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Working on v1.30.0, starting with cleaner separation of opcode function helpers from other (eg, control-flow) helpers

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Jeff Parsons 2016-03-04 16:23:22 -08:00
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/**
* @fileoverview Implements PCjs control flow helpers.
* @author <a href="mailto:Jeff@pcjs.org">Jeff Parsons</a>
* @version 1.0
* Created 2016-Mar-04
*
* 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";
if (NODE) {
var str = require("../../shared/lib/strlib");
var Messages = require("./messages");
var X86 = require("./x86");
}
/**
* fnCALLF(off, sel)
*
* For protected-mode, this function must attempt to load the new code segment first, because if the new segment
* requires a change in privilege level, the return address must be pushed on the NEW stack, not the current stack.
*
* Also, we rely on a new function, pushData(), instead of pushWord(), to accommodate the outgoing segment size,
* which may differ from the incoming segment. For example, when a 32-bit code segment performs a 16:32 call to a
* 16-bit code segment, we must push 32-bit segment and offset values.
*
* TODO: Since setCSIP() already informs the segCS load() function when it's making a call, the load() function
* could automatically push the old CS and IP values *before* segCS is updated -- which would be a better time to do
* those pushes AND eliminate the need for pushData(). Unfortunately, load() is also used by loadIDT(), and loadIDT()
* has different requirements (eg, pushing flags first), so it's not a trivial change.
*
* @this {X86CPU}
* @param {number} off
* @param {number} sel
*/
X86.fnCALLF = function(off, sel)
{
/*
* Since we always push the return address AFTER calling setCSIP(), and since either push could trigger a
* fault (eg, segment fault, page fault, etc), we must not only snapshot regLSP into opLSP, but also the
* current CS into opCS, so that fnFault() can always make CALLF restartable. Ditto for opSS and the SS register.
*/
this.opCS = this.getCS();
this.opSS = this.getSS();
this.opLSP = this.regLSP;
var oldIP = this.getIP();
var oldSize = (I386? this.sizeData : 2);
if (this.setCSIP(off, sel, true) != null) {
/*
* When the OPERAND size is 32 bits, the 80386 will decrement the stack pointer by 4, write the selector
* into the 2 lower bytes, and leave the 2 upper bytes untouched; at least, that's the case for all other
* segment register writes, so we assume this case is no different. Hence, the hard-coded size of 2.
*/
this.pushData(this.opCS, oldSize, 2);
this.pushData(oldIP, oldSize, oldSize);
}
this.opLSP = X86.ADDR_INVALID;
this.opCS = this.opSS = -1;
};
/**
* fnINT(nIDT, nError, nCycles)
*
* NOTE: We no longer use setCSIP(), because it always loads the new CS using segCS.load(), which only knows
* how to load GDT and LDT descriptors, whereas interrupts must use setCS.loadIDT(), which deals exclusively
* with IDT descriptors.
*
* @this {X86CPU}
* @param {number} nIDT
* @param {number|null} [nError]
* @param {number} [nCycles] (in addition to the default of nOpCyclesInt)
*/
X86.fnINT = function(nIDT, nError, nCycles)
{
/*
* TODO: We assess the cycle cost up front, because otherwise, if loadIDT() fails, no cost may be assessed.
*/
this.nStepCycles -= this.cycleCounts.nOpCyclesInt + (nCycles || 0);
var oldPS = this.getPS();
var oldCS = this.getCS();
var oldIP = this.getIP();
var addr = this.segCS.loadIDT(nIDT);
if (addr !== X86.ADDR_INVALID) {
/*
* TODO: Determine if we should use pushData() instead of pushWord() for oldCS and nError, to deal with
* the same 32-bit 80386 compatibility issue that fnCALLF(), opPUSHCS(), et al must deal with; namely, that
* 32-bit segment register writes (and, reportedly, 32-bit error codes) don't modify the upper 16 bits.
*
* Also, note that fnCALLF() is using the OPERAND size in effect *before* CS is loaded, whereas here we're
* using the OPERAND size in effect *after* CS is loaded. Is that correct? And does an explicit OPERAND
* size override on an "INT" instruction have any effect on that behavior? Is that even allowed?
*/
this.pushWord(oldPS);
this.pushWord(oldCS);
this.pushWord(oldIP);
if (nError != null) this.pushWord(nError);
this.nFault = -1;
this.setLIP(addr);
}
};
/**
* fnIRET()
*
* @this {X86CPU}
*/
X86.fnIRET = function()
{
/*
* Originally, we would snapshot regLSP into opLSP because newCS could trigger a segment fault,
* but additionally, the stack segment could trigger either a segment fault or a page fault; indeed,
* any operation that performs multiple stack modifications must take this precaution and snapshot regLSP.
