Motor_PMSM/Application/Math/fast_math.c

#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "math/fast_math.h"

/**
 * Fast sine and cosine implementation.
 *
 * See http://lab.polygonal.de/?p=205
 *
 * @param angle
 * The angle in radians
 * WARNING: Don't use too large angles.
 *
 * @param sin
 * A pointer to store the sine value.
 *
 * @param cos
 * A pointer to store the cosine value.
 */
void fast_sincos(float angle, float *sin, float *cos) {
	//always wrap input angle to -PI..PI
	while (angle < -M_PI) {
		angle += 2.0f * M_PI;
	}

	while (angle >  M_PI) {
		angle -= 2.0f * M_PI;
	}

	//compute sine
	if (angle < 0.0f) {
		*sin = 1.27323954f * angle + 0.405284735f * angle * angle;

		if (*sin < 0.0f) {
			*sin = 0.225f * (*sin * -*sin - *sin) + *sin;
		} else {
			*sin = 0.225f * (*sin * *sin - *sin) + *sin;
		}
	} else {
		*sin = 1.27323954f * angle - 0.405284735f * angle * angle;

		if (*sin < 0.0f) {
			*sin = 0.225f * (*sin * -*sin - *sin) + *sin;
		} else {
			*sin = 0.225f * (*sin * *sin - *sin) + *sin;
		}
	}

	// compute cosine: sin(x + PI/2) = cos(x)
	angle += 0.5f * M_PI;
	if (angle >  M_PI) {
		angle -= 2.0f * M_PI;
	}

	if (angle < 0.0f) {
		*cos = 1.27323954f * angle + 0.405284735f * angle * angle;

		if (*cos < 0.0f) {
			*cos = 0.225f * (*cos * -*cos - *cos) + *cos;
		} else {
			*cos = 0.225f * (*cos * *cos - *cos) + *cos;
		}
	} else {
		*cos = 1.27323954f * angle - 0.405284735f * angle * angle;

		if (*cos < 0.0f) {
			*cos = 0.225f * (*cos * -*cos - *cos) + *cos;
		} else {
			*cos = 0.225f * (*cos * *cos - *cos) + *cos;
		}
	}
}

/**
 * Make sure that 0 <= angle < 360
 *
 * @param angle
 * The angle to normalize.
 */
void fast_norm_angle(float *angle) {
	*angle = fmodf(*angle, 360.0f);

	if (*angle < 0.0f) {
		*angle += 360.0f;
	}
}

void normal_sincosf(float angle, float *sin, float *cos) {
	*sin = sinf(angle);
	*cos = cosf(angle);
}