i2c read write functions

uint8_t I2C_Read_Byte(uint8_t addr)
{
  uint8_t data = 0;
  uint8_t d;
  while (HAL_I2C_GetState(&hi2c1) != HAL_I2C_STATE_READY);
  d = HAL_I2C_Master_Transmit(&hi2c1, SLAVE_ADDR, &addr, 1, TIMEOUT);
  if ( d != HAL_OK) {
      return d;
  }

  while (HAL_I2C_GetState(&hi2c1) != HAL_I2C_STATE_READY);
  d = HAL_I2C_Master_Receive(&hi2c1, SLAVE_ADDR, &data, 1, TIMEOUT);
  if ( d != HAL_OK) {
      return d;
  }
  return data;
}

uint8_t I2C_Write_Byte(uint8_t addr, uint8_t data)
{
  uint8_t buf[] = {addr, data};
  uint8_t d;
  while (HAL_I2C_GetState(&hi2c1) != HAL_I2C_STATE_READY);
  d = HAL_I2C_Master_Transmit(&hi2c1, SLAVE_ADDR, buf, 2, TIMEOUT);
  if ( d != HAL_OK) {
      return d;
  }
  return HAL_OK;
}