tfv: working on fixed point

gr-sim/Makefile

@@ -5,10 +5,18 @@ LFLAGS = -lm
 SDL_LIBS= `sdl-config --libs`
 SDL_INCLUDE= `sdl-config --cflags`
 
-all:	rainbow sparkle kaleido tfv mode7_demo text
+all:	fixed_point rainbow sparkle kaleido tfv mode7_demo text
 
 
 
+####
+
+fixed_point:	fixed_point.o
+	$(CC) $(LFLAGS) -o fixed_point fixed_point.o
+
+fixed_point.o:	fixed_point.c
+	$(CC) $(CFLAGS) -c fixed_point.c
+
 ####
 
 rainbow:	rainbow.o gr-sim.o
@@ -129,6 +137,6 @@ 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 kaleido tfv text mode7_demo
+	rm -f *~ *.o gr-sim rainbow sparkle kaleido tfv text mode7_demo fixed_point
 
 

gr-sim/fixed_point.c

@@ -0,0 +1,79 @@
+#include <stdio.h>
+#include <math.h>
+
+
+struct fixed_type {
+	char i;
+	unsigned char f;
+};
+
+
+void double_to_fixed(double d, struct fixed_type *f) {
+
+	double temp;
+
+	f->i=(int)d;
+
+	temp=d-(f->i);
+
+	temp*=256;
+
+	f->f=temp;
+
+	printf("%lf=%02x.%02x (%d/0x%x)\n",d,f->i,f->f,(int)temp,(int)temp);
+}
+
+void 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);
+
+}
+
+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;
+}
+
+int main(int argc, char **argv) {
+
+	struct fixed_type f,fa,fb,fc;
+	double d,c;
+
+	double_to_fixed(4.25,&f);
+	fixed_to_double(&f,&d);
+
+	double_to_fixed(3.14159265358979,&f);
+	fixed_to_double(&f,&d);
+
+	double_to_fixed(127.333333333,&f);
+	fixed_to_double(&f,&d);
+
+	double_to_fixed(50.9,&f);
+	fixed_to_double(&f,&d);
+
+
+	double_to_fixed(2.75,&fa);
+	double_to_fixed(12.75,&fb);
+	fixed_add(&fa,&fb,&fc);
+	fixed_to_double(&fc,&c);
+
+	double_to_fixed(-1.25,&fa);
+	double_to_fixed(-1.75,&fb);
+	fixed_add(&fa,&fb,&fc);
+	fixed_to_double(&fc,&c);
+
+
+	return 0;
+}

gr-sim/tfv_flying.c

@@ -59,11 +59,6 @@ static int lookup_map(int x, int y) {
 	return color;
 }
 
-static double space_z=4.5; // height of the camera above the plane
-static int horizon=-2;    // number of pixels line 0 is below the horizon
-static double scale_x=20, scale_y=20;
-
-double BETA=-0.5;
 
 static int over_water;
 
@@ -74,12 +69,16 @@ static char angle=0;
 // map coordinates
 double cx=0.0,cy=0.0;
 
-
-
-
-
 #if 1
 
+static double space_z=4.5; // height of the camera above the plane
+static int horizon=-2;    // number of pixels line 0 is below the horizon
+
+double BETA=-0.5;
+
+#define SCALE_X	20.0
+#define SCALE_Y	20.0
+
 
 #define ANGLE_STEPS	16
 
@@ -146,14 +145,13 @@ void draw_background_mode7(void) {
 	color_equals(COLOR_GREY);
 	hlin_double(ram[DRAW_PAGE], 0, 40, 6);
 
-
 	for (screen_y = 8; screen_y < LOWRES_H; screen_y++) {
 		// first calculate the distance of the line we are drawing
-		distance = (space_z * scale_y) / (screen_y + horizon);
+		distance = (space_z * SCALE_Y) / (screen_y + horizon);
 
 		// then calculate the horizontal scale, or the distance between
 		// space points on this horizontal line
-		horizontal_scale = (distance / scale_x);
+		horizontal_scale = (distance / SCALE_X);
 
 		// calculate the dx and dy of points in space when we step
 		// through all points on this line
@@ -170,8 +168,6 @@ void draw_background_mode7(void) {
 
 		factor=space_z*BETA;
 
-//		factor=2.0*BETA;
-
 		space_x+=factor*our_cos(angle);
 		space_y+=factor*our_sin(angle);
 
@@ -225,23 +221,6 @@ int flying(void) {
 
 		if ((ch=='q') || (ch==27))  break;
 
-#if 0
-		if (ch=='g') {
-			BETA+=0.1;
-			printf("Horizon=%lf\n",BETA);
-		}
-		if (ch=='h') {
-			BETA-=0.1;
-			printf("Horizon=%lf\n",BETA);
-		}
-
-		if (ch=='s') {
-			scale_x++;
-			scale_y++;
-			printf("Scale=%lf\n",scale_x);
-		}
-#endif
-
 		if ((ch=='w') || (ch==APPLE_UP)) {
 			if (shipy>16) {
 				shipy-=2;
@@ -374,6 +353,13 @@ int flying(void) {
 
 #else
 
+static double space_z=4.5; // height of the camera above the plane
+static int horizon=-2;    // number of pixels line 0 is below the horizon
+static double scale_x=20, scale_y=20;
+
+double BETA=-0.5;
+
+
 #define ANGLE_STEPS	32
 
 double our_sin(unsigned char angle) {