#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>
#include <X11/keysym.h>

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <fcntl.h>

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "Xbit.h"

#define WINX		100
#define WINY		100
#define WINW		220
#define WINWH		110
#define WINH		250
#define WINHH		125

#define TAGLINE		242

#define RND(x)		(rand()%(x))

#define ITOF(x)		((x)<<8)
#define FTOI(x)		((x)>>8)

#define AT(p,x,y)	*((p)+(x)+(y)*WINW)

#define HISCFILE	"hisc.gal"

#define CH(x,y)		((x)*SCALE),((y)*SCALE),SCALE,SCALE

XSizeHints		size_hints;
ulong			black,white;
Display			*disp;
Window			top,sub;
Colormap		cm;
XFontStruct		*font;
XImage			*img;
char			*data;
char			*coll_data;

double			si[3600],co[3600];

static struct timespec	frame_start;

static XFuncControl	Key(Window w, XPressRelease s, XEvent *e);
static XFuncControl	ProcessTitle(void),ProcessIntro(void),ProcessGame(void),
			ProcessGameOver(void),ProcessHiScore(void),
			ProcessStartLevel(void);

/* Hiscore
*/
#define NOHI		10

typedef struct
	{
	char	name[4];
	int	score;
	int	level;
	double	percent;
	} HiSc;

HiSc			hisc[NOHI]=
			    {
			    {"A.B",10000,1,50.0},
			    {"C.D",5000,1,50.0},
			    {"E.F",3000,1,50.0},
			    {"G.H",1500,1,50.0},
			    {"I.J",1000,1,50.0},
			    {"K.L",800,1,50.0},
			    {"M.N",600,1,50.0},
			    {"O.P",400,1,50.0},
			    {"Q.R",200,1,50.0},
			    {"S.T",100,1,50.0},
			    };

/* Keycontrols
*/
static XWindowKeyCallback key[2]=
			    {
				{0,Key},
				{0,NULL}
			    };

#define NONE		-1
#define LEFT		0
#define RIGHT		1
#define FIRE		2
#define QUIT		3
#define PAUSE		4

int			inkey=NONE;
KeySym			last_keysym;
int			keymap[PAUSE+1]={False,False,False,False,False};


/* Sprite defs
*/
#define SPRW		8
#define SPRH		8

#define CHXSPR(a)	((a)*SPRW)

#define SPRMAXANIM	10
#define SPRANIMFRAME	10

unsigned int framectr	=0;
unsigned int sprframe	=0;

typedef struct
	{
	ulong		data[SPRH][SPRW];
	} SpriteDef;

typedef struct
	{
	int		no;
	char		data[SPRH*SPRW];
	} CollData;

typedef struct
	{
	int		no;
	SpriteDef	*spr[SPRMAXANIM];
	} SpriteAnim;

#define NOSPR		11

#define SHIP		0
#define ABULLET		1
#define SBULLET		2
#define GALAX1		3
#define GALAX2		4
#define GALAX3		5
#define FLAG1		6
#define FLAG10		7
#define ENTITY1		8
#define ALIENUFO	9
#define SAFESHIP	10

#include "sprdef.h"


/* Collision data codes
*/
#define CNONE		0
#define CSHIP		1
#define CALIEN		2
#define CABULL		3
#define CUBULLM		64
#define CUBULL(x)	(CUBULLM+(x))


/* Alien data
*/
#define NOSHOT		0
#define SISHOT		1
#define GASHOT		2
#define VISHOT		3

typedef struct
	{
	int	y;
	int	x;
	int	xi;
	int	yi;
	int	inuse;
	} Shot;

typedef struct
	{
	int	alive;
	int	type;
	Shot	shot;
	int	x,y;
	int	sx,sy;		/* Use for workspace for 'alternative' coords */
	} Alien;


#define MAXALIEN	100
int			no_aliens;
int			aliens_alive;

Alien			alien[MAXALIEN];


/* Explosion FX data
*/
#define MAXEXP		20
#define EXPPART		20
#define EXPLIFE		10
struct
	{
	int	inuse;
	int	cx[EXPPART],cy[EXPPART],x[EXPPART],y[EXPPART];
	} exp_fx[MAXEXP];

int			no_exp;


/* Level data
*/
#define NOLEV	11

struct
	{
	char	*title;
	int	sx,sy;
	int	shot_type;
	} levdata[NOLEV]=
		{
		    {"A CLASSIC...",0,1,SISHOT},
		    {"RUN AWAY - WATCH YOUR BACK",1,-2,GASHOT},
		    {"DIZZY",0,1,SISHOT},
		    {"VICIOUS CARNIVAL DUCKS!",0,1,VISHOT},
		    {"THE ALIEN WARFLEET - WAVE 1",-1,0,GASHOT},
		    {"BOUNCY",0,1,GASHOT},
		    {"THE 1ST COLLECTIVE",0,2,SISHOT},
		    {"THE 2ND COLLECTIVE",0,2,SISHOT},
		    {"THE 3RD COLLECTIVE",0,2,GASHOT},
		    {"THE ALIEN WARFLEET - WAVE 2",-1,0,GASHOT},
		    {"THE ALIEN MOTHERBRAIN",0,1,GASHOT},
		};



/* Colour vars
*/
#define NOCOLS		8
#define RNDCOL		(RND(NOCOLS-2)+2)
#define RGB(r,g,b)	{(r)*255,(g)*255,(b)*255}

static ulong		pix[NOCOLS];
static Colour		cols[NOCOLS]=
			    {
				RGB(0,0,0),		/* BLACK */
				RGB(255,255,255),	/* WHITE */
				RGB(255,100,100),	/* RED */
				RGB(100,255,100),	/* GREEN */
				RGB(100,100,255),	/* BLUE */
				RGB(255,255,0),		/* YELLOW */
				RGB(0,255,255),		/* CYAN */
				RGB(165,42,42)		/* BROWN */
			    };

#define BLACKI		0
#define WHITEI		1
#define REDI		2
#define GREENI		3
#define BLUEI		4
#define YELLOWI		5
#define CYANI		6
#define BROWNI		7

