deno.land / std@0.166.0 / encoding / binary.ts

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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
/** * Functions for encoding binary data in array buffers. * * @module */
type RawBaseType = "int8" | "int16" | "int32" | "uint8" | "uint16" | "uint32";type RawNumberType = RawBaseType | "float32" | "float64";type RawBigType = RawBaseType | "int64" | "uint64";export type DataType = RawNumberType | RawBigType;
/** How encoded binary data is ordered. */export type Endianness = "little" | "big";
/** Options for working with the `number` type. */export interface VarnumOptions { /** The binary format used. */ dataType?: RawNumberType; /** The binary encoding order used. */ endian?: Endianness;}
/** Options for working with the `bigint` type. */export interface VarbigOptions { /** The binary format used. */ dataType?: RawBigType; /** The binary encoding order used. */ endian?: Endianness;}
const rawTypeSizes: Record<DataType, number> = { int8: 1, uint8: 1, int16: 2, uint16: 2, int32: 4, uint32: 4, int64: 8, uint64: 8, float32: 4, float64: 8,} as const;
/** Number of bytes required to store `dataType`. */export function sizeof(dataType: DataType): number { return rawTypeSizes[dataType];}
/** Reads the exact number of bytes from `r` required to fill `b`. * * Throws `Deno.errors.UnexpectedEof` if `n` bytes cannot be read. */export async function readExact( r: Deno.Reader, b: Uint8Array,) { let totalRead = 0; do { const tmp = new Uint8Array(b.length - totalRead); const nRead = await r.read(tmp); if (nRead === null) throw new Deno.errors.UnexpectedEof(); b.set(tmp, totalRead); totalRead += nRead; } while (totalRead < b.length);}
/** Reads exactly `n` bytes from `r`. * * Resolves it in a `Uint8Array`, or throws `Deno.errors.UnexpectedEof` if `n` bytes cannot be read. */export async function getNBytes( r: Deno.Reader, n: number,): Promise<Uint8Array> { const scratch = new Uint8Array(n); await readExact(r, scratch); return scratch;}
/** Decodes a number from `b`. If `o.bytes` is shorter than `sizeof(o.dataType)`, returns `null`. * * `o.dataType` defaults to `"int32"`. */export function varnum(b: Uint8Array, o: VarnumOptions = {}): number | null { o.dataType = o.dataType ?? "int32"; const littleEndian = (o.endian ?? "big") === "little" ? true : false; if (b.length < sizeof(o.dataType)) return null; const view = new DataView(b.buffer); switch (o.dataType) { case "int8": return view.getInt8(b.byteOffset); case "uint8": return view.getUint8(b.byteOffset); case "int16": return view.getInt16(b.byteOffset, littleEndian); case "uint16": return view.getUint16(b.byteOffset, littleEndian); case "int32": return view.getInt32(b.byteOffset, littleEndian); case "uint32": return view.getUint32(b.byteOffset, littleEndian); case "float32": return view.getFloat32(b.byteOffset, littleEndian); case "float64": return view.getFloat64(b.byteOffset, littleEndian); }}
/** Decodes a bigint from `b`. If `o.bytes` is shorter than `sizeof(o.dataType)`, returns `null`. * * `o.dataType` defaults to `"int64"`. */export function varbig(b: Uint8Array, o: VarbigOptions = {}): bigint | null { o.dataType = o.dataType ?? "int64"; const littleEndian = (o.endian ?? "big") === "little" ? true : false; if (b.length < sizeof(o.dataType)) return null; const view = new DataView(b.buffer); switch (o.dataType) { case "int8": return BigInt(view.getInt8(b.byteOffset)); case "uint8": return BigInt(view.getUint8(b.byteOffset)); case "int16": return BigInt(view.getInt16(b.byteOffset, littleEndian)); case "uint16": return BigInt(view.getUint16(b.byteOffset, littleEndian)); case "int32": return BigInt(view.getInt32(b.byteOffset, littleEndian)); case "uint32": return BigInt(view.getUint32(b.byteOffset, littleEndian)); case "int64": return view.getBigInt64(b.byteOffset, littleEndian); case "uint64": return view.getBigUint64(b.byteOffset, littleEndian); }}
