apple1js/js/apple1io.ts

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/* Copyright 2010-2023 Will Scullin <scullin@scullinsteel.com>
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*/
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import {TextPage} from './canvas1';
import type {byte} from '@whscullin/cpu6502';
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const LOC = {
KBD: 0x10,
KBDRDY: 0x011,
DSP: 0x12,
DSPCTL: 0x13,
} as const;
export default class Apple1IO {
_key = 0;
_keyReady = false;
_displayReady = false;
_nextDSP = 0;
_buffer: string[] = [];
constructor(private text: TextPage) {}
start() {
return 0xd0;
}
end() {
return 0xd0;
}
read(_page: byte, off: byte): byte {
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let result = 0;
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off &= 0x13;
switch (off) {
case LOC.KBD:
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{
// Keyboard
const key = this._buffer.shift();
if (key != null) {
result = key.toUpperCase().charCodeAt(0) & 0x7f;
this._keyReady = this._buffer.length > 0;
} else {
result = this._key;
this._keyReady = false;
}
result |= 0x80;
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}
break;
case LOC.KBDRDY:
result = this._keyReady ? 0x80 : 0x00;
break;
case LOC.DSP:
// Display
// result = (Math.random() > 0.5) ? 0x80 : 0x00;
result = Date.now() > this._nextDSP ? 0x00 : 0x80;
break;
case LOC.DSPCTL:
break;
}
return result;
}
write(_page: byte, off: byte, val: byte): void {
off &= 0x13;
switch (off) {
case LOC.KBD:
break;
case LOC.KBDRDY:
break;
case LOC.DSP:
// Display
if (this._displayReady) {
this.text.write(val);
}
this._nextDSP = Date.now() + (this._buffer.length > 0 ? 0 : 17);
break;
case LOC.DSPCTL:
// Don't pretend we care what the value was...
this._displayReady = true;
break;
}
}
reset() {
this._buffer = [];
this._keyReady = false;
this._displayReady = false;
}
keyUp() {}
keyDown(key: byte) {
this._key = key;
this._keyReady = true;
}
paste(buffer: string) {
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buffer = buffer.replace(/\/\/.*\n/g, '');
buffer = buffer.replace(/\n/g, '\r');
this._buffer = buffer.split('');
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this._keyReady = true;
}
}