CompressData.h

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////////////////////////////////////////////////////////////////////////////////
//
//  File: CompressData.h
//
//  For more information, please see: http://www.nektar.info/
//
//  The MIT License
//
//  Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
//  Department of Aeronautics, Imperial College London (UK), and Scientific
//  Computing and Imaging Institute, University of Utah (USA).
//
//  Permission is hereby granted, free of charge, to any person obtaining a
//  copy of this software and associated documentation files (the "Software"),
//  to deal in the Software without restriction, including without limitation
//  the rights to use, copy, modify, merge, publish, distribute, sublicense,
//  and/or sell copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included
//  in all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
//  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
//  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
//  DEALINGS IN THE SOFTWARE.
//
//  Description: Routines for compressing and inflating data
//
////////////////////////////////////////////////////////////////////////////////

#ifndef NEKTAR_LIB_UTILITIES_BASIC_UTILS_COMPRESSDATA_H
#define NEKTAR_LIB_UTILITIES_BASIC_UTILS_COMPRESSDATA_H

#include <LibUtilities/BasicUtils/SessionReader.h>

#include "zlib.h"

// Buffer size for zlib compression/decompression
#define CHUNK 16384

namespace Nektar
{
namespace LibUtilities
{

    enum EndianType
    {
        eEndianUnknown,
        eEndianBig,
        eEndianLittle,
        eEndianBigWord,   /* Middle-endian, Honeywell 316 style */
        eEndianLittleWord /* Middle-endian, PDP-11 style */
    };

    const std::string EndianTypeMap[] =
    {
        "UnknownEndian",
        "BigEndian",
        "LittleEndian",
        "BigWordEndian",
        "LittleWordEndian"
    };

    LIB_UTILITIES_EXPORT EndianType Endianness(void);

    namespace CompressData
    {
        LIB_UTILITIES_EXPORT std::string GetCompressString(void);
        LIB_UTILITIES_EXPORT std::string GetBitSizeStr(void);

        /**
         * Compress a vector of NekDouble values into a string using zlib.
         */
        template<class T> int ZlibEncode(std::vector<T>& in, std::string& out)
        {
            int ret;
            unsigned have;
            std::string buffer;
            buffer.resize(CHUNK);
            z_stream strm;
            unsigned char* input = (unsigned char*)(&in[0]);

            /* allocate deflate state */
            strm.zalloc = Z_NULL;
            strm.zfree  = Z_NULL;
            strm.opaque = Z_NULL;
            ret = deflateInit(&strm, Z_DEFAULT_COMPRESSION);

            ASSERTL0(ret == Z_OK, "Error initializing Zlib.");

            strm.avail_in = (unsigned int)in.size() * sizeof(T) / sizeof(char);
            strm.next_in = input;

            // Deflate input until output buffer is no longer full.
            do {
                strm.avail_out = CHUNK;
                strm.next_out = (unsigned char*)(&buffer[0]);

                ret = deflate(&strm, Z_FINISH);

                // Deflate can return Z_OK, Z_STREAM_ERROR, Z_BUF_ERROR or
                // Z_STREAM_END. All, except Z_STREAM_ERROR are ok.
                ASSERTL0(ret != Z_STREAM_ERROR, "Zlib stream error");

                have = CHUNK - strm.avail_out;
                out += buffer.substr(0, have);

            } while (strm.avail_out == 0);

            // Check all input was processed.
            ASSERTL0(strm.avail_in == 0, "Not all input was used.");

            // Check stream is complete.
            ASSERTL0(ret == Z_STREAM_END, "Stream not finished");

            // Clean-up and return
            (void)deflateEnd(&strm);
            return Z_OK;
        }


        /**
         * Convert a string containing compressed binary (i.e. from
         * deflate) into a base 64 string
         */
        LIB_UTILITIES_EXPORT void BinaryStrToBase64Str(
                std::string &compressedDataString,
                std::string &base64string);

        /**
         * Compress a vector of NekDouble values into a base64 string.
         */
        template<class T>
        int ZlibEncodeToBase64Str(std::vector<T>& in, std::string& out64)
        {
            std::string out;

            int ok = ZlibEncode(in,out);

            BinaryStrToBase64Str(out,out64);

            return ok;
        }


        /**
         * Decompress a zlib-compressed string into a vector of NekDouble
         * values.
         */
        template<class T>
        int ZlibDecode(std::string& in, std::vector<T>& out)
        {
            int ret;
            unsigned have;
            z_stream strm;
            std::string buffer;
            buffer.resize(CHUNK);
            std::string output;

            strm.zalloc = Z_NULL;
            strm.zfree = Z_NULL;
            strm.opaque = Z_NULL;
            strm.avail_in = 0;
            strm.next_in = Z_NULL;
            ret = inflateInit(&strm);
            ASSERTL0(ret == Z_OK, "Error initializing zlib decompression.");

            strm.avail_in = (unsigned int)in.size();
            strm.next_in = (unsigned char*)(&in[0]);

            do {
                strm.avail_out = CHUNK;
                strm.next_out = (unsigned char*)(&buffer[0]);

                ret = inflate(&strm, Z_NO_FLUSH);

                ASSERTL0(ret != Z_STREAM_ERROR, "Stream error occured.");

                switch (ret) {
                    case Z_NEED_DICT:
                        ret = Z_DATA_ERROR;
                        /* Falls through. */
                    case Z_DATA_ERROR:
                    case Z_MEM_ERROR:
                        (void)inflateEnd(&strm);
                        return ret;
                }

                have = CHUNK - strm.avail_out;
                output += buffer.substr(0, have);

            } while (strm.avail_out == 0);

            (void)inflateEnd(&strm);

            if (ret == Z_STREAM_END)
            {
                T* readFieldData = (T*) output.c_str();
                unsigned int len = (unsigned int)output.size() * sizeof(*output.c_str())
                                                 / sizeof(T);
                out.assign( readFieldData, readFieldData + len);
                return Z_OK;
            }
            else
            {
                return Z_DATA_ERROR;
            }
        }



        /**
         * Convert a string containing base 64 (i.e. from xml file)
         * into a binary string
         */
        LIB_UTILITIES_EXPORT void Base64StrToBinaryStr(
                std::string &base64string,
                std::string &compressedDataString);



        /**
         * Decompress a base 64 compressed binary string into a vector
         * of NekDouble values.
         */
        template<class T>
        int ZlibDecodeFromBase64Str(std::string& in64, std::vector<T>& out)
        {
            std::string in;
            Base64StrToBinaryStr(in64,in);

            return ZlibDecode(in,out);
        }

    }
}
}
#endif