tfv: add screen clearing routines

gr-sim/gr-sim.c

@@ -1309,3 +1309,22 @@ int collision(int xx, int yy, int ground_color) {
 
 	return collide;
 }
+
+void clear_top(int page) {
+	int i;
+
+	ram[COLOR]=0x0;
+	for(i=0;i<40;i+=2) {
+		hlin_double(page,0,40,i);
+	}
+}
+
+void clear_bottom(int page) {
+	int i;
+
+	/* NORMAL space */
+	ram[COLOR]=0xa0;
+	for(i=40;i<48;i+=2) {
+		hlin_double(page,0,40,i);
+	}
+}

gr-sim/gr-sim.h

@@ -29,6 +29,9 @@ void soft_switch(unsigned short address);
 int soft_switch_read(unsigned short address);
 int vlin(int page, int y1, int y2, int at);
 int collision(int xx, int yy, int ground_color);
+void clear_top(int page);
+void clear_bottom(int page);
+
 
 #define APPLE_UP        11
 #define APPLE_DOWN      10

gr-sim/tfv.c

@@ -955,12 +955,22 @@ int main(int argc, char **argv) {
 
 	grsim_init();
 
-	ram[DISP_PAGE]=0;
-	ram[DRAW_PAGE]=0;
-
 	home();
 	gr();
 
+	/* Clear bottom of zero page */
+	apple_memset(&ram[0],0,16);
+
+	/* clear top page0 */
+	/* clear top page1 */
+	clear_top(0);
+	clear_top(1);
+
+	/* clear bottom page0 */
+	/* clear bottom page1 */
+	clear_bottom(0);
+	clear_bottom(1);
+
 	/* Do Opening */
 	opening();
 

gr-sim/tfv_utils.c

@@ -58,7 +58,7 @@ int select_menu(int x, int y, int num, char **items) {
 	return result;
 }
 
-void apple_memset(char *ptr, int value, int length) {
+void apple_memset(unsigned char *ptr, int value, int length) {
 
 	a=value;
 	x=length;

gr-sim/tfv_utils.h

@@ -1,6 +1,6 @@
 int repeat_until_keypressed(void);
 int select_menu(int x, int y, int num, char **items);
-void apple_memset(char *ptr, int value, int length);
+void apple_memset(unsigned char *ptr, int value, int length);
 void print_u8(unsigned char value);
 void print_byte(unsigned char value);
 void page_flip(void);