505 lines
19 KiB
JavaScript
505 lines
19 KiB
JavaScript
/**
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* @fileoverview Implements PCjs 8086 opcode helpers.
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* @author <a href="mailto:Jeff@pcjs.org">Jeff Parsons</a>
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* @version 1.0
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* Created 2012-Sep-05
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*
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* Copyright © 2012-2014 Jeff Parsons <Jeff@pcjs.org>
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*
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* This file is part of PCjs, which is part of the JavaScript Machines Project (aka JSMachines)
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* at <http://jsmachines.net/> and <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 source code file of every
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* copy or modified version of this work, and to display that copyright notice on every screen
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* that loads or runs any version of this software (see Computer.sCopyright).
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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 the
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* PCjs program for purposes of the GNU General Public License, and the author does not claim
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* any copyright as to their contents.
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*/
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"use strict";
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if (typeof module !== 'undefined') {
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var X86 = require("./x86");
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var Debugger = require("./debugger");
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}
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var X86Help = {
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/**
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* @this {X86CPU}
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* @param {number} dst (current value, ignored)
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* @param {number} src (new value)
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* @return {number} dst (updated value, from src)
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*/
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opHelpMOV: function(dst, src) {
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this.nStepCycles -= (this.regEAWrite < 0? (this.regEA < 0? this.CYCLES.nOpCyclesMovRR : this.CYCLES.nOpCyclesMovRM) : this.CYCLES.nOpCyclesMovMR);
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return src;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst (current value, ignored)
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* @param {number} src (new value)
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* @return {number} dst (src is overridden, replaced with regMD16, as specified by opMOVSegSrc)
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*/
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opHelpMOVSegSrc: function(dst, src) {
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return X86Help.opHelpMOV.call(this, dst, this.regMD16);
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpTESTb: function(dst, src) {
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this.resultValue = this.resultParitySign = this.resultAuxOverflow = dst & src;
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this.resultSize = X86.RESULT.SIZE_BYTE;
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this.nStepCycles -= (this.regEAWrite < 0? (this.regEA < 0? this.CYCLES.nOpCyclesTestRR : this.CYCLES.nOpCyclesTestRM) : this.CYCLES.nOpCyclesTestRM);
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if (EAFUNCS) this.setEAByte = this.setEAByteDisabled; else this.opFlags |= X86.OPFLAG.NOWRITE;
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return dst;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpTESTw: function(dst, src) {
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this.resultValue = this.resultParitySign = this.resultAuxOverflow = dst & src;
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this.resultSize = X86.RESULT.SIZE_WORD;
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this.nStepCycles -= (this.regEAWrite < 0? (this.regEA < 0? this.CYCLES.nOpCyclesTestRR : this.CYCLES.nOpCyclesTestRM) : this.CYCLES.nOpCyclesTestRM);
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if (EAFUNCS) this.setEAWord = this.setEAWordDisabled; else this.opFlags |= X86.OPFLAG.NOWRITE;
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return dst;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*
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* 80286_and_80287_Programmers_Reference_Manual_1987.pdf, p.B-44 (p.254) notes that:
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*
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* "The low 16 bits of the product of a 16-bit signed multiply are the same as those of an
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* unsigned multiply. The three operand IMUL instruction can be used for unsigned operands as well."
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*
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* However, we still sign-extend the operands before multiplying, making it easier to range-check the result.
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*
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* (80186/80188 and up)
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*/
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opHelpIMUL8: function(dst, src) {
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var result = ((src << 16) >> 16) * ((this.getIPByte() << 24) >> 24);
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this.resultValue = this.resultAuxOverflow = this.resultParitySign = result;
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this.resultSize = X86.RESULT.SIZE_BYTE;
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/*
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* TODO: Look into a more efficient way of setting/synchronizing CF and OF; this code works,
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* but it somewhat defeats the purpose of the indirect result variables that we've set above.
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*/
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if (result > 32767 || result < -32768) {
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this.setCF(); this.setOF();
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} else {
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this.clearCF(); this.clearOF();
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}
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result &= 0xffff;
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if (DEBUG && DEBUGGER) this.traceLog('IMUL8', dst, src, null, this.getPS(), result);
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/*
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* NOTE: These are the cycle counts for the 80286; the 80186/80188 have slightly different values (ranges):
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* 22-25 and 29-32 instead of 21 and 24, respectively. However, accurate cycle counts for the 80186/80188 is
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* not super-critical. TODO: Fix this someday.
