Formula: Add modulo 'a % b' operator

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.

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;

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 + ")";
+    }
+}

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);