*/
this.opLSP = this.regLSP;
this.nStepCycles -= this.cycleCounts.nOpCyclesIRet;
if ((this.regCR0 & X86.CR0.MSW.PE) && (this.regPS & X86.PS.NT)) {
var addrNew = this.segTSS.base;
/*
* Fortunately, X86.TSS286.PREV_TSS and X86.TSS386.PREV_TSS refer to the same TSS offset.
* TODO: Update switchTS() to assess a cycle cost; currently, all we assess is what's shown above.
*/
var sel = this.getShort(addrNew + X86.TSS286.PREV_TSS);
this.segCS.switchTSS(sel, false);
}
else {
var cpl = this.nCPL;
var newIP = this.popWord();
var newCS = this.popWord();
var newPS = this.popWord();
if (I386) {
if (this.regPS & X86.PS.VM) {
/*
* On the 80386, in V86-mode, RF is the only defined EFLAGS bit above bit 15 that may be changed by IRETD.
* This is less restrictive than POPFD, which cannot change ANY bits above bit 15; see opPOPF() for details.
*/
newPS = (newPS & (0xffff | X86.PS.RF)) | (this.regPS & ~(0xffff | X86.PS.RF));
}
else {
if (newPS & X86.PS.VM) {
/*
* As noted in loadDesc8(), where the V86-mode frame we're about to pop was originally pushed,
* these frames ALWAYS contain 32-bit values, so make sure that sizeData reflects that.
*/
this.assert(!!(this.regCR0 & X86.CR0.MSW.PE) && this.sizeData == 4);
/*
* We have to assume that a full V86-mode interrupt frame was on the protected-mode stack; namely:
*
* low: EIP
* CS (padded to 32 bits)
* EFLAGS
* ESP
* SS (padded to 32 bits)
* ES (padded to 32 bits)
* DS (padded to 32 bits)
* FS (padded to 32 bits)
* high: GS (padded to 32 bits)
*
* We've already popped EIP, CS, and EFLAGS into newIP, newCS and newPS, respectively, so we must now
* pop the rest, while we're still in protected-mode, before the switch to V86-mode alters the current
* operand size (among other things).
*/
var newSP = this.popWord();
var newSS = this.popWord();
var newES = this.popWord();
var newDS = this.popWord();
var newFS = this.popWord();
var newGS = this.popWord();
this.setProtMode(true, true); // flip the switch to V86-mode now
this.setSS(newSS);
this.setSP(newSP);
this.setES(newES);
this.setDS(newDS);
this.setFS(newFS);
this.setGS(newGS);
}
}
}
if (this.setCSIP(newIP, newCS, false) != null) {
this.setPS(newPS, cpl);
if (this.cIntReturn) this.checkIntReturn(this.regLIP);
}
}
this.opLSP = X86.ADDR_INVALID;
};
/**
* fnRETF(n)
*
* For protected-mode, this function must pop any arguments off the current stack AND whatever stack
* we may have switched to; setCSIP() returns true if a stack switch occurred, false if not, and null
* if an error occurred.
*
* @this {X86CPU}
* @param {number} n
*/
X86.fnRETF = function(n)
{
/*
* Originally, we would snapshot regLSP into opLSP because newCS could trigger a segment fault,
* but additionally, the stack segment could trigger either a segment fault or a page fault; indeed,
* any operation that performs multiple stack modifications must take this precaution and snapshot regLSP.
*/
this.opLSP = this.regLSP;
var newIP = this.popWord();
var newCS = this.popWord();
if (n) this.setSP(this.getSP() + n); // TODO: optimize
if (this.setCSIP(newIP, newCS, false)) { // returns true if a stack switch occurred
/*
* Fool me once, shame on... whatever. If setCSIP() indicates a stack switch occurred,
* make sure we're in protected mode, because automatic stack switches can't occur in real mode.
*/
this.assert(!!(this.regCR0 & X86.CR0.MSW.PE));
if (n) this.setSP(this.getSP() + n); // TODO: optimize
/*
* As per Intel documentation: "If any of [the DS or ES] registers refer to segments whose DPL is
* less than the new CPL (excluding conforming code segments), the segment register is loaded with
* the null selector."
*
* TODO: I'm not clear on whether a conforming code segment must also be marked readable, so I'm playing
* it safe and using CODE_CONFORMING instead of CODE_CONFORMING_READABLE. Also, for the record, I've not
* seen this situation occur yet (eg, in OS/2 1.0).
