36 lines
894 B
TypeScript
36 lines
894 B
TypeScript
import { MemoryPages, Restorable, byte, rom } from '../types';
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export type ROMState = null;
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export default class ROM implements MemoryPages, Restorable<ROMState> {
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constructor(
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private readonly startPage: byte,
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private readonly endPage: byte,
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private readonly rom: rom) {
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const expectedLength = (endPage - startPage + 1) * 256;
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if (rom.length !== expectedLength) {
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throw Error(`rom does not have the correct length: expected ${expectedLength} was ${rom.length}`);
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}
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}
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start() {
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return this.startPage;
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}
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end() {
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return this.endPage;
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}
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read(page: byte, off: byte) {
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return this.rom[(page - this.startPage) << 8 | off];
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}
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write() {
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// not writable
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}
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getState() {
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return null;
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}
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setState(_state: ROMState) {
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// not restorable
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}
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}
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