66 lines
2.1 KiB
TypeScript
66 lines
2.1 KiB
TypeScript
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// Chip select component for the LogicSimulator used on the 8-bit-computer
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// Copyright (C) 2022 Sascha Nitsch
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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// eslint-disable-next-line @typescript-eslint/no-unused-vars
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class ChipSelect extends BaseComponent {
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private addr = 0;
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private rom = true;
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private ram = true;
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constructor(simulator: Simulator, id: string, param: BaseComponentParam) {
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super(simulator, id, param);
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for (let a = 0; a < 8; ++a) {
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this.pins.set('A' + (15 - a), new TriState(this, -40, a * 10 - 35));
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}
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this.pins.set('rom', new TriState(this, 40, -25));
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this.pins.set('ram', new TriState(this, 40, -35));
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}
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setup(canvas: SVGElement) {
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super.doSetup('chipselect', canvas);
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}
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update(): boolean {
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const addr = this.addr;
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let changed = false;
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if (addr < 0x3fff) {
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// ROM
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changed ||= this.rom !== false || this.ram !== true;
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this.getPin('rom').setBool(false);
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this.getPin('ram').setBool(true);
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} else if (addr < 0x7fff) {
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// RAM
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changed ||= this.rom !== false || this.ram !== true;
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this.getPin('rom').setBool(true);
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this.getPin('ram').setBool(false);
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} else {
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this.getPin('rom').setBool(true);
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this.getPin('ram').setBool(true);
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}
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return changed;
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}
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io() {
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this.getPin('rom').getAndReset();
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this.getPin('ram').getAndReset();
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this.addr = 0;
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let multi = 256;
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for (let i = 8; i < 16; ++i) {
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this.addr += this.asint(this.binary(this.getPin('A' + i).getAndReset(), true), multi);
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multi <<= 1;
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}
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}
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}
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