% [data,errmsg]=nrn_vread(FileName,machineformat)
% machineformat like in fopen (i.e. 'b' for big endian, 'l' for little endian)
%
% reads binary files, that was written with Vector.vwrite in NEURON
% Published by Konstantin Miller on the Neuron forum.

function [data,errmsg]=nrn_vread(FileName,machineformat)

data = NaN;

[fid,errmsg] = fopen(FileName,'r',machineformat);
if fid==-1
   return;
else
   errmsg = sprintf('File opened successfully');
end

[header,cnt]=fread(fid,2,'int32');
if cnt~=2
   errmsg = sprintf('Could not read the vwrite header');
   fclose(fid);
   return;
end

precision = 'double'; % to avoid Matlab warning
if header(2)==4
   precision = 'double';
elseif header(2)==3
   precision = 'float32';
elseif header(2)==5
   precision = 'int';
else
   errmsg = sprintf('Unsupported precision argument');
   fclose(fid);
   return;
end

[data,cnt]=fread(fid,inf,precision);
if cnt~=header(1)
   errmsg = sprintf('Only %d instead of %d Samples read',cnt,header(1));
   data = NaN;
   fclose(fid);
   return;
else
   errmsg = sprintf('Successfully read %d Samples',cnt);
end

fclose(fid);