#include "project.h"

#define SCL 	GPIO6
#define SDA	GPIO7

static uint8_t
set (uint8_t sda, uint8_t scl)
{
  uint8_t ret;
  if (sda)
    gpio_set (GPIOB, SDA);
  else
    gpio_clear (GPIOB, SDA);

  if (scl)
    gpio_set (GPIOB, SCL);
  else
    gpio_clear (GPIOB, SCL);

  delay_us (10);
  ret = (gpio_get (GPIOB, SDA) & SDA) ? 1 : 0;

  return ret;
}




uint8_t
i2cb_send (uint8_t wot)
{
  uint8_t i;

  printf ("%02x", wot);

  for (i = 0; i < 8; ++i)
    {
      set (wot & 0x80, 0);
      set (wot & 0x80, 1);
      set (wot & 0x80, 0);
      wot <<= 1;
    }
  set (1, 0);
  i = set (1, 1);
  set (1, 0);

  printf ("%c", i ? '!' : '.');
  return i;
}

uint8_t
i2cb_send_addr (uint8_t addr, uint8_t rnw)
{
  return i2cb_send (addr << 1 | rnw);
}

uint8_t
i2cb_read (uint8_t ack)
{
  uint8_t i, wot = 0;

  for (i = 0; i < 8; ++i)
    {
      wot <<= 1;
      set (1, 0);
      wot |= set (1, 1);
      set (1, 0);
    }
  set (ack, 0);
  set (ack, 1);
  set (ack, 0);
  return wot;
}


void
i2cb_start (void)
{
  printf ("S");
  set (1, 1);
  set (0, 1);
  set (0, 0);
}

void
i2cb_stop (void)
{
  printf ("R\n");
  set (0, 0);
  set (0, 1);
  set (1, 1);
}


int
i2cb_start_transaction (uint8_t a, uint8_t rnw)
{
  i2cb_start ();
  return i2cb_send_addr (a, rnw);

}


void
i2cb_reset (void)
{
  i2cb_start ();
  i2cb_stop ();
  i2cb_start ();
  i2cb_stop ();
}



void
i2cb_scan (void)
{
  uint8_t r;
  uint16_t i;

  i2cb_reset ();

  printf ("Probing bus\n");
  for (i = 0; i < 128; ++i)
    {
      i2cb_start ();
      i2cb_stop ();
      i2cb_start ();
      r = i2cb_send ((i << 1) | I2C_WRITE);
      i2cb_stop ();

      if (!r)
        printf ("Found device at address 0x%x\n", i);
    }
  printf ("Done\n");
  i2cb_reset ();

}

void
i2cb_init (void)
{
  gpio_set_mode (GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL,
                 SCL);
  gpio_set_mode (GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN,
                 SDA);

  set (1, 1);
#ifdef DEBUG_I2C
  printf ("T11 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
#endif
  set (0, 1);
#ifdef DEBUG_I2C
  printf ("T01 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
#endif
  set (1, 0);
#ifdef DEBUG_I2C
  printf ("T10 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
#endif
  set (1, 1);
#ifdef DEBUG_I2C
  printf ("T11 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
#endif
}