nex_ts

 nex_ts(filename, varname): Read timestamps from a .nex file

 [n, ts] = nex_ts(filename, varname)

 INPUT:
   filename - if empty string, will use File Open dialog
   varname - variable name
 OUTPUT:
   n - number of timestamps
   ts - array of timestamps (in seconds)

0001 function [n, ts] = nex_ts(filename, varname)
0002 % nex_ts(filename, varname): Read timestamps from a .nex file
0003 %
0004 % [n, ts] = nex_ts(filename, varname)
0005 %
0006 % INPUT:
0007 %   filename - if empty string, will use File Open dialog
0008 %   varname - variable name
0009 % OUTPUT:
0010 %   n - number of timestamps
0011 %   ts - array of timestamps (in seconds)
0012 
0013 n = 0;
0014 ts = 0;
0015 
0016 if(nargin ~= 2)
0017    disp('2 input arguments are required')
0018    return
0019 end
0020 
0021 if(ischar(filename) == 0)
0022    disp('input arguments should be character arrays')
0023    return
0024 end
0025 
0026 if(ischar(varname) == 0)
0027    disp('input arguments should be character arrays')
0028    return
0029 end
0030 
0031 if(isempty(filename))
0032    [fname, pathname] = uigetfile('*.nex', 'Select a Nex file');
0033     filename = strcat(pathname, fname);
0034 end
0035 
0036 fid = fopen(filename, 'r');
0037 if(fid == -1)
0038     disp('cannot open file');
0039    return
0040 end
0041 
0042 disp(strcat('file = ', filename));
0043 magic = fread(fid, 1, 'int32');
0044 version = fread(fid, 1, 'int32');
0045 comment = fread(fid, 256, 'char');
0046 freq = fread(fid, 1, 'double');
0047 tbeg = fread(fid, 1, 'int32');
0048 tend = fread(fid, 1, 'int32');
0049 nvar = fread(fid, 1, 'int32');
0050 fseek(fid, 260, 'cof');
0051 name = zeros(1, 64);
0052 found = 0;
0053 for i=1:nvar
0054     type = fread(fid, 1, 'int32');
0055     var_version = fread(fid, 1, 'int32');
0056     name = fread(fid, [1 64], 'char');
0057     offset = fread(fid, 1, 'int32');
0058     n = fread(fid, 1, 'int32');
0059     name = char(name);
0060     name = deblank(name);
0061     k = strcmp(name, deblank(varname));
0062     if(k == 1)
0063         found = 1;
0064         fseek(fid, offset, 'bof');
0065         ts = fread(fid, [1 n], 'int32');
0066         break
0067     end
0068     dummy = fread(fid, 128, 'char');
0069 end
0070 
0071 fclose(fid);
0072 
0073 if found == 0
0074     disp('did not find variable in the file');
0075 else
0076     ts = ts/freq;
0077     disp(strcat('number of timestamps = ', num2str(n)));
0078 end