apple2js/js/formats/d13.ts

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import { explodeSector13, D13O } from './format_utils';
import { NibbleDisk, DiskOptions, ENCODING_NIBBLE } from './types';
/**
* Returns a `Disk` object from DOS 3.2-ordered image data.
* @param options the disk image and options
* @returns A nibblized disk
*/
export default function createDiskFromDOS13(options: DiskOptions) {
const { data, name, side, rawData, volume, readOnly } = options;
const disk: NibbleDisk = {
format: 'd13',
encoding: ENCODING_NIBBLE,
name,
side,
volume,
readOnly,
tracks: []
};
if (!data && !rawData) {
throw new Error('data or rawData required');
}
/*
* DOS 13-sector disks have the physical sectors skewed on the track. The skew
* between physical sectors is 10 (A), resulting in the following physical order:
*
* 0 A 7 4 1 B 8 5 2 C 9 6 3
*
* Note that because physical sector == logical sector, this works slightly
* differently from the DOS and ProDOS nibblizers.
*/
for (let t = 0; t < 35; t++) {
let track: number[] = [];
for (let disk_sector = 0; disk_sector < 13; disk_sector++) {
const physical_sector = D13O[disk_sector];
let sector: Uint8Array;
if (rawData) {
const off = (13 * t + physical_sector) * 256;
sector = new Uint8Array(rawData.slice(off, off + 256));
} else if (data) {
sector = data[t][physical_sector];
} else {
throw new Error('Requires data or rawData');
}
track = track.concat(
explodeSector13(volume, t, physical_sector, sector)
);
}
disk.tracks.push(new Uint8Array(track));
}
return disk;
}