*/
this.zeroSeg(this.segDS);
this.zeroSeg(this.segES);
if (I386 && this.model >= X86.MODEL_80386) {
this.zeroSeg(this.segFS);
this.zeroSeg(this.segGS);
}
}
if (n == 2 && this.cIntReturn) this.checkIntReturn(this.regLIP);
this.opLSP = X86.ADDR_INVALID;
};
/**
* fnGRPFault(dst, src)
*
* @this {X86CPU}
* @param {number} dst
* @param {number} src
* @return {number}
*/
X86.fnGRPFault = function(dst, src)
{
/*
* This should NEVER be called on 8086/8088 CPUs, and yet we preset some of the handlers in aOpGrpPOPw,
* aOpGrp4b, and aOpGrp4w to call it. initProcessor() DOES patch aOpGrp4b[0x07] and aOpGrp4w[0x07] to
* fnGRPInvalid, but that's it.
*
* However, given the infrequency of this call, it's simpler to continue presetting all the handlers in
* aOpGrpPOPw to their post-8086 default, and deal with the appropriate 8086 behavior here (which for now,
* is to call fnGRPUndefined instead).
*/
if (this.model < X86.MODEL_80186) {
return X86.fnGRPUndefined.call(this, dst, src);
}
X86.fnFault.call(this, X86.EXCEPTION.GP_FAULT, 0);
return dst;
};
/**
* fnGRPInvalid(dst, src)
*
* @this {X86CPU}
* @param {number} dst
* @param {number} src
* @return {number}
*/
X86.fnGRPInvalid = function(dst, src)
{
X86.opInvalid.call(this);
return dst;
};
/**
* fnGRPUndefined(dst, src)
*
* @this {X86CPU}
* @param {number} dst
* @param {number} src
* @return {number}
*/
X86.fnGRPUndefined = function(dst, src)
{
X86.opUndefined.call(this);
return dst;
};
/**
* fnDivOverflow()
*
* @this {X86CPU}
*/
X86.fnDivOverflow = function()
{
/*
* Divide error exceptions are traps on the 8086 and faults on later processors. I question the value of that
* change, because it implies that someone might actually want to restart a failing divide. The only reasonable
* explanation I can see for the change is to enable the exception handler to accurately record the address of
* the failing divide, which seems like a very minor benefit. It doesn't change the fact that, on any processor,
* the exception handler's only reasonable recourse is to unwind execution to a safe point (or terminate the app).
*
* TODO: Determine the proper cycle cost.
*/
if (this.model == X86.MODEL_8086) {
X86.fnTrap.call(this, X86.EXCEPTION.DE_EXC, 2);
} else {
X86.fnFault.call(this, X86.EXCEPTION.DE_EXC, null, 2);
}
};
/**
* fnInterrupt(nIDT, nCycles)
*
* Helper to dispatch external interrupts. nCycles defaults to 11 for the 8086/8088
* if no alternate value is specified.
*
* @this {X86CPU}
* @param {number} nIDT
* @param {number} [nCycles] (number of cycles in addition to the default of nOpCyclesInt)
*/
X86.fnInterrupt = function(nIDT, nCycles)
{
this.nFault = nIDT;
if (nCycles === undefined) nCycles = 11;
X86.fnINT.call(this, nIDT, null, nCycles);
};
/**
* fnTrap(nIDT, nCycles)
*
* Helper to dispatch traps (ie, exceptions that occur AFTER the instruction, with NO error code)
*
* @this {X86CPU}
* @param {number} nIDT
* @param {number} [nCycles] (number of cycles in addition to the default of nOpCyclesInt)
*/
X86.fnTrap = function(nIDT, nCycles)
{
this.nFault = -1;
X86.fnINT.call(this, nIDT, null, nCycles);
};
/**
* fnFault(nFault, nError, nCycles, fHalt)
*
* Helper to dispatch faults (ie, exceptions that occur DURING an instruction and MAY generate an error code)
*
* @this {X86CPU}
* @param {number} nFault
* @param {number|null} [nError] (if omitted, no error code will be pushed)
* @param {number} [nCycles] cycle count to pass through to fnINT(), if any
* @param {boolean} [fHalt] (true to halt the CPU, false to not, undefined if "it depends")
*/
X86.fnFault = function(nFault, nError, nCycles, fHalt)
{
var fDispatch = false;
if (!this.aFlags.fComplete) {
/*
* Prior to each new burst of instructions, stepCPU() sets fComplete to true, and the only (normal) way
* for fComplete to become false is through stopCPU(), which isn't ordinarily called, except by the Debugger.
*/
this.setLIP(this.opLIP);
}
else if (this.model >= X86.MODEL_80186) {
fDispatch = true;
if (this.nFault < 0) {
/*
* Single-fault (error code is passed through, and the responsible instruction is restartable.
*/
if (this.opCS != -1) {
/*
* HACK: We must slam 3 into this.segCS.cpl to ensure that loading the original CS segment doesn't
* fail. For example, if we faulted in the middle of a ring transition that loaded CS with a higher
* privilege (lower CPL) code segment, then our attempt here to reload the lower privilege (higher CPL)
* code segment could be viewed as a privilege violation (which it would be outside this context).
