+// 获取v最近的最大k倍数 (k=2^n)
+#define ROUNDUP(v, k) (((v) + (k)-1) & ~((k)-1))
+
+// 获取v最近的最小k倍数 (k=2^m)
+#define ROUNDDOWN(v, k) ((v) & ~((k)-1))
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+/**
+ * @brief Fast log base 2 for integer, utilizing constant unfolding.
+ * Adopted from
+ * https://elixir.bootlin.com/linux/v4.4/source/include/linux/log2.h#L85
+ *
+ */
+#define ILOG2(x) \
+ (__builtin_constant_p(x) ? ((x) == 0 ? 0 \
+ : ((x) & (1ul << 31)) ? 31 \
+ : ((x) & (1ul << 30)) ? 30 \
+ : ((x) & (1ul << 29)) ? 29 \
+ : ((x) & (1ul << 28)) ? 28 \
+ : ((x) & (1ul << 27)) ? 27 \
+ : ((x) & (1ul << 26)) ? 26 \
+ : ((x) & (1ul << 25)) ? 25 \
+ : ((x) & (1ul << 24)) ? 24 \
+ : ((x) & (1ul << 23)) ? 23 \
+ : ((x) & (1ul << 22)) ? 22 \
+ : ((x) & (1ul << 21)) ? 21 \
+ : ((x) & (1ul << 20)) ? 20 \
+ : ((x) & (1ul << 19)) ? 19 \
+ : ((x) & (1ul << 18)) ? 18 \
+ : ((x) & (1ul << 17)) ? 17 \
+ : ((x) & (1ul << 16)) ? 16 \
+ : ((x) & (1ul << 15)) ? 15 \
+ : ((x) & (1ul << 14)) ? 14 \
+ : ((x) & (1ul << 13)) ? 13 \
+ : ((x) & (1ul << 12)) ? 12 \
+ : ((x) & (1ul << 11)) ? 11 \
+ : ((x) & (1ul << 10)) ? 10 \
+ : ((x) & (1ul << 9)) ? 9 \
+ : ((x) & (1ul << 8)) ? 8 \
+ : ((x) & (1ul << 7)) ? 7 \
+ : ((x) & (1ul << 6)) ? 6 \
+ : ((x) & (1ul << 5)) ? 5 \
+ : ((x) & (1ul << 4)) ? 4 \
+ : ((x) & (1ul << 3)) ? 3 \
+ : ((x) & (1ul << 2)) ? 2 \
+ : ((x) & (1ul << 1)) ? 1 \
+ : 0) \
+ : (31 - __builtin_clz(x)))
+
+inline static void noret
+spin()
+{
+ volatile int __infloop = 1;
+ while (__infloop)
+ ;
+ __builtin_unreachable();