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function varargout = octavezmat(data, iscompress, zipmethod)
%
% output = octavezmat(input, iscompress, zipmethod)
% or
% [output, info] = octavezmat(input, iscompress, zipmethod)
% unzipdata = octavezmat(zipdata, info)
%
% Compress or decompress zlib and gzip memory buffers using zip/unzip/gzip/gunzip on Octave
% in case ZMat toolbox (http://github.com/NeuroJSON/zmat) was not installed (ZMat is much faster)
%
% Author: Qianqian Fang (q.fang <at> neu.edu)
%
% input:
% input: the input data (can be either compressed or before compression),
% can be a string, a numerical vector or array
% iscompress: (optional) if iscompress is 1, zmat compresses/encodes the input,
% if 0, it decompresses/decodes the input. Default value is 1.
%
% if iscompress is set to a negative integer, (-iscompress) specifies
% the compression level. For zlib/gzip, default level is 6 (1-9); for
% lzma/lzip, default level is 5 (1-9); for lz4hc, default level is 8 (1-16).
% the default compression level is used if iscompress is set to 1.
%
% zmat removes the trailing newline when iscompress=2 and method='base64'
% all newlines are kept when iscompress=3 and method='base64'
%
% if one defines iscompress as the info struct (2nd output of zmat), zmat
% will perform a decoding/decompression operation and recover the original
% input using the info stored in the info structure.
% method: (optional) compression method, only the below two methods are supported
% 'zlib': zlib/zip based data compression (default)
% 'gzip': gzip formatted data compression
%
% output:
% output: the decompressed byte stream stored in a uint8 vector; if info is
% given, output will restore the original data's type and dimensions
% info: (optional) a struct storing additional info regarding the input data, may have
% 'type': the class of the input array
% 'size': the dimensions of the input array
% 'byte': the number of bytes per element in the input array
% 'method': a copy of the 3rd input indicating the encoding method
% 'status': the zlib/lzma/lz4 compression/decompression function return value,
% including potential error codes; see documentation of the respective
% libraries for details
% 'level': a copy of the iscompress flag; if non-zero, specifying compression
% level, see above
%
% examples:
% NO_ZMAT=1 % by setting this flag to 1 in the caller or global workspace, octavezmat won't warn zmat is missing
% [ss,info]=octavezmat(ones(10))
% orig=octavezmat(ss,info)
%
% license:
% BSD or GPL version 3, see LICENSE_{BSD,GPLv3}.txt files for details
%
% -- this function is part of JSONLab toolbox (http://iso2mesh.sf.net/cgi-bin/index.cgi?jsonlab)
%
nowarning = getvarfrom({'caller', 'base'}, 'NO_ZMAT');
if (isempty(nowarning) || nowarning == 0)
warning('You are recommended to install ZMat (http://github.com/NeuroJSON/zmat) get much faster speed in Octave');
end
if (nargin < 1)
fprintf(1, 'Format: output = octavezmat(data, iscompress, zipmethod)\n');
return
end
if (nargin < 2)
iscompress = 1;
end
if (nargin < 3)
zipmethod = 'zlib';
end
if (isstruct(iscompress))
inputinfo = iscompress;
iscompress = 0;
end
if (~(ischar(data) || islogical(data) || (isnumeric(data) && isreal(data))))
error('input must be a char, non-complex numeric or logical vector or N-D array');
end
if (ischar(data))
data = uint8(data);
end
fname = tempname;
tmpfile = fname;
outputfile = fname;
suff = struct('zlib', '.zip', 'gzip', '.gz');
if (~isfield(suff, zipmethod))
error('zipmethod is not supported');
end
if (~iscompress)
tmpfile = [fname suff.(zipmethod)];
end
fd = fopen(tmpfile, 'wb');
if (~fd)
error('unable to create temporary file');
end
fwrite(fd, typecast(data(:), 'uint8'), 'uint8');
fclose(fd);
if (iscompress)
outputfile = [fname suff.(zipmethod)];
end
if (~iscompress)
if (strcmp(zipmethod, 'zlib'))
outputfile = unzip(tmpfile, tempdir);
if ((exist('OCTAVE_VERSION', 'builtin') ~= 0))
outputfile = [tempdir filesep outputfile{1}];
else
outputfile = outputfile{1};
end
elseif (strcmp(zipmethod, 'gzip'))
gunzip(tmpfile);
end
else
if (strcmp(zipmethod, 'zlib'))
zip(outputfile, tmpfile);
elseif (strcmp(zipmethod, 'gzip'))
gzip(tmpfile);
end
end
if (exist(tmpfile, 'file'))
delete(tmpfile);
end
fd = fopen(outputfile, 'rb');
if (~fd)
error('failed to unzip buffer');
end
varargout{1} = fread(fd, [1 inf], 'uint8=>uint8');
fclose(fd);
if (exist(outputfile, 'file'))
delete(outputfile);
end
if (nargout > 1)
varargout{2} = struct('type', class(data), 'size', size(data), 'method', zipmethod, 'status', 0, 'level', iscompress);
end
if (exist('inputinfo', 'var') && isfield(inputinfo, 'type'))
if (strcmp(inputinfo.type, 'logical'))
varargout{1} = logical(varargout{1});
else
varargout{1} = typecast(varargout{1}, inputinfo.type);
end
varargout{1} = reshape(varargout{1}, inputinfo.size);
end
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