/** Encodes number `x` into `b`. Returns the number of bytes used, or `0` if `b` is shorter than `sizeof(o.dataType)`. * * `o.dataType` defaults to `"int32"`. */export function putVarnum( b: Uint8Array, x: number, o: VarnumOptions = {},): number { o.dataType = o.dataType ?? "int32"; const littleEndian = (o.endian ?? "big") === "little" ? true : false; if (b.length < sizeof(o.dataType)) return 0; const view = new DataView(b.buffer); switch (o.dataType) { case "int8": view.setInt8(b.byteOffset, x); break; case "uint8": view.setUint8(b.byteOffset, x); break; case "int16": view.setInt16(b.byteOffset, x, littleEndian); break; case "uint16": view.setUint16(b.byteOffset, x, littleEndian); break; case "int32": view.setInt32(b.byteOffset, x, littleEndian); break; case "uint32": view.setUint32(b.byteOffset, x, littleEndian); break; case "float32": view.setFloat32(b.byteOffset, x, littleEndian); break; case "float64": view.setFloat64(b.byteOffset, x, littleEndian); break; } return sizeof(o.dataType);}
/** Encodes bigint `x` into `b`. Returns the number of bytes used, or `0` if `b` is shorter than `sizeof(o.dataType)`. * * `o.dataType` defaults to `"int64"`. */export function putVarbig( b: Uint8Array, x: bigint, o: VarbigOptions = {},): number { o.dataType = o.dataType ?? "int64"; const littleEndian = (o.endian ?? "big") === "little" ? true : false; if (b.length < sizeof(o.dataType)) return 0; const view = new DataView(b.buffer); switch (o.dataType) { case "int8": view.setInt8(b.byteOffset, Number(x)); break; case "uint8": view.setUint8(b.byteOffset, Number(x)); break; case "int16": view.setInt16(b.byteOffset, Number(x), littleEndian); break; case "uint16": view.setUint16(b.byteOffset, Number(x), littleEndian); break; case "int32": view.setInt32(b.byteOffset, Number(x), littleEndian); break; case "uint32": view.setUint32(b.byteOffset, Number(x), littleEndian); break; case "int64": view.setBigInt64(b.byteOffset, x, littleEndian); break; case "uint64": view.setBigUint64(b.byteOffset, x, littleEndian); break; } return sizeof(o.dataType);}
/** Decodes a number from `r`, consuming `sizeof(o.dataType)` bytes. If less than `sizeof(o.dataType)` bytes were read, throws `Deno.errors.unexpectedEof`. * * `o.dataType` defaults to `"int32"`. */export async function readVarnum( r: Deno.Reader, o: VarnumOptions = {},): Promise<number> { o.dataType = o.dataType ?? "int32"; const scratch = await getNBytes(r, sizeof(o.dataType)); return varnum(scratch, o) as number;}
/** Decodes a bigint from `r`, consuming `sizeof(o.dataType)` bytes. If less than `sizeof(o.dataType)` bytes were read, throws `Deno.errors.unexpectedEof`. * * `o.dataType` defaults to `"int64"`. */export async function readVarbig( r: Deno.Reader, o: VarbigOptions = {},): Promise<bigint> { o.dataType = o.dataType ?? "int64"; const scratch = await getNBytes(r, sizeof(o.dataType)); return varbig(scratch, o) as bigint;}
/** Encodes and writes `x` to `w`. Resolves to the number of bytes written. * * `o.dataType` defaults to `"int32"`. */export function writeVarnum( w: Deno.Writer, x: number, o: VarnumOptions = {},): Promise<number> { o.dataType = o.dataType ?? "int32"; const scratch = new Uint8Array(sizeof(o.dataType)); putVarnum(scratch, x, o); return w.write(scratch);}
/** Encodes and writes `x` to `w`. Resolves to the number of bytes written. * * `o.dataType` defaults to `"int64"`. */export function writeVarbig( w: Deno.Writer, x: bigint, o: VarbigOptions = {},): Promise<number> { o.dataType = o.dataType ?? "int64"; const scratch = new Uint8Array(sizeof(o.dataType)); putVarbig(scratch, x, o); return w.write(scratch);}
/** Encodes `x` into a new `Uint8Array`. * * `o.dataType` defaults to `"int32"` */export function varnumBytes(x: number, o: VarnumOptions = {}): Uint8Array { o.dataType = o.dataType ?? "int32"; const b = new Uint8Array(sizeof(o.dataType)); putVarnum(b, x, o); return b;}
/** Encodes `x` into a new `Uint8Array`. * * `o.dataType` defaults to `"int64"` */export function varbigBytes(x: bigint, o: VarbigOptions = {}): Uint8Array { o.dataType = o.dataType ?? "int64"; const b = new Uint8Array(sizeof(o.dataType)); putVarbig(b, x, o); return b;}
std
Deno standard library
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