function exesuff=fallbackexeext(exesuffix, exename)
%
% exesuff=fallbackexeext(exesuffix, exename)
%
% get the fallback external tool extension names for the current platform
%
% author: Qianqian Fang, <q.fang at neu.edu>
%
% input:
%     exesuffix: the output executable suffix from getexeext
%     exename: the executable name
%
% output:
%     exesuff: file extension for iso2mesh tool binaries
%
% -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
%

exesuff=exesuffix;
if(strcmp(exesuff,'.mexa64') & exist([mcpath(exename) exesuff],'file')==0) % fall back to i386 linux
    exesuff='.mexglx';
end
if(strcmp(exesuff,'.mexmaci64') & exist([mcpath(exename) exesuff],'file')==0) % fall back to i386 mac
    exesuff='.mexmaci';
end
if(strcmp(exesuff,'.mexmaci') & exist([mcpath(exename) exesuff],'file')==0) % fall back to ppc mac
    exesuff='.mexmac';
end
if(exist([mcpath(exename) exesuff],'file')==0) % fall back to OS native package
    exesuff='';
end

if(exist([mcpath(exename) exesuff],'file')==0)
    if(strcmp(mcpath(exename),'tetgen'))
        return;
    end
    error([ 'The following executable:\n' ...
        '\t%s%s\n' ...
        'is missing. Please download it from ' ...
        'https://github.com/fangq/iso2mesh/tree/master/bin/ ' ...
        'and save it to the above path, then rerun the script.\n' ...
        ],mcpath(exename),getexeext);
end