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*/
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this.nStepCycles -= (this.regEA < 0? 21 : 24);
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return result;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*
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* 80286_and_80287_Programmers_Reference_Manual_1987.pdf, p.B-44 (p.254) notes that:
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*
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* "The low 16 bits of the product of a 16-bit signed multiply are the same as those of an
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* unsigned multiply. The three operand IMUL instruction can be used for unsigned operands as well."
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*
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* However, we still sign-extend the operands before multiplying, making it easier to range-check the result.
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*
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* (80186/80188 and up)
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*/
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opHelpIMUL16: function(dst, src) {
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var result = ((src << 16) >> 16) * ((this.getIPWord() << 16) >> 16);
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this.resultValue = this.resultAuxOverflow = this.resultParitySign = result;
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this.resultSize = X86.RESULT.SIZE_WORD;
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/*
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* TODO: Look into a more efficient way of setting/synchronizing CF and OF; this code works,
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* but it somewhat defeats the purpose of the indirect result variables that we've set above.
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*/
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if (result > 32767 || result < -32768) {
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this.setCF(); this.setOF();
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} else {
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this.clearCF(); this.clearOF();
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}
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result &= 0xffff;
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if (DEBUG && DEBUGGER) this.traceLog('IMUL16', dst, src, null, this.getPS(), result);
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/*
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* NOTE: These are the cycle counts for the 80286; the 80186/80188 have slightly different values (ranges):
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* 22-25 and 29-32 instead of 21 and 24, respectively. However, accurate cycle counts for the 80186/80188 is
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* not super-critical. TODO: Fix this someday.
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*/
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this.nStepCycles -= (this.regEA < 0? 21 : 24);
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return result;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number} dst unchanged
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*/
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opHelpESC: function(dst, src) {
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return dst;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpLEA: function(dst, src) {
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if (this.regEA < 0) {
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X86Help.opUndefined.call(this);
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return dst;
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}
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this.nStepCycles -= this.CYCLES.nOpCyclesLEA;
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return this.regEA;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpLDS: function(dst, src) {
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if (this.regEA < 0) {
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X86Help.opUndefined.call(this);
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return dst;
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}
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this.setDS(this.getWord(this.regEA + 2));
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this.nStepCycles -= this.CYCLES.nOpCyclesLS;
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return src;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpLES: function(dst, src) {
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if (this.regEA < 0) {
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X86Help.opUndefined.call(this);
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return dst;
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}
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this.setES(this.getWord(this.regEA + 2));
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this.nStepCycles -= this.CYCLES.nOpCyclesLS;
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return src;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpBOUND: function(dst, src) {
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if (this.regEA < 0) {
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/*
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* Generate a #UD fault (INT 0x06: Undefined Opcode) if src is not a memory operand.
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*/
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X86Help.opInvalid.call(this);
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return dst;
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}
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/*
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* Note that BOUND performs signed comparisons, so we must transform all arguments into signed values.
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*/
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var wIndex = (dst << 16) >> 16;
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var wLower = (this.getWord(this.regEA) << 16) >> 16;
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var wUpper = (this.getWord(this.regEA + 2) << 16) >> 16;
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this.nStepCycles -= this.CYCLES.nOpCyclesBound;
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if (wIndex < wLower || wIndex > wUpper) {
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/*
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* The INT 0x05 handler must be called with CS:IP pointing to the BOUND instruction.
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*
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* TODO: Determine the cycle impact when a BOUND exception is triggered, over and above nOpCyclesBound.
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*/
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this.setIP(this.opEA - this.segCS.base);
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X86Help.opHelpINT.call(this, X86.EXCEPTION.BOUND_ERR, null, 0);
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}
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if (EAFUNCS) this.setEAByte = this.setEAByteDisabled; else this.opFlags |= X86.OPFLAG.NOWRITE;
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return dst;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpARPL: function(dst, src) {
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this.nStepCycles -= (10 + (this.regEA < 0? 0 : 1));
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if ((dst & X86.SEL.RPL) < (src & X86.SEL.RPL)) {
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dst = (dst & ~X86.SEL.RPL) | (src & X86.SEL.RPL);
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this.setZF();
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return dst;
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}
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this.clearZF();
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return dst;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpLAR: function(dst, src) {
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this.nStepCycles -= (14 + (this.regEA < 0? 0 : 2));
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/*
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* Currently, segVER.load() will return an error only if the selector is beyond the bounds of the
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* descriptor table or the descriptor is not for a segment.
