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Added a (temporary) auto-XON hack to the VT100's SerialPort component to prevent ugly buffer overflows when a PC is shoveling the data in too fast (to be replaced later with real flow-control interfaces)

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This commit is contained in:
Jeff Parsons 2016-08-18 18:49:01 -07:00
commit b52e794997
3 changed files with 149 additions and 127 deletions
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24
modules/pc8080/lib/serialport.js
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@ -103,6 +103,17 @@ function SerialPort8080(parmsSerial) {
this.charBOL = parmsSerial['charBOL'];
this.iLogicalCol = 0;
/*
* fAutoXOFF enables some experimental auto-XOFF/XON processing. It assumes if the VT100 firmware
* issues an XOFF, receiveByte() should stop accepting more data until the firmware issues an XOFF.
*
* The downside is that this doesn't really do anything to stem the flow of incoming data; it just
* prevents the VT100's internal buffer from overflowing. TODO: Eliminate the need for this hack
* and add some *real* flow-control interfaces between connected SerialPort components.
*/
this.fAutoXOFF = true;
this.fAutoStop = false;
Component.call(this, "SerialPort", parmsSerial, SerialPort8080, Messages8080.SERIAL);
var sBinding = parmsSerial['binding'];
@ -592,7 +603,7 @@ SerialPort8080.prototype.getBaudTimeout = function(maskRate)
SerialPort8080.prototype.receiveByte = function(b)
{
this.printMessage("receiveByte(" + str.toHexByte(b) + "), status=" + str.toHexByte(this.bStatus));
if (!(this.bStatus & SerialPort8080.UART8251.STATUS.RECV_FULL)) {
if (!this.fAutoStop && !(this.bStatus & SerialPort8080.UART8251.STATUS.RECV_FULL)) {
this.bDataIn = b;
this.bStatus |= SerialPort8080.UART8251.STATUS.RECV_FULL;
this.cpu.requestINTR(this.nIRQ);
@ -645,6 +656,17 @@ SerialPort8080.prototype.transmitByte = function(b)
this.printMessage("transmitByte(" + str.toHexByte(b) + ")");
if (this.fAutoXOFF) {
if (b == 0x13) { // XOFF
this.fAutoStop = true;
return false;
}
if (b == 0x11) { // XON
this.fAutoStop = false;
return false;
}
}
if (this.sendData) {
if (this.sendData.call(this.connection, b)) {
fTransmitted = true;