#define BLACK		pix[BLACKI]
#define WHITE		pix[WHITEI]
#define RED		pix[REDI]
#define GREEN		pix[GREENI]
#define BLUE		pix[BLUEI]
#define YELLOW		pix[YELLOWI]
#define CYAN		pix[CYANI]
#define BROWN		pix[BROWNI]


/* Parallax vars
*/
#define NOPLXST		30
#define NOPLXPL		3

struct
{
    int x;
    int y;
    ulong c;
} plxst[NOPLXST][NOPLXPL];


/* User bullet vars
*/
#define MAXBULL		100
#define BULLYI		-3

typedef struct
	{
	int	inuse,x,y;
	} UserBullet;

UserBullet		ubull[MAXBULL];
int			bullctr=0;

/* Control vars
*/
int	NOLIVES		=3;
int	NOBULL		=4;
int	BULLDEL		=10;
int	LEVEL		=0;
int	SCORE		=0;
int	PAUSESKIP	=0;
int	FONT		=0;

int	SCALE		=1;

static void	POKEIMG_NS(XImage *img, int x, int y, ulong c);
static void	POKEIMG_S(XImage *img, int x, int y, ulong c);

void		(*POKEIMG)(XImage *img, int x, int y, ulong c);


/* Game and control vars
*/
#define SHXINIT		WINW/2-SPRW/2
#define SHIPY		WINH-16
#define BLYINIT		SHIPY-8

int			quit=False;

int			score,level,levelndx,lives;
int			shipx,hit,miss,dead;
int			aliendead;

static void ReadScores(void);
static void WriteScores(void);
static void ClearExplosions(void);
static void NewExplosion(int x, int y, int w);
static void UpdateExplosions(void);
static void InitAlien(int f, int x, int y, int t);
static void SinCos(int cx, int cy, int a, int rx, int ry, int *x, int *y);
static void DefineAliens(void);
static void MoveAliens(void);
static void CheckAlienShot(Alien *a);
static void DrawAndKillAliens(void);
static void ClearBullets(void);
static void ClearKeys(void);
static void DoDebugMenu(void);
static int Paused(int k);
static void StartFrame(void);
static void EndFrame(void);


int main(int argc, char *argv[])
{
    void IntrHandler();
    int f,r,x,y,arg,noshm;
    unsigned long evmask;

    arg=1;
    noshm=False;

    if (argc>arg)
	if (!strcmp(argv[arg],"-noshm"))
	    {
	    noshm=True;
	    arg++;
	    }

    if (argc>arg)
	{
	SCALE=atoi(argv[arg]);

	if (SCALE<1)
	    {
	    fprintf(stderr,"scale param must be +ve\n");
	    exit(1);
	    }
	}

    if (SCALE==1)
	POKEIMG=POKEIMG_NS;
    else
	POKEIMG=POKEIMG_S;

    for(f=0;f<NOPLXST;f++)
	for(r=0;r<NOPLXPL;r++)
	    {
	    plxst[f][r].x=RND(WINW);
	    plxst[f][r].y=RND(WINH);
	    plxst[f][r].c=pix[RNDCOL];
	    }

    for(f=0;f<3600;f++)
	{
	si[f]=sin(M_PI/1800.0*f);
	co[f]=cos(M_PI/1800.0*f);
	}

    umask(0);
    srand(getpid());

    size_hints.flags=PPosition|PSize|PMinSize|PMaxSize;
    size_hints.x=WINX;
    size_hints.y=WINY;
    size_hints.width=size_hints.min_width=WINW*SCALE;
    size_hints.height=size_hints.min_height=WINH*SCALE;
    size_hints.max_width=WINW;
    size_hints.max_height=WINH;

    evmask=KeyPressMask|KeyReleaseMask;

    top=OpenWin(argc,argv,argv[0],
		   WINX,WINY,WINW*SCALE,WINH*SCALE,
		   WINW*SCALE,WINH*SCALE,
		   evmask,
		   &size_hints,&black,&white);

    key[0].w=top;

    DisableDoubleBuffer();
    disp=GetDisplay();

    DisablePixmap();

    if (noshm)
	DisableShm();

    img=CreateXImage();

    if (!(coll_data=(char *)malloc(WINW*WINH)))
	{
	fprintf(stderr,"Couldn't malloc() collision data\n");
	exit(1);
	}

    AllocColoursRGB(NOCOLS,pix,cols);

    for(f=0;f<NOSPR;f++)
	for(r=0;r<SPRMAXANIM;r++)
	    if (anim[f].spr[r])
		for(x=0;x<SPRW;x++)
		    for(y=0;y<SPRH;y++)
			anim[f].spr[r]->data[y][x]=
					pix[anim[f].spr[r]->data[y][x]];

    XAutoRepeatOff(disp);

    XISetFont(FONT);

    ReadScores();

    XDoWindows(NULL,NULL,key,ProcessTitle);

    while(!quit)
	{
	score=SCORE;
	level=LEVEL;
	levelndx=LEVEL%NOLEV;
	lives=NOLIVES;
	hit=0;
	miss=0;

	do
	    {
	    shipx=SHXINIT;
	    dead=False;

	    ClearBullets();
	    ClearExplosions();
	    ClearKeys();
	    XDoWindows(NULL,NULL,key,ProcessStartLevel);

	    DefineAliens();

	    ClearBullets();
	    ClearExplosions();
	    ClearKeys();
	    XDoWindows(NULL,NULL,key,ProcessGame);
	    } while (lives>0);

	if (score>-1)
	    {
	    ClearBullets();
	    ClearExplosions();
	    ClearKeys();
	    XDoWindows(NULL,NULL,key,ProcessGameOver);

	    ReadScores();
	    if (score>hisc[NOHI-1].score)
		{
		XDoWindows(NULL,NULL,key,ProcessHiScore);
		WriteScores();
		}
	    }

