apple2js/js/roms/rom.ts

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import { MemoryPages, Restorable, byte, rom } from '../types';
export type ROMState = null;
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export default class ROM implements MemoryPages, Restorable<ROMState> {
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constructor(
private readonly startPage: byte,
private readonly endPage: byte,
private readonly rom: rom) {
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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start() {
return this.startPage;
}
end() {
return this.endPage;
}
read(page: byte, off: byte) {
return this.rom[(page - this.startPage) << 8 | off];
}
write() {
// not writable
}
getState() {
return null;
}
setState(_state: ROMState) {
// not restorable
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}
}