Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | 3x 20x 20x 20x 20x 20x 131174x 65587x 65587x 65587x 65587x 10x 10x 10x 65584x 65584x 1x 1x 65584x 9x 9x 65584x | /**
* Centronics printer attached to the user VIA: acknowledges each character and keeps the most
* recent output so it can be shown whenever a printer window is opened. Dispatches "output" with
* each character as its detail, and "first-output" once, when the machine first prints.
*/
export const MaxBufferedChars = 64 * 1024;
export class Printer extends EventTarget {
constructor() {
super();
this._cpu = null;
this._olderText = "";
this._newerText = "";
this._hasPrinted = false;
}
outputStrobe(level, output) {
if (!output || level) return;
const { uservia, replaying } = this._cpu;
// Ack the character by pulsing CA1 low.
uservia.setca1(false);
uservia.setca1(true);
if (!replaying) this._append(String.fromCharCode(uservia.ora));
}
attach(cpu) {
this._cpu = cpu;
// The ack line idles high, so that each ack is a falling edge.
cpu.uservia.setca1(true);
}
/** The most recent output, at most MaxBufferedChars of it. */
get text() {
return (this._olderText + this._newerText).slice(-MaxBufferedChars);
}
_append(char) {
// Two chunks so the bound costs a trim when the text is read, not one per character.
this._newerText += char;
if (this._newerText.length >= MaxBufferedChars) {
this._olderText = this._newerText;
this._newerText = "";
}
if (!this._hasPrinted) {
this._hasPrinted = true;
this.dispatchEvent(new Event("first-output"));
}
this.dispatchEvent(new CustomEvent("output", { detail: char }));
}
}
|