Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / strings-1.1.0 / base64decode.m

diff --git a/octave_packages/strings-1.1.0/base64decode.m b/octave_packages/strings-1.1.0/base64decode.m
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+## Copyright (C) 2007 Muthiah Annamalai <muthiah.annamalai@uta.edu>
+##
+## 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 3 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, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{rval} =} base64decode (@var{code})
+## @deftypefnx {Function File} {@var{rval} =} base64decode (@var{code}, @var{as_string})
+## Convert a base64 @var{code}  (a string of printable characters according to RFC 2045) 
+## into the original ASCII data set of range 0-255. If option @var{as_string} is 
+## passed, the return value is converted into a string.
+##
+## @example
+## @group
+##           ##base64decode(base64encode('Hakuna Matata'),true)
+##           base64decode('SGFrdW5hIE1hdGF0YQ==',true)
+##           ##returns 'Hakuna Matata'
+## @end group
+## @end example
+##
+## See: http://www.ietf.org/rfc/rfc2045.txt
+##
+## @seealso {base64encode}
+## @end deftypefn
+
+function z = base64decode (X, as_string)
+  if (nargin < 1 )
+    print_usage;
+  elseif nargin == 1
+    as_string=false;
+  endif
+
+  if ( any(X(:) < 0) || any(X(:) > 255))
+    error("base64decode is expecting integers in the range 0 .. 255");
+  endif
+
+  ## decompose strings into the 4xN matrices 
+  ## formatting issues.
+  if( rows(X) == 1 )
+    Y=[];
+    L=length(X);
+    for z=4:4:L
+        Y=[Y X(z-3:z)']; #keep adding columns
+    end
+    if min(size(Y))==1
+        Y=reshape(Y,[L, 1]);
+    else
+        Y=reshape(Y,[4,L/4]);
+    end
+    X=Y;
+    Y=[];
+  end
+
+  X = toascii(X);
+  Xa= X;
+
+  ## Work backwards. Starting at step in table,
+  ## lookup the index of the element in the table.
+
+  ## 6-bit encoding table, plus 1 for padding
+  ## 26*2 + 10 + 2 + 1  = 64 + 1, '=' is EOF stop mark.
+  table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+
+  S=size(X);
+  SRows=S(1);
+  SCols=S(2);
+  Y=zeros(S);
+
+  ## decode the incoming matrix & 
+  ## write the values into Va matrix.
+  Va = -1*ones(size(Xa));
+
+  iAZ = (Xa >= 'A').*(Xa <= 'Z') > 0; 
+  Va(iAZ)=Xa(iAZ)-'A';
+
+  iaz = (Xa >= 'a').*(Xa <= 'z') > 0;
+  Va(iaz)=Xa(iaz)-'a'+26;
+
+  i09 = (Xa >= '0').*(Xa <= '9') > 0;
+  Va(i09)=Xa(i09)-'0'+52;
+
+  is = (Xa == '/') ;  Va(is) = 63;
+  ip = (Xa == '+') ;  Va(ip) = 62;
+  ieq = (Xa == '=') ;  Va(ieq) = 0;
+  clear is; clear ieq; clear ip; clear i09;
+  clear iaz; clear iAZ;  clear Xa; clear X;
+
+  Y=Va; clear Va;
+  Y1=Y(1,:);
+  if (SRows > 1)
+     Y2=Y(2,:);
+  else 
+     Y2=zeros(1,SCols);
+  end;
+
+  if (SRows > 2)
+     Y3=Y(3,:);
+  else 
+     Y3=zeros(1,SCols);
+  end;
+
+  if (SRows > 3)
+     Y4=Y(4,:);
+  else 
+     Y4=zeros(1,SCols);
+  end;
+
+  ## +1 not required due to ASCII subtraction
+  ## actual decoding work
+  b1 = Y1*4 + fix(Y2/16);
+  b2 = mod(Y2,16)*16+fix(Y3/4);
+  b3 = mod(Y3,4)*64 + Y4;
+
+  ZEROS=sum(sum(Y==0));
+  L=length(b1)*3;
+  z=zeros(1,L);
+  z(1:3:end)=b1;
+  if (SRows > 1)
+     z(2:3:end)=b2;
+  else
+     z(2:3:end)=[];
+  end;
+
+  if (SRows > 2)
+     z(3:3:end)=b3;
+  else
+     z(3:3:end)=[];
+  end
+
+  ## FIXME
+  ## is this expected behaviour?
+  if ( as_string )
+    L=length(z);
+    while ( ( L > 0) && ( z(L)==0 ) )
+      L=L-1;
+    end
+    z=char(z(1:L));
+  end
+
+endfunction
+
+%!assert(base64decode(base64encode('Hakuna Matata'),true),'Hakuna Matata')
+%!assert(base64decode(base64encode([1:255])),[1:255])
+%!assert(base64decode(base64encode('taken'),true),'taken')
+%!assert(base64decode(base64encode('sax'),true),'sax')
+%!assert(base64decode(base64encode('H'),true),'H')
+%!assert(base64decode(base64encode('Ta'),true),'Ta')