text: // sample struct that keeps 3 samples in memory
  struct sample_t {
    int values[6];
    int min;
    int max;
  } sample_t_default = {{0}, 0, 0};
  
  // safety code requires floats
  struct lookup_t {
    float x[3];
    float y[3];
  };
  
  void safety_rx_hook(CAN_FIFOMailBox_TypeDef *to_push);
  int safety_tx_hook(CAN_FIFOMailBox_TypeDef *to_send);
  int safety_tx_lin_hook(int lin_num, uint8_t *data, int len);
  uint32_t get_ts_elapsed(uint32_t ts, uint32_t ts_last);
  int to_signed(int d, int bits);
  void update_sample(struct sample_t *sample, int sample_new);
  bool max_limit_check(int val, const int MAX, const int MIN);
  bool dist_to_meas_check(int val, int val_last, struct sample_t *val_meas,
    const int MAX_RATE_UP, const int MAX_RATE_DOWN, const int MAX_ERROR);
  bool driver_limit_check(int val, int val_last, struct sample_t *val_driver,
    const int MAX, const int MAX_RATE_UP, const int MAX_RATE_DOWN,
    const int MAX_ALLOWANCE, const int DRIVER_FACTOR);
  bool rt_rate_limit_check(int val, int val_last, const int MAX_RT_DELTA);
  float interpolate(struct lookup_t xy, float x);
  
  typedef void (*safety_hook_init)(int16_t param);
  typedef void (*rx_hook)(CAN_FIFOMailBox_TypeDef *to_push);
  typedef int (*tx_hook)(CAN_FIFOMailBox_TypeDef *to_send);
  typedef int (*tx_lin_hook)(int lin_num, uint8_t *data, int len);
  typedef int (*fwd_hook)(int bus_num, CAN_FIFOMailBox_TypeDef *to_fwd);
  typedef CAN_FIFOMailBox_TypeDef * (*pump_hook)(void);
  
  void enable_message_pump(uint32_t divider, pump_hook hook);
  void update_message_pump_rate(uint32_t divider);
  void disable_message_pump(void);
  
  
  typedef struct {
    safety_hook_init init;
    rx_hook rx;
    tx_hook tx;
    tx_lin_hook tx_lin;
    fwd_hook fwd;
  } safety_hooks;
  
  // This can be set by the safety hooks.
  bool controls_allowed = 0;
  bool gas_interceptor_detected = 0;
  int gas_interceptor_prev = 0;
  
  // This is set by USB command 0xdf
  bool long_controls_allowed = 1;
  
  bool message_pump_active = false;
  
  // avg between 2 tracks
  #define GET_INTERCEPTOR(msg) (((GET_BYTE((msg), 0) << 8) + GET_BYTE((msg), 1) + ((GET_BYTE((msg), 2) << 8) + GET_BYTE((msg), 3)) / 2 ) / 2)
  