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authorAlexander Harkness <bearbin@gmail.com>2013-11-24 15:19:41 +0100
committerAlexander Harkness <bearbin@gmail.com>2013-11-24 15:19:41 +0100
commit675b4aa878f16291ce33fced48a2bc7425f635ae (patch)
tree409914df27a98f65adf866da669429c4de141b6f /src/StringCompression.cpp
parentLineBlockTracer: Using the coord-based block faces. (diff)
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Diffstat (limited to 'src/StringCompression.cpp')
-rw-r--r--src/StringCompression.cpp180
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diff --git a/src/StringCompression.cpp b/src/StringCompression.cpp
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+++ b/src/StringCompression.cpp
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+
+// 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)
+}
+
+
+
+