fp2bin.m

function binary = fp2bin(flpoint, format)
%FP2BIN Convert a floating point number into it's binary representation
%
% Usage:
% x = 3.25;
% s = fp2bin(x, 'single');
%
% -------------------------------------------------------------------------
% Author:  Michael Wulf
%          Washington University in St. Louis
%          Kepecs Lab
%
% Date:    04/15/2022
% Version: 1.0.2
% Github:  https://github.com/Michael-Wulf/OSCMessage
%
% Copyright (C) 2022 Michael Wulf
%
% This program is free software; you can redistribute it and/or
% modify it under the terms of the GNU General Public License
% as published by the Free Software Foundation; either version 2
% of the License, or (at your option) any later version.
% 
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
% 
% You should have received a copy of the GNU General Public License
% along with this program; if not, write to the Free Software
% Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
% MA  02110-1301, USA.
% -------------------------------------------------------------------------

if ( nargin < 1)
    error('No floating point number give!');
end

% Validate the flpoint argument
validateattributes(flpoint, {'single', 'double'}, {'nonempty', 'scalar'}, 'fp2bin', 'flpoint');

if ( nargin == 1 )
    format = 'double';
end

% Validate the format argument
validateattributes(format, {'char'}, {'nonempty'}, 'fp2bin', 'format');

% Remove leading and trailing whitespaces...
format = strtrim(format);

if ( (strcmpi(format, 'single')) || (strcmpi(format, 'float')) )
    % Take the internal function num2hex to convert a single/float value
    % into the corresponding hex notation
    hexValues = num2hex(single(flpoint));
    
    % Now take the hex representation and interprete it as a decimal value
    % and convert this to a binary representation
    binary    = dec2bin(hex2dec(hexValues),32);
    
elseif ( strcmpi(format, 'double') )
    % Take the internal function num2hex to convert a double value
    % into the corresponding hex notation
    hexValues = num2hex(double(flpoint));
    
    % ATTENTION:
    % It is not possible to just do it the same way as for the single/float
    % format! The problem is, that especcially larger values can't be
    % stored accurate enough! hex2dec tries to convert a hex representation
    % (as an integer value!!!) into the double format. Up until 2^53, integer
    % values can be stored precisely, but from 2^53 the double format will even
    % lose precisions for integers! From 2^53 to 2^54 only the even numbers
    % can be stored. From 2^42 to 2^55 only multiples of 4 can be stored.
    % Than multiples of 8 and so on. Distance between two adjacent numbers
    % in the range between 2^n and 2^(n+1) can be calculated by 2^(n-52)!
    %
    % Solution:
    % To avoid the previously described circumstance, we can split it into
    % 2x32-bit values!
    
    % Take the internal function num2hex to convert the first 8 hex values
    % to a binary representation y first converting it to an integer and
    % than take it's binary representation
    binary1 = dec2bin(hex2dec(hexValues(1:8)),32);
    % Now do the same thing with the second 32-bit part
    binary2 = dec2bin(hex2dec(hexValues(9:16)),32);
    % Finally, combine both binary representations
    binary = [binary1 binary2];
else
    error('Unknown format: %s', format);
end
end