rms.h

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#ifndef _RMS_H
#define _RMS_H
 
#include <math.h>
 
#define RMS_BUF_SIZE 64
 
typedef struct {
        float        buffer[RMS_BUF_SIZE];
        unsigned int pos;
        float        sum;
} rms_env;
 
rms_env *rms_env_new();
 
static inline float rms_env_process(rms_env *r, float x);
 
void rms_env_reset(rms_env *r);
 
void rms_env_free(rms_env *r);
 
inline static float rms_env_process(rms_env *r, const float x)
{
        r->sum -= r->buffer[r->pos];
        r->sum += x;
        if (r->sum < 1.0e-6) {
                r->sum = 0.0f;
        }
        r->buffer[r->pos] = x;
        r->pos = (r->pos + 1) & (RMS_BUF_SIZE - 1);
 
        return sqrt(r->sum / (float)RMS_BUF_SIZE);
}
 
#endif