periphery = require('periphery')
Serial 	  = periphery.Serial

serial 	  = Serial("/dev/ttyAMA0",9600)

COMMAND_POSITION	=	0x19
COMMAND_POSITION_X	=	0x13
COMMAND_POSITION_Y	=	0x11

COMMAND_01H			=	0x01
COMMAND_03H			=	0x03

COMMAND_CURSOR_OFF 	=	0x0E

COMMAND_BLINK		=	0x0B
COMMAND_UNBLINK		=	0x0C

COMMAND_CR			=	0x0D
COMMAND_LF			=	0x0A

blinkFlag           =   false

posX                =   0
posY                =   0

function checkY(y)
	if y < 0 then 
	    y = 0 
	end
	if y > 5 then
		y = 5
	end
	posY = y
	return y
end

function checkX(x) 
	if x < 0  then
		x = 39;
		posY = posY - 1
		checkY(posY)
	end
	if x > 39  then
		if posY == 5 then
			x = 39;
		else 
			x = 0;
			posY = posY + 1
			checkY(posY);
		end
    end
    posX = x
	return x
end

function gotoXY(x,y) 
	checkX(x);
	checkY(y);
end

function lineFeed(void) 
    posY = posY + 1
	gotoXY(posX, checkY(posY));
end

function carriageReturn(void) 
	gotoXY(0, posY);
end

while (1) do
    while serial:poll(100) do
    	local c = serial:read(1)
    	if c:byte() == COMMAND_POSITION then
    	    local cmd = serial:read(1)
    	    if cmd:byte() == COMMAND_POSITION_X then
    	        local x = string.byte(serial:read(1))
    	        gotoXY(x,posY)
    	    elseif cmd:byte() == COMMAND_POSITION_Y then
    	        local y = string.byte(serial:read(1))
    	        gotoXY(posX,y)
            end
    	elseif c:byte() == COMMAND_03H then
    	    serial:read(1)
    	    serial:read(1)
    	elseif c:byte() == COMMAND_BLINK then
		        blinkFlag = true
		elseif c:byte() == COMMAND_UNBLINK then
		        blinkFlag = false
		elseif c:byte() == COMMAND_CURSOR_OFF then
		        -- curs_set(0);
		elseif c:byte() == COMMAND_CR then
		        carriageReturn()
		elseif c:byte() == COMMAND_LF then
		        lineFeed()
		else
		    if  c:byte() >= 0x20 and c:byte() < 0x7F then
		    print(c.." at "..posX.." "..posY.."\n")
		    posX = posX + 1
	        checkX(posX)
    	    --[[
    	    	if ( c >= 0x20 && c < 0x7F ) {
			(c==buf_char[y_now][x_now])?(buf_chng[y_now][x_now]='n'):(buf_chng[y_now][x_now]='y');
			(BLINK_FLAG?(buf_args[y_now][x_now] = 'b'):( buf_args[y_now][x_now] = 'n'));
			buf_char[y_now][x_now] = c;
			checkX(++x_now);
			--]]
	    	else
			    print("Unknown: "..c:byte().."\n");
		    end
    	end
--
--    	io.stderr:write(string.format('%02X ',c:byte(1)));
    end 
end