function [dlen,cnt] = rateSearch(resposition,target,yposition,resAdjust)
%% ===========================================================================
% Copyright (C):
%       2002-2009 by Forschungszentrum Telekommunikation Wien, Austria;
%                                                         All rights reserved.
% Description   : ETSI VDSL performance simulations
%
% Project       : B1, FTW
% Author(s)     : Tomas Nordstrom (Tomas.Nordstrom@FTW.at)
%
% Reference:
%
% CVS:       $Id: rateSearch.m 752 2009-01-02 13:03:52Z tono $
%% ===========================================================================

%% ===========================================================================
% Change History
%      2002-06-14 (ToNo) Created as a seperate search function
%      2003-11-03 (ToNo) Lists now use cell arrays for both Octave and Matlab
%% ===========================================================================
global ex;

DEBUG=0;

if nargin<3,
        error('Not enough input arguments.');
end

if nargin<4,
        yposition = 2;
end

if nargin<5,
    DoAdjustForNID = 0;
    DoAdjustForMN  = 0;
else
    DoAdjustForNID = resAdjust.DoAdjustForNID;
    DoAdjustForMN  = resAdjust.DoAdjustForMN;
end

ds_target = target.ds;
us_target = target.us;

%% ========================================================================
% Prepare the search, by setting a lower and upper bound on the reach value

minlen=2;

%% ========================================================================
% Prepare the search for reach, by setting a lower and upper bound 
% on the reach.

%%%% Get first bitrate at a minimum distance
xlen=minlen;    
ex.tt.topology{yposition}{1}=xlen;
result = evalExperiment;
% Adjust for VDSL performance tests
if DoAdjustForNID, AdjustForNID; end;            % Adjust for noise inject.dev.
if DoAdjustForMN,  AdjustForMN; end;             % Floor for modem noise

[bitrate_LT, bitrate_NT, margin_LT, margin_NT] = calcXDSLresult(ex,result);
low_rate_ds=bitrate_NT(resposition); % XXX/rsoh-framingoh
low_rate_us=bitrate_LT(resposition); % XXX/rsoh-framingoh
cnt=1;
low_xlen_ds=xlen;
low_xlen_us=xlen;

if DEBUG,
    fprintf('\n');
end;

xlen=1500;
high_xlen_ds=xlen-1;
high_xlen_us=xlen-1;
high_rate_ds=low_rate_ds-1;
high_rate_us=low_rate_us-1;
%%% Now get the upper bound (if first bitrate is valid). Focus on DS direction
if (low_rate_ds < ds_target) || (low_rate_us < us_target)
    quitloop=1;
else
    quitloop=0;
    contsearch=1;
    while contsearch
        ex.tt.topology{yposition}{1}=xlen;
        result = evalExperiment;
% Adjust for VDSL performance tests
if DoAdjustForNID, AdjustForNID; end;            % Adjust for noise inject.dev.
if DoAdjustForMN,  AdjustForMN; end;             % Floor for modem noise

        [bitrate_LT, bitrate_NT, margin_LT, margin_NT] = calcXDSLresult(ex,result);
        if DEBUG,
            fprintf('Itr #%d (%.0f m) -- Rate:(US=>%.2f,DS=>%.2f), Margin:(%.3f,%.3f)\n',...
                    cnt,xlen,bitrate_LT, bitrate_NT, margin_LT, margin_NT);
        end;

        high_rate_ds=bitrate_NT(resposition); % XXX/rsoh-framingoh
        high_rate_us=bitrate_LT(resposition); % XXX/rsoh-framingoh
        cnt=cnt+1;

        if high_rate_ds<=0,
            % To far out -- no bitrate at all
            xlen = low_xlen_ds + (xlen-low_xlen_ds)/2;
        elseif (high_rate_ds < ds_target)
            % A useful distance outside reach
            contsearch=0;
            high_xlen_ds=xlen;
        else
            % Still above target bitrate aim higher and move minimum distance
            lenrate=(low_xlen_ds-xlen)/(low_rate_ds-high_rate_ds);
            low_rate_ds=high_rate_ds;
            low_xlen_ds=xlen;
            xlen=low_xlen_ds + lenrate*(ds_target-high_rate_ds) + 100;
        end;
        if DEBUG,
            fprintf('Itr #%d-- Pre, DS High:(%.1f,%.1f),Low:(%.1f,%.1f)\n\n',...
                    cnt,high_xlen_ds,high_rate_ds*1e3,low_xlen_ds,low_rate_ds*1e3);
        end;
    end;
end;

