From 79a083f28e9df04768151c8a916934716b4a2646 Mon Sep 17 00:00:00 2001
From: Richard Knight <q@1bpm.net>
Date: Mon, 24 Aug 2020 05:20:46 +0100
Subject: initial

---
 src/walsh2.cpp | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 src/walsh2.cpp

(limited to 'src/walsh2.cpp')

diff --git a/src/walsh2.cpp b/src/walsh2.cpp
new file mode 100644
index 0000000..3e15592
--- /dev/null
+++ b/src/walsh2.cpp
@@ -0,0 +1,58 @@
+/*
+    walsh2.cpp
+    Copyright (C) 2018 Mottakin Chowdhury
+    Copyright (C) 2019 Richard Knight
+
+
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 3 of the License, or (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ 
+ */
+#include <plugin.h>
+
+const int N = 1<<16;
+
+
+void fwtanal(csnd::Vector<MYFLT> io) {
+    int n = io.len();
+    for (int d = 1; d < n; d <<= 1) {
+        for (int i = 0, m = d<<1; i < n; i += m) {
+            for (int j = 0; j < d; j++) { /// Don't forget modulo if required
+                MYFLT x = io[i+j], y = io[i+j+d];
+                io[i+j] = (x+y), io[i+j+d] = (x-y);	// xor
+                // io[i+j] = x+y; // and
+                // io[i+j+d] = x+y; // or
+            }
+        }
+    }
+}
+
+
+void fwtsynth(csnd::Vector<MYFLT> io) {
+    int n = io.len();
+    for (int d = 1; d < n; d <<= 1) {
+        for (int i = 0, m = d<<1; i < n; i += m) {
+            for (int j = 0; j < d; j++) { /// Don't forget modulo if required
+                MYFLT x = io[i+j]; 
+                MYFLT y = io[i+j+d];
+                 /// Modular inverse if required here
+                ///////io[i+j] = (x+y)>>1, io[i+j+d] = (x-y)>>1; // xor
+                io[i+j] = (x+y)/2;
+                io[i+j+d] = (x-y)/2;
+                // io[i+j] = x-y; // and
+                // io[i+j+d] = y-x; // or
+            }
+        }
+    }
+}
\ No newline at end of file
-- 
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