77 lines
2.6 KiB
JavaScript
77 lines
2.6 KiB
JavaScript
import { BLOCK_SIZE, STORAGE_TYPES } from './constants';
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export function SaplingFile (volume, fileEntry) {
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var blocks = volume.blocks();
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var bitMap = volume.bitMap();
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return {
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getBlockPointers() {
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var saplingBlock = blocks[fileEntry.keyPointer];
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var seedlingPointers = new DataView(saplingBlock);
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var pointers = [fileEntry.keyPointer];
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for (var idx = 0; idx < 256; idx++) {
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var seedlingPointer = seedlingPointers.getUint16(idx * 2);
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if (seedlingPointer) {
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pointers.push(seedlingPointer);
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}
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}
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return pointers;
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},
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read: function() {
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var saplingBlock = blocks[fileEntry.keyPointer];
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var seedlingPointers = new DataView(saplingBlock);
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var remainingLength = fileEntry.oef;
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var data = new Uint8Array(remainingLength);
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var offset = 0;
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var idx = 0;
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while (remainingLength > 0) {
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var seedlingPointer = seedlingPointers.getUint16(idx * 2);
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if (seedlingPointer) {
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var seedlingBlock = blocks[seedlingPointer];
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var bytes = seedlingBlock.slice(0, Math.min(BLOCK_SIZE, remainingLength));
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data.set(bytes, offset);
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}
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idx++;
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offset += BLOCK_SIZE;
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remainingLength -= BLOCK_SIZE;
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}
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return data;
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},
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write: function(data) {
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fileEntry.storageType = STORAGE_TYPES.SAPLING;
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fileEntry.keyPointer = bitMap.allocBlock();
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fileEntry.eof = data.byteLength;
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var saplingBlock = blocks[fileEntry.keyPointer];
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var seedlingPointers = new DataView(saplingBlock);
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var remainingLength = data.byteLength;
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var offset = 0;
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var idx = 0;
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while (remainingLength > 0) {
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var seedlingPointer = bitMap.allocBlock();
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seedlingPointers.setUint16(idx * 2, seedlingPointer, true);
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var seedlingBlock = blocks[seedlingPointer];
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seedlingBlock.set(data.slice(offset, Math.min(BLOCK_SIZE, remainingLength)));
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idx++;
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offset += BLOCK_SIZE;
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remainingLength -= BLOCK_SIZE;
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}
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fileEntry.write();
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},
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delete: function() {
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var pointers = this.getBlockPointers();
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for (var idx; idx < pointers.length; idx++) {
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bitMap.freeBlock(pointers[idx]);
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}
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}
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};
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}
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