import { decode, encode } from './text';
const defaultByteLength = 1024 * 8;
const hostBigEndian = (() => {
const array = new Uint8Array(4);
const view = new Uint32Array(array.buffer);
return !((view[0] = 1) & array[0]);
})();
const typedArrays = {
int8: globalThis.Int8Array,
uint8: globalThis.Uint8Array,
int16: globalThis.Int16Array,
uint16: globalThis.Uint16Array,
int32: globalThis.Int32Array,
uint32: globalThis.Uint32Array,
uint64: globalThis.BigUint64Array,
int64: globalThis.BigInt64Array,
float32: globalThis.Float32Array,
float64: globalThis.Float64Array,
};
export class IOBuffer {
/**
* Reference to the internal ArrayBuffer object.
*/
buffer;
/**
* Byte length of the internal ArrayBuffer.
*/
byteLength;
/**
* Byte offset of the internal ArrayBuffer.
*/
byteOffset;
/**
* Byte length of the internal ArrayBuffer.
*/
length;
/**
* The current offset of the buffer's pointer.
*/
offset;
lastWrittenByte;
littleEndian;
_data;
_mark;
_marks;
/**
* Create a new IOBuffer.
* @param data - The data to construct the IOBuffer with.
* If data is a number, it will be the new buffer's length
* If data is `undefined`, the buffer will be initialized with a default length of 8Kb
* If data is an ArrayBuffer, SharedArrayBuffer, an ArrayBufferView (Typed Array), an IOBuffer instance,
* or a Node.js Buffer, a view will be created over the underlying ArrayBuffer.
* @param options - An object for the options.
* @returns A new IOBuffer instance.
*/
constructor(data = defaultByteLength, options = {}) {
let dataIsGiven = false;
if (typeof data === 'number') {
data = new ArrayBuffer(data);
}
else {
dataIsGiven = true;
this.lastWrittenByte = data.byteLength;
}
const offset = options.offset ? options.offset >>> 0 : 0;
const byteLength = data.byteLength - offset;
let dvOffset = offset;
if (ArrayBuffer.isView(data) || data instanceof IOBuffer) {
if (data.byteLength !== data.buffer.byteLength) {
dvOffset = data.byteOffset + offset;
}
data = data.buffer;
}
if (dataIsGiven) {
this.lastWrittenByte = byteLength;
}
else {
this.lastWrittenByte = 0;
}
this.buffer = data;
this.length = byteLength;
this.byteLength = byteLength;
this.byteOffset = dvOffset;
this.offset = 0;
this.littleEndian = true;
this._data = new DataView(this.buffer, dvOffset, byteLength);
this._mark = 0;
this._marks = [];
}
/**
* Checks if the memory allocated to the buffer is sufficient to store more
* bytes after the offset.
* @param byteLength - The needed memory in bytes.
* @returns `true` if there is sufficient space and `false` otherwise.
*/
available(byteLength = 1) {
return this.offset + byteLength <= this.length;
}
/**
* Check if little-endian mode is used for reading and writing multi-byte
* values.
* @returns `true` if little-endian mode is used, `false` otherwise.
*/
isLittleEndian() {
return this.littleEndian;
}
/**
* Set little-endian mode for reading and writing multi-byte values.
* @returns This.
*/
setLittleEndian() {
this.littleEndian = true;
return this;
}
/**
* Check if big-endian mode is used for reading and writing multi-byte values.
* @returns `true` if big-endian mode is used, `false` otherwise.
*/
isBigEndian() {
return !this.littleEndian;
}
/**
* Switches to big-endian mode for reading and writing multi-byte values.
* @returns This.
*/
setBigEndian() {
this.littleEndian = false;
return this;
}
/**
* Move the pointer n bytes forward.
* @param n - Number of bytes to skip.
* @returns This.
*/
skip(n = 1) {
this.offset += n;
return this;
}
/**
* Move the pointer n bytes backward.
