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dff41a8 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 | /** Binary reader/writer utilities for subtitle format parsing */
export class BinaryReader {
private buf: Buffer;
private _offset = 0;
constructor(buf: Buffer) {
this.buf = buf;
}
get offset(): number {
return this._offset;
}
get remaining(): number {
return this.buf.length - this._offset;
}
get eof(): boolean {
return this._offset >= this.buf.length;
}
seek(offset: number): void {
this._offset = offset;
}
skip(bytes: number): void {
this._offset += bytes;
}
readUInt8(): number {
const v = this.buf[this._offset];
this._offset += 1;
return v;
}
readInt8(): number {
const v = this.buf.readInt8(this._offset);
this._offset += 1;
return v;
}
readUInt16LE(): number {
const v = this.buf.readUInt16LE(this._offset);
this._offset += 2;
return v;
}
readUInt32LE(): number {
const v = this.buf.readUInt32LE(this._offset);
this._offset += 4;
return v;
}
readInt32LE(): number {
const v = this.buf.readInt32LE(this._offset);
this._offset += 4;
return v;
}
readBytes(count: number): Buffer {
const data = this.buf.subarray(this._offset, this._offset + count);
this._offset += count;
return data;
}
/** Read a PMW tag: [TAG:4][SIZE:4][DATA:N] */
readTag(): { tag: number; size: number; data: Buffer } {
const tag = this.readUInt32LE();
const size = this.readUInt32LE();
const data = this.readBytes(size);
return { tag, size, data };
}
/** Read a PMW multi-string (BOM-aware: UTF-16LE or Latin1) */
readMultiString(data: Buffer): string {
if (data.length === 0) return "";
if (data.length >= 2) {
const bom = data.readUInt16LE(0);
if (bom === 0xFEFF || bom === 0xFFFE) {
return data.subarray(2).toString("utf16le");
}
}
return data.toString("latin1");
}
/** Validate a PMW tag prefix */
static isValidPMWTag(tag: number): boolean {
return (tag & 0xFFFF0000) === 0xFA500000;
}
/** Scan forward to find the next valid PMW tag */
recoverToNextTag(): { tag: number; size: number; data: Buffer } | null {
while (this._offset + 8 <= this.buf.length) {
const candidate = this.buf.readUInt32LE(this._offset);
if (BinaryReader.isValidPMWTag(candidate)) {
return this.readTag();
}
this._offset += 1;
}
return null;
}
readString(length: number, encoding: BufferEncoding = "latin1"): string {
const data = this.readBytes(length);
return data.toString(encoding).replace(/\0+$/, "");
}
}
export class BinaryWriter {
private chunks: Buffer[] = [];
writeUInt8(v: number): void {
const buf = Buffer.alloc(1);
buf[0] = v;
this.chunks.push(buf);
}
writeUInt16LE(v: number): void {
const buf = Buffer.alloc(2);
buf.writeUInt16LE(v);
this.chunks.push(buf);
}
writeUInt32LE(v: number): void {
const buf = Buffer.alloc(4);
buf.writeUInt32LE(v);
this.chunks.push(buf);
}
writeInt32LE(v: number): void {
const buf = Buffer.alloc(4);
buf.writeInt32LE(v);
this.chunks.push(buf);
}
writeBytes(data: Buffer): void {
this.chunks.push(data);
}
/** Write a PMW tag: [TAG:4][SIZE:4][DATA:N] */
writeTag(tag: number, data: Buffer): void {
this.writeUInt32LE(tag);
this.writeUInt32LE(data.length);
this.writeBytes(data);
}
/** Write a PMW DWORD tag */
writeTagDWORD(tag: number, value: number): void {
const buf = Buffer.alloc(4);
buf.writeUInt32LE(value);
this.writeTag(tag, buf);
}
/** Write a PMW multi-string (with UTF-16LE BOM) */
writeTagMultiString(tag: number, str: string): void {
if (!str) {
this.writeTag(tag, Buffer.alloc(0));
return;
}
// Always write as UTF-16LE with BOM
const bom = Buffer.from([0xFF, 0xFE]);
const strBuf = Buffer.from(str, "utf16le");
const data = Buffer.concat([bom, strBuf]);
this.writeTag(tag, data);
}
writeString(str: string, length: number, encoding: BufferEncoding = "latin1"): void {
const buf = Buffer.alloc(length, 0);
buf.write(str, 0, length, encoding);
this.chunks.push(buf);
}
toBuffer(): Buffer {
return Buffer.concat(this.chunks);
}
}
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