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*
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* TODO: This instruction's 80286 documentation does not discuss conforming code segments; determine
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* if we need a special check for them.
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*/
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if (this.segVER.load(src, true) >= 0) {
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if (this.segVER.dpl >= this.segCS.cpl && this.segVER.dpl >= (src & X86.SEL.RPL)) {
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this.setZF();
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return this.segVER.acc & X86.DESC.ACC.MASK;
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}
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}
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this.clearZF();
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return dst;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src (the selector)
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* @return {number}
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*/
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opHelpLSL: function(dst, src) {
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/*
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* TODO: Is this an invalid operation if regEAWrite is set? dst is required to be a register.
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*/
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this.nStepCycles -= (14 + (this.regEA < 0? 0 : 2));
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/*
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* Currently, segVER.load() will return an error only if the selector is beyond the bounds of the
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* descriptor table or the descriptor is not for a segment.
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*
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* TODO: LSL is explicitly documented as ALSO requiring a non-null selector, so we check X86.SEL.MASK;
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* are there any other instructions that were, um, less explicit but also require a non-null selector?
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*/
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if ((src & X86.SEL.MASK) && this.segVER.load(src, true) >= 0) {
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var fConforming = ((this.segVER.acc & X86.DESC.ACC.TYPE.CODE_CONFORMING_EXECONLY) == X86.DESC.ACC.TYPE.CODE_CONFORMING_EXECONLY);
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if ((fConforming || this.segVER.dpl >= this.segCS.cpl) && this.segVER.dpl >= (src & X86.SEL.RPL)) {
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this.setZF();
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return this.segVER.limit;
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}
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}
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this.clearZF();
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return dst;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpXCHGrb: function(dst, src) {
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if (this.regEA < 0) {
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switch (this.bModRM & 0x7) {
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case 0x0: // AL
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this.regAX = (this.regAX & ~0xff) | dst;
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break;
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case 0x1: // CL
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this.regCX = (this.regCX & ~0xff) | dst;
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break;
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case 0x2: // DL
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this.regDX = (this.regDX & ~0xff) | dst;
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break;
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case 0x3: // BL
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this.regBX = (this.regBX & ~0xff) | dst;
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break;
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case 0x4: // AH
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this.regAX = (this.regAX & 0xff) | (dst << 8);
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break;
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case 0x5: // CH
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this.regCX = (this.regCX & 0xff) | (dst << 8);
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break;
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case 0x6: // DH
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this.regDX = (this.regDX & 0xff) | (dst << 8);
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break;
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case 0x7: // BH
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this.regBX = (this.regBX & 0xff) | (dst << 8);
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break;
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default:
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break; // there IS no other case, but JavaScript inspections don't know that
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}
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this.nStepCycles -= this.CYCLES.nOpCyclesXchgRR;
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} else {
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/*
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* This is a case where the ModRM decoder that's calling us didn't know it should have called modEAByte()
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* instead of getEAByte(), so we compensate by updating regEAWrite.
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*/
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this.regEAWrite = this.regEA;
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this.setEAByte(dst);
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this.nStepCycles -= this.CYCLES.nOpCyclesXchgRM;
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}
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return src;
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},
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/**
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* @this {X86CPU}
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* @param {number} dst
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* @param {number} src
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* @return {number}
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*/
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opHelpXCHGrw: function(dst, src) {
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if (this.regEA < 0) {
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switch (this.bModRM & 0x7) {
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case 0x0: // AX
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this.regAX = dst;
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break;
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case 0x1: // CX
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this.regCX = dst;
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break;
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case 0x2: // DX
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this.regDX = dst;
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break;
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case 0x3: // BX
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this.regBX = dst;
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break;
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case 0x4: // SP
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this.regSP = dst;
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break;
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case 0x5: // BP
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this.regBP = dst;
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break;
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case 0x6: // SI
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this.regSI = dst;
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break;
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case 0x7: // DI
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this.regDI = dst;
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break;
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default:
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break; // there IS no other case, but JavaScript inspections don't know that
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}
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this.nStepCycles -= this.CYCLES.nOpCyclesXchgRR;
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} else {
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/*
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* This is a case where the ModRM decoder that's calling us didn't know it should have called modEAByte()
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* instead of getEAByte(), so we compensate by updating regEAWrite.