* @param n - Number of bytes to move back.
* @returns This.
*/
back(n = 1) {
this.offset -= n;
return this;
}
/**
* Move the pointer to the given offset.
* @param offset - The offset to move to.
* @returns This.
*/
seek(offset) {
this.offset = offset;
return this;
}
/**
* Store the current pointer offset.
* @see {@link IOBuffer#reset}
* @returns This.
*/
mark() {
this._mark = this.offset;
return this;
}
/**
* Move the pointer back to the last pointer offset set by mark.
* @see {@link IOBuffer#mark}
* @returns This.
*/
reset() {
this.offset = this._mark;
return this;
}
/**
* Push the current pointer offset to the mark stack.
* @see {@link IOBuffer#popMark}
* @returns This.
*/
pushMark() {
this._marks.push(this.offset);
return this;
}
/**
* Pop the last pointer offset from the mark stack, and set the current
* pointer offset to the popped value.
* @see {@link IOBuffer#pushMark}
* @returns This.
*/
popMark() {
const offset = this._marks.pop();
if (offset === undefined) {
throw new Error('Mark stack empty');
}
this.seek(offset);
return this;
}
/**
* Move the pointer offset back to 0.
* @returns This.
*/
rewind() {
this.offset = 0;
return this;
}
/**
* Make sure the buffer has sufficient memory to write a given byteLength at
* the current pointer offset.
* If the buffer's memory is insufficient, this method will create a new
* buffer (a copy) with a length that is twice (byteLength + current offset).
* @param byteLength - The needed memory in bytes.
* @returns This.
*/
ensureAvailable(byteLength = 1) {
if (!this.available(byteLength)) {
const lengthNeeded = this.offset + byteLength;
const newLength = lengthNeeded * 2;
const newArray = new Uint8Array(newLength);
newArray.set(new Uint8Array(this.buffer));
this.buffer = newArray.buffer;
this.length = newLength;
this.byteLength = newLength;
this._data = new DataView(this.buffer);
}
return this;
}
/**
* Read a byte and return false if the byte's value is 0, or true otherwise.
* Moves pointer forward by one byte.
* @returns The read boolean.
*/
readBoolean() {
return this.readUint8() !== 0;
}
/**
* Read a signed 8-bit integer and move pointer forward by 1 byte.
* @returns The read byte.
*/
readInt8() {
return this._data.getInt8(this.offset++);
}
/**
* Read an unsigned 8-bit integer and move pointer forward by 1 byte.
* @returns The read byte.
*/
readUint8() {
return this._data.getUint8(this.offset++);
}
/**
* Alias for {@link IOBuffer#readUint8}.
* @returns The read byte.
*/
readByte() {
return this.readUint8();
}
/**
* Read `n` bytes and move pointer forward by `n` bytes.
* @param n - Number of bytes to read.
* @returns The read bytes.
*/
readBytes(n = 1) {
return this.readArray(n, 'uint8');
}
/**
* Creates an array of corresponding to the type `type` and size `size`.
* For example type `uint8` will create a `Uint8Array`.
* @param size - size of the resulting array
* @param type - number type of elements to read
* @returns The read array.
*/
readArray(size, type) {
const bytes = typedArrays[type].BYTES_PER_ELEMENT * size;
const offset = this.byteOffset + this.offset;
const slice = this.buffer.slice(offset, offset + bytes);
if (this.littleEndian === hostBigEndian &&
type !== 'uint8' &&
type !== 'int8') {
const slice = new Uint8Array(this.buffer.slice(offset, offset + bytes));
slice.reverse();
const returnArray = new typedArrays[type](slice.buffer);
this.offset += bytes;
returnArray.reverse();
return returnArray;
}
const returnArray = new typedArrays[type](slice);
this.offset += bytes;
return returnArray;
}
/**
* Read a 16-bit signed integer and move pointer forward by 2 bytes.
* @returns The read value.
