PC6502 work-in-progress

modules/pc6502/lib/cpudef.js

@@ -0,0 +1,92 @@
+/**
+ * @fileoverview Defines PC6502 CPU constants.
+ * @author <a href="mailto:Jeff@pcjs.org">Jeff Parsons</a>
+ * @version 1.0
+ * Created 2016-May-12
+ *
+ * Copyright © 2012-2016 Jeff Parsons <Jeff@pcjs.org>
+ *
+ * This file is part of PCjs, which is part of the JavaScript Machines Project (aka JSMachines)
+ * at <http://jsmachines.net/> and <http://pcjs.org/>.
+ *
+ * PCjs is free software: you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation, either version 3
+ * of the License, or (at your option) any later version.
+ *
+ * PCjs 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with PCjs.  If not,
+ * see <http://www.gnu.org/licenses/gpl.html>.
+ *
+ * You are required to include the above copyright notice in every source code file of every
+ * copy or modified version of this work, and to display that copyright notice on every screen
+ * that loads or runs any version of this software (see Computer.COPYRIGHT).
+ *
+ * Some PCjs files also attempt to load external resource files, such as character-image files,
+ * ROM files, and disk image files. Those external resource files are not considered part of the
+ * PCjs program for purposes of the GNU General Public License, and the author does not claim
+ * any copyright as to their contents.
+ */
+
+"use strict";
+
+var CPUDef = {
+    /*
+     * CPU model numbers (supported)
+     */
+    MODEL_6502: 6502,
+
+    /*
+     * This constant is used to mark points in the code where the physical address being returned
+     * is invalid and should not be used.
+     *
+     * In a 32-bit CPU, -1 (ie, 0xffffffff) could actually be a valid address, so consider changing
+     * ADDR_INVALID to NaN or null (which is also why all ADDR_INVALID tests should use strict equality
+     * operators).
+     *
+     * The main reason I'm NOT using NaN or null now is my concern that, by mixing non-numbers
+     * (specifically, values outside the range of signed 32-bit integers), performance may suffer.
+     *
+     * WARNING: Like many of the properties defined here, ADDR_INVALID is a common constant, which the
+     * Closure Compiler will happily inline (with or without @const annotations; in fact, I've yet to
+     * see a @const annotation EVER improve automatic inlining).  However, if you don't make ABSOLUTELY
+     * certain that this file is included BEFORE the first reference to any of these properties, that
+     * automatic inlining will no longer occur.
+     */
+    ADDR_INVALID: -1,
+
+    /*
+     * Processor Status flag definitions (stored in regPS)
+     */
+    PS: {
+        SF:     0x80,           // this.BIT_PN = 0x80;     // N = sign
+        OF:     0x40,           // this.BIT_PV = 0x40;     // V = overflow
+        BF:     0x10,           // this.BIT_PB = 0x10;     // B = break
+        DF:     0x08,           // this.BIT_PD = 0x08;     // D = decimal
+        IF:     0x04,           // this.BIT_PI = 0x04;     // I = interrupt
+        ZF:     0x02,           // this.BIT_PZ = 0x02;     // Z = zero
+        CF:     0x01            // this.BIT_PC = 0x01;     // C = carry
+    },
+    VECTOR: {
+        NMI:    0xFFFA,         // this.VECTOR_NMI     = 0xfffa;
+        RESET:  0xFFFC,         // this.VECTOR_RESET   = 0xfffc;
+        IRQ:    0xFFFE          // this.VECTOR_IRQ     = 0xfffe;
+    },
+    /*
+     * Opcode definitions
+     */
+    OPCODE: {
+        JSR:    0x20,
+        /*
+         * opSim operation codes
+         */
+        SIM:    0x02,
+        SIMOP_HLT:  0x00,
+        SIMOP_MSG:  0x01
+        // to be continued....
+    }
+};
+
+if (NODE) module.exports = CPUDef;