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*/
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this.regEAWrite = this.regEA;
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this.setEAWord(dst);
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this.nStepCycles -= this.CYCLES.nOpCyclesXchgRM;
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}
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return src;
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},
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/**
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* @this {X86CPU}
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* @param {number} nIDT
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* @param {number|null|undefined} nError
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* @param {number} nCycles (in addition to the default of nOpCyclesInt)
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*/
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opHelpINT: function(nIDT, nError, nCycles) {
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if (this.loadIDTEntry(nIDT)) {
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this.pushWord(this.getPS());
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this.regPS &= this.descIDT.maskPS;
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this.pushWord(this.segCS.sel);
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this.pushWord(this.regIP);
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if (nError != null) this.pushWord(nError);
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this.setCSIP(this.descIDT.off, this.descIDT.sel);
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this.nStepCycles -= this.CYCLES.nOpCyclesInt + nCycles;
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}
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/*
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* TODO: Now what?
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*/
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},
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/**
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* opHelpLMSW(w)
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*
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* Factored out of x86op0f.js, since both opLMSW and opLOADALL are capable of loading a new MSW.
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* The caller is responsible for assessing the appropriate cycle cost.
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*
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* @this {X86CPU}
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* @param {number} w
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*/
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opHelpLMSW: function(w) {
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/*
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* This instruction is always allowed to set MSW.PE, but it cannot clear MSW.PE once set;
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* therefore, we always OR the previous value of MSW.PE into the new value before loading.
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*/
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w |= (this.regMSW & X86.MSW.PE);
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this.regMSW = (this.regMSW & X86.MSW.SET) | (w & ~X86.MSW.SET);
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/*
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* Since the 80286 cannot return to real-mode via this instruction, the only transition we
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* must worry about is to protected-mode. And don't worry, there's no harm calling setProtMode()
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* if the CPU is already in protected-mode (we could certainly optimize the call out in that
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* case, but this instruction isn't used frequently enough to warrant it).
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*/
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if (this.regMSW & X86.MSW.PE) this.setProtMode(true);
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},
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/**
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* @this {X86CPU}
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|
*/
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|
opHelpDIVOverflow: function() {
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|
this.setIP(this.opEA - this.segCS.base);
|
|
/*
|
|
* TODO: Determine the proper cycle count
|
|
*/
|
|
X86Help.opHelpINT.call(this, X86.EXCEPTION.DIV_ERR, null, 2);
|
|
},
|
|
/**
|
|
* @this {X86CPU}
|
|
* @param {number} nFault
|
|
* @param {number} [nError]
|
|
* @param {boolean} [fHalt] will halt the CPU if true *and* a Debugger is loaded
|
|
*/
|
|
opHelpFault: function(nFault, nError, fHalt) {
|
|
if (DEBUGGER && this.dbg) {
|
|
/*
|
|
* NOTE: By using Debugger.message(), we have the option of setting "m halt on" and halting on messages like this.
|
|
*/
|
|
if (this.dbg.messageEnabled(Debugger.MESSAGE.CPU)) {
|
|
this.dbg.message("Fault 0x" + str.toHexByte(nFault) + (nError != null? " (0x" + str.toHexWord(nError) + ")" : "") + " on opcode 0x" + str.toHexByte(this.bus.getByteDirect(this.regEIP)) + " at " + str.toHexAddr(this.regIP, this.segCS.sel));
|
|
}
|
|
if (fHalt) this.haltCPU();
|
|
}
|
|
if (this.model >= X86.MODEL_80186) {
|
|
this.setIP(this.opEA - this.segCS.base);
|
|
X86Help.opHelpINT.call(this, nFault, nError, 0);
|
|
}
|
|
},
|
|
/**
|
|
* @this {X86CPU}
|
|
*/
|
|
opInvalid: function() {
|
|
X86Help.opHelpFault.call(this, X86.EXCEPTION.UD_FAULT);
|
|
this.haltCPU();
|
|
},
|
|
/**
|
|
* @this {X86CPU}
|
|
*/
|
|
opUndefined: function() {
|
|
this.setIP(this.opEA - this.segCS.base);
|
|
this.setError("Undefined opcode 0x" + str.toHexByte(this.bus.getByteDirect(this.regEIP)) + " at " + str.toHexAddr(this.regIP, this.segCS.sel));
|
|
this.haltCPU();
|
|
}
|
|
};
|
|
|
|
if (typeof module !== 'undefined') module.exports = X86Help;
|