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50 lines
2.1 KiB
50 lines
2.1 KiB
8 years ago
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# heatshrink
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A data compression/decompression library for embedded/real-time systems.
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## Key Features:
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- **Low memory usage (as low as 50 bytes)**
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It is useful for some cases with less than 50 bytes, and useful
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for many general cases with < 300 bytes.
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- **Incremental, bounded CPU use**
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You can chew on input data in arbitrarily tiny bites.
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This is a useful property in hard real-time environments.
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- **Can use either static or dynamic memory allocation**
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The library doesn't impose any constraints on memory management.
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- **ISC license**
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You can use it freely, even for commercial purposes.
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## Getting Started:
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There is a standalone command-line program, `heatshrink`, but the
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encoder and decoder can also be used as libraries, independent of each
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other. To do so, copy `heatshrink_common.h`, `heatshrink_config.h`, and
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either `heatshrink_encoder.c` or `heatshrink_decoder.c` (and their
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respective header) into your project.
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Dynamic allocation is used by default, but in an embedded context, you
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probably want to statically allocate the encoder/decoder. Set
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`HEATSHRINK_DYNAMIC_ALLOC` to 0 in `heatshrink_config.h`.
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## More Information and Benchmarks:
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heatshrink is based on [LZSS], since it's particularly suitable for
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compression in small amounts of memory. It can use an optional, small
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[index] to make compression significantly faster, but otherwise can run
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in under 100 bytes of memory. The index currently adds 2^(window size+1)
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bytes to memory usage for compression, and temporarily allocates 512
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bytes on the stack during index construction.
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For more information, see the [blog post] for an overview, and the
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`heatshrink_encoder.h` / `heatshrink_decoder.h` header files for API
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documentation.
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[blog post]: http://spin.atomicobject.com/2013/03/14/heatshrink-embedded-data-compression/
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[index]: http://spin.atomicobject.com/2014/01/13/lightweight-indexing-for-embedded-systems/
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[LZSS]: http://en.wikipedia.org/wiki/Lempel-Ziv-Storer-Szymanski
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## Build Status
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[](http://travis-ci.org/atomicobject/heatshrink)
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