index_to_blocks.m

function blocks = index_to_blocks(index)

index_length = length(index);
            
if any(index == 0)
    
    d_index = diff(index);
    
    starts = find(d_index == 1) + 1;
    
    stops = find(d_index == -1);
    
else
    
    starts = 1;
    
    stops = index_length;
    
end

if ~isempty(stops) || ~isempty(starts)
    
    if ~isempty(stops)
        
        if isempty(starts) || stops(1) < starts(1)
            
            starts = [1; starts];
            
        end
        
    end
    
    if ~isempty(starts)
        
        if isempty(stops) || starts(end) > stops(end)
            
            stops = [stops; index_length];
            
        end
        
    end
    
    stops(end) = min(stops(end), index_length);
    
    blocks = [starts stops];
    
else
    
    blocks = [];
    
end