From 3b53300ca26f14f13b2b1ea8bec383733b16605c Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Thu, 28 Dec 2017 23:27:31 -0500
Subject: [PATCH] mode7: update fixed-point starfield

---
 gr-sim/Makefile          |  10 +-
 gr-sim/starfield.c       |  75 +++++++++---
 gr-sim/starfield_fixed.c | 252 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 318 insertions(+), 19 deletions(-)
 create mode 100644 gr-sim/starfield_fixed.c

diff --git a/gr-sim/Makefile b/gr-sim/Makefile
index 39814b09..4e00c808 100644
--- a/gr-sim/Makefile
+++ b/gr-sim/Makefile
@@ -5,7 +5,7 @@ LFLAGS = -lm
 SDL_LIBS= `sdl-config --libs`
 SDL_INCLUDE= `sdl-config --cflags`
 
-all:	fade fixed_point rainbow sparkle starfield kaleido \
+all:	fade fixed_point rainbow sparkle starfield starfield_fixed kaleido \
 	tfv mode7_demo text tfv_multiply
 
 
@@ -163,12 +163,18 @@ starfield:	starfield.o gr-sim.o
 starfield.o:	starfield.c
 	$(CC) $(CFLAGS) -c starfield.c
 
+starfield_fixed:	starfield_fixed.o gr-sim.o
+	$(CC) $(LFLAGS) $(SDL_LIBS) -o starfield_fixed starfield_fixed.o gr-sim.o
+
+starfield_fixed.o:	starfield_fixed.c
+	$(CC) $(CFLAGS) -c starfield_fixed.c
+
 
 gr-sim.o:	gr-sim.c gr-sim.h apple2_font.h
 	$(CC) $(CFLAGS) $(SDL_INCLUDE) -c gr-sim.c
 
 clean:	
-	rm -f *~ *.o gr-sim rainbow sparkle starfield kaleido \
+	rm -f *~ *.o gr-sim rainbow sparkle starfield starfield_fixed kaleido \
 			tfv text mode7_demo fade fixed_point tfv_multiply
 
 
diff --git a/gr-sim/starfield.c b/gr-sim/starfield.c
index 28b3d647..3fc042e3 100644
--- a/gr-sim/starfield.c
+++ b/gr-sim/starfield.c
@@ -32,10 +32,12 @@ static void double_to_fixed(double d, struct fixed_type *f) {
 
 }
 
+#if 0
 static void print_fixed(struct fixed_type *f) {
 
         printf("%02X.%02X",f->i,f->f);
 }
+#endif
 
 static void fixed_add(struct fixed_type *x, struct fixed_type *y, struct fixed_type *z) {
         int carry;
@@ -66,29 +68,73 @@ static double fixed_to_double(struct fixed_type *f) {
 
 static struct star_type stars[NUMSTARS];
 
+static	int random_table[256];
+static	int random_pointer=0;
+
+static void random_star(int i) {
+
+		/* -128 to 128 */
+
+		/* Should we xor? */
+		stars[i].x.i=random_table[random_pointer++];
+		if (random_pointer>255) random_pointer=0;
+
+		stars[i].x.f=random_table[random_pointer++];
+		if (random_pointer>255) random_pointer=0;
+
+		stars[i].y.i=random_table[random_pointer++];
+		if (random_pointer>255) random_pointer=0;
+		stars[i].y.f=random_table[random_pointer++];
+		if (random_pointer>255) random_pointer=0;
+
+//		double_to_fixed( (drand48()-0.5)*spreadx,&stars[i].x);
+//		double_to_fixed( (drand48()-0.5)*spready,&stars[i].y);
+
+		/* 0.1 to 16 */
+		stars[i].z.i=random_table[random_pointer++]/16;
+		if (random_pointer>255) random_pointer=0;
+		stars[i].z.f=0x1;
+
+//		double_to_fixed( ((drand48())*spreadz)+0.1,&stars[i].z);
+//		print_fixed(&stars[i].x);
+//		printf(",");
+//		print_fixed(&stars[i].y);
+//		printf(",");
+//		print_fixed(&stars[i].z);
+//		printf("\n");
+
+
+//	double_to_fixed((drand48()-0.5)*spreadx,&stars[i].x);
+//	double_to_fixed((drand48()-0.5)*spready,&stars[i].y);
+//	stars[i].z.i=spreadz;
+
+}
+
 int main(int argc, char **argv) {
 
 	int ch,i;
 
