81 lines
3.1 KiB
JavaScript
81 lines
3.1 KiB
JavaScript
import { dateToUint32, readFileName, writeFileName, uint32ToDate } from './utils';
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import { readEntries, writeEntries } from './file_entry';
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import { STORAGE_TYPES, ACCESS_TYPES } from './constants';
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export function VDH(volume) {
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var blocks = volume.blocks();
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var VDH_BLOCK = 2;
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var VDH_OFFSETS = {
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PREV: 0x00,
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NEXT: 0x02,
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STORAGE_TYPE: 0x04,
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NAME_LENGTH: 0x04,
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VOLUME_NAME: 0x05,
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RESERVED_1: 0x14,
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CASE_BITS: 0x1A,
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CREATION: 0x1C,
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VERSION: 0x20,
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MIN_VERSION: 0x21,
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ACCESS: 0x22,
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ENTRY_LENGTH: 0x23,
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ENTRIES_PER_BLOCK: 0x24,
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FILE_COUNT: 0x25,
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BIT_MAP_POINTER: 0x27,
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TOTAL_BLOCKS: 0x29,
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};
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return {
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prev: 0,
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next: 0,
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storageType: STORAGE_TYPES.VDH_HEADER,
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name: '',
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creation: new Date(),
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access: ACCESS_TYPES.ALL,
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entryLength: 0x27,
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entriesPerBlock: 23,
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fileCount: 0,
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bitMapPointer: 0,
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totalBlocks: 0,
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entries: [],
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read: function () {
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var block = new DataView(blocks[VDH_BLOCK].buffer);
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this.next = block.getUint16(VDH_OFFSETS.NEXT, true);
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this.storageType = block.getUint8(VDH_OFFSETS.STORAGE_TYPE) >> 4;
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var nameLength = block.getUint8(VDH_OFFSETS.NAME_LENGTH) & 0xF;
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var caseBits = block.getUint8(VDH_OFFSETS.CASE_BITS);
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this.name = readFileName(block, VDH_OFFSETS.VOLUME_NAME, nameLength, caseBits);
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this.creation = uint32ToDate(block.getUint32(VDH_OFFSETS.CREATION, true));
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this.access = block.getUint8(VDH_OFFSETS.ACCESS);
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this.entryLength = block.getUint8(VDH_OFFSETS.ENTRY_LENGTH);
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this.entriesPerBlock = block.getUint8(VDH_OFFSETS.ENTRIES_PER_BLOCK);
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this.fileCount = block.getUint16(VDH_OFFSETS.FILE_COUNT, true);
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this.bitMapPointer = block.getUint16(VDH_OFFSETS.BIT_MAP_POINTER, true);
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this.totalBlocks = block.getUint16(VDH_OFFSETS.TOTAL_BLOCKS, true);
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this.entries = readEntries(volume, block, this);
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},
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write: function() {
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var block = new DataView(blocks[VDH_BLOCK].buffer);
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var nameLength = name.length & 0x0f;
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block.setUint8(VDH_OFFSETS.STORAGE_TYPE, this.storageType << 4 & nameLength);
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var caseBits = writeFileName(block, VDH_OFFSETS.FILE_NAME, this.name);
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block.setUint32(VDH_OFFSETS.CREATION, dateToUint32(this.creation), true);
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block.setUint16(VDH_OFFSETS.CASE_BITS, caseBits);
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block.setUint8(VDH_OFFSETS.ACCESS, this.access);
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block.setUint8(VDH_OFFSETS.ENTRY_LENGTH, this.entryLength);
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block.setUint8(VDH_OFFSETS.ENTRIES_PER_BLOCK, this.entriesPerBlock);
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block.setUint16(VDH_OFFSETS.FILE_COUNT, this.fileCount, true);
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block.setUint16(VDH_OFFSETS.BIT_MAP_POINTER, this.bitMapPointer, true);
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block.setUint16(VDH_OFFSETS.TOTAL_BLOCKS, this.totalBlocks, true);
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writeEntries(blocks, block, this);
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}
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};
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}
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