apple2js/js/formats/woz.js

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/* 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 { debug, toHex } from '../util';
var WOZ_HEADER_START = 0;
var WOZ_HEADER_SIZE = 12;
var WOZ1_SIGNATURE = 0x315A4F57;
var WOZ2_SIGNATURE = 0x325A4F57;
var WOZ_INTEGRITY_CHECK = 0x0a0d0aff;
function stringFromBytes(data, start, end) {
return String.fromCharCode.apply(
null,
new Uint8Array(data.buffer.slice(data.byteOffset + start, data.byteOffset + end))
);
}
function grabNibble(bits, offset) {
var nibble = 0;
var waitForOne = true;
while (offset < bits.length) {
var bit = bits[offset];
if (bit) {
nibble = (nibble << 1) | 0x01;
waitForOne = false;
} else {
if (!waitForOne) {
nibble = nibble << 1;
}
}
if (nibble & 0x80) {
// nibble complete return it
break;
}
offset += 1;
}
return {
nibble: nibble,
offset: offset
};
}
function InfoChunk(data) {
Object.assign(this, {
version: data.getUint8(0),
diskType: data.getUint8(1),
writeProtected: data.getUint8(2),
synchronized: data.getUint8(3),
cleaned: data.getUint8(4),
creator: stringFromBytes(data, 5, 37)
});
if (this.version === 2) {
Object.assign(this, {
sides: data.getUint8(37),
bootSector: data.getUint8(38),
bitTiming: data.getUint8(39),
compatibleHardware: data.getUint16(40, true),
requiredRAM: data.getUint16(42, true),
largestTrack: data.getUint16(44, true)
});
}
return this;
}
function TMapChunk(data) {
this.trackMap = [];
for (var idx = 0; idx < 160; idx++) {
this.trackMap.push(data.getUint8(idx));
}
return this;
}
function TrksChunk(data) {
var WOZ_TRACK_SIZE = 6656;
var WOZ_TRACK_INFO_BITS = 6648;
this.rawTracks = [];
this.tracks = [];
for (var trackNo = 0, idx = 0; idx < data.byteLength; idx += WOZ_TRACK_SIZE, trackNo++) {
var jdx;
var track = [];
var rawTrack = [];
var slice = data.buffer.slice(data.byteOffset + idx, data.byteOffset + idx + WOZ_TRACK_SIZE);
var trackData = new Uint8Array(slice);
var trackInfo = new DataView(slice);
var trackBitCount = trackInfo.getUint16(WOZ_TRACK_INFO_BITS, true);
for (jdx = 0; jdx < trackBitCount; jdx++) {
var byteIndex = jdx >> 3;
var bitIndex = 7 - (jdx & 0x07);
rawTrack[jdx] = (trackData[byteIndex] >> bitIndex) & 0x1;
}
track = [];
var offset = 0;
while (offset < rawTrack.length) {
var result = grabNibble(rawTrack, offset);
if (!result.nibble) { break; }
track.push(result.nibble);
offset = result.offset + 1;
}
this.tracks[trackNo] = track;
this.rawTracks[trackNo] = rawTrack;
}
return this;
}
function TrksChunk2(data) {
var trackNo;
this.trks = [];
for (trackNo = 0; trackNo < 160; trackNo++) {
var startBlock = data.getUint16(trackNo * 8, true);
var blockCount = data.getUint16(trackNo * 8 + 2, true);
var bitCount = data.getUint32(trackNo * 8 + 4, true);
if (bitCount === 0) { break; }
this.trks.push({
startBlock: startBlock,
blockCount: blockCount,
bitCount: bitCount
});
}
this.tracks = [];
this.rawTracks = [];
var bits = data.buffer;
for (trackNo = 0; trackNo < this.trks.length; trackNo++) {
var trk = this.trks[trackNo];
var track = [];
var rawTrack = [];
var start = trk.startBlock * 512;
var end = start + trk.blockCount * 512;
var slice = bits.slice(start, end);
var trackData = new Uint8Array(slice);
for (var jdx = 0; jdx < trk.bitCount; jdx++) {
var byteIndex = jdx >> 3;
var bitIndex = 7 - (jdx & 0x07);
rawTrack[jdx] = (trackData[byteIndex] >> bitIndex) & 0x1;
}
track = [];
var offset = 0;
while (offset < rawTrack.length) {
var result = grabNibble(rawTrack, offset);
if (!result.nibble) { break; }
track.push(result.nibble);
offset = result.offset + 1;
}
this.tracks[trackNo] = track;
this.rawTracks[trackNo] = rawTrack;
}
return this;
}
function MetaChunk(data) {
var infoStr = stringFromBytes(data, 0, data.byteLength);
var parts = infoStr.split('\n');
var info = parts.reduce(function(acc, part) {
var subParts = part.split('\t');
acc[subParts[0]] = subParts[1];
return acc;
}, {});
Object.assign(this, info);
return this;
}
export default function Woz(options) {
var { rawData } = options;
var dv = new DataView(rawData, 0);
var dvOffset = 0;
var disk = {
format: 'woz'
};
var wozVersion;
var chunks = {};
function readHeader() {
var wozSignature = dv.getUint32(WOZ_HEADER_START + 0, true);
switch (wozSignature) {
case WOZ1_SIGNATURE:
wozVersion = 1;
break;
case WOZ2_SIGNATURE:
wozVersion = 2;
break;
default:
return false;
}
if (dv.getUint32(WOZ_HEADER_START + 4, true) !== WOZ_INTEGRITY_CHECK) {
return false;
}
return true;
}
function readChunk() {
if (dvOffset >= dv.byteLength) {
return null;
}
var type = dv.getUint32(dvOffset, true);
var size = dv.getUint32(dvOffset + 4, true);
var data = new DataView(dv.buffer, dvOffset + 8, size);
dvOffset += size + 8;
return {
type: type,
size: size,
data: data
};
}
if (readHeader()) {
dvOffset = WOZ_HEADER_SIZE;
var chunk = readChunk();
while (chunk) {
switch (chunk.type) {
case 0x4F464E49: // INFO
chunks.info = new InfoChunk(chunk.data);
break;
case 0x50414D54: // TMAP
chunks.tmap = new TMapChunk(chunk.data);
break;
case 0x534B5254: // TRKS
if (wozVersion === 1) {
chunks.trks = new TrksChunk(chunk.data);
} else {
chunks.trks = new TrksChunk2(chunk.data);
}
break;
case 0x4154454D: // META
chunks.meta = new MetaChunk(chunk.data);
break;
case 0x54495257: // WRIT
// Ignore
break;
default:
debug('Unsupported chunk', toHex(chunk.type, 8));
}
chunk = readChunk();
}
}
debug(chunks);
disk.trackMap = chunks.tmap.trackMap;
disk.tracks = chunks.trks.tracks;
disk.rawTracks = chunks.trks.rawTracks;
disk.readOnly = true; //chunks.info.writeProtected === 1;
disk.name = chunks.info.title;
return disk;
}