/*
   Pontificia Universidade Catolica do Rio Grande do Sul
   Projeto PISH
   Sub-projeto Prototipacao
   Responsavel: Prof. Ney Calazans

   Implementacao de uma Unidade Logica e Aritmetica (ULA)
   de 16 operacoes

   Autores: Eduardo Augusto Bezerra
            Luciano Minuzzi 

   Data da ultima alteracao: 27/03/97
   Alterado por: Eduardo Augusto Bezerra
*/


/*
 *  Target board definition
 */

const spec alu74181 = {
  fpga_type       = "Xilinx4000",
  fpga_chip       = "4003APC84-6",
  /*clock_pad       = "P13", */   /* Estamos utilizando gerador interno de clock */
  not_error_pad   = "",
  finish_pad      = "",
  carry_weight    = "50",           /* routing parameter */
  critical_weight = "100",          /* routing parameter */
  osc4_divider    = "F8M",        /* 500 kHz clock */
};

/* output to row of leds */
const spec leds = {
  data = { "P61", "P62", "P65", "P66", "P57", "P58", "P59", "P60" }
};

/* output to left-hand seven segment display DISPB */
const spec seg7a = {
  data = { "P39",  "P38",  "P36",  "P35",  "P29",  "P40",  "P44", "P37" }
};

/* input RESET */
const spec sw_reset = {
  data = { "P56" }
};

/* input SHOW */
const spec sw_show = {
  data = { "P18" }
};

/* input M */
const spec sw_m = {
  data = { "P25" }
};

/* input CN */
const spec sw_cn = {
  data = { "P26" }
};

/* input OPCODE */
const spec sw_opcode = {
  data = { "P19", "P20", "P23", "P24" }
};

/* input OPERA */
const spec sw_opera = {
  data = { "P3", "P4", "P5", "P6" }
};

/* input OPERB */
const spec sw_operb = {
  data = { "P7", "P8", "P9", "P10" }
};

const dw = 4;
const aw = 1;

void main(target = alu74181,
	  port (out) led_array = leds,
	  port (out) seven_one = seg7a,
	  port (in) reset = sw_reset,
	  port (in) show = sw_show,
	  port (in) m = sw_m,
	  port (in) cn = sw_cn,
	  port (in) opcode = sw_opcode,
	  port (in) opera = sw_opera,
	  port (in) operb = sw_operb)
{
	int a, b, c, f, aux7 : dw;
	int mode, aux, equal, x, y, c4, cin : aw;
	int display : 8;
	int auxdisp : 6;

	while(true)
	{
		opera ? a;
		operb ? b;
		opcode ? c;
		m ? mode;
		cn ? cin;

		if (mode == 1)		/* logica */
			case(c) 
			{
				0   : f = ~a;
				1   : f = ~(a & b);
				2   : f = ~a | b;
				3   : f = 1;
				4   : f = ~(a | b);
				5   : f = ~b;
				6   : f = ~(((~a) & b) | (a & (~b)));
				7   : f = a | ~b;                 
				8   : f = ~(a) & b;
				9   : f = ((~a) & b) | (a & (~b));
				10  : f = b;
				11  : f = a | b;
				12  : f = 0;
				13  : f = a & (~b);
				14  : f = a & b;
				15  : f = a;
			}
		else			/* aritmetica */
			case(c)
			{
				0   : f = a - 1 + cin;
				1   : f = (a & b) - 1 + cin;
				2   : f = (a & (~b)) - 1 + cin;
				3   : f = - 1 + cin; /* complemento 2 ??*/
				4   : f = a + (a | (~b)) + cin;
				5   : f = (a & b) + (a | (~b)) + cin;
				6   : f = a - b - 1 + cin;
				7   : f = (a | (~b)) + cin;                 
				8   : f = a + (a | b) + cin;
				9   : f = a + b + cin;
				10  : f = (a & (~b)) + (a | b) + cin;
				11  : f = (a | b) + cin;
				12  : f = a + a + a + cin;
				13  : f = (a & b) + a + cin;
				14  : f = (a & (~b)) + a + cin;
				15  : f = a + cin;
			}

		equal = (f == 15);
		/* Alterar as linhas abaixo na versao final */
		c4 = 0;
		x = 0;
		y = 0;

		/* coloca em auxdisp:  /M /CN equal y c4 x */

		auxdisp = ((((~mode @ ~cin) @ equal) @ y) @ c4) @ x;

		void prep_disp()
		{
			case (aux7)
			{
				0   : display = 0b00000011;
				1   : display = 0b10011111;
				2   : display = 0b00100101;
				3   : display = 0b00001101;
				4   : display = 0b10011001;
				5   : display = 0b01001001;
				6   : display = 0b01000001;
				7   : display = 0b00011111;                 
				8   : display = 0b00000001;
				9   : display = 0b00011001;
				10  : display = 0b00010001;
				11  : display = 0b11000001;
				12  : display = 0b01100011;
				13  : display = 0b10000101;
				14  : display = 0b01100001;
				15  : display = 0b01110001;
			}
		}

		/********** opcode **********/
		show ? aux;
		aux7 = c;
		prep_disp();
		seven_one ! display;

		/* manda p/ led: 0 0 /M /CN equal y c4 x */
		display = 0b00 @ auxdisp;
		led_array ! display;

		/********** operando A **********/
		show ? aux;
		aux7 = opera;
		prep_disp();
		seven_one ! display;

		/* manda p/ led: 0 1 /M /CN equal y c4 x */
		display = 0b01 @ auxdisp;
		led_array ! display;


		/********** operando B **********/
		show ? aux;
		aux7 = operb;
		prep_disp();
		seven_one ! display;

		/* manda p/ led: 1 0 /M /CN equal y c4 x */
		display = 0b10 @ auxdisp;
		led_array ! display;


		/********** resultado da operacao **********/
		show ? aux;
		aux7 = f;
		prep_disp();
		seven_one ! display;

		/* manda p/ led: 1 1 /M /CN equal y c4 x */
		display = 0b11 @ auxdisp;
		led_array ! display;
	}
}