*/
this.segCS.cpl = 3;
this.setCS(this.opCS);
this.opCS = -1;
}
this.setLIP(this.opLIP);
if (this.opSS != -1) {
this.setSS(this.opSS);
this.opSS = -1;
}
if (this.opLSP !== X86.ADDR_INVALID) {
this.setSP((this.regESP & ~this.segSS.maskAddr) | (this.opLSP - this.segSS.base));
this.opLSP = X86.ADDR_INVALID;
}
}
else if (this.nFault != X86.EXCEPTION.DF_FAULT) {
/*
* Double-fault (error code is always zero, and the responsible instruction is not restartable)
*/
nError = 0;
nFault = X86.EXCEPTION.DF_FAULT;
}
else {
/*
* Triple-fault (usually referred to in Intel literature as a "shutdown", but at least on the 80286,
* it's actually a "reset")
*/
nError = 0;
nFault = -1;
this.resetRegs();
fDispatch = fHalt = false;
}
}
if (X86.fnCheckFault.call(this, nFault, nError, fHalt)) {
/*
* If this is a fault that would normally be dispatched BUT fnCheckFault() wants us to halt,
* then we throw a bogus fault number (-1), simply to interrupt the current instruction in exactly
* the same way that a dispatched fault would interrupt it.
*/
if (fDispatch) throw -1;
}
if (fDispatch) {
this.nFault = nFault;
X86.fnINT.call(this, nFault, nError, nCycles);
/*
* REP'eated instructions that rewind regLIP to opLIP used to screw up this dispatch,
* so now we slip the new regLIP into opLIP, effectively turning their action into a no-op.
*/
this.opLIP = this.regLIP;
/*
* X86.OPFLAG.FAULT flag is used by selected opcodes to provide an early exit, restore register(s),
* or whatever is needed to help ensure instruction restartability; there is currently no general
* mechanism for snapping and restoring all registers for any instruction that might fault.
*
* X86.EXCEPTION.DB_EXC exceptions set their own special flag, X86.OPFLAG.DBEXC, to prevent redundant
* DEBUG exceptions, so we don't need to set OPFLAG.FAULT in that case, because a DEBUG exception
* doesn't actually prevent an instruction from executing (and therefore doesn't need to be restarted).
*/
if (nFault == X86.EXCEPTION.DB_EXC) {
this.opFlags |= X86.OPFLAG.DBEXC;
} else {
this.assert(nFault >= 0);
this.opFlags |= X86.OPFLAG.FAULT;
}
/*
* Since this fault is likely being issued in the context of an instruction that hasn't finished
* executing, if we don't do anything to interrupt that execution (eg, throw a JavaScript exception),
* then we would need to shut off all further reads/writes for the current instruction.
*
* That's easy for any EA-based memory accesses: simply set both the NOREAD and NOWRITE flags.
* However, there are also direct, non-EA-based memory accesses to consider. A perfect example is
* opPUSHA(): if a GP fault occurs on any PUSH other than the last, a subsequent PUSH is likely to
* cause another fault, which we will misinterpret as a double-fault -- unless the handler for
* such an opcode checks this.opFlags for X86.OPFLAG.FAULT after each step of the operation.
*
* this.opFlags |= (X86.OPFLAG.NOREAD | X86.OPFLAG.NOWRITE);
*
* Fortunately, we now throw an exception that terminates the current instruction, so the above hack
* should no longer be necessary.
*/
throw nFault;
}
};
/**
* fnPageFault(addr, fPresent, fWrite)
*
* Helper to dispatch page faults.
*
* @this {X86CPU}
* @param {number} addr
* @param {boolean} fPresent
* @param {boolean} fWrite
*/
X86.fnPageFault = function(addr, fPresent, fWrite)
{
this.regCR2 = addr;
var nError = 0;
if (fPresent) nError |= X86.PTE.PRESENT;
if (fWrite) nError |= X86.PTE.READWRITE;
if (this.nCPL == 3) nError |= X86.PTE.USER;
X86.fnFault.call(this, X86.EXCEPTION.PF_FAULT, nError);
};
/**
* fnCheckFault(nFault, nError, fHalt)
*
* Aside from giving the Debugger an opportunity to report every fault, this also gives us the ability to
* halt exception processing in tracks: return true to prevent the fault handler from being dispatched.
*
* At the moment, the only Debugger control you have over fault interception is setting MESSAGE.FAULT, which
* will display faults as they occur, and MESSAGE.HALT, which will halt after any Debugger message, including
* MESSAGE.FAULT. If you want execution to continue after halting, clear MESSAGE.FAULT and/or MESSAGE.HALT,
* or single-step over the offending instruction, which will allow the fault to be dispatched.