	ClearKeys();
	XDoWindows(NULL,NULL,key,ProcessTitle);
	}

    XAutoRepeatOn(disp);
    DestroyXImage(img);
    XCloseDisplay(disp);
}


/* ----------------------------------------------- KEY AND UTILITY
*/
static XFuncControl Key(Window w, XPressRelease s, XEvent *e)
{
    if (s==XRELEASE)
	{
	last_keysym=XK_VoidSymbol;

	switch(XLookupKeysym((XKeyEvent *)e,ShiftMapIndex))
	    {
	    case XK_Z:
	    case XK_z:
		keymap[LEFT]=False;
		break;

	    case XK_C:
	    case XK_c:
		keymap[RIGHT]=False;
		break;

	    case XK_period:
		keymap[FIRE]=False;
		break;

	    case XK_P:
	    case XK_p:
		keymap[PAUSE]=False;
		break;

	    case XK_Q:
	    case XK_q:
		keymap[QUIT]=False;
		break;

	    default:
		keymap[NONE]=False;
		break;
	    }
	}

    if (s==XPRESS)
	{
	inkey=NONE;

	switch(last_keysym=XLookupKeysym((XKeyEvent *)e,ShiftMapIndex))
	    {
	    case XK_Z:
	    case XK_z:
		inkey=LEFT;
		break;

	    case XK_C:
	    case XK_c:
		inkey=RIGHT;
		break;

	    case XK_period:
		inkey=FIRE;
		break;

	    case XK_P:
	    case XK_p:
		inkey=PAUSE;
		break;

	    case XK_Q:
	    case XK_q:
		inkey=QUIT;
		break;

	    default:
		inkey=NONE;
		break;
	    }

	if (inkey!=NONE)
	    keymap[inkey]=True;
	}

    return (XFUNCCONT);
}


static int GetKey(void)

{
    int k=inkey;

    if ((inkey==PAUSE)||(inkey==QUIT)||(inkey=FIRE))
	inkey=NONE;

    return(k);
}


static KeySym RawKey(void)

{
    KeySym k=last_keysym;

    last_keysym=XK_VoidSymbol;
    return(k);
}


static void ClearKeys(void)
{
    int f;

    inkey=NONE;

    for(f=0;f<5;f++)
	keymap[f]=False;
}


/* ----------------------------------------------- GRAPHICS UTILS
*/
static void Cls(int plx,int xi,int yi,int clr)
{
    static unsigned int col;
    int f,r,x,y;

    if (!((framectr++)%SPRANIMFRAME))
	{
	sprframe++;

	for(f=0;f<NOSPR;f++)
	    spr[f]=anim[f].spr[sprframe%anim[f].no];
	}

    if (clr)
	{
	/* memset(data,black,WINW*WINH*SCALE*SCALE); */
	ClsXImage(img);
	memset(coll_data,CNONE,WINW*WINH);
	}

    if (plx)
	{
	col++;

	for(f=0;f<NOPLXST;f++)
	    for(r=0;r<NOPLXPL;r++)
		{
		plxst[f][r].y+=((r+1)*yi);

		if (plxst[f][r].y<0)
		    plxst[f][r].y+=WINH;

		if (plxst[f][r].y>=WINH)
		    plxst[f][r].y-=WINH;

		plxst[f][r].x+=((r+1)*xi);

		if (plxst[f][r].x<0)
		    plxst[f][r].x+=WINW;

		if (plxst[f][r].x>=WINW)
		    plxst[f][r].x-=WINW;

		if (!(col%10))
		    plxst[f][r].c=pix[RNDCOL];

		(*POKEIMG)(img,plxst[f][r].x,plxst[f][r].y,plxst[f][r].c);
		}
	}
}


static void Update(void)
{
    DrawXImage(img);
    XSync(disp,False);
}


static void Centre(int y, ulong c, const char *s)
{
    XIprintf(img,CH(WINWH-strlen(s)*4,y),c,"%s",s);
}


static void POKEIMG_NS(XImage *img, int x, int y, ulong c)
{
    XPutPixel(img,x,y,c);
}


static void POKEIMG_S(XImage *img, int x, int y, ulong c)
{
    int sx,sy;

    for(sx=0;sx<SCALE;sx++)
	for(sy=0;sy<SCALE;sy++)
	    XPutPixel(img,x*SCALE+sx,y*SCALE+sy,c);
}


static void Plot(int x, int y, ulong c)
{
    if ((x>=0)&&(x<WINW)&&(y>=0)&&(y<WINH))
	(*POKEIMG)(img,x,y,c);
}


static void Sprite(int s, int x, int y, CollData *coll, int collcode)
{
    int sx,sy;

    if (coll)
	coll->no=0;

    for(sy=0;sy<SPRW;sy++)
	if (((y+sy)>=0)&&((y+sy)<WINH))
	    for(sx=0;sx<SPRW;sx++)
		if (spr[s]->data[sy][sx]!=BLACKI)
		    if (((x+sx)>=0)&&((x+sx)<WINW))
			{
			if (coll)
			    {
			    if (AT(coll_data,x+sx,y+sy)!=CNONE)
				coll->data[coll->no++]=AT(coll_data,x+sx,y+sy);

			    AT(coll_data,x+sx,y+sy)=collcode;
			    }

			(*POKEIMG)(img,x+sx,y+sy,spr[s]->data[sy][sx]);
			}
}


/* ----------------------------------------------- USER BULLET UTILS
*/
static void ClearBullets(void)
{
    int f;

    bullctr=0;

    for(f=0;f<NOBULL;f++)
	ubull[f].inuse=False;
}


static void NewBullet(int x, int y)
{
    int f;

    for(f=0;f<NOBULL;f++)
	if (!ubull[f].inuse)
	    {
	    ubull[f].inuse=True;
	    ubull[f].x=x;
	    ubull[f].y=y;
	    return;
	    }
}


static void DeleteBullet(int f)
{
    ubull[f].inuse=False;
}


static int BulletsInUse(void)
{
    int f,c;

    for(f=c=0;f<NOBULL;f++)
	if (ubull[f].inuse)
	    c++;

    return(c);
}


static int FreeBullets(void)
{
    return(BulletsInUse()<NOBULL);
}


static void UpdateBullets(void)
{
    CollData coll;
    int f;

    for(f=0;f<NOBULL;f++)
	if (ubull[f].inuse)
	    {
	    Sprite(SBULLET,ubull[f].x,ubull[f].y,&coll,CUBULL(f));

	    if ((ubull[f].y+=BULLYI)<-8)
		{
		ubull[f].inuse=False;
		miss++;
		}
	    }
}


/* ----------------------------------------------- TITLE SCREEN
*/
static XFuncControl ProcessTitle(void)

