85 lines
2.1 KiB
TypeScript
85 lines
2.1 KiB
TypeScript
import DOS from './do';
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import Nibble from './nib';
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import ProDOS from './po';
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import { DiskOptions } from './types';
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import { numToString, debug } from '../util';
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const OFFSETS = {
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CREATOR: 0x04,
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FLAGS: 0x0A,
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FORMAT: 0x0C,
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BLOCKS: 0x14,
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DATA_OFFSET: 0x18,
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BYTES: 0x1C,
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};
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const FLAGS = {
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READ_ONLY: 0x80000000,
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VOLUME_VALID: 0x00000100,
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VOLUME_MASK: 0x000000FF
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};
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export function read2MGHeader(rawData: ArrayBuffer) {
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const prefix = new DataView(rawData);
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const signature = numToString(prefix.getInt32(0x0, true));
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if (signature !== '2IMG') {
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throw new Error('Unrecognized 2mg signature: ' + signature);
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}
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const creator = numToString(prefix.getInt32(OFFSETS.CREATOR, true));
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const format = prefix.getInt32(OFFSETS.FORMAT, true);
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const bytes = prefix.getInt32(OFFSETS.BYTES, true);
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const offset = prefix.getInt32(OFFSETS.DATA_OFFSET, true);
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const flags = prefix.getInt32(OFFSETS.FLAGS, true);
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const readOnly = (flags & FLAGS.READ_ONLY) !== 0;
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let volume = 254;
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if (flags & FLAGS.VOLUME_VALID) {
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volume = flags & FLAGS.VOLUME_MASK;
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}
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debug('created by', creator);
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return {
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bytes,
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creator,
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format,
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offset,
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readOnly,
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volume,
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};
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}
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/**
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* Returns a `Disk` object from a 2mg image.
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* @param options the disk image and options
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*/
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export default function createDiskFrom2MG(options: DiskOptions) {
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let { rawData } = options;
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let disk;
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if (!rawData) {
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throw new Error('Requires rawData');
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}
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const { bytes, format, offset, readOnly, volume } = read2MGHeader(rawData);
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rawData = rawData.slice(offset, offset + bytes);
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options = { ...options, rawData, readOnly, volume };
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// Check image format.
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// Sure, it's really 64 bits. But only 2 are actually used.
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switch (format) {
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case 1: // PO
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disk = ProDOS(options);
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break;
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case 2: // NIB
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disk = Nibble(options);
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break;
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case 0: // dsk
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default: // Something hinky, assume 'dsk'
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disk = DOS(options);
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break;
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}
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return disk;
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}
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