*
* @this {X86CPU}
* @param {number} nFault
* @param {number|null} [nError] (if omitted, no error code will be reported)
* @param {boolean} [fHalt] (true to halt the CPU, false to not, undefined if "it depends")
* @return {boolean|undefined} true to block the fault (often desirable when fHalt is true), otherwise dispatch it
*/
X86.fnCheckFault = function(nFault, nError, fHalt)
{
var bitsMessage = Messages.FAULT;
var bOpcode = this.probeAddr(this.regLIP);
/*
* OS/2 1.0 uses an INT3 (0xCC) opcode in conjunction with an invalid IDT to trigger a triple-fault
* reset and return to real-mode, and these resets happen quite frequently during boot; for example,
* OS/2 startup messages are displayed using a series of INT 0x10 BIOS calls for each character, and
* each series of BIOS calls requires a round-trip mode switch.
*
* Since we really only want to halt on "bad" faults, not "good" (ie, intentional) faults, we take
* advantage of the fact that all 3 faults comprising the triple-fault point to an INT3 (0xCC) opcode,
* and so whenever we see that opcode, we ignore the caller's fHalt flag, and suppress FAULT messages
* unless CPU messages are also enabled.
*
* When a triple fault shows up, nFault is -1; it displays as 0xff only because we use toHexByte().
*/
if (bOpcode == X86.OPCODE.INT3 && !this.addrIDTLimit) {
fHalt = false;
}
/*
* There are a number of V86-mode exceptions we don't need to know about. For starters, Windows 3.00
* (and other versions of enhanced-mode Windows) use an ARPL to switch out of V86-mode, so we can ignore
* those UD_FAULTs.
*
* Ditto for software interrupts, which will generate a GP_FAULT when the interrupt number (eg, 0x6D)
* exceeds the protected-mode IDT's limit (eg, a limit of 0x2FF corresponds to a maximum interrupt number
* of 0x5F). Windows doesn't really care if its IDT is too small, because it has to simulate all software
* interrupts in V86-mode regardless (they generate a GP_FAULT if IOPL < 3, and even when IOPL == 3, only
* the protected-mode IDT handler gets to run).
*/
if ((this.regPS & X86.PS.VM)) {
if (nFault == X86.EXCEPTION.UD_FAULT && bOpcode == X86.OPCODE.ARPL ||
nFault == X86.EXCEPTION.GP_FAULT && bOpcode == X86.OPCODE.INTN) {
fHalt = false;
}
}
/*
* If fHalt has been explicitly set to false, we also take that as a cue to disable fault messages
* (which you can override by turning on CPU messages).
*/
if (fHalt === false) {
bitsMessage |= Messages.CPU;
}
/*
* Similarly, the PC AT ROM BIOS deliberately generates a couple of GP faults as part of the POST
* (Power-On Self Test); we don't want to ignore those, but we don't want to halt on them either. We
* detect those faults by virtue of the LIP being in the range 0x0F0000 to 0x0FFFFF.
*
* TODO: Be aware that this test can trigger false positives, such as when a V86-mode ARPL is hit; eg:
*
* &FD82:22F7 6338 ARPL [BX+SI],DI
*/
if (this.regLIP >= 0x0F0000 && this.regLIP <= 0x0FFFFF) {
fHalt = false;
}
/*
* However, the foregoing notwithstanding, if MESSAGE.HALT is enabled along with all the other required
* MESSAGE bits, then we want to halt regardless.
*/
if (this.messageEnabled(bitsMessage | Messages.HALT)) {
fHalt = true;
}
if (this.messageEnabled(bitsMessage) || fHalt) {
var fRunning = this.aFlags.fRunning;
var sMessage = "Fault " + str.toHexByte(nFault) + (nError != null? " (" + str.toHexWord(nError) + ")" : "") + " on opcode " + str.toHexByte(bOpcode);
if (fHalt && fRunning) sMessage += " (blocked by PCjs Debugger)";
if (DEBUGGER && this.dbg) {
this.printMessage(sMessage, fHalt || bitsMessage, true);
if (fHalt) {
/*
* By setting fHalt to fRunning (which is true while running but false while single-stepping),
* this allows a fault to be dispatched when you single-step over a faulting instruction; you can
* then continue single-stepping into the fault handler, or start running again.
*
* Note that we had to capture fRunning before calling printMessage(), because if MESSAGE.HALT
* is set, printMessage() will have already halted the CPU.
*/
fHalt = fRunning;
this.dbg.stopCPU();
}
} else {
/*
* If there's no Debugger, then messageEnabled() must have returned false, which means that fHalt must
* be true. Which means we should shut the machine down.
*/
this.assert(fHalt);
this.notice(sMessage);
this.stopCPU();
}
}
return fHalt;
};

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/**
* @fileoverview Implements PCjs opcode helpers.