{
    static unsigned int ctr=0;
    static int xi[8]={ 0,-1,-1,-1, 0, 1, 1, 1};
    static int yi[8]={ 1, 1, 0,-1,-1,-1, 0, 1};
    int f,k;

    ctr++;

    StartFrame();
    Cls(True,xi[(ctr%800)/100],yi[(ctr%800)/100],True);

    Centre(20,YELLOW,"GALAXY INVADERS");
    Centre(12,YELLOW,"________________");
    Centre(22,YELLOW,"________________");

    if ((ctr/100)%2)
	{
	Centre(70,pix[RNDCOL],"ALL TIME HEROES");
	for(f=0;f<NOHI;f++)
	    XIprintf(img,CH(4,95+f*10),WHITE,
			"%2d %-3s %8d %5.1f%% %3d",
			    f+1,hisc[f].name,hisc[f].score,
				hisc[f].percent,hisc[f].level);
	    /*
	    XIprintf(img,CH(8,85+f*10),WHITE,
			"%2d  %3s  %8d  %5.1f%%",
			    f+1,hisc[f].name,hisc[f].score,hisc[f].percent);
	    */
	}
    else
	{
	Centre(100,RED,"  - 10 POINTS");
	Centre(115,RED,"  - 20 POINTS");
	Centre(130,RED,"  - 40 POINTS");

	Sprite(GALAX1,7*8,100,NULL,CNONE);
	Sprite(GALAX2,7*8,115,NULL,CNONE);
	Sprite(GALAX3,7*8,130,NULL,CNONE);
	}

    if ((ctr/10)%2)
	Centre(220,WHITE,"PRESS FIRE TO PLAY");

    DoDebugMenu();

    Update();
    EndFrame();

    k=GetKey();

    if (k==FIRE)
	return(XFUNCSTOP);
    else if (k==QUIT)
	{
	quit=True;
	return(XFUNCSTOP);
	}
    else
	return(XFUNCCONT);
}


static void DoDebugMenu(void)
{
    static int debug_menu=False;
    KeySym k;
    int f;

    if ((k=RawKey())=='r')
	debug_menu=!debug_menu;

    if (debug_menu)
	{
	Cls (False,0,0,True);

	for(f=0;f<128;f++)
	    XIprintf(img,CH((f%20)*8,(f/20)*8),CYAN,"%c",f);

	for(f=0;f<NOSPR;f++)
	    Sprite(f,f*8,80,NULL,CNONE);

	XIprintf(img,CH(0,TAGLINE-56),CYAN,
				"(f)  FONT        : %5d",FONT);
	XIprintf(img,CH(0,TAGLINE-48),CYAN,
				"(k)  PAUSE==SKIP : %5d",PAUSESKIP);
	XIprintf(img,CH(0,TAGLINE-40),CYAN,
				"(h)  SCORE       : %5d",SCORE);
	XIprintf(img,CH(0,TAGLINE-32),CYAN,
				"(l)  LIVES       : %5d",NOLIVES);
	XIprintf(img,CH(0,TAGLINE-24),CYAN,
				"(d)  GUN DELAY   : %5d",BULLDEL);
	XIprintf(img,CH(0,TAGLINE-16),CYAN,
				"(m)  NO BULLETS  : %5d",NOBULL);
	XIprintf(img,CH(0,TAGLINE-8),CYAN,
				"(s)  START LEVEL : %5d",LEVEL);
	XIprintf(img,CH(0,TAGLINE),CYAN,
				"(%s)",levdata[LEVEL%NOLEV].title);

	XIprintf(img,CH(0,100),CYAN,"(x)  SET TO DEFAULTS");
	XIprintf(img,CH(0,108),CYAN,"(o)  SET TO DEBUG");
	XIprintf(img,CH(0,116),CYAN,"(w)  SET TO SMALLER DEBUG");

	switch(k)
	    {
	    case 'f':
		FONT^=1;
		XISetFont(FONT);
		break;
	    case 'k':
		PAUSESKIP=!PAUSESKIP;
		break;
	    case 'h':
		SCORE=hisc[0].score;
		break;
	    case 'l':
		if ((++NOLIVES)>10)
		    NOLIVES=1;
		break;
	    case 'd':
		if (BULLDEL==10)
		    BULLDEL=1;
		else
		    BULLDEL=10;
		break;
	    case 'm':
		if (NOBULL==4)
		    NOBULL=MAXBULL;
		else
		    NOBULL=4;
		break;
	    case 's':
		LEVEL++;
		break;
	    case 'x':
		SCORE=0;
		NOLIVES=3;
		BULLDEL=10;
		NOBULL=4;
		LEVEL=0;
		break;
	    case 'o':
		PAUSESKIP=1;
		NOLIVES=1;
		BULLDEL=1;
		NOBULL=MAXBULL;
		LEVEL=NOLEV-1;
		SCORE=hisc[0].score;
		break;
	    case 'w':
		PAUSESKIP=1;
		LEVEL=NOLEV-1;
		break;
	    }
	}
}


/* ----------------------------------------------- START LEVEL
*/
static XFuncControl ProcessStartLevel(void)
{
    char s[80];

    StartFrame();
    Cls(True,levdata[levelndx].sx,levdata[levelndx].sy,True);

    sprintf(s,"LEVEL %d",level+1);

    Centre (50,YELLOW,s);
    Centre (100,RED,levdata[levelndx].title);

