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diff --git a/source/codes/Code39.mc b/source/codes/Code39.mc
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+// Author:  cirakg & claude ai
+// Summary: Code 39 encoder: 43 characters, optional mod-43 check character, wide bars 2 modules (as zxing).
+
+import Toybox.Lang;
+
+module Code39 {
+
+    const ALPHABET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. $/+%"; // lint: allow-literal (Code 39 character set)
+    // Nine elements per character, bit 8 first, 1 = wide; index 43 is '*'.
+    const PATTERNS = [
+        0x034, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064,
+        0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x04C, 0x01C,
+        0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016,
+        0x181, 0x0C1, 0x1C0, 0x091, 0x190, 0x0D0, 0x085, 0x184, 0x0C4, 0x0A8,
+        0x0A2, 0x08A, 0x02A, 0x094
+    ];
+    const STAR = 43;
+
+    // withCheck adds the mod-43 check character (the sum of the character
+    // values modulo 43).
+    function encode(text as String, withCheck as Boolean) as Codes.LinearCode or Codes.CodeError {
+        var chars = text.toCharArray();
+        if (chars.size() == 0) {
+            return new Codes.CodeError("Code 39 needs some text");
+        }
+        var values = [] as Array<Number>;
+        var sum = 0;
+        for (var i = 0; i < chars.size(); i++) {
+            var v = ALPHABET.find(chars[i].toString());
+            if (v == null) {
+                return new Codes.CodeError("Code 39: '" + chars[i] + "' (position " + (i + 1)
+                    + ") isn't allowed (0-9, A-Z, space, - . $ / + %)");
+            }
+            values.add(v);
+            sum += v;
+        }
+        var readable = text;
+        if (withCheck) {
+            values.add(sum % 43);
+            readable += ALPHABET.substring(sum % 43, sum % 43 + 1);
+        }
+        var m = []b;
+        addChar(m, STAR);
+        for (var i = 0; i < values.size(); i++) {
+            m.add(0); // narrow gap between characters
+            addChar(m, values[i]);
+        }
+        m.add(0);
+        addChar(m, STAR);
+        return new Codes.LinearCode(m, readable);
+    }
+
+    function addChar(m as ByteArray, value as Number) as Void {
+        var pattern = PATTERNS[value] as Number;
+        for (var i = 8; i >= 0; i--) {
+            var width = ((pattern >> i) & 1) == 1 ? 2 : 1;
+            var bar = (8 - i) % 2 == 0;
+            for (var k = 0; k < width; k++) {
+                m.add(bar ? 1 : 0);
+            }
+        }
+    }
+}