* @author <a href="mailto:Jeff@pcjs.org">Jeff Parsons</a>
* @version 1.0
* Created 2016-Mar-04
*
* 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";
if (NODE) {
var str = require("../../shared/lib/strlib");
var Messages = require("./messages");
var X86 = require("./x86");
}
/**
* fnAdd64(dst, src)
*
* Adds src to dst.
*
* @param {Array} dst is a 64-bit value
* @param {Array} src is a 64-bit value
*/
X86.fnAdd64 = function(dst, src)
{
dst[0] += src[0];
dst[1] += src[1];
if (dst[0] > 0xffffffff) {
dst[0] >>>= 0; // truncate dst[0] to 32 bits AND keep it unsigned
dst[1]++;
}
};
/**
* fnCmp64(dst, src)
*
* Compares dst to src, by computing dst - src.
*
* @param {Array} dst is a 64-bit value
* @param {Array} src is a 64-bit value
* @return {number} > 0 if dst > src, == 0 if dst == src, < 0 if dst < src
*/
X86.fnCmp64 = function(dst, src)
{
var result = dst[1] - src[1];
if (!result) result = dst[0] - src[0];
return result;
};
/**
* fnSet64(lo, hi)
*
* @param {number} lo
* @param {number} hi
*/
X86.fnSet64 = function(lo, hi)
{
return [lo >>> 0, hi >>> 0];
};
/**
* fnShr64(dst)
*
* Shifts dst right one bit.
*
* @param {Array} dst is a 64-bit value
*/
X86.fnShr64 = function(dst)
{
dst[0] >>>= 1;
if (dst[1] & 0x1) {
dst[0] = (dst[0] | 0x80000000) >>> 0;
}
dst[1] >>>= 1;
};
/**
* fnSub64(dst, src)
*
* Subtracts src from dst.
*
* @param {Array} dst is a 64-bit value
* @param {Array} src is a 64-bit value
*/
X86.fnSub64 = function(dst, src)
{
dst[0] -= src[0];
dst[1] -= src[1];
if (dst[0] < 0) {
dst[0] >>>= 0; // truncate dst[0] to 32 bits AND keep it unsigned
dst[1]--;
}
};
/**
* fnDECr(w)
*
* @this {X86CPU}
* @param {number} w
* @return {number}
*/
X86.fnDECr = function(w)
{
var result = (w - 1)|0;
this.setArithResult(w, 1, result, this.typeData | X86.RESULT.NOTCF, true);
this.nStepCycles -= 2; // the register form of DEC takes 2 cycles on all CPUs
return (w & ~this.maskData) | (result & this.maskData);
};
/**
* fnDIV32(dstLo, dstHi, src)
*
* This sets regMDLo to dstHi:dstLo / src, and regMDHi to dstHi:dstLo % src; all inputs are treated as unsigned.
*
* Refer to: http://lxr.linux.no/linux+v2.6.22/lib/div64.c
*
* @this {X86CPU}
* @param {number} dstLo (low 32-bit portion of dividend)
* @param {number} dstHi (high 32-bit portion of dividend)
* @param {number} src (32-bit divisor)
* @return {boolean} true if successful, false if overflow (ie, the divisor was either zero or too small)
*/
X86.fnDIV32 = function(dstLo, dstHi, src)
{
src >>>= 0;
if (!src || src <= (dstHi >>> 0)) {
return false;
}
var result = 0, bit = 1;
var div = X86.fnSet64(src, 0);
var rem = X86.fnSet64(dstLo, dstHi);
while (X86.fnCmp64(rem, div) > 0) {
X86.fnAdd64(div, div);
bit += bit;
}
do {
if (X86.fnCmp64(rem, div) >= 0) {
X86.fnSub64(rem, div);
result += bit;
}
X86.fnShr64(div);
bit /= 2;
} while (bit >= 1);
this.assert(result <= 0xffffffff && !rem[1]);
this.regMDLo = result; // result is the quotient, which callers expect in the low MD register
this.regMDHi = rem[0]; // rem[0] is the remainder, which callers expect in the high MD register
return true;
};
/**
* fnIDIV32(dstLo, dstHi, src)
*
* This sets regMDLo to dstHi:dstLo / src, and regMDHi to dstHi:dstLo % src; all inputs are treated as signed.