    Update();
    EndFrame();

    if (GetKey()!=NONE)
	return(XFUNCSTOP);

    return(XFUNCCONT);
}


/* ----------------------------------------------- PLAY LEVEL
*/
static XFuncControl ProcessGame(void)

{
    static unsigned int ctr=0;
    static int immune=0;
    int f,k;
    CollData coll;

    ctr++;

    k=GetKey();

    if (!PAUSESKIP)
	if (Paused(k))
	    return (XFUNCCONT);

    StartFrame();
    Cls(True,levdata[levelndx].sx,levdata[levelndx].sy,True);

    if (lives)
	for(f=0;f<lives;f++)
	    Sprite(SHIP,WINW-CHXSPR(f),TAGLINE,NULL,CNONE);

    if ((level+1)/10)
	for(f=0;f<(level+1)/10;f++)
	    Sprite(FLAG10,CHXSPR(f),TAGLINE,NULL,CNONE);

    if ((level+1)%10)
	for(f=0;f<(level+1)%10;f++)
	    Sprite(FLAG1,CHXSPR((level+1)/10+f),TAGLINE,NULL,CNONE);

    XIprintf(img,CH(0,0),YELLOW,"SCORE %d",score);

    if (!dead)
	{
	if (keymap[LEFT])
	    if (shipx>1)
		shipx-=2;

	if (keymap[RIGHT])
	    if (shipx<WINW-SPRW-1)
		shipx+=2;

	if (keymap[FIRE])
	    if (bullctr==0)
		{
		bullctr=BULLDEL;
		NewBullet(shipx,BLYINIT);
		}
	}

    if (bullctr)
	bullctr--;

    MoveAliens();

    UpdateBullets();
    UpdateExplosions();
    DrawAndKillAliens();

    if (!dead)
	{
	if (immune)
	    Sprite(SAFESHIP,shipx,SHIPY,&coll,CSHIP);
	else
	    Sprite(SHIP,shipx,SHIPY,&coll,CSHIP);

	if ((bullctr==0)&&(FreeBullets()))
	    Sprite(SBULLET,shipx,BLYINIT,NULL,CNONE);

	if (immune)
	    immune--;

	if ((coll.no)&&(!immune))
	    {
	    dead=True;

	    for(f=0;f<5;f++)
		{
		NewExplosion(shipx+SPRW/2-(SPRW/2*f),SHIPY+SPRH/2,6-f);
		NewExplosion(shipx+SPRW/2+(SPRW/2*f),SHIPY+SPRH/2,6-f);
		NewExplosion(shipx+SPRW/2,SHIPY+SPRH/2-(SPRH/2*f),6-f);
		}
	    }
	}

    Update();
    EndFrame();

    if (k==QUIT)
	{
	score=-1;
	lives=0;
	return(XFUNCSTOP);
	}

    if ((k==PAUSE)&&(PAUSESKIP))
	{
	level++;
	levelndx=(levelndx+1)%NOLEV;
	return(XFUNCSTOP);
	}

    if ((dead)&&(no_exp==0))
	{
	lives--;

	if (lives==0)
	    return(XFUNCSTOP);
	else
	    {
	    shipx=SHXINIT;
	    dead=False;
	    immune=100;
	    }
	}

    if ((aliendead)&&(no_exp==0)&&(!dead))
	{
	level++;
	levelndx=(levelndx+1)%NOLEV;

	if ((levelndx==0)&&(level>1))
	    lives++;

	return(XFUNCSTOP);
	}

    return(XFUNCCONT);
}


/* ----------------------------------------------- PAUSE CODE
*/
static void DoPause(void)
{
    static unsigned int c=0;

    c++;

    if ((c/10)%2)
	Centre(WINH/2-4,WHITE,"PAUSED");
    else
	Centre(WINH/2-4,YELLOW,"PAUSED");

    Update();
}


static int Paused(int k)
{
    static int paused=False;

    if (k==PAUSE)
	paused=!paused;

    if (paused)
	DoPause();

    return(paused);
}


/* ----------------------------------------------- GAME OVER
*/
static XFuncControl ProcessGameOver(void)
{
    static int posx=32;
    static unsigned int ctr=0;

    StartFrame();
    Cls (True,0,1,True);

    ctr++;

    XIprintf(img,CH(posx,32),YELLOW,"SHOTS FIRED : %6d",hit+miss);
    XIprintf(img,CH(posx,48),YELLOW,"HIT         : %6d",hit);
    XIprintf(img,CH(posx,64),YELLOW,"MISS        : %6d",miss);
    if (hit+miss)
	XIprintf(img,CH(posx,80),YELLOW,"PERCENTAGE  :  %5.1f",
				((double)hit/(hit+miss))*100.0);
    else
	XIprintf(img,CH(posx,80),YELLOW,"PERCENTAGE  :    0.0");

    if ((ctr/10)%2)
	Centre(120,WHITE,"GAME OVER");

    Update();
    EndFrame();

    if (GetKey()==NONE)
	return(XFUNCCONT);
    else
	return(XFUNCSTOP);
}


/* ----------------------------------------------- HI SCORES
*/
static void ReadScores(void)
{
    int fd,f;

    if ((fd=open(HISCFILE,O_RDONLY))==-1)
	return;

    for(f=0;f<NOHI;f++)
	read(fd,hisc+f,sizeof(HiSc));

    close(fd);
}


static void WriteScores(void)
{
    int fd,f;

    if ((fd=open(HISCFILE,O_WRONLY|O_CREAT|O_TRUNC,0777))==-1)
	{
	fprintf(stderr,"Failed to write hiscores!\n");
	return;
	}

    for(f=0;f<NOHI;f++)
	write(fd,hisc+f,sizeof(HiSc));

    close(fd);
}


static XFuncControl ProcessHiScore(void)
{
    static char *hisc_let="ABCDEFGHIJKLMNOPQRSTUVWXYZ.\177";
    static char *let;
    static int len=0;
    static char name[4];
    static int first=True;
    static int pos=0;
    static int bounce=0;
    int f,done=False;

    if (first)
	{
	len=0;
	strcpy(name,"");
	let=hisc_let;
	bounce=0;

	for(f=NOHI-1;f>-1;f--)
	    if (hisc[f].score<score)
		pos=f;

	if (pos<NOHI-1)
	    for(f=NOHI-1;f>pos;f--)
		hisc[f]=hisc[f-1];

	strcpy(hisc[pos].name,"");
	hisc[pos].score=score;
	hisc[pos].level=level+1;
	if (hit+miss)
	    hisc[pos].percent=((double)hit/(hit+miss))*100.0;
	else
	    hisc[pos].percent=0.0;

	first=False;
	}

    StartFrame();
    Cls (True,1,1,True);

