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If a SerialPort is installed, the transmitter portion of the hardware is no longer required to be connected to anything, which avoids blocking software (eg, the OS/2 kernel debugger) that uses that port; uninstalling the SerialPort would be another option, but that's no longer required

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Jeff Parsons 2017-08-25 08:53:58 -07:00 • committed by Jeff Parsons
commit dbaf381f9b
8 changed files with 52 additions and 44 deletions
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38
modules/pcx86/lib/serial.js
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@ -70,7 +70,10 @@ class SerialPort extends Component {
*
* adapter: 1 (port 0x3F8) or 2 (port 0x2F8); 0 if not defined
*
* binding: name of a control (based on its "binding" attribute) to bind to this port's I/O
* binding: name of a control (based on its "binding" attribute) to bind to this port's I/O;
* as a special case, it can be set to "console" to direct all output to the component's default
* println() handler (eg, the Control Panel's "print" control, if any, or console.log() if using
* a DEBUG or non-COMPILED machine)
*
* tabSize: a non-zero number specifies the tab-stop multiple to use for automatic tab-to-space
* conversion; it applies only to the above binding, and the default is 0 (no tab conversion)
@ -731,22 +734,23 @@ class SerialPort extends Component {
} else {
this.bTHR = bOut;
this.bLSR &= ~(SerialPort.LSR.THRE | SerialPort.LSR.TSRE);
if (this.transmitByte(bOut)) {
/*
* If we're transmitting to a virtual device that has no measurable delay, this code may set the
* transmitter empty bits too quickly:
*
* this.bLSR |= (SerialPort.LSR.THRE | SerialPort.LSR.TSRE);
*
* A better solution is to arm a timer based on the baud rate, and clear the above bits when that
* timer fires.
*/
if (this.cpu) this.cpu.setTimer(this.timerTransmitNext, this.getBaudTimeout());
this.updateIRR();
/*
* QUESTION: Does this mean we should also flush/zero bTHR?
*/
}
/*
* If transmitByte() returned success, we used to immediately re-set the transmitter empty bits:
*
* this.bLSR |= (SerialPort.LSR.THRE | SerialPort.LSR.TSRE);
*
* But when we're connected to a virtual device that has no measurable delay, that sets the bits
* too quickly. We now arm a timer based on the programmed baud rate, and set the above bits only
* when that timer fires.
*
* Additionally, we no longer care if transmitByte() succeeds, because whether or not a connected
* device or component received the data is irrelevant to the internal mechanics of the serial port.
*
* TODO: Determine if we should also flush/zero bTHR after transmission.
*/
this.transmitByte(bOut);
if (this.cpu) this.cpu.setTimer(this.timerTransmitNext, this.getBaudTimeout());
this.updateIRR();
}
}