/* Timer driver */

#include "aduc812.h"
#include "timer.h"
#include "interrupt.h"

unsigned char time;
unsigned long init_value;

unsigned char emulated_tank_volume = 30;
unsigned char medium_volume = 30;
unsigned char low_add_volume = 20;
unsigned char period = 50;
unsigned char dif = 3;
unsigned char threshold = 4;
unsigned char del = 0;


unsigned char get_tank_value() {
	return emulated_tank_volume;
}

void emulator()
{
	//if (time % period == 0)  emulated_tank_volume = emulated_tank_volume - 1;
	//if (time % period == 0) emulated_tank_volume = emulated_tank_volume - next_rand() % dif;
	if (time == 254) 
	{
		del++;
		if (del == 10)
		{
			del = 0;
			if (emulated_tank_volume > 1)
			emulated_tank_volume = emulated_tank_volume - next_rand() % dif;
		}
	}
	if (emulated_tank_volume < threshold) emulated_tank_volume = next_rand() % medium_volume + low_add_volume;
}

void process_timer(void) interrupt 1
{
	time++;
	TH0 = (0xFF00 & init_value) >> 8;
	TL0 = (0x00FF & init_value);
	emulator();
}

// Получение текущей метки времени в миллисекундах.
unsigned char get_current_millis(void)
{
	unsigned char temp = 0;
	
	EA = 0;
	temp = time;
	EA = 1;

	return temp;
}

// Измерение количества миллисекунд, прошедших с временной метки t0 и до текущего времени.
unsigned char get_time_interval(unsigned char t0)
{
	return get_current_millis() - t0;
}

// Задержка на t миллисекунд.
void sleep(unsigned char delay)
{
	unsigned char startTime = get_current_millis();
	
	while (get_time_interval(startTime) < delay);
}

// Инициализация таймера.
void init_timer(unsigned long frequency)
{
	time = 0;

	set_vector(0x200B, (void *) process_timer);
	
	init_value = 65536 - (921600 / frequency);
	TH0 = (0xFF00 & init_value) >> 8;
	TL0 = (0x00FF & init_value);

	// Разрешение прерываний от таймера 0
	TMOD |= 0x01;	
	ET0 = 1;		// Маска прерывания таймера 1
	TR0 = 1;		// Разрешаем таймеру 0 считать
}

unsigned char pre_rand = 17;
unsigned char next_rand(void) 
{
	unsigned char timerValue = get_current_millis();
	unsigned char newRandom = (timerValue * pre_rand + timerValue) % 256;
	pre_rand = newRandom;
	return newRandom;
}