    Centre(16,WHITE,"CONGRATULATIONS!");
    Centre(30,YELLOW,"ENTER YOUR INITIALS");
    Centre(40,YELLOW,"FOR THE ALL TIME HEROES");

    hisc[pos].name[len]=*let;
    hisc[pos].name[len+1]=0;

    for(f=0;f<NOHI;f++)
	XIprintf(img,CH(4,110+f*10),(f==pos) ? (CYAN) : (RED),
		    "%2d %-3s %8d %5.1f%% %3d",
			f+1,hisc[f].name,hisc[f].score,
			    hisc[f].percent,hisc[f].level);

    if ((keymap[LEFT])&&(!bounce))
	{
	bounce=10;
	if (let==hisc_let)
	    let=hisc_let+strlen(hisc_let)-1;
	else
	    let--;
	}

    if ((keymap[RIGHT])&&(!bounce))
	{
	bounce=10;
	if (!(*++let))
	    let=hisc_let;
	}

    switch (GetKey())
	{
	case FIRE:
	    len++;
	    break;
	}

    if (!keymap[LEFT] && !keymap[RIGHT] && !keymap[FIRE])
    	bounce=0;

    if (bounce)
	bounce--;

    Update();
    EndFrame();

    if (len==3)
	{
	first=True;
	return(XFUNCSTOP);
	}
    else
	return(XFUNCCONT);
}


/* ----------------------------------------------- PARTICLE EXPLOSION ROUTINES
*/
static void ClearExplosions(void)
{
    int f;

    no_exp=0;

    for(f=0;f<MAXEXP;f++)
	exp_fx[f].inuse=0;
}


static void NewExplosion(int x, int y, int w)
{
    int f,r;

    for(f=0;f<MAXEXP;f++)
	if (!exp_fx[f].inuse)
	    {
	    exp_fx[f].inuse=EXPLIFE*w;
	    for(r=0;r<EXPPART;r++)
		{
		exp_fx[f].cx[r]=x+RND(5)-2;
		exp_fx[f].cy[r]=y+RND(5)-2;
		exp_fx[f].x[r]=RND(5)-2;
		exp_fx[f].y[r]=RND(5)-2;
		}
	    no_exp++;
	    return;
	    }
}


static void UpdateExplosions(void)
{
    int f,r;

    for(f=0;f<MAXEXP;f++)
	if (exp_fx[f].inuse)
	    {
	    for(r=0;r<EXPPART;r++)
		Plot(exp_fx[f].cx[r]+=exp_fx[f].x[r],
		     exp_fx[f].cy[r]+=exp_fx[f].y[r],
		     CYAN);

	    if ((--exp_fx[f].inuse)==0)
		no_exp--;
	    }
}


/* ----------------------------------------------- ALIEN DEFINITION AND MOVEMENT
*/
int alienctr;
int alienyi;
int alienxi;

static void InitAlien(int f, int x, int y, int t)
{
    alien[f].alive=True;
    alien[f].type=t;
    alien[f].x=x;
    alien[f].y=y;
    alien[f].shot.inuse=False;
}


static void SinCos(int cx, int cy, int a, int rx, int ry, int *x, int *y)
{
    double dx,dy;

    dx=cx+si[a]*rx;
    dy=cy+co[a]*ry;

    *x=(int)dx;
    *y=(int)dy;
}


static void DefineAliens(void)
{
    int f,x,y;

    alienctr=0;

    switch(levelndx)
	{
	case 0:			/* CLASSIC */
	    no_aliens=0;

	    for (x=0;x<10;x++)
		for (y=0;y<3;y++)
		    {
		    InitAlien(no_aliens,x*16,y*16+50,GALAX3-y);
		    no_aliens++;
		    }

	    alienxi=1;

	    break;

	case 1:			/* RUN AWAY */
	    no_aliens=0;

	    for(f=0;f<20;f++)
		{
		InitAlien(no_aliens,RND(WINW-SPRW*2)+SPRW,RND(WINH/2)+WINH/4,
							    GALAX1+RND(3));
		no_aliens++;
		}

	    break;

	case 2:			/* DIZZY */
	    no_aliens=0;

	    for(y=0;y<3;y++)
		for(x=0;x<10;x++)
		    {
		    InitAlien(no_aliens,360*x,y*20+20,GALAX3-y);
		    alien[no_aliens].sx=alien[no_aliens].x;
		    alien[no_aliens].sy=alien[no_aliens].y;
		    no_aliens++;
		    }

	    break;

	case 3:			/* CARNIVAL */
	    no_aliens=0;

	    for(f=0;f<WINW/10;f++)
		{
		InitAlien(no_aliens,f*10,WINH-120,GALAX1+RND(3));
		no_aliens++;
		}

	    break;

	case 4:			/* FLEET WAVE 1 */
	    no_aliens=0;

	    for(x=0;x<24;x++)
		for(y=0;y<3;y++)
		{
		InitAlien(no_aliens,3+x*9,50+8*y,ALIENUFO);
		no_aliens++;
		}

	    break;

	case 5:			/* BOUNCY */
	    no_aliens=0;

	    for(f=0;f<20;f++)
		{
		InitAlien(no_aliens,RND(WINW),RND(WINH/2)+WINH/4,GALAX1);

		do
		   {
		   alien[no_aliens].sx=RND(3)-1;
		   } while (alien[no_aliens].sx==0);

