#include "lib/mystd.h"

#include <avr/io.h>
#include <util/twi.h>

#include "lib/i2c.h"

static inline t_error i2c_wait(void) {
	uint16_t o = 0;
	// wait until done
	while (!(TWCR & BV(TWINT)) && o < 32768)
		o++;
	if (o >= 32768)
		return ERROR;
	return NO_ERROR;
}

void i2c_init(void) {
	// clear the status registers
	TWSR = 0x00;
	// set the i2c clock speed
	TWBR = ((F_CPU / I2C_CLOCK) - 16) / 2;
}

t_error i2c_start(void) {
	//     CLR INT    | SET MASTER |  ENABLE  ;
	TWCR = BV(TWINT) | BV(TWSTA) | BV(TWEN);
	ERR_RET(i2c_wait());

	return NO_ERROR;
}

t_error i2c_stop(void) {
	//     CLR INT    | ENABLE    |  STOP     ;
	TWCR = BV(TWINT) | BV(TWEN) | BV(TWSTO);

	return NO_ERROR;
}

t_error i2c_write(uint8_t data) {
	// set data to write
	TWDR = data;
	//     CLR INT    | ENABLE   ;
	TWCR = BV(TWINT) | BV(TWEN);
	ERR_RET(i2c_wait());

	return NO_ERROR;
}

t_error i2c_read_ack(uint8_t* out) {
	TWCR = BV(TWINT) | BV(TWEN) | BV(TWEA);
	ERR_RET(i2c_wait());

	*out = TWDR;
	return NO_ERROR;
}

t_error i2c_read_nack(uint8_t* out) {
	TWCR = BV(TWINT) | BV(TWEN);
	ERR_RET(i2c_wait());

	*out = TWDR;
	return NO_ERROR;
}