From d2e22555aa4406a81252360b3389a25ef80b376b Mon Sep 17 00:00:00 2001
From: kasemir <ky9@ornl.gov>
Date: Wed, 13 May 2026 10:20:18 -0400
Subject: [PATCH 1/2] Formula: Add modulo 'a % b' operator

---
 .../org/csstudio/apputil/formula/Formula.java |  8 +++-
 .../apputil/formula/node/ModNode.java         | 38 +++++++++++++++++++
 .../apputil/formula/FormulaUnitTest.java      | 14 ++++++-
 3 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 core/formula/src/main/java/org/csstudio/apputil/formula/node/ModNode.java

diff --git a/core/formula/src/main/java/org/csstudio/apputil/formula/Formula.java b/core/formula/src/main/java/org/csstudio/apputil/formula/Formula.java
index 2b5b8671f0..e515e7aeb6 100644
--- a/core/formula/src/main/java/org/csstudio/apputil/formula/Formula.java
+++ b/core/formula/src/main/java/org/csstudio/apputil/formula/Formula.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2010-2020 Oak Ridge National Laboratory.
+ * Copyright (c) 2010-2026 Oak Ridge National Laboratory.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -28,6 +28,7 @@
 import org.csstudio.apputil.formula.node.LessThanNode;
 import org.csstudio.apputil.formula.node.MaxNode;
 import org.csstudio.apputil.formula.node.MinNode;
+import org.csstudio.apputil.formula.node.ModNode;
 import org.csstudio.apputil.formula.node.MulNode;
 import org.csstudio.apputil.formula.node.NotEqualNode;
 import org.csstudio.apputil.formula.node.NotNode;
@@ -434,6 +435,11 @@ else if (s.get() == '/')
                 s.next();
                 n = new DivNode(n, parseUnary(s));
             }
+            else if (s.get() == '%')
+            {
+                s.next();
+                n = new ModNode(n, parseUnary(s));
+            }
             else break;
         }
         return n;
diff --git a/core/formula/src/main/java/org/csstudio/apputil/formula/node/ModNode.java b/core/formula/src/main/java/org/csstudio/apputil/formula/node/ModNode.java
new file mode 100644
index 0000000000..feb9e80340
--- /dev/null
+++ b/core/formula/src/main/java/org/csstudio/apputil/formula/node/ModNode.java
@@ -0,0 +1,38 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Oak Ridge National Laboratory.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ ******************************************************************************/
+package org.csstudio.apputil.formula.node;
+
+import org.csstudio.apputil.formula.Node;
+
+/** Modulo
+ *  @author Kay Kasemir
+ */
+public class ModNode extends AbstractBinaryNode
+{
+    /**
+     * Constructor
+     * @param left , left node
+     * @param right , right node
+     */
+	public ModNode(final Node left, final Node right)
+    {
+        super(left, right);
+    }
+
+    @Override
+    protected double calc(final double a, final double b)
+    {
+        return a%b;
+    }
+
+    @Override
+    public String toString()
+    {
+        return "(" + left + " % " + right + ")";
+    }
+}
diff --git a/core/formula/src/test/java/org/csstudio/apputil/formula/FormulaUnitTest.java b/core/formula/src/test/java/org/csstudio/apputil/formula/FormulaUnitTest.java
index 5ce412dd28..bbd7337e9e 100644
--- a/core/formula/src/test/java/org/csstudio/apputil/formula/FormulaUnitTest.java
+++ b/core/formula/src/test/java/org/csstudio/apputil/formula/FormulaUnitTest.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2010-2020 Oak Ridge National Laboratory.
+ * Copyright (c) 2010-2026 Oak Ridge National Laboratory.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -81,6 +81,18 @@ public void testBasics() throws Exception {
         f = new Formula("-12/-3");
         assertEquals(4.0, VTypeHelper.toDouble(f.eval()), epsilon);
 
+        f = new Formula("3%4");
+        assertEquals(3.0, VTypeHelper.toDouble(f.eval()), epsilon);
+
+        f = new Formula("4%4");
+        assertEquals(0.0, VTypeHelper.toDouble(f.eval()), epsilon);
+
+        f = new Formula("5%4");
+        assertEquals(1.0, VTypeHelper.toDouble(f.eval()), epsilon);
+
+        f = new Formula("-5%4");
+        assertEquals(-1.0, VTypeHelper.toDouble(f.eval()), epsilon);
+
         // Order, quotes
         f = new Formula("1 + 2 * 3 - 4");
         assertEquals(3.0, VTypeHelper.toDouble(f.eval()), epsilon);

From 5628f8170a1dc2e17454d243500ca3c060686952 Mon Sep 17 00:00:00 2001
From: kasemir <ky9@ornl.gov>
Date: Wed, 13 May 2026 10:23:34 -0400
Subject: [PATCH 2/2] Mention modulo in doc

---
 core/formula/doc/index.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/core/formula/doc/index.rst b/core/formula/doc/index.rst
index bf354a1afa..dc2a5fd190 100644
--- a/core/formula/doc/index.rst
+++ b/core/formula/doc/index.rst
@@ -16,6 +16,7 @@ You can use the following operators :
 | " **\*** " - Multiplication.
 | " **/** " - Division.
 | " **^** " - Power.
+| " **%** " - Modulo.
 | **rnd(x)** - Return a floating point number between 0 and x.
 | **max(expression...)** - Return the maximum between all expressions.
 | **min(expression...)** - Return the minimum between all expressions.