From f6170cc923276a785844288c23f00528aa9ec004 Mon Sep 17 00:00:00 2001
From: Ahmet Inan <inan@aicodix.de>
Date: Sat, 25 Mar 2023 10:52:39 +0100
Subject: [PATCH] added bit-reversal permutation

---
 permute.hh | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/permute.hh b/permute.hh
index 988e48e..82ee3a9 100644
--- a/permute.hh
+++ b/permute.hh
@@ -35,5 +35,19 @@ public:
 	}
 };
 
+template <typename TYPE>
+void BitReversalPermute(TYPE *array, int n) {
+	for (int i = 0, j = 0; i < n - 1; ++i) {
+		if (i < j)
+			std::swap(array[i], array[j]);
+		int k = n >> 1;
+		while (j & k) {
+			j ^= k;
+			k >>= 1;
+		}
+		j ^= k;
+	}
+}
+
 }