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import { assert } from '../../common/util/util.js';
import { float16ToUint16, uint16ToFloat16 } from './conversion.js';
import { align } from './math.js';
/**
* BinaryStream is a utility to efficiently encode and decode numbers to / from a Uint8Array.
* BinaryStream uses a number of internal typed arrays to avoid small array allocations when reading
* and writing.
*/
export default class BinaryStream {
/**
* Constructor
* @param buffer the buffer to read from / write to. Array length must be a multiple of 8 bytes.
*/
constructor(buffer: ArrayBufferLike) {
this.offset = 0;
this.view = new DataView(buffer);
}
/** buffer() returns the stream's buffer sliced to the 8-byte rounded read or write offset */
buffer(): Uint8Array {
return new Uint8Array(this.view.buffer, 0, align(this.offset, 8));
}
/** writeBool() writes a boolean as 255 or 0 to the buffer at the next byte offset */
writeBool(value: boolean) {
this.view.setUint8(this.offset++, value ? 255 : 0);
}
/** readBool() reads a boolean from the buffer at the next byte offset */
readBool(): boolean {
const val = this.view.getUint8(this.offset++);
assert(val === 0 || val === 255);
return val !== 0;
}
/** writeU8() writes a uint8 to the buffer at the next byte offset */
writeU8(value: number) {
this.view.setUint8(this.offset++, value);
}
/** readU8() reads a uint8 from the buffer at the next byte offset */
readU8(): number {
return this.view.getUint8(this.offset++);
}
/** writeU16() writes a uint16 to the buffer at the next 16-bit aligned offset */
writeU16(value: number) {
this.view.setUint16(this.alignedOffset(2), value, /* littleEndian */ true);
}
/** readU16() reads a uint16 from the buffer at the next 16-bit aligned offset */
readU16(): number {
return this.view.getUint16(this.alignedOffset(2), /* littleEndian */ true);
}
/** writeU32() writes a uint32 to the buffer at the next 32-bit aligned offset */
writeU32(value: number) {
this.view.setUint32(this.alignedOffset(4), value, /* littleEndian */ true);
}
/** readU32() reads a uint32 from the buffer at the next 32-bit aligned offset */
readU32(): number {
return this.view.getUint32(this.alignedOffset(4), /* littleEndian */ true);
}
/** writeI8() writes a int8 to the buffer at the next byte offset */
writeI8(value: number) {
this.view.setInt8(this.offset++, value);
}
/** readI8() reads a int8 from the buffer at the next byte offset */
readI8(): number {
return this.view.getInt8(this.offset++);
}
/** writeI16() writes a int16 to the buffer at the next 16-bit aligned offset */
writeI16(value: number) {
this.view.setInt16(this.alignedOffset(2), value, /* littleEndian */ true);
}
/** readI16() reads a int16 from the buffer at the next 16-bit aligned offset */
readI16(): number {
return this.view.getInt16(this.alignedOffset(2), /* littleEndian */ true);
}
/** writeI64() writes a bitint to the buffer at the next 64-bit aligned offset */
writeI64(value: bigint) {
this.view.setBigInt64(this.alignedOffset(8), value, /* littleEndian */ true);
}
/** readI64() reads a bigint from the buffer at the next 64-bit aligned offset */
readI64(): bigint {
return this.view.getBigInt64(this.alignedOffset(8), /* littleEndian */ true);
}
/** writeI32() writes a int32 to the buffer at the next 32-bit aligned offset */
writeI32(value: number) {
this.view.setInt32(this.alignedOffset(4), value, /* littleEndian */ true);
}
/** readI32() reads a int32 from the buffer at the next 32-bit aligned offset */
readI32(): number {
return this.view.getInt32(this.alignedOffset(4), /* littleEndian */ true);
}
/** writeF16() writes a float16 to the buffer at the next 16-bit aligned offset */
writeF16(value: number) {
this.writeU16(float16ToUint16(value));
}
/** readF16() reads a float16 from the buffer at the next 16-bit aligned offset */
readF16(): number {
return uint16ToFloat16(this.readU16());
}
/** writeF32() writes a float32 to the buffer at the next 32-bit aligned offset */
writeF32(value: number) {
this.view.setFloat32(this.alignedOffset(4), value, /* littleEndian */ true);
}
/** readF32() reads a float32 from the buffer at the next 32-bit aligned offset */
readF32(): number {
return this.view.getFloat32(this.alignedOffset(4), /* littleEndian */ true);
}
/** writeF64() writes a float64 to the buffer at the next 64-bit aligned offset */
writeF64(value: number) {
this.view.setFloat64(this.alignedOffset(8), value, /* littleEndian */ true);
}
/** readF64() reads a float64 from the buffer at the next 64-bit aligned offset */
readF64(): number {
return this.view.getFloat64(this.alignedOffset(8), /* littleEndian */ true);
}
/**
* writeString() writes a length-prefixed UTF-16 string to the buffer at the next 32-bit aligned
* offset
*/
writeString(value: string) {
this.writeU32(value.length);
for (let i = 0; i < value.length; i++) {
this.writeU16(value.charCodeAt(i));
}
}
/**
* readString() writes a length-prefixed UTF-16 string from the buffer at the next 32-bit aligned
* offset
*/
readString(): string {
const len = this.readU32();
const codes = new Array<number>(len);
for (let i = 0; i < len; i++) {
codes[i] = this.readU16();
}
return String.fromCharCode(...codes);
}
/**
* writeArray() writes a length-prefixed array of T elements to the buffer at the next 32-bit
* aligned offset, using the provided callback to write the individual elements
*/
writeArray<T>(value: readonly T[], writeElement: (s: BinaryStream, element: T) => void) {
this.writeU32(value.length);
for (const element of value) {
writeElement(this, element);
}
}
/**
* readArray() reads a length-prefixed array of T elements from the buffer at the next 32-bit
* aligned offset, using the provided callback to read the individual elements
*/
readArray<T>(readElement: (s: BinaryStream) => T): T[] {
const len = this.readU32();
const array = new Array<T>(len);
for (let i = 0; i < len; i++) {
array[i] = readElement(this);
}
return array;
}
/**
* writeCond() writes the boolean condition `cond` to the buffer, then either calls if_true if
* `cond` is true, otherwise if_false
*/
writeCond<T, F>(cond: boolean, fns: { if_true: () => T; if_false: () => F }) {
this.writeBool(cond);
if (cond) {
return fns.if_true();
} else {
return fns.if_false();
}
}
/**
* readCond() reads a boolean condition from the buffer, then either calls if_true if
* the condition was is true, otherwise if_false
*/
readCond<T, F>(fns: { if_true: () => T; if_false: () => F }) {
if (this.readBool()) {
return fns.if_true();
} else {
return fns.if_false();
}
}
/**
* alignedOffset() aligns this.offset to `bytes`, then increments this.offset by `bytes`.
* @returns the old offset aligned to the next multiple of `bytes`.
*/
private alignedOffset(bytes: number) {
const aligned = align(this.offset, bytes);
this.offset = aligned + bytes;
return aligned;
}
private offset: number;
private view: DataView;
}
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