-	int spreadx=256;
-	int spready=256;
+//	int spreadx=256;
+//	int spready=256;
 	int spreadz=16;
 	struct fixed_type speedz;
+	
+
+
+	for(i=0;i<256;i++) {
+		random_table[i]=rand()%256;
+		printf("%d\n",random_table[i]);
+	}
 
 	double_to_fixed(-0.25,&speedz);
 
 	grsim_init();
 
+	/* Should NUMSTARS be prime to help with randomness */
+
 	for(i=0;i<NUMSTARS;i++) {
-		double_to_fixed( (drand48()-0.5)*spreadx,&stars[i].x);
-		double_to_fixed( (drand48()-0.5)*spready,&stars[i].y);
-		double_to_fixed( ((drand48())*spreadz)+0.1,&stars[i].z);
-		print_fixed(&stars[i].x);
-		printf(",");
-		print_fixed(&stars[i].y);
-		printf(",");
-		print_fixed(&stars[i].z);
-		printf("\n");
+		random_star(i);
+
 	}
 	gr();
 
@@ -121,12 +167,7 @@ int main(int argc, char **argv) {
 			if ((tempx<0) || (tempy<0) || (tempx>=40) ||
 				(tempy>=40)) {
 
-				double_to_fixed((drand48()-0.5)*spreadx,
-					&stars[i].x);
-				double_to_fixed((drand48()-0.5)*spready,
-					&stars[i].y);
-				stars[i].z.i=spreadz;
-
+				random_star(i);
 			}
 			else {
 				color_equals(stars[i].color);
diff --git a/gr-sim/starfield_fixed.c b/gr-sim/starfield_fixed.c
new file mode 100644
index 00000000..dbb1d68f
--- /dev/null
+++ b/gr-sim/starfield_fixed.c
@@ -0,0 +1,252 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "gr-sim.h"
+
+#define NUMSTARS	16
+
+struct fixed_type {
+	char i;
+	unsigned char f;
+};
+
+
+struct star_type {
+	struct fixed_type x;
+	struct fixed_type y;
+	int z;
+	int color;
+};
+
+static void double_to_fixed(double d, struct fixed_type *f) {
+
+        int temp;
+
+        temp=d*256;
+
+        f->i=(temp>>8)&0xff;
+
+        f->f=temp&0xff;
+
+
+}
+
+#if 0
+static void print_fixed(struct fixed_type *f) {
+
+        printf("%02X.%02X",f->i,f->f);
+}
+#endif
+
+#if 0
+static void fixed_add(struct fixed_type *x, struct fixed_type *y, struct fixed_type *z) {
+        int carry;
+        short sum;
+
+        sum=(short)(x->f)+(short)(y->f);
+
+        if (sum>=256) carry=1;
+        else carry=0;
+
+        z->f=sum&0xff;
+
+        z->i=x->i+y->i+carry;
+}
+#endif
+
+#if 0
+static double fixed_to_double(struct fixed_type *f) {
+
+	double d;
+
+        d=f->i;
+        d+=((double)(f->f))/256.0;
+
+//      printf("(%02x.%02x)=%lf\n",f->i,f->f,*d);
+
+	return d;
+}
+#endif
+
+static struct star_type stars[NUMSTARS];
+
+static int random_table[256];
+static int random_pointer=0;
+
+static int z_table[256];
+
+static void random_star(int i) {
+
+	/* -128 to 128 */
+
+	/* Should we xor? */
+	stars[i].x.i=random_table[random_pointer++];
+	if (random_pointer>255) random_pointer=0;
+
+	stars[i].x.f=random_table[random_pointer++];
+	if (random_pointer>255) random_pointer=0;
+
+	stars[i].y.i=random_table[random_pointer++];
+	if (random_pointer>255) random_pointer=0;
+	stars[i].y.f=random_table[random_pointer++];
+	if (random_pointer>255) random_pointer=0;
+
+//	double_to_fixed( (drand48()-0.5)*spreadx,&stars[i].x);
