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function y = base64decode(x)
b'%BASE64DECODE Perform base64 decoding on a string.'
b'% BASE64DECODE(STR) decodes the given base64 string STR.'
b'% Any character not part of the 65-character base64 subset set is silently'
b"% ignored. Characters occuring after a '=' padding character are never"
b"% STR doesn't have to be a string. The only requirement is that it is a"
b'% vector containing values in the range 0-255.'
b'% If the length of the string to decode (after ignoring non-base64 chars) is'
b'% not a multiple of 4, then a warning is generated.'
b'% This function is used to decode strings from the Base64 encoding specified'
b'% in RFC 2045 - MIME (Multipurpose Internet Mail Extensions). The Base64'
b'% encoding is designed to represent arbitrary sequences of octets in a form'
b'% that need not be humanly readable. A 65-character subset ([A-Za-z0-9+/=])'
b'% of US-ASCII is used, enabling 6 bits to be represented per printable'
b'% See also BASE64ENCODE.'
b'% Author: Peter J. Acklam'
b'% Time-stamp: 2004-09-20 08:20:50 +0200'
b'% E-mail: pjacklam@online.no'
b'% URL: http://home.online.no/~pjacklam'
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% check number of input arguments
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error(nargchk(1, 1, nargin));
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% remove non-base64 chars
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x = x ( ( 'A' <= x & x <= 'Z' ) ...
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| ( 'a' <= x & x <= 'z' ) ...
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| ( '0' <= x & x <= '9' ) ...
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| ( x == '+' ) | ( x == '=' ) | ( x == '/' ) );
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warning('Length of base64 data not a multiple of 4; padding input.');
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k = find(x == '=');
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Now perform the following mapping
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y = repmat(uint8(0), size(x));
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i = 'A' <= x & x <= 'Z'; y(i) = - 'A' + x(i);
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i = 'a' <= x & x <= 'z'; y(i) = 26 - 'a' + x(i);
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i = '0' <= x & x <= '9'; y(i) = 52 - '0' + x(i);
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i = x == '+'; y(i) = 62 - '+' + x(i);
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i = x == '/'; y(i) = 63 - '/' + x(i);
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nebytes = length(x); % number of encoded bytes
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nchunks = ceil(nebytes/4); % number of chunks/groups
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% add padding if necessary
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x(end+1 : 4*nchunks) = 0;
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x = reshape(uint8(x), 4, nchunks);
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y = repmat(uint8(0), 3, nchunks); % for the decoded data
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Rearrange every 4 bytes into 3 bytes
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% 00aaaaaa 00bbbbbb 00cccccc 00dddddd
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% aaaaaabb bbbbcccc ccdddddd
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y(1,:) = bitshift(x(1,:), 2); % 6 highest bits of y(1,:)
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y(1,:) = bitor(y(1,:), bitshift(x(2,:), -4)); % 2 lowest bits of y(1,:)
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y(2,:) = bitshift(x(2,:), 4); % 4 highest bits of y(2,:)
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y(2,:) = bitor(y(2,:), bitshift(x(3,:), -2)); % 4 lowest bits of y(2,:)
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y(3,:) = bitshift(x(3,:), 6); % 2 highest bits of y(3,:)
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y(3,:) = bitor(y(3,:), x(4,:)); % 6 lowest bits of y(3,:)
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switch rem(nebytes, 4)
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% reshape to a row vector and make it a character array
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y = char(reshape(y, 1, numel(y)));
b'\\ No newline at end of file'
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function y = base64decode(x)
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%BASE64DECODE Perform base64 decoding on a string.
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% BASE64DECODE(STR) decodes the given base64 string STR.
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% Any character not part of the 65-character base64 subset set is silently
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% ignored. Characters occuring after a '=' padding character are never
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% STR doesn't have to be a string. The only requirement is that it is a
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% vector containing values in the range 0-255.
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% If the length of the string to decode (after ignoring non-base64 chars) is
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% not a multiple of 4, then a warning is generated.
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% This function is used to decode strings from the Base64 encoding specified
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% in RFC 2045 - MIME (Multipurpose Internet Mail Extensions). The Base64
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% encoding is designed to represent arbitrary sequences of octets in a form
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% that need not be humanly readable. A 65-character subset ([A-Za-z0-9+/=])
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% of US-ASCII is used, enabling 6 bits to be represented per printable
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% See also BASE64ENCODE.
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% Author: Peter J. Acklam
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% Time-stamp: 2004-09-20 08:20:50 +0200
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% E-mail: pjacklam@online.no
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% URL: http://home.online.no/~pjacklam
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% check number of input arguments
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error(nargchk(1, 1, nargin));
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% remove non-base64 chars
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x = x ( ( 'A' <= x & x <= 'Z' ) ...
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| ( 'a' <= x & x <= 'z' ) ...
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| ( '0' <= x & x <= '9' ) ...
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| ( x == '+' ) | ( x == '=' ) | ( x == '/' ) );
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warning('Length of base64 data not a multiple of 4; padding input.');
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Now perform the following mapping
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y = repmat(uint8(0), size(x));
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i = 'A' <= x & x <= 'Z'; y(i) = - 'A' + x(i);
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i = 'a' <= x & x <= 'z'; y(i) = 26 - 'a' + x(i);
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i = '0' <= x & x <= '9'; y(i) = 52 - '0' + x(i);
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i = x == '+'; y(i) = 62 - '+' + x(i);
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i = x == '/'; y(i) = 63 - '/' + x(i);
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nebytes = length(x); % number of encoded bytes
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nchunks = ceil(nebytes/4); % number of chunks/groups
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% add padding if necessary
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x(end+1 : 4*nchunks) = 0;
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x = reshape(uint8(x), 4, nchunks);
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y = repmat(uint8(0), 3, nchunks); % for the decoded data
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Rearrange every 4 bytes into 3 bytes
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% 00aaaaaa 00bbbbbb 00cccccc 00dddddd
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% aaaaaabb bbbbcccc ccdddddd
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y(1,:) = bitshift(x(1,:), 2); % 6 highest bits of y(1,:)
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y(1,:) = bitor(y(1,:), bitshift(x(2,:), -4)); % 2 lowest bits of y(1,:)
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y(2,:) = bitshift(x(2,:), 4); % 4 highest bits of y(2,:)
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y(2,:) = bitor(y(2,:), bitshift(x(3,:), -2)); % 4 lowest bits of y(2,:)
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y(3,:) = bitshift(x(3,:), 6); % 2 highest bits of y(3,:)
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y(3,:) = bitor(y(3,:), x(4,:)); % 6 lowest bits of y(3,:)
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switch rem(nebytes, 4)
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% reshape to a row vector and make it a character array
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y = char(reshape(y, 1, numel(y)));
added
removed
Psychtoolbox/PsychHardware/iViewXToolbox/cbase64/base64decode.m