		do
		   {
		   alien[no_aliens].sy=RND(5)-2;
		   } while (alien[no_aliens].sy==0);

		no_aliens++;
		}

	    break;

	case 6:			/* THE COLLECTIVE 1 */
	    no_aliens=0;

	    for(y=0;y<SPRH;y++)
		for(x=0;x<SPRW;x++)
		    if (galax1_1.data[y][x]!=BLACK)
			{
			InitAlien(no_aliens,0,0,GALAX1);
			alien[no_aliens].sx=x;
			alien[no_aliens].sy=y;
			no_aliens++;
			}
		    else if (galax1_2.data[y][x]!=BLACK)
			{
			InitAlien(no_aliens,0,0,GALAX1);
			alien[no_aliens].sx=x;
			alien[no_aliens].sy=y;
			no_aliens++;
			}
	    break;

	case 7:			/* THE COLLECTIVE 2 */
	    no_aliens=0;

	    for(y=0;y<SPRH;y++)
		for(x=0;x<SPRW;x++)
		    if (galax2_1.data[y][x]!=BLACK)
			{
			InitAlien(no_aliens,0,0,GALAX2);
			alien[no_aliens].sx=x;
			alien[no_aliens].sy=y;
			no_aliens++;
			}
		    else if (galax2_2.data[y][x]!=BLACK)
			{
			InitAlien(no_aliens,0,0,GALAX2);
			alien[no_aliens].sx=x;
			alien[no_aliens].sy=y;
			no_aliens++;
			}
	    break;

	case 8:			/* THE COLLECTIVE 2 */
	    no_aliens=0;

	    for(y=0;y<SPRH;y++)
		for(x=0;x<SPRW;x++)
		    if (galax3_1.data[y][x]!=BLACK)
			{
			InitAlien(no_aliens,0,0,GALAX3);
			alien[no_aliens].sx=x;
			alien[no_aliens].sy=y;
			no_aliens++;
			}
		    else if (galax3_2.data[y][x]!=BLACK)
			{
			InitAlien(no_aliens,0,0,GALAX3);
			alien[no_aliens].sx=x;
			alien[no_aliens].sy=y;
			no_aliens++;
			}
		    else if (galax3_3.data[y][x]!=BLACK)
			{
			InitAlien(no_aliens,0,0,GALAX3);
			alien[no_aliens].sx=x;
			alien[no_aliens].sy=y;
			no_aliens++;
			}
	    break;

	case 9:			/* FLEET WAVE 2 */
	    no_aliens=0;

	    for (y=0;y<3;y++)
		for (x=0;x<20;x++)
		    {
		    InitAlien(no_aliens,(WINW*x)/20,y*10+WINH/2-10,GALAX3-y);
		    no_aliens++;
		    }

	    break;

	case 10:		/* ALIEN MOTHERBRAIN */
	    no_aliens=0;

	    x=10;
	    y=3;
	    for(f=0;f<44;f++)
		{
		InitAlien(no_aliens,0,0,ENTITY1);
		alien[no_aliens].sx=x;
		alien[no_aliens].sy=y;

		no_aliens++;

		x+=y;

		if ((x<10)||(x>WINW/3))
		    {
		    y=-y;
		    x+=y;
		    }
		}
	    break;

	default:
	    printf("undefined level %d?\n",levelndx);
	    exit(1);
	}
}


static void MoveAliens(void)
{
    int f,x,y;
    int flag=False;

    alienctr++;

    switch(levelndx)
	{
	case 0:			/* CLASSIC */
	    for (f=0;f<no_aliens;f++)
		if (alien[f].alive)
		    {
		    alien[f].x+=alienxi;

		    if ((alien[f].x<1)||(alien[f].x>WINW-SPRW-1))
			flag=True;
		    }

	    if (flag)
		{
		alienxi=-alienxi;

		for (f=0;f<no_aliens;f++)
		    if (alien[f].alive)
			if ((alien[f].y+=4)>WINH)
			    alien[f].y-=WINH;
		}

	    break;

	case 1:			/* RUN AWAY */
	    for (f=0;f<no_aliens;f++)
		if (alien[f].alive)
		    if ((alien[f].y-=1)<=-SPRH)
			alien[f].y+=WINH+SPRH;

	    break;

	case 2:			/* DIZZY */
	   for(y=f=0;y<3;y++)
	       for(x=0;x<10;x++,f++)
		    if (alien[f].alive)
			{
			if (y%2)
			    {
			    if ((alien[f].sx+=10)>3599)
				alien[f].sx-=3600;
			    }
			else
			    {
			    if ((alien[f].sx-=10)<0)
				alien[f].sx+=3600;
			    }

			SinCos(WINW/2,WINH/2,alien[f].sx,alien[f].sy*2,
					alien[f].sy/2,&alien[f].x,&alien[f].y);
			}

	   break;

	case 3:			/* CARNIVAL */
	   for(f=0;f<no_aliens;f++)
		if (alien[f].alive)
		    if ((alien[f].x+=1)>=WINW)
			alien[f].x-=WINW+SPRW;

	   break;

	case 4:			/* FLEET WAVE 1 */
	   break;

	case 5:			/* BOUNCY */
	   for(f=0;f<no_aliens;f++)
		if (alien[f].alive)
		    {
		    alien[f].x+=alien[f].sx;
		    if ((alien[f].x<=0)||(alien[f].x>=WINW))
			alien[f].sx=-alien[f].sx;

		    alien[f].y+=alien[f].sy;
		    if ((alien[f].y<=0)||(alien[f].y>=SHIPY))
		        alien[f].sy=-alien[f].sy;
		    }
	   break;

	case 6:			/* THE COLLECTIVE 1 */
	   for(f=0;f<no_aliens;f++)
		if (alien[f].alive)
		    if (spr[GALAX1]->data[alien[f].sy][alien[f].sx]!=BLACK)
			{
			alien[f].x=WINW/2-(SPRW+2)*4+alien[f].sx*(SPRW+2);
			alien[f].y=WINH/2-(SPRH+2)*4+alien[f].sy*(SPRH+2);
			}
		    else
			{
			alien[f].x=-100;
			alien[f].y=SHIPY;
			}

