toolkit/components/workerlz4/lz4.cpp@925c144e1f1f (annotated)
toolkit/components/workerlz4/lz4.cpp
Fri, 16 Jan 2015 18:13:44 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Fri, 16 Jan 2015 18:13:44 +0100
- branch
- TOR_BUG_9701
- changeset 14
- 925c144e1f1f
- permissions
- -rw-r--r--
Integrate suggestion from review to improve consistency with existing code.
| michael@0 | 1 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 2 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 3 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 4 | |
| michael@0 | 5 | #include "mozilla/Compression.h" |
| michael@0 | 6 | |
| michael@0 | 7 | /** |
| michael@0 | 8 | * LZ4 is a very fast byte-wise compression algorithm. |
| michael@0 | 9 | * |
| michael@0 | 10 | * Compared to Google's Snappy it is faster to compress and decompress and |
| michael@0 | 11 | * generally produces output of about the same size. |
| michael@0 | 12 | * |
| michael@0 | 13 | * Compared to zlib it compresses at about 10x the speed, decompresses at about |
| michael@0 | 14 | * 4x the speed and produces output of about 1.5x the size. |
| michael@0 | 15 | * |
| michael@0 | 16 | */ |
| michael@0 | 17 | |
| michael@0 | 18 | using namespace mozilla::Compression; |
| michael@0 | 19 | |
| michael@0 | 20 | /** |
| michael@0 | 21 | * Compresses 'inputSize' bytes from 'source' into 'dest'. |
| michael@0 | 22 | * Destination buffer must be already allocated, |
| michael@0 | 23 | * and must be sized to handle worst cases situations (input data not compressible) |
| michael@0 | 24 | * Worst case size evaluation is provided by function LZ4_compressBound() |
| michael@0 | 25 | * |
| michael@0 | 26 | * @param inputSize is the input size. Max supported value is ~1.9GB |
| michael@0 | 27 | * @param return the number of bytes written in buffer dest |
| michael@0 | 28 | */ |
| michael@0 | 29 | extern "C" MOZ_EXPORT size_t |
| michael@0 | 30 | workerlz4_compress(const char* source, size_t inputSize, char* dest) { |
| michael@0 | 31 | return LZ4::compress(source, inputSize, dest); |
| michael@0 | 32 | } |
| michael@0 | 33 | |
| michael@0 | 34 | /** |
| michael@0 | 35 | * If the source stream is malformed, the function will stop decoding |
| michael@0 | 36 | * and return a negative result, indicating the byte position of the |
| michael@0 | 37 | * faulty instruction |
| michael@0 | 38 | * |
| michael@0 | 39 | * This function never writes outside of provided buffers, and never |
| michael@0 | 40 | * modifies input buffer. |
| michael@0 | 41 | * |
| michael@0 | 42 | * note : destination buffer must be already allocated. |
| michael@0 | 43 | * its size must be a minimum of 'outputSize' bytes. |
| michael@0 | 44 | * @param outputSize is the output size, therefore the original size |
| michael@0 | 45 | * @return true/false |
| michael@0 | 46 | */ |
| michael@0 | 47 | extern "C" MOZ_EXPORT int |
| michael@0 | 48 | workerlz4_decompress(const char* source, size_t inputSize, |
| michael@0 | 49 | char* dest, size_t maxOutputSize, |
| michael@0 | 50 | size_t *bytesOutput) { |
| michael@0 | 51 | return LZ4::decompress(source, inputSize, |
| michael@0 | 52 | dest, maxOutputSize, |
| michael@0 | 53 | bytesOutput); |
| michael@0 | 54 | } |
| michael@0 | 55 | |
| michael@0 | 56 | |
| michael@0 | 57 | /* |
| michael@0 | 58 | Provides the maximum size that LZ4 may output in a "worst case" |
| michael@0 | 59 | scenario (input data not compressible) primarily useful for memory |
| michael@0 | 60 | allocation of output buffer. |
| michael@0 | 61 | note : this function is limited by "int" range (2^31-1) |
| michael@0 | 62 | |
| michael@0 | 63 | @param inputSize is the input size. Max supported value is ~1.9GB |
| michael@0 | 64 | @return maximum output size in a "worst case" scenario |
| michael@0 | 65 | */ |
| michael@0 | 66 | extern "C" MOZ_EXPORT size_t |
| michael@0 | 67 | workerlz4_maxCompressedSize(size_t inputSize) |
| michael@0 | 68 | { |
| michael@0 | 69 | return LZ4::maxCompressedSize(inputSize); |
| michael@0 | 70 | } |
| michael@0 | 71 | |
| michael@0 | 72 | |
| michael@0 | 73 |
