busread(busfilename)

function [strings, sizes, message] = busread(busfilename)
%BUSREAD Returns the Strings and Sizes for a given bus file.
%
%For use only with the SIMULINK Bus connection blocks.
%
%See also 'help simbus'

%Copyright (c) 1995 by The MathWorks, Inc.
%$Revision: 1.1 $ $Date: 1997/02/11 20:50:15 $

strings = '';
message = '';
sizes = [];
busfilename=lower(busfilename);
% Make sure there is no crud in the filename
if any(busfilename == '.')
    [busfilename,ext] = strtok(busfilename,'.');
    if ~strcmp(ext,'txt')
        message = ['Unknown bus file format ' busfilename '.' ext];
        return;
    end
end
busfilename = [busfilename '.txt'];

% First check in the current directory
directory = cd;
if strtok(version,'.') < '5'
    c = computer;
    if isunix,
        sep = '/';
    elseif isvms
        sep = '.';
    elseif strcmp(c(1:2),'PC')
        sep = '\';
    elseif strcmp(c(1:2),'MA')
        sep = ':';
    end
else
    sep = filesep;
end
busfile = [directory sep busfilename];
exists = exist(busfile);
if ~exists
    %
    % Can't find file in current directory - try using fwhich
    %
    busfile = fwhich(busfilename,'file','first');
end

if isempty(busfile)
    %    
    % Can't find file using fwhich - return error message
    %
    message = ['Can''t locate file ' busfilename];
    return;
end

fid = fopen(busfile,'rt');
if fid < 0
    %    
    % Can't read file - return error message
    %
    message = ['Can''t read file ' busfilename];
    return;
end

%
% Read in whole file
% 
[txt,count] = fread(fid,'char');
fclose(fid);
if count == 0
    %
    % Empty file
    %
    message=['The file ' busfilename ' is empty.'];
    return;
end

txt = setstr(txt);
%
BLANK = 32;
CRETURN = 13;
comp = computer;
if comp(1:3) == 'MAC'
    NEWLINE = 13;
else
    NEWLINE = 10;
end
%
nl = find(txt == NEWLINE);
lnl = length(nl);
%
% Be sure that the last line is covered in case NEWLINE
% is missing
%
if isempty(nl)
    nl = count;
    lnl = 1;
elseif nl(lnl) ~= count 
    nl = [ nl; count ];
    lnl = lnl + 1;
end
%
% Skip comments and blank lines
%
line = txt(1:nl(1)-1);
if isempty(line)
    flag=1;
elseif txt(nl(1)-1) == CRETURN
    line = txt(1:nl(1)-2);
    if isempty(line)
        flag = 1;
    else
        flag = strcmp(line(1),'%');
    end
else  
    flag = strcmp(line(1),'%');
end  
i = 1; 
while flag
    i = i + 1;
    if i > lnl
        %
        % No strings in file
        %
        message = ['File ' busfilename ' is not in a valid bus file.'];
        return;
    end
    line = txt(nl(i-1)+1:nl(i)-1);
    if isempty(line)
        flag = 1;
    elseif txt(nl(i)-1) == CRETURN    
        line = txt(nl(i-1)+1:nl(i)-2);
        if isempty(line)
            flag = 1;
        else
            flag = strcmp(line(1),'%');
        end
    else    
        flag = strcmp(line(1),'%');
    end
end
%
astrings = '';
lstrings = [];
while 1
    [text,count] = sscanf(line, '%s %d%*');
    if count > 0
        len = length(text);
        lstrings = [lstrings; len-1];
        astrings = [astrings setstr(text(1:len-1)')];
        sizes = [sizes; text(len:len)];
    end  
    i = i + 1;
    if i > lnl
        %
        % Finished:
        % Build strings from size vector and one long string
        %
        len = length(lstrings);
        mx = max(lstrings);
        strings = setstr(ones(1,len * mx) * BLANK); 
        ssum = 1;
        asum = 1;
        for i=1:len
            strings(ssum:ssum+lstrings(i)-1) = astrings(asum:asum+lstrings(i)-1);
            ssum = ssum + mx;
            asum = asum + lstrings(i);
        end
        strings = reshape(strings,mx,len)';
        return;
    end
    if txt(nl(i)-1) ~= CRETURN
        line = txt(nl(i-1)+1:nl(i)-1);
    else
        line = txt(nl(i-1)+1:nl(i)-2);
    end
end