discrete-lib.h

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#ifndef DISCRETE_LIB_H_
#define DISCRETE_LIB_H_
 
#include <float.h>
 
 
/* Non-saturation constants */
 
 
#define POS_INF DBL_MAX
#define NEG_INF (-DBL_MAX)
 
 
/* Discrete-Time Data Structures */
 
 
typedef struct {
 
    double numerator[3];
 
    double denominator[3];
 
    double prev_input[2];
 
    double prev_output[2];
} Biquad;
 
typedef float Proportional;
 
typedef struct {
    Proportional gain;   
    double prev_input;   
    double prev_output;  
} Integrator;
 
typedef struct {
    Proportional gain;   
    double prev_input;   
    double prev_output;  
} Differentiator;
 
 
/* Initialization Functions */
 
 
void IntegratorInit(Proportional gain, double timestep, Integrator *result);
 
void DifferentiatorInit(Proportional gain,
                        double timestep,
                        Differentiator *result);
 
 
/* Time-Stepping Functions */
 
 
inline double Cascade(double input,
                      Biquad sys[],
                      int size,
                      double lower_lim,
                      double upper_lim);
 
inline double Integrate(double input,
                        Integrator *term,
                        double lower_lim,
                        double upper_lim);
 
inline double Differentiate(double input,
                            Differentiator *term,
                            double lower_lim,
                            double upper_lim);
 
inline double PID(double input,
                  Proportional *p,
                  Integrator *i,
                  Differentiator *d,
                  double lower_lim,
                  double upper_lim);
 
#endif  // DISCRETE_LIB_H_