#ifndef __GALAXY_H__
#define __GALAXY_H__

#include <sys/types.h>
#include <pthread.h>

/* sort forces by fabs before additinal. Additional by pair */ 
#define SORT_STAR

/* add third part of taylor series */ 
#define TAYLOR3

/* sort energy. impulse and moment by fabs before additinal. Additional by pair. Very slow */ 
/* #define SORT_ENERGYSTAR */

typedef struct {
	double	x;
	double	y;
	double	z;
} Vector;

typedef struct {
	double	mass;
	Vector	c; /* coordinate */
	Vector	v; /* velocity */
	Vector  a; /* acceleration */
#ifdef TAYLOR3
	Vector	pa;
#endif
} Star;

typedef struct {
	u_int32_t	nstars;
	Star	*stars;
	Vector	*forces; /* forces between i-th and j-th stars */

	/* stat data */
	double Impulse;
	double Moment;
	double potentialEnergy;
	double kineticEnergy;
	double elapsedTime;

	/* cfg options */
	double delta;
	double desiredDelta;
	
	double errorLimit;
	double error;

#ifdef TAYLOR3
	int	firsttime;
#endif
} Galaxy;


#define CNT_FARRAY(n)	( (((n)+1)*((n)+2)) >> 1 )
/* 
  XXX 0<=i<j<nstars 
  #define GET_FORCE(g, i, j)  ( (g)->forces + CNT_FARRAY(n) - CNT_FARRAY(n-i) + (j) - (i) - 1)
*/ 
#define GET_FORCE(g, i, j)  ( (g)->forces + (((j)*((j)+1))>>1) + i )


void initGalaxy(Galaxy *galaxy, u_int32_t nstars);
void forceGalaxy(Galaxy *galaxy);
void accelerationGalaxy(Galaxy *galaxy);
void stepGalaxy(Galaxy *galaxy, double delta);
void unstepGalaxy(Galaxy *galaxy, double delta);
void freeGalaxy(Galaxy *galaxy);
void EnergyImpulseGalaxy(Galaxy *galaxy); 
void initLiveGalaxy(Galaxy *galaxy);
void liveGalaxy(Galaxy *galaxy, pthread_mutex_t *mutex);
void printStar(Star *star);

#define G	(6.742e-11)
#endif