88 lines
3.6 KiB
JavaScript
88 lines
3.6 KiB
JavaScript
/**
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* @fileoverview Defines PC6502 CPU constants.
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* @author <a href="mailto:Jeff@pcjs.org">Jeff Parsons</a>
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* @copyright © Jeff Parsons 2012-2017
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*
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* This file is part of PCjs, a computer emulation software project at <http://pcjs.org/>.
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*
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* PCjs is free software: you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation, either version 3
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* of the License, or (at your option) any later version.
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*
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* PCjs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
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* even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along with PCjs. If not,
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* see <http://www.gnu.org/licenses/gpl.html>.
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*
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* You are required to include the above copyright notice in every modified copy of this work
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* and to display that copyright notice when the software starts running; see COPYRIGHT in
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* <http://pcjs.org/modules/shared/lib/defines.js>.
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*
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* Some PCjs files also attempt to load external resource files, such as character-image files,
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* ROM files, and disk image files. Those external resource files are not considered part of PCjs
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* for purposes of the GNU General Public License, and the author does not claim any copyright
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* as to their contents.
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*/
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"use strict";
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var CPUDef = {
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/*
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* CPU model numbers (supported)
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*/
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MODEL_6502: 6502,
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/*
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* This constant is used to mark points in the code where the physical address being returned
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* is invalid and should not be used.
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*
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* In a 32-bit CPU, -1 (ie, 0xffffffff) could actually be a valid address, so consider changing
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* ADDR_INVALID to NaN or null (which is also why all ADDR_INVALID tests should use strict equality
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* operators).
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*
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* The main reason I'm NOT using NaN or null now is my concern that, by mixing non-numbers
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* (specifically, values outside the range of signed 32-bit integers), performance may suffer.
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*
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* WARNING: Like many of the properties defined here, ADDR_INVALID is a common constant, which the
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* Closure Compiler will happily inline (with or without @const annotations; in fact, I've yet to
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* see a @const annotation EVER improve automatic inlining). However, if you don't make ABSOLUTELY
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* certain that this file is included BEFORE the first reference to any of these properties, that
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* automatic inlining will no longer occur.
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*/
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ADDR_INVALID: -1,
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/*
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* Processor Status flag definitions (stored in regPS)
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*/
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PS: {
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SF: 0x80, // this.BIT_PN = 0x80; // N = sign
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OF: 0x40, // this.BIT_PV = 0x40; // V = overflow
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BF: 0x10, // this.BIT_PB = 0x10; // B = break
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DF: 0x08, // this.BIT_PD = 0x08; // D = decimal
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IF: 0x04, // this.BIT_PI = 0x04; // I = interrupt
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ZF: 0x02, // this.BIT_PZ = 0x02; // Z = zero
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CF: 0x01 // this.BIT_PC = 0x01; // C = carry
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},
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VECTOR: {
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NMI: 0xFFFA, // this.VECTOR_NMI = 0xfffa;
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RESET: 0xFFFC, // this.VECTOR_RESET = 0xfffc;
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IRQ: 0xFFFE // this.VECTOR_IRQ = 0xfffe;
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},
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/*
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* Opcode definitions
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*/
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OPCODE: {
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JSR: 0x20,
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/*
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* opSim operation codes
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*/
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SIM: 0x02,
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SIMOP_HLT: 0x00,
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SIMOP_MSG: 0x01
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// to be continued....
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}
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};
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if (NODE) module.exports = CPUDef;
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