The Tor Browser: toolkit/components/workerlz4/lz4.cpp@925c144e1f1f

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 #include "mozilla/Compression.h"

     7 /**

     8  * LZ4 is a very fast byte-wise compression algorithm.

     9  *

    10  * Compared to Google's Snappy it is faster to compress and decompress and

    11  * generally produces output of about the same size.

    12  *

    13  * Compared to zlib it compresses at about 10x the speed, decompresses at about

    14  * 4x the speed and produces output of about 1.5x the size.

    15  *

    16  */

    18 using namespace mozilla::Compression;

    20 /**

    21  * Compresses 'inputSize' bytes from 'source' into 'dest'.

    22  * Destination buffer must be already allocated,

    23  * and must be sized to handle worst cases situations (input data not compressible)

    24  * Worst case size evaluation is provided by function LZ4_compressBound()

    25  *

    26  * @param inputSize is the input size. Max supported value is ~1.9GB

    27  * @param return the number of bytes written in buffer dest

    28  */

    29 extern "C" MOZ_EXPORT size_t

    30 workerlz4_compress(const char* source, size_t inputSize, char* dest) {

    31   return LZ4::compress(source, inputSize, dest);

    32 }

    34 /**

    35  * If the source stream is malformed, the function will stop decoding

    36  * and return a negative result, indicating the byte position of the

    37  * faulty instruction

    38  *

    39  * This function never writes outside of provided buffers, and never

    40  * modifies input buffer.

    41  *

    42  * note : destination buffer must be already allocated.

    43  *        its size must be a minimum of 'outputSize' bytes.

    44  * @param outputSize is the output size, therefore the original size

    45  * @return true/false

    46  */

    47 extern "C" MOZ_EXPORT int

    48 workerlz4_decompress(const char* source, size_t inputSize,

    49                      char* dest, size_t maxOutputSize,

    50                      size_t *bytesOutput) {

    51   return LZ4::decompress(source, inputSize,

    52                          dest, maxOutputSize,

    53                          bytesOutput);

    54 }

    57 /*

    58   Provides the maximum size that LZ4 may output in a "worst case"

    59   scenario (input data not compressible) primarily useful for memory

    60   allocation of output buffer.

    61   note : this function is limited by "int" range (2^31-1)

    63   @param inputSize is the input size. Max supported value is ~1.9GB

    64   @return maximum output size in a "worst case" scenario

    65 */

    66 extern "C" MOZ_EXPORT size_t

    67 workerlz4_maxCompressedSize(size_t inputSize)

    68 {

    69   return LZ4::maxCompressedSize(inputSize);

    70 }

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