*/
readInt16() {
const value = this._data.getInt16(this.offset, this.littleEndian);
this.offset += 2;
return value;
}
/**
* Read a 16-bit unsigned integer and move pointer forward by 2 bytes.
* @returns The read value.
*/
readUint16() {
const value = this._data.getUint16(this.offset, this.littleEndian);
this.offset += 2;
return value;
}
/**
* Read a 32-bit signed integer and move pointer forward by 4 bytes.
* @returns The read value.
*/
readInt32() {
const value = this._data.getInt32(this.offset, this.littleEndian);
this.offset += 4;
return value;
}
/**
* Read a 32-bit unsigned integer and move pointer forward by 4 bytes.
* @returns The read value.
*/
readUint32() {
const value = this._data.getUint32(this.offset, this.littleEndian);
this.offset += 4;
return value;
}
/**
* Read a 32-bit floating number and move pointer forward by 4 bytes.
* @returns The read value.
*/
readFloat32() {
const value = this._data.getFloat32(this.offset, this.littleEndian);
this.offset += 4;
return value;
}
/**
* Read a 64-bit floating number and move pointer forward by 8 bytes.
* @returns The read value.
*/
readFloat64() {
const value = this._data.getFloat64(this.offset, this.littleEndian);
this.offset += 8;
return value;
}
/**
* Read a 64-bit signed integer number and move pointer forward by 8 bytes.
* @returns The read value.
*/
readBigInt64() {
const value = this._data.getBigInt64(this.offset, this.littleEndian);
this.offset += 8;
return value;
}
/**
* Read a 64-bit unsigned integer number and move pointer forward by 8 bytes.
* @returns The read value.
*/
readBigUint64() {
const value = this._data.getBigUint64(this.offset, this.littleEndian);
this.offset += 8;
return value;
}
/**
* Read a 1-byte ASCII character and move pointer forward by 1 byte.
* @returns The read character.
*/
readChar() {
// eslint-disable-next-line unicorn/prefer-code-point
return String.fromCharCode(this.readInt8());
}
/**
* Read `n` 1-byte ASCII characters and move pointer forward by `n` bytes.
* @param n - Number of characters to read.
* @returns The read characters.
*/
readChars(n = 1) {
let result = '';
for (let i = 0; i < n; i++) {
result += this.readChar();
}
return result;
}
/**
* Read the next `n` bytes, return a UTF-8 decoded string and move pointer
* forward by `n` bytes.
* @param n - Number of bytes to read.
* @returns The decoded string.
*/
readUtf8(n = 1) {
return decode(this.readBytes(n));
}
/**
* Read the next `n` bytes, return a string decoded with `encoding` and move pointer
* forward by `n` bytes.
* If no encoding is passed, the function is equivalent to @see {@link IOBuffer#readUtf8}
* @param n - Number of bytes to read.
* @param encoding - The encoding to use. Default is 'utf8'.
* @returns The decoded string.
*/
decodeText(n = 1, encoding = 'utf8') {
return decode(this.readBytes(n), encoding);
}
/**
* Write 0xff if the passed value is truthy, 0x00 otherwise and move pointer
* forward by 1 byte.
* @param value - The value to write.
* @returns This.
*/
writeBoolean(value) {
this.writeUint8(value ? 0xff : 0x00);
return this;
}
/**
* Write `value` as an 8-bit signed integer and move pointer forward by 1 byte.
* @param value - The value to write.
* @returns This.
*/
writeInt8(value) {
this.ensureAvailable(1);
this._data.setInt8(this.offset++, value);
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as an 8-bit unsigned integer and move pointer forward by 1
* byte.
* @param value - The value to write.
* @returns This.
*/
writeUint8(value) {
this.ensureAvailable(1);
this._data.setUint8(this.offset++, value);
this._updateLastWrittenByte();
return this;
}
/**
* An alias for {@link IOBuffer#writeUint8}.
* @param value - The value to write.
* @returns This.
