2014-06-16 21:27:47 +00:00
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# crc32
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Standard CRC-32 algorithm implementation in JS (for the browser and nodejs).
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Emphasis on correctness and performance.
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## Installation
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In [nodejs](https://www.npmjs.org/package/crc-32):
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npm install crc-32
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In the browser:
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<script lang="javascript" src="crc32.js"></script>
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The browser exposes a variable CRC32
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## Usage
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- `CRC32.buf(byte array or buffer)` assumes the argument is a set of 8 bit
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unsigned integers (e.g. nodejs `Buffer` or simple array of ints)
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- `CRC32.bstr(binary string)` interprets the argument as a binary string where
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the `i`-th byte is `str.charCodeAt(i)`
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- `CRC32.str(string)` interprets the argument as a standard JS string
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## Testing
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`make test` will run the nodejs-based test. To run the in-browser tests, run a
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local server and go to the `ctest` directory. To update the browser artifacts,
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run `make ctest`.
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## Performance
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2014-06-17 23:20:41 +00:00
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`make perf` will run algorithmic performance tests (which should justify certain
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decisions in the code).
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`make perf-all` compares the performance of various crc-32 algorithms that
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implement the correct form (note that the SSE intrinsic is designed for the
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CRC32C checksum and uses a different polynomial).
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2014-06-16 21:27:47 +00:00
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2014-06-16 21:34:13 +00:00
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Unexpected code patterns were based on performance testing in node and browser:
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- [Loop unrolling helps!](http://jsperf.com/crc32-table/2)
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2014-06-16 21:27:47 +00:00
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## In the future ...
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- Specifying an arbitrary initial CRC value
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- Supporting different polynomials (e.g. CRC32C)
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## License
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Please consult the attached LICENSE file for details. All rights not explicitly
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granted by the Apache 2.0 license are reserved by the Original Author.
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2014-06-17 06:30:04 +00:00
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[](https://travis-ci.org/SheetJS/js-crc32)
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2014-06-16 21:27:47 +00:00
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[](https://coveralls.io/r/SheetJS/js-crc32?branch=master)
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[](http://githalytics.com/SheetJS/js-crc32)
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