Adafruit_NMEA.h

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#ifndef ADAFRUIT_NMEA_H
#define ADAFRUIT_NMEA_H

#include <stddef.h>
#include <stdint.h>

#define NMEA_COMMAND_OVERHEAD 7 


typedef enum : uint8_t {
  NMEA_FRAME_INCOMPLETE,   
  NMEA_FRAME_VALID,        
  NMEA_FRAME_BAD_FORMAT,   
  NMEA_FRAME_BAD_CHECKSUM, 
  NMEA_FRAME_OVERFLOW 
} nmea_frame_status_t;

typedef struct {
  const char *data; 
  size_t length;    
} nmea_span_t;

typedef struct {
  nmea_frame_status_t status; 
  nmea_span_t text;    
  nmea_span_t address; 
  nmea_span_t fields;  
} nmea_sentence_t;

typedef enum : uint8_t {
  NMEA_NUMBER_VALID,       
  NMEA_NUMBER_MISSING,     
  NMEA_NUMBER_EMPTY,       
  NMEA_NUMBER_BAD_FORMAT,  
  NMEA_NUMBER_OUT_OF_RANGE 
} nmea_number_status_t;

typedef struct {
  nmea_number_status_t status; 
  int64_t coefficient;   
  uint8_t decimalPlaces; 
} nmea_decimal_t;

class Adafruit_NMEA {
public:
  Adafruit_NMEA(volatile char *firstBuffer, volatile char *secondBuffer,
                size_t capacity);
  Adafruit_NMEA(const Adafruit_NMEA &other) = delete;
  Adafruit_NMEA &operator=(const Adafruit_NMEA &other) = delete;
  void reset();
  nmea_frame_status_t feed(uint8_t byte, uint32_t receivedAtMs);
  nmea_span_t lastText() const;
  nmea_sentence_t lastSentence() const;
  uint32_t sentenceStartedAt() const;
  uint32_t sentenceReceivedAt() const;

  static nmea_sentence_t validate(const char *data, size_t length);
  static nmea_span_t nextField(nmea_span_t &remaining);
  static nmea_decimal_t parseDecimal(nmea_span_t field);
  static nmea_number_status_t validateDecimal(nmea_span_t field,
                                              bool allowNegative = true);
  static size_t buildCommand(char *output, size_t capacity, const char *body,
                             size_t bodyLength);

private:
  volatile char *_buffer;     
  volatile char *_lastBuffer; 
  size_t _capacity;       
  size_t _length;         
  size_t _lastLength;     
  uint32_t _startedAt;    
  uint32_t _lastStarted;  
  uint32_t _lastReceived; 
};

#endif // ADAFRUIT_NMEA_H