*
* Refer to: http://lxr.linux.no/linux+v2.6.22/lib/div64.c
*
* @this {X86CPU}
* @param {number} dstLo (low 32-bit portion of dividend)
* @param {number} dstHi (high 32-bit portion of dividend)
* @param {number} src (32-bit divisor)
* @return {boolean} true if successful, false if overflow (ie, the divisor was either zero or too small)
*/
X86.fnIDIV32 = function(dstLo, dstHi, src)
{
var bNegLo = 0, bNegHi = 0;
/*
* dividend divisor quotient remainder
* (dst) (src) (lo) (hi)
* -------- ------- -------- ---------
* + + -> + +
* + - -> - +
* - + -> - -
* - - -> + -
*/
if (src < 0) {
src = -src|0;
bNegLo = 1 - bNegLo;
}
if (dstHi < 0) {
dstLo = -dstLo|0;
dstHi = (~dstHi + (dstLo? 0 : 1))|0;
bNegHi = 1;
bNegLo = 1 - bNegLo;
}
if (!X86.fnDIV32.call(this, dstLo, dstHi, src) || this.regMDLo > 0x7fffffff+bNegLo || this.regMDHi > 0x7fffffff+bNegHi) {
return false;
}
if (bNegLo) this.regMDLo = -this.regMDLo;
if (bNegHi) this.regMDHi = -this.regMDHi;
return true;
};
/**
* fnINCr(w)
*
* @this {X86CPU}
* @param {number} w
* @return {number}
*/
X86.fnINCr = function(w)
{
var result = (w + 1)|0;
this.setArithResult(w, 1, result, this.typeData | X86.RESULT.NOTCF);
this.nStepCycles -= 2; // the register form of INC takes 2 cycles on all CPUs
return (w & ~this.maskData) | (result & this.maskData);
};
/**
* fnLCR0(l)
*
* This is called by an 80386 control instruction (ie, MOV CR0,reg).
*
* TODO: Determine which CR0 bits, if any, cannot be modified by MOV CR0,reg.
*
* @this {X86CPU}
* @param {number} l
*/
X86.fnLCR0 = function(l)
{
this.regCR0 = l;
this.setProtMode();
if (this.regCR0 & X86.CR0.PG) {
/*
* TODO: Determine if setting X86.CR0.PG when already set should really act as a flush;
* I'm not currently worried about it, because I'm assuming CR0 is not rewritten that often.
*/
this.enablePageBlocks();
} else {
this.disablePageBlocks();
}
};
/**
* fnLCR3(l)
*
* This is called by an 80386 control instruction (ie, MOV CR3,reg) or an 80386 task switch.
*
* @this {X86CPU}
* @param {number} l
*/
X86.fnLCR3 = function(l)
{
this.regCR3 = l;
/*
* Normal use of regCR3 involves adding a 0-4K (12-bit) offset to obtain a page directory entry,
* so let's ensure that the low 12 bits of regCR3 are always zero.
*/
this.assert(!(this.regCR3 & X86.LADDR.OFFSET));
this.flushPageBlocks();
};
/**
* fnSETcc()
*
* @this {X86CPU}
* @param {function(number,number)} fnSet
*/
X86.fnSETcc = function(fnSet)
{
this.opFlags |= X86.OPFLAG.NOREAD;
this.aOpModMemByte[this.getIPByte()].call(this, fnSet);
this.nStepCycles -= (this.regEA === X86.ADDR_INVALID? 4 : 5);
};
/**
* fnSHLDw(dst, src, count)
*
* @this {X86CPU}
* @param {number} dst
* @param {number} src
* @param {number} count (0-31)
* @return {number}
*/
X86.fnSHLDw = function(dst, src, count)
{
if (count) {
if (count > 16) {
dst = src;
count -= 16;
}
var carry = dst << (count - 1);
dst = ((carry << 1) | (src >>> (16 - count))) & 0xffff;
this.setLogicResult(dst, X86.RESULT.WORD, carry & X86.RESULT.WORD);
}
return dst;
};
/**
* fnSHLDd(dst, src, count)
*
* @this {X86CPU}
* @param {number} dst
* @param {number} src
* @param {number} count
* @return {number}
*/
X86.fnSHLDd = function(dst, src, count)
{
if (count) {
var carry = dst << (count - 1);
dst = (carry << 1) | (src >>> (32 - count));
this.setLogicResult(dst, X86.RESULT.DWORD, carry & X86.RESULT.DWORD);
}
return dst;
};
/**
* fnSHRDw(dst, src, count)
*
* @this {X86CPU}
* @param {number} dst
* @param {number} src
* @param {number} count (0-31)
* @return {number}
*/
X86.fnSHRDw = function(dst, src, count)
{
if (count) {
if (count > 16) {
dst = src;
count -= 16;
}
var carry = dst >>> (count - 1);
