function fqstruct=planConvertion(frequencies,directions,guardband)
%% ===========================================================================
%planConvertion - Convert a frequency plan into centre frequencies and bw
%
% Parameter:    frequencies	Array of switching frequencies
% Parameter:    directions	Direction at these frequencies
% Parameter:    guardband	Size (0-1) or (f Hz) of guardbands
% Returns:      fqstruct	Frequency and bw struct
%			.up.fc  	Center frequencies for upstream
%			.up.bw  	Bandwidth for each upstream band
%			.down.fc  	Center frequencies for downstream
%			.down.bw  	Bandwidth for each downstream band
%
% Example(s):
%   fqstruct=planConvertion([.138e6 2.6e6 5.4e6 10.25e6  20e6],'dudu')
%   Defines a four band plan
%
%   fqstruct=planConvertion([.138e6 2.6e6 5.4e6 10.25e6 15e6 20e6],'dudnu')
%   Defines a four band plan with a gap between 10.25 and 15 MHz
%
%   fqstruct=planConvertion([.138e6 2.6e6 5.4e6 10.25e6 15e6 20e6],'dudud',0.1)
%   Defines a five band plan with guard bands of 10%
%
%   fqstruct=planConvertion([.138e6 2.6e6 5.4e6 10.25e6 15e6 20e6],'dudud',100e3)
%   Defines a five band plan with guard bands of 100e3kHz
%
%% ===========================================================================

%% ===========================================================================
% Copyright (C):                                        
%       1999 by Telia Research AB, Lulea, Sweden;                
%       2000-2009 by Forschungszentrum Telekommunikation Wien, Austria;
%                                                         All rights reserved.
% Project       : FTW's xDSLsimu
% Author(s)     : Tomas Nordstrom (Tomas.Nordstrom@FTW.at)
%               : Daniel Bengtsson (Daniel.J.Bengtsson@Telia.se)
%
% CVS:       $Id: planConvertion.m 752 2009-01-02 13:03:52Z tono $
%% ===========================================================================
% Change History
%      1999-10-10 (ToNo) Created
%      1999-11-02 (ToNo) Modified the way guard bands is defined
%      2000-03-09 (ToNo) Fixed a mixup in ui/di index
%      2005-03-24 (ToNo) Added support for absolute valued guardbands
%% ===========================================================================

if nargin<2,
    error('Not enough input arguments.');
end

if nargin<3
   guardband = 0;
end;

if length(frequencies) ~= length(directions)+1,
    error('planConvertion: length mismatch');
end;

ui=1;
di=1;
endi=length(frequencies);
i=1;
while i <= length(directions),
    stopi=i+1;
    while ((stopi<endi) && (directions(i) == directions(stopi))),
        stopi=stopi+1;
    end;

    % define guard bands based on switch freqencies
    if guardband<1
    gbl = frequencies(i)*guardband/2;                        % guard band low
    gbh = frequencies(stopi)*guardband/2;                    % guard band high
    bw  = (frequencies(stopi) - frequencies(i) - gbl - gbh); % bandwidth used
    cfq = (frequencies(i) + gbh + bw/2);                     % center frequency
    else
        if i == 1, 
            gbl = frequencies(i);
        else
            gbl = frequencies(i)+guardband/2;                % guard band low
        end;
        if stopi==endi
            gbh = frequencies(stopi);
        else
            gbh = frequencies(stopi)-guardband/2;            % guard band high
        end;
        bw  = gbh-gbl;                                       % bandwidth used
        cfq = (gbh+gbl)/2;                                   % center frequency
    end        

    switch directions(i),
     case 'u'
      fqstruct.up.fc(ui)=cfq;
      fqstruct.up.bw(ui)=bw;
      ui=ui+1;
     case 'd'
      fqstruct.down.fc(di)=cfq;
      fqstruct.down.bw(di)=bw;
      di=di+1;
     case 'n'
      ui=ui; % Do Nothing
     otherwise
      errstr=sprintf('planConvertion: unknown direction char "%s"',directions(i));
      error(errstr);
    end;
    
    i=stopi;
end;