#include <avr/io.h>

void I2C_Init()
{
	TWBR = 0x02;
	TWCR = (1<<TWEN);
	TWSR = 0x00;
	TWAR = 0b00000010;
}

void I2C_Start()
{
	TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
	while(!(TWCR & (1<<TWINT)));
}

void I2C_Stop()
{
	TWCR = (1<<TWINT)|(1<<TWSTO)|(1<<TWEN);
}

void I2C_Write(uint8_t data)
{
	TWDR = data;
	TWCR = (1<<TWINT)|(1<<TWEN);
	while(!(TWCR & (1<<TWINT)));
}

uint8_t I2C_Read_ACK()
{
	TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWEA);
	while(!(TWCR & (1<<TWINT)));
	return TWDR;
}

uint8_t I2C_Read_NO_ACK()
{
	TWCR = (1<<TWINT)|(1<<TWEN);
	while(!(TWCR & (1<<TWINT)));
	return TWDR;
}

uint8_t I2C_Status()
{
	uint8_t status;
	status = (TWSR & 0xF8);
	return status;
}

enum i2c_transfer_direction {
	 I2C_TRANSFER_WRITE = 0,
	 I2C_TRANSFER_READ  = 1,
};

enum status_code {
	STATUS_OK           = 0x00,
	STATUS_ERR_OVERFLOW	= 0x01,
	STATUS_ERR_TIMEOUT  = 0x02,
};

struct i2c_master_packet {
	 // Address to slave device
	 uint16_t address;
	 // Length of data array
	 uint16_t data_length;
	 // Data array containing all data to be transferred
	 uint8_t *data;
};

// Die nachfolgenden Funktionen werden von der Bibliothek benötigt

void i2c_master_init(void)
{
	I2C_Init();
}

enum status_code i2c_master_read_packet_wait(struct i2c_master_packet *const packet)
{
	I2C_Start();
	for (int i = 0; i < packet->data_length - 1; ++i) {
		packet->data[i] = I2C_Read_ACK();
	}
	packet->data[packet->data_length] = I2C_Read_NO_ACK();
	I2C_Stop();
	return STATUS_OK;
}

enum status_code i2c_master_write_packet_wait(struct i2c_master_packet *const packet)
{
	I2C_Start();
	for (int i = 0; i < packet->data_length; ++i) {
		I2C_Write(packet->data[i]);
	}
	I2C_Stop();
	
	return STATUS_OK;
}

enum status_code i2c_master_write_packet_wait_no_stop(struct i2c_master_packet *const packet)
{
	I2C_Start();
	for (int i = 0; i < packet->data_length; ++i) {
		I2C_Write(packet->data[i]);
	}
	I2C_Stop();
	
	return STATUS_OK;
}