dst = ((carry >>> 1) | (src << (16 - count))) & 0xffff;
this.setLogicResult(dst, X86.RESULT.WORD, carry & 0x1);
}
return dst;
};
/**
* fnSHRDd(dst, src, count)
*
* @this {X86CPU}
* @param {number} dst
* @param {number} src
* @param {number} count
* @return {number}
*/
X86.fnSHRDd = function(dst, src, count)
{
if (count) {
var carry = dst >>> (count - 1);
dst = (carry >>> 1) | (src << (32 - count));
this.setLogicResult(dst, X86.RESULT.DWORD, carry & 0x1);
}
return dst;
};
/**
* fnSRC1()
*
* @this {X86CPU}
* @return {number}
*/
X86.fnSRC1 = function()
{
this.nStepCycles -= (this.regEA === X86.ADDR_INVALID? 2 : this.cycleCounts.nOpCyclesShift1M);
return 1;
};
/**
* fnSRCCL()
*
* @this {X86CPU}
* @return {number}
*/
X86.fnSRCCL = function()
{
var count = this.regECX & 0xff;
this.nStepCycles -= (this.regEA === X86.ADDR_INVALID? this.cycleCounts.nOpCyclesShiftCR : this.cycleCounts.nOpCyclesShiftCM) + (count << this.cycleCounts.nOpCyclesShiftCS);
return count;
};
/**
* fnSRCByte()
*
* @this {X86CPU}
* @return {number}
*/
X86.fnSRCByte = function()
{
var count = this.getIPByte();
this.nStepCycles -= (this.regEA === X86.ADDR_INVALID? this.cycleCounts.nOpCyclesShiftCR : this.cycleCounts.nOpCyclesShiftCM) + (count << this.cycleCounts.nOpCyclesShiftCS);
return count;
};
/**
* fnSRCNone()
*
* @this {X86CPU}
* @return {number|null}
*/
X86.fnSRCNone = function()
{
return null;
};
/**
* fnSRCxx()
*
* This is used by opPOPmw(), because the actual pop must occur BEFORE the effective address (EA)
* calculation. So opPOPmw() does the pop, saves the popped value in regXX, and this passes src function
* to the EA worker.
*
* @this {X86CPU}
* @return {number} regXX
*/
X86.fnSRCxx = function()
{
return this.regXX;
};

14
modules/pcjs/lib/x86ops.js
View file

@ -3441,7 +3441,7 @@ X86.opMOVDI = function()
*/
X86.opGRP2bn = function()
{
this.aOpModGrpByte[this.getIPByte()].call(this, X86.aOpGrp2b, X86.fnSRCCountN);
this.aOpModGrpByte[this.getIPByte()].call(this, X86.aOpGrp2b, X86.fnSRCByte);
};
/**
@ -3451,7 +3451,7 @@ X86.opGRP2bn = function()
*/
X86.opGRP2wn = function()
{
this.aOpModGrpWord[this.getIPByte()].call(this, this.sizeData == 2? X86.aOpGrp2w : X86.aOpGrp2d, X86.fnSRCCountN);
this.aOpModGrpWord[this.getIPByte()].call(this, this.sizeData == 2? X86.aOpGrp2w : X86.aOpGrp2d, X86.fnSRCByte);
};
/**
@ -3710,7 +3710,7 @@ X86.opIRET = function()
*/
X86.opGRP2b1 = function()
{
this.aOpModGrpByte[this.getIPByte()].call(this, X86.aOpGrp2b, X86.fnSRCCount1);
this.aOpModGrpByte[this.getIPByte()].call(this, X86.aOpGrp2b, X86.fnSRC1);
};
/**
@ -3720,7 +3720,7 @@ X86.opGRP2b1 = function()
*/
X86.opGRP2w1 = function()
{
this.aOpModGrpWord[this.getIPByte()].call(this, this.sizeData == 2? X86.aOpGrp2w : X86.aOpGrp2d, X86.fnSRCCount1);
this.aOpModGrpWord[this.getIPByte()].call(this, this.sizeData == 2? X86.aOpGrp2w : X86.aOpGrp2d, X86.fnSRC1);
};
/**
@ -3730,7 +3730,7 @@ X86.opGRP2w1 = function()
*/
X86.opGRP2bCL = function()
{
this.aOpModGrpByte[this.getIPByte()].call(this, X86.aOpGrp2b, X86.fnSRCCountCL);
this.aOpModGrpByte[this.getIPByte()].call(this, X86.aOpGrp2b, X86.fnSRCCL);
};
/**
@ -3740,7 +3740,7 @@ X86.opGRP2bCL = function()
*/
X86.opGRP2wCL = function()
{
this.aOpModGrpWord[this.getIPByte()].call(this, this.sizeData == 2? X86.aOpGrp2w : X86.aOpGrp2d, X86.fnSRCCountCL);
this.aOpModGrpWord[this.getIPByte()].call(this, this.sizeData == 2? X86.aOpGrp2w : X86.aOpGrp2d, X86.fnSRCCL);
};
/**
@ -3788,7 +3788,7 @@ X86.opAAM = function()
{
var b = this.getIPByte();
if (!b) {
X86.fnDIVOverflow.call(this);
X86.fnDivOverflow.call(this);
return;
}
var AL = this.regEAX & 0xff;