apple2js/js/formats/prodos/tree_file.ts
2022-07-23 12:00:38 -07:00

126 lines
4.6 KiB
TypeScript

import type { ProDOSVolume } from '.';
import { ProDOSFile } from './base_file';
import { BitMap } from './bit_map';
import { BLOCK_SIZE, STORAGE_TYPES } from './constants';
import type { FileEntry } from './file_entry';
export class TreeFile extends ProDOSFile {
private bitMap: BitMap;
private blocks: Uint8Array[];
constructor(volume: ProDOSVolume, private fileEntry: FileEntry) {
super(volume);
this.blocks = volume.blocks();
this.bitMap = volume.bitMap();
}
getBlockPointers() {
const treeBlock = this.blocks[this.fileEntry.keyPointer];
const saplingPointers = new DataView(treeBlock);
const pointers = [];
for (let idx = 0; idx < 256; idx++) {
const saplingPointer =
saplingPointers.getUint8(idx) |
(saplingPointers.getUint8(0x100 + idx) << 8);
if (saplingPointer) {
pointers.push(saplingPointer);
const seedlingPointers = new DataView(this.blocks[saplingPointer]);
for (let jdx = 0; jdx < 256; jdx++) {
const seedlingPointer =
seedlingPointers.getUint8(idx) |
(seedlingPointers.getUint8(0x100 + idx) << 8);
if (seedlingPointer) {
pointers.push(seedlingPointer);
}
}
}
}
return pointers;
}
// TODO(whscullin): Why did I not use getBlockPointers for these...
read() {
const treeBlock = this.blocks[this.fileEntry.keyPointer];
const saplingPointers = new DataView(treeBlock);
let remainingLength = this.fileEntry.eof;
const data = new Uint8Array(remainingLength);
let offset = 0;
let idx = 0;
while (remainingLength > 0) {
const saplingPointer =
saplingPointers.getUint8(idx) |
(saplingPointers.getUint8(0x100 + idx) << 8);
let jdx = 0;
if (saplingPointer) {
const saplingBlock = this.blocks[saplingPointer];
const seedlingPointers = new DataView(saplingBlock);
while (jdx < 256 && remainingLength > 0) {
const seedlingPointer =
seedlingPointers.getUint8(idx) |
(seedlingPointers.getUint8(0x100 + idx) << 8);
if (seedlingPointer) {
const seedlingBlock = this.blocks[seedlingPointer];
const bytes = seedlingBlock.slice(Math.min(BLOCK_SIZE, remainingLength));
data.set(bytes, offset);
}
jdx++;
offset += BLOCK_SIZE;
remainingLength -= BLOCK_SIZE;
}
} else {
offset += BLOCK_SIZE * 256;
remainingLength -= BLOCK_SIZE * 256;
}
idx++;
}
return data;
}
write(data: Uint8Array) {
this.fileEntry.storageType = STORAGE_TYPES.TREE;
this.fileEntry.keyPointer = this.bitMap.allocBlock();
this.fileEntry.eof = data.byteLength;
const treeBlock = this.blocks[this.fileEntry.keyPointer];
const saplingPointers = new DataView(treeBlock);
let remainingLength = this.fileEntry.eof;
let offset = 0;
let idx = 0;
while (remainingLength > 0) {
const saplingPointer = this.bitMap.allocBlock();
const saplingBlock = this.blocks[saplingPointer];
saplingPointers.setUint8(idx, saplingPointer & 0xff);
saplingPointers.setUint8(0x100 + idx, saplingPointer >> 8);
const seedlingPointers = new DataView(saplingBlock);
let jdx = 0;
while (jdx < 256 && remainingLength > 0) {
const seedlingPointer = this.bitMap.allocBlock();
seedlingPointers.setUint8(idx, seedlingPointer & 0xff);
seedlingPointers.setUint8(0x100 + idx, seedlingPointer >> 8);
const seedlingBlock = this.blocks[seedlingPointer];
seedlingBlock.set(data.slice(offset, Math.min(BLOCK_SIZE, remainingLength)));
jdx++;
offset += BLOCK_SIZE;
remainingLength -= BLOCK_SIZE;
}
idx++;
}
this.fileEntry.write();
}
delete() {
const pointers = this.getBlockPointers();
for (let idx = 0; idx < pointers.length; idx++) {
this.bitMap.freeBlock(pointers[idx]);
}
}
}