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::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);
}
 
} // namespace CompressData
} // namespace Nektar::LibUtilities
#endif