ucl 数据压缩开源库简介

Key Facts 事实

Overview

How fast is fast ? 快就是快？

Portability 可塑性

UCL is a portable lossless data compression library written in ANSI C.

是一个用 ANSI c 编写的便携式无损数据压缩库。

UCL implements a number of compression algorithms that achieve an excellent compression ratio while allowing *very* fast decompression. Decompression requires no additional memory.

实现了一系列压缩算法，这些算法在实现优秀的压缩比/值的同时允许非常快速的解压缩。解压缩不需要额外的内存。

UCL is an OpenSource re-implementation of some NRV compression algorithms.

UCL 是对一些 NRV 压缩算法的 OpenSource 重新实现。

As compared to LZO, the UCL algorithms achieve a better compression ratio but decompression is a little bit slower. See below for some rough timings.

与 LZO 相比，UCL 算法实现了更好的压缩比/值，但是解压缩速度有点慢。以下是一些粗略的时间安排。

Overview

UCL is written in ANSI C. Both the source code and the compressed data format are designed to be portable across platforms.

UCL 是用 ANSI c 编写的，源代码和压缩的数据格式都被设计成可跨平台移植的。

UCL implements a number of algorithms with the following features:

伦敦大学学院实现了一系列具有以下特点的算法:

Decompression is simple and * 减压很简单 *very 非常* fast. * 快速
Requires no memory for decompression. 不需要解压缩内存
The decompressors can be squeezed into less than 200 bytes of code. 可以将解压缩器压缩到少于200字节的代码中
Focuses on compression levels for generating pre-compressed data which achieve a quite competitive compression ratio. 集中于压缩级别生成预压缩数据，实现一个相当有竞争力的压缩比
Allows you to dial up extra compression at a speed cost in the compressor. The speed of the decompressor is not reduced. 允许您以压缩机中的速度成本拨号进行额外的压缩。减压器的速度并没有降低
Algorithm is thread safe. 算法是线程安全的
Algorithm is lossless. 算法是无损的

UCL supports in-place decompression.

UCL 支持就地减压。

UCL and the UCL algorithms and implementations are distributed under the terms of the GNU General Public License (GPL) { auf Deutsch }. Special licenses for commercial and other applications are available by contacting the author.

UCL 和 UCL 的算法和实现都是在 GNU通用公共许可协议协议(GPL)的条款下发布的。特殊许可证的商业和其他应用可与作者联系。

How fast is fast ? 快就是快？

Here are some original timings on an ancient Intel Pentium 133 back in the year 2000:

以下是2000年英特尔奔腾133的一些原始时间:

memcpy(): ~60 MB/sec Memcpy () : ~ 60mb/sec
UCL decompression in optimized assembler: ~13 MB/sec 优化汇编程序的 UCL 解压缩: ~ 13mb/sec
LZO decompression in optimized assembler: ~20 MB/sec 优化汇编器中的 LZO 解压缩: ~ 20mb/sec
LZO decompression in C: ~16 MB/sec C 中的 LZO 解压缩: ~ 16 MB/sec

Portability 可塑性

UCL's decompressors should work on any system around - they could even get ported to 8-bit processors such as the Z-80 or 6502. (In fact I expect a 6502 implementation too happen soon in the process of extending the UPX executable packer).

UCL 的解压缩器应该可以在周围的任何系统上工作——它们甚至可以被移植到8位处理器上，比如 z-80或6502。(事实上，我期望在扩展 UPX 可执行封装程序的过程中很快就能实现6502)。

The compressors currently require at least 32-bit integers. While porting them to more restricted environments (such as 16-bit DOS) should be possible without too much effort this is not considered important at this time.

压缩器目前至少需要32位整数。虽然可以将它们移植到更受限制的环境(例如16位 DOS) ，但不需要付出太多努力，这一点目前并不重要。