module ec;

import system;

const
	S_char = 0;
	S_module = 1;
	
var
	col : integer;
	row : integer;
	look : char;
	sym : integer;

procedure Err0( s : array of char );
begin
	system.writestring( "Error line " );
	system.writeinteger( row );
	system.writestring( ", pos " );
	system.writeinteger( col );
	system.writestring( ": " );
	system.writeline( s );
end

(* TODO: segfault when defining parameter *)
procedure Err1N( s : array of char, n : integer );
begin
	system.writestring( "Error line " );
	system.writeinteger( row );
	system.writestring( ", pos " );
	system.writeinteger( col );
	system.writestring( ": " );
	system.writestring( s );
	system.writestring( " " );
	system.writeinteger( n );
end

procedure Halt;
begin
	system.halt( 1 )
end

procedure Abort0( s : array of char );
begin
	Err0( s );
	Halt;
end

procedure Abort1N( s : array of char, n : integer );
begin
	Err1N( s, n );
	Halt;
end

(* scanner *)

procedure getChar : char;
var
	c : char;
	
begin
	c := system.readchar( );
	if ( c = char( 0 ) ) do
		return c;
	end;
	col := col + 1;
	if ( c = char( 10 ) ) do
		col := 1;
		row := row + 1;
	end;
	return c;
end

procedure isWhite( c : char ) : boolean;
begin
	if ( c = char( 0 ) ) or ( c = char( 10 ) ) or ( c = char( 13 ) ) or ( c = char( 9 ) ) do
		return true
	else
		return false
	end
end

procedure skipWhite;
begin
	while ( isWhite( look ) ) do
		look := getChar( );
	end
end

procedure getSym : integer;
begin
	skipWhite;
	return S_char;
end

(* parser *)
	
procedure Expect( expect : integer );
begin
	if ( sym = expect ) do
		sym := getSym( );
	else
		(* TODO: symtable names
		Abort( "Expected symbol", symname[expect] );
		*)
		Abort0( "Expected symbol" );
	end
end

procedure init;
begin
	col := 1;
	row := 1;
	look := getChar( );
	sym := getSym( );
end

procedure prologue;
begin
	system.writeline( "[bits 32]" );
	system.writeline( "cpu 486" );
	system.writeline( "org 0x1000000" );
end

procedure doModule;
begin
	Expect( S_module );
(*
	look := getChar( );
	while ( look <> char( 0 ) ) do
		if not isWhite( look ) do
			system.writechar( look );
		end;
		look := getChar( );
	end;
*)
end

procedure epilogue;
begin
	system.writeline( "hlt" );
end

begin
	prologue;
	init;
	doModule;
	epilogue;
		
	system.halt( 0 );
end