/*
 * File: ir_decoder.c
 * Date: 12.01.2013
 * Denis Zheleznyakov aka ZiB @ http://ziblog.ru
 */

#include "main.h"

struct ir_decoder_type ir_decoder;

static uint16_t button_code_received;
static uint32_t buffer_received_bits;

static int8_t counter_intervals;

static uint16_t interval_length_reference_minimum;
static uint16_t interval_length_reference_maximum;

//------------------------------------------------------------------------------
void ir_decoder_refresh(void)
{
	uint16_t timer_value;

	// считываем длительность имсульса в тиках таймера
	timer_value = TIM2->CCR1H << 8;
	timer_value += TIM2->CCR1L;

	// начало посылки (импульc больше информационного или равен нулю)
	if ((timer_value > ((IR_DECODER_PULSE_MAXIMUM * 1000UL) / IR_DECODER_TIMER_TICK)) || (timer_value == 0))
	{
		// обнуление приемного буффера
		buffer_received_bits = 0;

		// "сброс" счетика интервалов
		counter_intervals = (int8_t) (-IR_DECODER_NUMBER_OF_MISSING_INTERVAL);
	}
	else
	{
		// проверка максимальной длины посылки
		if (counter_intervals < IR_DECODER_COMMAND_LENGHT_MAXIMUM)
		{
			// декодирование посылки
			if (counter_intervals++ > 0)
			{
				// сравниваем с эталоном
				if ((timer_value < interval_length_reference_minimum) || (timer_value > interval_length_reference_maximum))
				{
					buffer_received_bits++;
				}

				// сдвигаем данные
				buffer_received_bits <<= 1;
			}

			//  запоминаем интервал
			interval_length_reference_minimum = timer_value;
			interval_length_reference_maximum = timer_value;

			// рассчитываем отклонение
			timer_value *= IR_DECODER_INTERVAL_REFERENCE_PERCENT;
			timer_value /= 100;

			// устанавливаем границы
			interval_length_reference_maximum += timer_value;
			interval_length_reference_minimum -= timer_value;
		}
	}
}

//------------------------------------------------------------------------------
void ir_decoder_refresh_timeout(void)
{
	uint16_t hash = 0xFFFF;
	uint8_t data;
	uint16_t temp;
	uint8_t byte_number;

	if (!ir_decoder.is_received)
	{
		for (byte_number = 0; byte_number < 4; byte_number++)
		{
			data = (uint8_t) buffer_received_bits;
			buffer_received_bits >>= 8;

			data ^= (uint8_t) hash;
			data ^= (uint8_t) (data << 4);
			temp = ((uint16_t) data << 8) | (uint8_t) (hash >> 8);
			temp ^= data >> 4;
			temp ^= data << 3;

			hash = temp;
		}

		ir_decoder.hash_code_received = hash;
		ir_decoder.is_received = TRUE;
	}
}