Added zeropage labels

lib/zeropage.asm

@@ -0,0 +1,49 @@
+/**
+ * @file zeropage.asm
+ * @brief Zeropage module
+ * @details This file contains labels that map some usable zeropage location of the Commodore 128.
+ *
+ * @author Raffaele Intorcia raffaele.intorcia@gmail.com
+ *
+ * @copyright MIT License
+ * Copyright (c) 2024 c128lib - https://github.com/c128lib
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * @date 2024
+ */
+
+#importonce
+
+.filenamespace c128lib
+
+.namespace Zeropage {
+  /**
+  @remarks This is a free location, however a bug
+  * in the screen editor CINT ($C07B) and SWAPPER ($CD2E)
+  * routines causes this location to be overwritten whenever those
+  * routines are executed. This happens in a RUN/STOP-RESTORE sequence
+  * or whenever you switch screens between 40 and 80 columns.
+   */
+  .label FA = $FA
+  .label FB = $FB
+  .label FC = $FC
+  .label FD = $FD
+  .label FE = $FE
+}