (CHAR_BIT * sizeof(t))
+#define BIT(n) (1 << (n))