+//	double_to_fixed( (drand48()-0.5)*spready,&stars[i].y);
+
+	/* 0 to 63 corresponding to  */
+	stars[i].z=random_table[random_pointer++]&0x3f;
+	if (random_pointer>255) random_pointer=0;
+	if (stars[i].z>58) stars[i].z=0;
+
+//	double_to_fixed( ((drand48())*spreadz)+0.1,&stars[i].z);
+//	print_fixed(&stars[i].x);
+//	printf(",");
+//	print_fixed(&stars[i].y);
+//	printf(",");
+//	print_fixed(&stars[i].z);
+//	printf("\n");
+
+
+//	double_to_fixed((drand48()-0.5)*spreadx,&stars[i].x);
+//	double_to_fixed((drand48()-0.5)*spready,&stars[i].y);
+//	stars[i].z.i=spreadz;
+
+}
+
+static void fixed_mul(struct fixed_type *x, struct fixed_type *y, struct fixed_type *z) {
+
+        int a,b,c;
+
+        a=((x->i)<<8)+(x->f);
+        b=((y->i)<<8)+(y->f);
+
+        c=a*b;
+//      printf("%x %x %x\n",a,b,c);
+
+        c>>=8;
+
+        z->i=(c>>8);
+        z->f=(c&0xff);
+}
+
+
+int main(int argc, char **argv) {
+
+	int ch,i;
+
+//	int spreadx=256;
+//	int spready=256;
+//	int spreadz=16;
+//	struct fixed_type speedz;
+
+	for(i=0;i<256;i++) {
+		random_table[i]=rand()%256;
+		printf("%d,",random_table[i]);
+	}
+	printf("\n");
+
+	double g;
+	struct fixed_type gf;
+	i=0;
+
+	for(g=16.0;g>0;g-=0.25) {
+		double_to_fixed(1.0/g,&gf);
+		printf("%d %.2f: %.2f %2X %2X\n",i,g,1.0/g,
+			gf.i,gf.f);
+		z_table[i]=gf.f;
+		i++;
+	}
+	printf("\n");
+
+
+//	double_to_fixed(-0.25,&speedz);
+
+	grsim_init();
+
+	/* Should NUMSTARS be prime to help with randomness */
+
+	for(i=0;i<NUMSTARS;i++) {
+		random_star(i);
+	}
+	gr();
+
+	while(1) {
+		gr();
+
+		/* Set color */
+		for(i=0;i<NUMSTARS;i++) {
+			if (stars[i].z<16) stars[i].color=5;
+			else if (stars[i].z<32) stars[i].color=13;
+			else stars[i].color=15;
+
+		}
+
+		/* draw stars */
+		for(i=0;i<NUMSTARS;i++) {
+//			int tempx,tempy;
+			struct fixed_type dx,dy,temp;
+
+			temp.i=0;//z_table[stars[i].z];
+			if ((stars[i].z==60)  || (stars[i].z==61)) {
+				temp.i=1;
+			}
+			if (stars[i].z==62) {
+				temp.i=2;
+			}
+			if (stars[i].z==63) {
+				temp.i=4;
+			}
+
+			temp.f=z_table[stars[i].z];
+
+			fixed_mul(&stars[i].x,&temp,&dx);
+
+//			dx=fixed_to_double(&stars[i].x)/
+//				fixed_to_double(&stars[i].z);
+
+//			tempx=dx+20;
+
+			dx.i+=20;
+
+			fixed_mul(&stars[i].y,&temp,&dy);
+
+//			dy=fixed_to_double(&stars[i].y)/
+//				fixed_to_double(&stars[i].z);
+
+//			tempy=dy+20;
+
+			dy.i+=20;
+
+			if ((dx.i<0) || (dy.i<0) || (dx.i>=40) ||
+				(dy.i>=40)) {
+
+				random_star(i);
+			}
+			else {
+//				if (stars[i].z>58) {
+//					printf("EEK! %2X.%2X\n",
+//						stars[i].z,stars[i].z);
+//				}
+				color_equals(stars[i].color);
+				basic_plot(dx.i,dy.i);
+			}
+
+		}
+
+		/* Move stars */
+		for(i=0;i<NUMSTARS;i++) {
+//			fixed_add(&stars[i].z,&speedz,&stars[i].z);
+			stars[i].z++;
+			if (stars[i].z>=64) random_star(i);
+		}
+
+		grsim_update();
+		ch=grsim_input();
+		if (ch=='q') exit(0);
+		usleep(10000);
+	}
+
+	return 0;
+}