%% ========================================================================
% Now search for the DS reach, between upper and lower bound, 
% downto a 1m accuracy.

xlen=low_xlen_ds + (high_xlen_ds-low_xlen_ds)/2;

while ~quitloop
    cnt=cnt+1;
    ex.tt.topology{yposition}{1}=xlen;
    result = evalExperiment;
% Adjust for VDSL performance tests
if DoAdjustForNID, AdjustForNID; end;            % Adjust for noise inject.dev.
if DoAdjustForMN,  AdjustForMN; end;             % Floor for modem noise
    [bitrate_LT, bitrate_NT, margin_LT, margin_NT] = calcXDSLresult(ex,result);
    if DEBUG,
        fprintf('Itr #%d (%.0f m) -- Rate:(%.2f,%.2f), Margin:(%.3f,%.3f)\n',...
                cnt,xlen,bitrate_LT, bitrate_NT, margin_LT, margin_NT);
    end;
    new_rate_ds=bitrate_NT(resposition); % XXX/rsoh-framingoh
    new_rate_us=bitrate_LT(resposition); % XXX/rsoh-framingoh

    if new_rate_ds>ds_target,
        low_rate_ds=new_rate_ds;
        low_xlen_ds=xlen;
    else
        high_rate_ds=new_rate_ds;
        high_rate_us=new_rate_us;
        high_xlen_ds=xlen;
        high_xlen_us=xlen;
    end;
    
    xlen=low_xlen_ds + (high_xlen_ds-low_xlen_ds)/2;
    if high_xlen_ds-xlen < 0.5,
        quitloop=1;
    end;
    if DEBUG,
        fprintf('Itr #%d -- DS High:(%.1f,%.1f),Low:(%.1f,%.1f)\n\n',...
                cnt,high_xlen_ds,high_rate_ds*1e3,low_xlen_ds,low_rate_ds*1e3);
    end;
end %while  

ds_xlen=low_xlen_ds;

%% ========================================================================
% Search for the US reach (if needed)

if ds_xlen<minlen,
    % Print result if DS didn't get a reach
    fprintf('Loop %d, - \n',loopno);
    quitloop=0;
    dlen = 0;
elseif (high_rate_us > us_target)
    % Print result if US is OK and DS is determining the reach
    %fprintf('Loop %d, Len=%.0fm, IL = %.1fdB (@300kHz), DS\n',...
    %        loopno,ds_xlen+offsetlen(loopno),...
    %        VDSLIL(loopno,f_T,ds_xlen+offsetlen(loopno)));
    dlen = ds_xlen;
else
    % Search US reach (between starting reach and DS reach)
    xlen=low_xlen_us + (high_xlen_us-low_xlen_us)/2;
    quitloop=0;
    while ~quitloop
        cnt=cnt+1;
        ex.tt.topology{yposition}{1}=xlen;

% Adjust for VDSL performance tests
if DoAdjustForNID, AdjustForNID; end;            % Adjust for noise inject.dev.
if DoAdjustForMN,  AdjustForMN; end;             % Floor for modem noise
        result = evalExperiment;
        [bitrate_LT, bitrate_NT, margin_LT, margin_NT] = calcXDSLresult(ex,result);
        if DEBUG,
            fprintf('Itr #%d (%.0f m) -- Rate:(%.2f,%.2f), Margin:(%.3f,%.3f)\n',...
                    cnt,xlen,bitrate_LT, bitrate_NT, margin_LT, margin_NT);
        end;
        new_rate_ds=bitrate_NT(resposition); % XXX/rsoh-framingoh
        new_rate_us=bitrate_LT(resposition); % XXX/rsoh-framingoh
        
        if new_rate_us>us_target,
            low_rate_us=new_rate_us;
            low_xlen_us=xlen;
        else
            high_rate_ds=new_rate_ds;
            high_rate_us=new_rate_us;
            high_xlen_ds=xlen;
            high_xlen_us=xlen;
        end;
        
        xlen=low_xlen_us + (high_xlen_us-low_xlen_us)/2;
        if high_xlen_us-xlen < 0.5,
            quitloop=1;
        end;
        if DEBUG,
            fprintf('Itr #%d -- US High:(%.1f,%.1f),Low:(%.1f,%.1f)\n',...
                    cnt,high_xlen_us,high_rate_us*1e3,low_xlen_us,low_rate_us*1e3);
        end;
    end %while  
    us_xlen=low_xlen_us;

    dlen = us_xlen;
end;