apple2js/js/formats/2mg.js
Will Scullin b647b3c2bb
CFFA (#20)
* CFFA

* CFFA multi-disk and write functionaliity.

* Clean up multi-devices/partition behavior.

* ProDOS WIP

* Update against refactored codebase.

* WIP

* Wait until disks load, show progress.

* Don't wait so long to boot floppies.

* Forgot to save :|.

* Credit.
2020-01-02 11:11:04 -08:00

83 lines
2.5 KiB
JavaScript

/* Copyright 2010-2019 Will Scullin <scullin@scullinsteel.com>
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*/
import BlockVolume from './block';
import DOS from './do';
import Nibble from './nib';
import ProDOS from './po';
import { numToString, debug } from '../util';
export default function _2MG(options) {
var OFFSETS = {
CREATOR: 0x04,
FLAGS: 0x0A,
FORMAT: 0x0C,
BLOCKS: 0x14,
DATA_OFFSET: 0x18,
BYTES: 0x1C,
};
var FLAGS = {
READ_ONLY: 0x80000000,
VOLUME_VALID: 0x00000100,
VOLUME_MASK: 0x000000FF
};
var { rawData, arrayConstructor } = options;
var disk;
var volume = 254;
// Standard header size is 64 bytes. Make assumptions.
var prefix = new DataView(rawData);
var signature = numToString(prefix.getInt32(0x0, true));
if (signature !== '2IMG') {
throw new Error('Unrecognized 2mg signature: ' + signature);
}
var creator = numToString(prefix.getInt32(OFFSETS.CREATOR, true));
var format = prefix.getInt32(OFFSETS.FORMAT, true);
var bytes = prefix.getInt32(OFFSETS.BYTES, true);
var offset = prefix.getInt32(OFFSETS.DATA_OFFSET, true);
var flags = prefix.getInt32(OFFSETS.FLAGS, true);
var readOnly = (flags & FLAGS.READ_ONLY) !== 0;
if (flags & FLAGS.VOLUME_VALID) {
volume = flags & FLAGS.VOLUME_MASK;
}
debug('created by', creator);
rawData = rawData.slice(offset, offset + bytes);
var blockVolume = options.blockVolume || rawData.byteLength >= (800 * 1024);
options = { rawData, readOnly, volume, arrayConstructor };
if (blockVolume) {
disk = new BlockVolume(options);
} else {
// Check image format.
// Sure, it's really 64 bits. But only 2 are actually used.
switch (format) {
case 1: // PO
disk = new ProDOS(options);
break;
case 2: // NIB
disk = new Nibble(options);
break;
case 0: // dsk
default: // Something hinky, assume 'dsk'
disk = new DOS(options);
break;
}
}
return disk;
}