	    break;

	case 7:			/* THE COLLECTIVE 2 */
	   for(f=0;f<no_aliens;f++)
		if (alien[f].alive)
		    if (spr[GALAX2]->data[alien[f].sy][alien[f].sx]!=BLACK)
			{
			alien[f].x=WINW/2-(SPRW+2)*4+alien[f].sx*(SPRW+2);
			alien[f].y=WINH/2-(SPRH+2)*4+alien[f].sy*(SPRH+2);
			}
		    else
			{
			alien[f].x=-100;
			alien[f].y=SHIPY;
			}

	    break;

	case 8:			/* THE COLLECTIVE 3 */
	   for(f=0;f<no_aliens;f++)
		if (alien[f].alive)
		    if (spr[GALAX3]->data[alien[f].sy][alien[f].sx]!=BLACK)
			{
			alien[f].x=WINW/2-(SPRW+2)*4+alien[f].sx*(SPRW+2);
			alien[f].y=WINH/2-(SPRH+2)*4+alien[f].sy*(SPRH+2);
			}
		    else
			{
			alien[f].x=-100;
			alien[f].y=SHIPY;
			}

	    break;

	case 9:			/* FLEET WAVE 2 */
	   for(y=f=0;y<3;y++)
	       for(x=0;x<20;x++,f++)
		    if (alien[f].alive)
			if (y%2)
			    {
			    if ((alien[f].x+=(y+1))>=WINW)
				alien[f].x-=WINW+SPRW;
			    }
			else
			    {
			    if ((alien[f].x-=(y+1))<=-SPRW)
				alien[f].x+=WINW+SPRW;
			    }

	   break;

	case 10:		/* ALIEN MOTHERBRAIN */
	    for(f=0;f<44;f++)
		if (alien[f].alive)
		    {
		    SinCos(WINW/2,WINH/2,f*81,alien[f].sx,
					alien[f].sx,&alien[f].x,&alien[f].y);

		    alien[f].sx+=alien[f].sy;

		    if ((alien[f].sx<10)||(alien[f].sx>WINW/3))
			{
			alien[f].sy=-alien[f].sy;
			alien[f].sx+=alien[f].sy;
			}
		    }
	    break;

	default:
	    printf("undefined level %d?\n",levelndx);
	    exit(1);
	}
}


static void CheckAlienShot(Alien *a)
{
    if ((levdata[levelndx].shot_type==NOSHOT)||(dead))
	return;

    if (a->shot.inuse)
	return;

    if (RND(200)<(1+level))
	{
	a->shot.inuse=True;

	a->shot.x=ITOF(a->x);
	a->shot.y=a->y+SPRH;

	switch (levdata[levelndx].shot_type)
	    {
	    case VISHOT:
		a->shot.yi=1+RND(2);
		break;
	    default:
		a->shot.yi=1;
		break;
	    }

	switch (levdata[levelndx].shot_type)
	    {
	    case SISHOT:
		a->shot.xi=0;
		break;

	    case VISHOT:
		if (shipx<a->x)
		    a->shot.xi=-16*a->shot.yi;
		else if (shipx<a->x)
		    a->shot.xi=16*a->shot.yi;
		else
		    a->shot.xi=0;
		break;

	    case GASHOT:
		if (shipx<a->x)
		    a->shot.xi=-64;
		else if (shipx>a->x)
		    a->shot.xi=64;
		else
		    a->shot.xi=0;
		break;

	    default:
		a->shot.xi=0;
		break;
	    }
	}
}


static void DrawAndKillAliens(void)
{
    CollData coll;
    int f,r;

    aliendead=True;

    for(f=0;f<no_aliens;f++)
	{
	if (alien[f].alive)
	    {
	    aliendead=False;

	    CheckAlienShot(&alien[f]);

	    Sprite(alien[f].type,alien[f].x,alien[f].y,&coll,CALIEN);

	    if (BulletsInUse())
		if (coll.no)
		    for(r=0;r<coll.no;r++)
			if (coll.data[r]&CUBULLM)
			    {
			    NewExplosion(alien[f].x+SPRW/2,alien[f].y+SPRH/2,1);

			    alien[f].alive=False;

			    switch(alien[f].type)
				{
				case GALAX1:
				    score+=10;
				    break;
				case GALAX2:
				    score+=20;
				    break;
				case GALAX3:
				    score+=40;
				    break;
				case ALIENUFO:
				case ENTITY1:
				    score+=50;
				    break;
				}

			    DeleteBullet(coll.data[r]-CUBULLM);
			    hit++;
			    r=coll.no+1;
			    }
	    }

	if (alien[f].shot.inuse)
	    {
	    aliendead=False;

	    alien[f].shot.x+=alien[f].shot.xi;
	    alien[f].shot.y+=alien[f].shot.yi;

	    if (alien[f].shot.y>WINH)
		alien[f].shot.inuse=False;
	    else
		Sprite(ABULLET,FTOI(alien[f].shot.x),alien[f].shot.y,
								&coll,CABULL);
	    }
	}
}


static void StartFrame(void)
{
    clock_gettime(CLOCK_REALTIME, &frame_start);
}


static void EndFrame(void)
{
    static const long FRAME = 1000000000 / 50;
    struct timespec now;
    struct timespec diff;

    clock_gettime(CLOCK_REALTIME, &now);

    diff.tv_sec = now.tv_sec - frame_start.tv_sec;
    diff.tv_nsec = now.tv_nsec - frame_start.tv_nsec;

    if (diff.tv_sec > 0)
    {
    	diff.tv_sec--;
	diff.tv_nsec += 1000000000;
    }

    if (diff.tv_nsec >= 1000000000)
    {
    	diff.tv_sec++;
	diff.tv_nsec -= 1000000000;
    }

    if (diff.tv_sec == 0 && diff.tv_nsec < FRAME)
    {
	diff.tv_nsec = FRAME - diff.tv_nsec;

	nanosleep(&diff, NULL);
    }
}