From 675b4aa878f16291ce33fced48a2bc7425f635ae Mon Sep 17 00:00:00 2001 From: Alexander Harkness Date: Sun, 24 Nov 2013 14:19:41 +0000 Subject: Moved source to src --- src/StringCompression.cpp | 180 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 180 insertions(+) create mode 100644 src/StringCompression.cpp (limited to 'src/StringCompression.cpp') diff --git a/src/StringCompression.cpp b/src/StringCompression.cpp new file mode 100644 index 000000000..36946b282 --- /dev/null +++ b/src/StringCompression.cpp @@ -0,0 +1,180 @@ + +// StringCompression.cpp + +// Implements the wrapping functions for compression and decompression using AString as their data + +#include "Globals.h" +#include "StringCompression.h" + + + + + +/// Compresses a_Data into a_Compressed; returns Z_XXX error constants same as zlib's compress2() +int CompressString(const char * a_Data, int a_Length, AString & a_Compressed) +{ + uLongf CompressedSize = compressBound(a_Length); + + // HACK: We're assuming that AString returns its internal buffer in its data() call and we're overwriting that buffer! + // It saves us one allocation and one memcpy of the entire compressed data + // It may not work on some STL implementations! (Confirmed working on MSVC 2008 & 2010) + a_Compressed.resize(CompressedSize); + int errorcode = compress2( (Bytef*)a_Compressed.data(), &CompressedSize, (const Bytef*)a_Data, a_Length, Z_DEFAULT_COMPRESSION); + if (errorcode != Z_OK) + { + return errorcode; + } + a_Compressed.resize(CompressedSize); + return Z_OK; +} + + + + + +/// Uncompresses a_Data into a_Decompressed; returns Z_XXX error constants same as zlib's uncompress() +int UncompressString(const char * a_Data, int a_Length, AString & a_Uncompressed, int a_UncompressedSize) +{ + // HACK: We're assuming that AString returns its internal buffer in its data() call and we're overwriting that buffer! + // It saves us one allocation and one memcpy of the entire compressed data + // It may not work on some STL implementations! (Confirmed working on MSVC 2008 & 2010) + a_Uncompressed.resize(a_UncompressedSize); + uLongf UncompressedSize = (uLongf)a_UncompressedSize; // On some architectures the uLongf is different in size to int, that may be the cause of the -5 error + int errorcode = uncompress((Bytef*)a_Uncompressed.data(), &UncompressedSize, (const Bytef*)a_Data, a_Length); + if (errorcode != Z_OK) + { + return errorcode; + } + a_Uncompressed.resize(UncompressedSize); + return Z_OK; +} + + + + + +int CompressStringGZIP(const char * a_Data, int a_Length, AString & a_Compressed) +{ + // Compress a_Data into a_Compressed using GZIP; return Z_XXX error constants same as zlib's compress2() + + a_Compressed.reserve(a_Length); + + char Buffer[64 KiB]; + z_stream strm; + memset(&strm, 0, sizeof(strm)); + strm.next_in = (Bytef *)a_Data; + strm.avail_in = a_Length; + strm.next_out = (Bytef *)Buffer; + strm.avail_out = sizeof(Buffer); + + int res = deflateInit2(&strm, 9, Z_DEFLATED, 31, 9, Z_DEFAULT_STRATEGY); + if (res != Z_OK) + { + LOG("%s: compression initialization failed: %d (\"%s\").", __FUNCTION__, res, strm.msg); + return res; + } + + while (true) + { + res = deflate(&strm, Z_FINISH); + switch (res) + { + case Z_OK: + { + // Some data has been compressed. Consume the buffer and continue compressing + a_Compressed.append(Buffer, sizeof(Buffer) - strm.avail_out); + strm.avail_out = sizeof(Buffer); + if (strm.avail_in == 0) + { + // All data has been compressed + deflateEnd(&strm); + return Z_OK; + } + break; + } + + case Z_STREAM_END: + { + // Finished compressing. Consume the rest of the buffer and return + a_Compressed.append(Buffer, sizeof(Buffer) - strm.avail_out); + deflateEnd(&strm); + return Z_OK; + } + + default: + { + // An error has occurred, log it and return the error value + LOG("%s: compression failed: %d (\"%s\").", __FUNCTION__, res, strm.msg); + deflateEnd(&strm); + return res; + } + } // switch (res) + } // while (true) +} + + + + + +extern int UncompressStringGZIP(const char * a_Data, int a_Length, AString & a_Uncompressed) +{ + // Uncompresses a_Data into a_Uncompressed using GZIP; returns Z_OK for success or Z_XXX error constants same as zlib + + a_Uncompressed.reserve(a_Length); + + char Buffer[64 KiB]; + z_stream strm; + memset(&strm, 0, sizeof(strm)); + strm.next_in = (Bytef *)a_Data; + strm.avail_in = a_Length; + strm.next_out = (Bytef *)Buffer; + strm.avail_out = sizeof(Buffer); + + int res = inflateInit2(&strm, 31); // Force GZIP decoding + if (res != Z_OK) + { + LOG("%s: uncompression initialization failed: %d (\"%s\").", __FUNCTION__, res, strm.msg); + return res; + } + + while (true) + { + res = inflate(&strm, Z_FINISH); + switch (res) + { + case Z_OK: + { + // Some data has been uncompressed. Consume the buffer and continue uncompressing + a_Uncompressed.append(Buffer, sizeof(Buffer) - strm.avail_out); + strm.avail_out = sizeof(Buffer); + if (strm.avail_in == 0) + { + // All data has been uncompressed + inflateEnd(&strm); + return Z_OK; + } + break; + } + + case Z_STREAM_END: + { + // Finished uncompressing. Consume the rest of the buffer and return + a_Uncompressed.append(Buffer, sizeof(Buffer) - strm.avail_out); + inflateEnd(&strm); + return Z_OK; + } + + default: + { + // An error has occurred, log it and return the error value + LOG("%s: uncompression failed: %d (\"%s\").", __FUNCTION__, res, strm.msg); + inflateEnd(&strm); + return res; + } + } // switch (res) + } // while (true) +} + + + + -- cgit v1.2.3