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@1-/z85 : Ultra-Fast and Minimal Z85 Encoding and Decoding Implementation

• @1-/z85 : Ultra-Fast and Minimal Z85 Encoding and Decoding Implementation
  • Functionality
  • Usage
    • Install
    • Encoding
    • Decoding
  • Design Rationale
  • Technology Stack
  • Code Structure
  • Historical Context
  • About

Functionality

Provides Z85 encoding and decoding compliant with ZeroMQ RFC 32. Solves the problem of excessive bundle size and suboptimal performance in general-purpose Base85 libraries for browsers and lightweight runtimes, achieving industry-leading metrics through algorithmic optimization and zero-dependency design.

Usage

Install

npm install @1-/z85

Encoding

Encodes a Uint8Array to a Z85-encoded Uint8Array. The input length must be a multiple of 4.

import z85e from "@1-/z85/src/z85e.js";

const data = new Uint8Array([1, 2, 3, 4]);
const encoded = z85e(data);
// Returns Uint8Array(5) [ 48, 48, 48, 48, 103 ] (represents string "0000g")

Decoding

Decodes a Z85-encoded Uint8Array back to a Uint8Array. The input length must be a multiple of 5.

import z85d from "@1-/z85/src/z85d.js";

const decoded = z85d(encoded);
// Returns Uint8Array(4) [ 1, 2, 3, 4 ]

Design Rationale

The library uses a hybrid table-lookup and bit-manipulation approach, refactored with low-coupling and high-cohesion principles to extract and reuse common assets:

• Common Module (_.js): Defines the standard Z85 character set and converts it to UTF-8 encoded bytes, shared by both the encoder and decoder.
• Encoder (z85e.js): Imports the character mapping table from the common module, performing five modulo-85 operations and table-lookups per 32-bit unsigned integer, utilizing >>> 0 and | 0 for bitwise operations and truncation.
• Decoder (z85d.js): Imports the character set from the common module. Precomputes dual-layer lookup tables upon module load: a first-tier DECODE_MAP (256-byte Int8Array) for fast single-byte validation, and a second-tier DECODE_MAP_2 (65536-byte Int16Array) mapping all double-byte combinations (85×85=7225) to their values. This decomposes 5-byte decoding into three lookups and two multiply-add operations.

Technology Stack

• Runtime: Standard ECMAScript 2022 (ES13)
• External Dependency: None

Code Structure

src/
├── _.js        # Z85 Shared character set table (UTF-8 encoded)
├── z85e.js     # Primary Z85 encoder logic
└── z85d.js     # Primary Z85 decoder logic

Historical Context

Z85 encoding was designed by Pieter Hintjens in 2011 for the ZeroMQ protocol as a replacement for Base64 and Ascii85. Its key innovation is the selection of 85 printable ASCII characters (0–9, a–z, A–Z, .-:+=^!/*?&<>()[]{}@%$#), reducing encoded data size by ~12% compared to Base64 while completely avoiding the parsing ambiguity introduced by the z character in Ascii85. RFC 32 formally standardized it, establishing Z85 as the de facto standard for textual binary data transport within the ZeroMQ ecosystem.

About

This library is developed by WebC.site.

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@1-/z85 : 极速、超轻量、零依赖的 Z85 编解码实现

• @1-/z85 : 极速、超轻量、零依赖的 Z85 编解码实现
  • 功能介绍
  • 使用演示
    • 安装
    • 编码
    • 解码
  • 设计思路
  • 技术栈
  • 代码结构
  • 历史故事
  • 关于

功能介绍

提供符合 ZeroMQ RFC 32 规范的 Z85 编码与解码功能。解决通用 Base85 库在浏览器与轻量级运行时中体积过大、性能不足的问题，通过算法优化与零依赖设计，达成业界领先的体积与吞吐量指标。

使用演示

安装

npm install @1-/z85

编码

将 Uint8Array 编码为 Z85 格式的 Uint8Array。输入长度必须是 4 的倍数。

import z85e from "@1-/z85/src/z85e.js";

const data = new Uint8Array([1, 2, 3, 4]);
const encoded = z85e(data);
// 返回 Uint8Array(5) [ 48, 48, 48, 48, 103 ] (代表字符串 "0000g")

解码

将 Z85 格式的 Uint8Array 解码为原始的 Uint8Array。输入长度必须是 5 的倍数。

import z85d from "@1-/z85/src/z85d.js";

const decoded = z85d(encoded);
// 返回 Uint8Array(4) [ 1, 2, 3, 4 ]

设计思路

本库采用查表法与位运算结合的设计，以低耦合、高内聚为原则进行重构，将公共字符集与工具提取复用：

• 公共模块（_.js）：定义 Z85 标准字符集，并使用 UTF-8 编码转换为字节数组，供编码器和解码器共享。
• 编码器（z85e.js）：从公共模块导入字符映射表，对每个 32 位无符号整数进行五次模除与查表操作，辅以 >>> 0 与 | 0 进行位运算及截断。
• 解码器（z85d.js）：从公共模块导入字符集。在模块加载时预计算双层查表：第一层 DECODE_MAP（256 字节 Int8Array）用于快速单字节合法性校验；第二层 DECODE_MAP_2（65536 字节 Int16Array）预计算所有双字节组合的值（85×85=7225）。将五字节解码操作简化为三次查表与两次乘加运算。

技术栈

• 运行时：标准 ECMAScript 2022（ES13）
• 外部依赖：无

代码结构

src/
├── _.js        # Z85 共享字符集表（UTF-8 编码）
├── z85e.js     # Z85 编码器主逻辑
└── z85d.js     # Z85 解码器主逻辑

历史故事

Z85 编码由 Pieter Hintjens 于 2011 年为 ZeroMQ 协议设计，旨在替代 Base64 和 Ascii85。其核心创新在于选用 85 个可打印 ASCII 字符（0–9, a–z, A–Z, .-:+=^!/*?&<>()[]{}@%$#），使编码后数据体积比 Base64 减少约 12%，且完全规避了 Ascii85 中因 z 字符导致的解析歧义问题。RFC 32 将其正式标准化，成为 ZeroMQ 生态中二进制数据文本化传输的事实标准。

关于

本库由 WebC.site 开发。

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