From 41fa2c7f40112113e00bf6b94a2cd61171d918b8 Mon Sep 17 00:00:00 2001
From: Ahmet Inan <inan@aicodix.de>
Date: Fri, 21 Apr 2023 12:00:40 +0200
Subject: [PATCH] use much faster __builtin_clz

---
 galois_field.hh | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/galois_field.hh b/galois_field.hh
index c8c16c3..3d188dc 100644
--- a/galois_field.hh
+++ b/galois_field.hh
@@ -398,10 +398,14 @@ GaloisFieldReference<M, POLY, TYPE> rcp(GaloisFieldReference<M, POLY, TYPE> a)
 	TYPE newr = a.P, r = a.v;
 	TYPE newt = 0, t = 1;
 	auto degree = [](TYPE a) {
+#if 1
+		return 31 - __builtin_clz(a);
+#else
 		int d = 0;
 		while (a >>= 1)
 			++d;
 		return d;
+#endif
 	};
 	int k = degree(r);
 	int j = M - k;