#define GPIO_BASE 0x6000d000
#define SCL_BIT (1 << 3)
#define SDA_BIT (1 << 2)
#define GPIO_P_OFFSET 0x400

void delay() {
  for (volatile int i = 0; i < 500; i++)
    ;
}

void i2c_start() {
  *(volatile unsigned int *)(GPIO_BASE + GPIO_P_OFFSET + 0x18) =
      SDA_BIT; // SDA High
  *(volatile unsigned int *)(GPIO_BASE + GPIO_P_OFFSET + 0x18) =
      SCL_BIT; // SCL High
  delay();
  *(volatile unsigned int *)(GPIO_BASE + GPIO_P_OFFSET + 0x18) &=
      ~SDA_BIT; // SDA Low
  delay();
  *(volatile unsigned int *)(GPIO_BASE + GPIO_P_OFFSET + 0x18) &=
      ~SCL_BIT; // SCL Low
}

void _start() {
  *(volatile unsigned int *)(0x60006010) |= (1 << 8);

  *(volatile unsigned int *)(GPIO_BASE + GPIO_P_OFFSET + 0x10) =
      (SCL_BIT | SDA_BIT);
  *(volatile unsigned int *)(GPIO_BASE + GPIO_P_OFFSET + 0x14) =
      (SCL_BIT | SDA_BIT);

  i2c_start();

  *(volatile unsigned int *)(GPIO_BASE + 0x500 + 0x14) = 0x01;

  while (1) {
    *(volatile unsigned int *)(GPIO_BASE + 0x500 + 0x18) ^= 0x01; // Toggle TX
    for (volatile int i = 0; i < 10000; i++)
      ;
  }
}