function saturation_cb(blk,callback,uplimsrc,uplim,lowlimsrc,lowlim)
% implements the callbacks for saturation block
switch callback
    case 'init'
        init_cb(blk,uplimsrc,uplim,lowlimsrc,lowlim)
    case 'uplimsrc'
        uplimsrc_cb(blk)
    case 'lowlimsrc'
        lowlimsrc_cb(blk)
    otherwise
        disp('saturation_cb: callback not implemented')
end


% uplimsrc_cb Dialog Callback
function uplimsrc_cb(blk)
en = get_param(blk,'MaskEnables');
switch get_param(blk,'uplimsrc')
    case 'external'
        en{2} = 'off';
    case 'internal'
        en{2} = 'on';
    otherwise
        disp('Should never get here')
end
set_param(blk,'MaskEnables',en)


% lowlimsrc_cb Dialog Callback
function lowlimsrc_cb(blk)
en = get_param(gcb,'MaskEnables');
switch get_param(gcb,'lowlimsrc')
    case 'external'
        en{4} = 'off';
    case 'internal'
        en{4} = 'on';
    otherwise
        disp('Should never get here')
end
set_param(gcb,'MaskEnables',en)


% init_cb Mask Initialization
function init_cb(blk,uplimsrc,uplim,lowlimsrc,lowlim)

% Check for upper limit source
switch uplimsrc
    case 'external'
        % Check for constant
        if strcmp(get_param([blk '/up'],'BlockType'),'Constant')
            replace([blk '/up'],'built-in/Inport');
        end
    case 'internal'
        % Check for inport
        if strcmp(get_param([blk '/up'],'BlockType'),'Inport')
            replace([blk '/up'],'built-in/Constant')
            set_param([blk '/up'],'Value','uplim')
        end
    otherwise
        disp('Error: uplimsrc = ')
        disp(uplimsrc)
end

% Check for lower limit source
switch lowlimsrc
    case 'external'
        % Check for constant
        if strcmp(get_param([blk '/lo'],'BlockType'),'Constant')
            replace([blk '/lo'],'built-in/Inport')
        end
    case 'internal'
        % Check for inport
        if strcmp(get_param([blk '/lo'],'BlockType'),'Inport')
            replace([blk,'/lo'],'built-in/Constant')
            set_param([blk '/lo'],'Value','lowlim')
        end
    otherwise
        disp('Error: lowlimsrc = ')
        disp(lowlimsrc)
end

% Renumber ports
% when using external upper limit, set blk/up port to 1
n = 1;
if strcmp(uplimsrc,'external')
    set_param([blk '/up'],'Port',num2str(n))
    n = 2; % increase n
end

% set u port to n
set_param([blk '/u'],'Port',num2str(n))

% when using external lower limit, set blk/lo port to n+1
if strcmp(lowlimsrc,'external')
    set_param([blk '/lo'],'Port',num2str(n+1))
end

% Local replace function
function replace(oldblock,newblock)
pos = get_param(oldblock,'Position');
orient = get_param(oldblock,'Orientation');
delete_block(oldblock);
add_block(newblock,oldblock,'Position',pos,...
    'Orientation',orient);