SAMI/MissingNodes_SrcCode2014/FindLineNumber.m

function [ line ] = FindLineNumber( fid, fileSize, lineNum )
%FindLineNumber Find a line number in file where each line starts with the
%number
%   Detailed explanation goes here

currPos = floor(fileSize / 2);
minPos = 0;
maxPos = fileSize;
while(1)
    
    %fprintf('searching for %d, currPos %d, minPos %d, maxPos %d\n', lineNum, currPos, minPos, maxPos);
    res = fseek(fid, currPos, 'bof');
    line = fgetl(fid);
    if currPos > 0
        line = fgetl(fid);
        if line == -1
            fprintf('line == -1');
            currNode = -1;
            break;
        end
    end
    
    %split the line into a vector of node numbers
    r = str2double(regexp(line, ' ', 'split'));
    %r(2) = []; %the second number is a timestamp
    currNode = r(1); %the first number is the node and the following numbers are the neighbor indexes

    %if we are close to the node, start linear search
    if lineNum >= currNode && lineNum - currNode < 10
        while currNode < lineNum
            line = fgetl(fid);
            r = str2double(regexp(line, ' ', 'split'));
            currNode = r(1); %the first number is the node and the following numbers are the neighbor indexes
        end
        break;
        %otherwise continue with binary search
    else
        if currNode > lineNum
            maxPos = currPos;
            currPos = floor((currPos + minPos) / 2);
        else
            minPos = currPos;
            currPos = floor((currPos + maxPos) / 2);
        end    
    end
    
end

%fprintf('searched for %d, found %d\n', lineNum, currNode);
end