*/
writeByte(value) {
return this.writeUint8(value);
}
/**
* Write all elements of `bytes` as uint8 values and move pointer forward by
* `bytes.length` bytes.
* @param bytes - The array of bytes to write.
* @returns This.
*/
writeBytes(bytes) {
this.ensureAvailable(bytes.length);
// eslint-disable-next-line @typescript-eslint/prefer-for-of
for (let i = 0; i < bytes.length; i++) {
this._data.setUint8(this.offset++, bytes[i]);
}
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 16-bit signed integer and move pointer forward by 2
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeInt16(value) {
this.ensureAvailable(2);
this._data.setInt16(this.offset, value, this.littleEndian);
this.offset += 2;
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 16-bit unsigned integer and move pointer forward by 2
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeUint16(value) {
this.ensureAvailable(2);
this._data.setUint16(this.offset, value, this.littleEndian);
this.offset += 2;
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 32-bit signed integer and move pointer forward by 4
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeInt32(value) {
this.ensureAvailable(4);
this._data.setInt32(this.offset, value, this.littleEndian);
this.offset += 4;
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 32-bit unsigned integer and move pointer forward by 4
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeUint32(value) {
this.ensureAvailable(4);
this._data.setUint32(this.offset, value, this.littleEndian);
this.offset += 4;
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 32-bit floating number and move pointer forward by 4
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeFloat32(value) {
this.ensureAvailable(4);
this._data.setFloat32(this.offset, value, this.littleEndian);
this.offset += 4;
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 64-bit floating number and move pointer forward by 8
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeFloat64(value) {
this.ensureAvailable(8);
this._data.setFloat64(this.offset, value, this.littleEndian);
this.offset += 8;
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 64-bit signed bigint and move pointer forward by 8
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeBigInt64(value) {
this.ensureAvailable(8);
this._data.setBigInt64(this.offset, value, this.littleEndian);
this.offset += 8;
this._updateLastWrittenByte();
return this;
}
/**
* Write `value` as a 64-bit unsigned bigint and move pointer forward by 8
* bytes.
* @param value - The value to write.
* @returns This.
*/
writeBigUint64(value) {
this.ensureAvailable(8);
this._data.setBigUint64(this.offset, value, this.littleEndian);
this.offset += 8;
this._updateLastWrittenByte();
return this;
}
/**
* Write the charCode of `str`'s first character as an 8-bit unsigned integer
* and move pointer forward by 1 byte.
* @param str - The character to write.
* @returns This.
*/
writeChar(str) {
// eslint-disable-next-line unicorn/prefer-code-point
return this.writeUint8(str.charCodeAt(0));
}
/**
* Write the charCodes of all `str`'s characters as 8-bit unsigned integers
* and move pointer forward by `str.length` bytes.
* @param str - The characters to write.
* @returns This.
*/
writeChars(str) {
for (let i = 0; i < str.length; i++) {
// eslint-disable-next-line unicorn/prefer-code-point
this.writeUint8(str.charCodeAt(i));
}
return this;
}
/**
* UTF-8 encode and write `str` to the current pointer offset and move pointer
* forward according to the encoded length.
* @param str - The string to write.
* @returns This.
*/
writeUtf8(str) {
return this.writeBytes(encode(str));
}
/**
* Export a Uint8Array view of the internal buffer.
* The view starts at the byte offset and its length
* is calculated to stop at the last written byte or the original length.
* @returns A new Uint8Array view.
*/
toArray() {
return new Uint8Array(this.buffer, this.byteOffset, this.lastWrittenByte);
}
/**
* Get the total number of bytes written so far, regardless of the current offset.
* @returns - Total number of bytes.
*/
getWrittenByteLength() {
return this.lastWrittenByte - this.byteOffset;
}
/**
* Update the last written byte offset
* @private
*/
_updateLastWrittenByte() {
if (this.offset > this.lastWrittenByte) {
this.lastWrittenByte = this.offset;
}
}
}
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