MC100/Applications/math/fast_math.h

#ifndef _Fast_Math_H__
#define _Fast_Math_H__

// Constants
#define ONE_BY_SQRT3			(0.57735026919f) // 1/sqrt(3)
#define TWO_BY_SQRT3			(2.0f * 0.57735026919f)
#define SQRT3_BY_2				(0.86602540378f)
#define SQRT3                   (1.73205080757f)
#define SQRT2_BY_SQRT3          (0.8164966f)
#define M_PI (3.14159265f)

#define ONE_BY_SQRT3_Q14  (9459L) //0.57735026919 * 16384.0F
#define SQRT3_BY_2_Q14    (14189L)//0.86602540378 * 16384.0F
#define TWO_BY_SQRT3_Q14  (18918L)

#ifndef SQ
#define SQ(x) ((x)*(x))
#endif
void fast_sincos(float angle, float *sin, float *cos);
void fast_norm_angle(float *angle);
void normal_sincosf(float angle, float *sin, float *cos);

/**
 * A simple low pass filter.
 *
 * @param value
 * The filtered value.
 *
 * @param sample
 * Next sample.
 *
 * @param filter_constant
 * Filter constant. Range 0.0 to 1.0, where 1.0 gives the unfiltered value.
 */
#define LowPass_Filter(value, sample, filter_constant)	(value = value * (1.0f - filter_constant) + sample * filter_constant)

#endif /* _Fast_Math_H__ */