84 lines
2.7 KiB
TypeScript
84 lines
2.7 KiB
TypeScript
import { ProDOSVolume } from '.';
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import type { BitMap } from './bit_map';
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import { BLOCK_SIZE, STORAGE_TYPES } from './constants';
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import { FileEntry } from './file_entry';
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export class SaplingFile {
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blocks: Uint8Array[];
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bitMap: BitMap;
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constructor(private volume: ProDOSVolume, private fileEntry: FileEntry) {
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this.blocks = this.volume.blocks();
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this.bitMap = this.volume.bitMap();
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}
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getBlockPointers() {
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const saplingBlock = this.blocks[this.fileEntry.keyPointer];
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const seedlingPointers = new DataView(saplingBlock);
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const pointers = [this.fileEntry.keyPointer];
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for (let idx = 0; idx < 256; idx++) {
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const 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() {
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const saplingBlock = this.blocks[this.fileEntry.keyPointer];
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const seedlingPointers = new DataView(saplingBlock);
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let remainingLength = this.fileEntry.eof;
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const data = new Uint8Array(remainingLength);
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let offset = 0;
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let idx = 0;
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while (remainingLength > 0) {
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const seedlingPointer = seedlingPointers.getUint16(idx * 2);
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if (seedlingPointer) {
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const seedlingBlock = this.blocks[seedlingPointer];
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const 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(data: Uint8Array) {
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this.fileEntry.storageType = STORAGE_TYPES.SAPLING;
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this.fileEntry.keyPointer = this.bitMap.allocBlock();
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this.fileEntry.eof = data.byteLength;
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const saplingBlock = this.blocks[this.fileEntry.keyPointer];
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const seedlingPointers = new DataView(saplingBlock);
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let remainingLength = data.byteLength;
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let offset = 0;
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let idx = 0;
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while (remainingLength > 0) {
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const seedlingPointer = this.bitMap.allocBlock();
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seedlingPointers.setUint16(idx * 2, seedlingPointer, true);
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const seedlingBlock = this.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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this.fileEntry.write();
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}
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delete() {
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const pointers = this.getBlockPointers();
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for (let idx = 0; idx < pointers.length; idx++) {
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this.bitMap.freeBlock(pointers[idx]);
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}
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}
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}
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