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Allow callers to tell set8042OutBuff() whether or not to delay the response

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This commit is contained in:
Jeff Parsons 2015-05-18 17:20:46 -07:00 • committed by jeffpar
commit c005748e57
1 changed files with 24 additions and 6 deletions
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30
modules/pcjs/lib/chipset.js
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@ -4515,17 +4515,35 @@ ChipSet.prototype.set8042CmdData = function(b)
};
/**
* set8042OutBuff(b)
* set8042OutBuff(b, fNoDelay)
*
* The 5170 ROM BIOS assumed there would be a slight delay after certain 8042 commands, like SELF_TEST
* (0xAA), before there was an OUTBUFF response; in fact, there is BIOS code that will fail without such
* a delay. This is discussed in greater detail in in8042Status().
*
* So we default to a "single poll" delay, setting OUTBUFF_DELAY instead of OUTBUFF_FULL, unless the caller
* explicitly asks for no delay. The fNoDelay parameter was added later, so that notifyKbdData() could
* request immediate delivery of keyboard scan codes, because some operating systems (eg, Microport's 1986
* version of Unix for PC AT machines) poll the status port only once, immediately giving up if no data is
* available.
*
* TODO: Determine if we can/should invert the fNoDelay default (from false to true) and delay only in
* specific cases; perhaps only the SELF_TEST command required a delay.
*
* @this {ChipSet}
* @param {number} b
* @param {boolean} [fNoDelay]
*/
ChipSet.prototype.set8042OutBuff = function(b)
ChipSet.prototype.set8042OutBuff = function(b, fNoDelay)
{
if (b >= 0) {
this.b8042OutBuff = b;
this.b8042Status &= ~ChipSet.KBC.STATUS.OUTBUFF_FULL;
this.b8042Status |= ChipSet.KBC.STATUS.OUTBUFF_DELAY;
if (fNoDelay) {
this.b8042Status |= ChipSet.KBC.STATUS.OUTBUFF_FULL;
} else {
this.b8042Status &= ~ChipSet.KBC.STATUS.OUTBUFF_FULL;
this.b8042Status |= ChipSet.KBC.STATUS.OUTBUFF_DELAY;
}
if (DEBUG && this.messageEnabled(Messages.KEYBOARD | Messages.PORT)) {
this.printMessage("set8042OutBuff(" + str.toHexByte(b) + ")", true);
}
@ -4563,7 +4581,7 @@ ChipSet.prototype.set8042OutPort = function(b)
*
* In the old days of PCjs, the Keyboard component would simply call setIRR() when it had some data for the
* keyboard controller. However, the Keyboard's sole responsibility is to emulate an actual keyboard and call
* notifyKbdData() whenever it has some data; it's not supposed to mess with IRQ lines.
* notifyKbdData() whenever it has some data; it's not allowed to mess with IRQ lines.
*
* If there's an 8042, we check (this.b8042CmdData & ChipSet.KBC.DATA.CMD.NO_CLOCK); if NO_CLOCK is clear,
* we can raise the IRQ immediately. Well, not quite immediately....
@ -4651,7 +4669,7 @@ ChipSet.prototype.notifyKbdData = function(b)
* which will call notifyKbdData() again if there's still keyboard data to process.
*/
if (!(this.b8042Status & (ChipSet.KBC.STATUS.OUTBUFF_FULL | ChipSet.KBC.STATUS.OUTBUFF_DELAY))) {
this.set8042OutBuff(b);
this.set8042OutBuff(b, true);
this.kbd.shiftScanCode();
/*
* A delay of 4 instructions was originally requested as part of the the Keyboard's resetDevice()