alex4 (1.1-3) save-some-cpu-cycles.patch

Fix the 100% CPU usage of alex4. We can't do this properly (the game
is written with a DOS mindset), but we can do two things easily:
 - Put a rest() in every busy loop.
 - Limit the frame rate to 50Hz (the speed of the game logic).

For future reference, the counters used by the game:
game_count  = increments at 50Hz
cycle_count = increments at 50Hz, but is reset whenever the game feels like it
frame_count = number of frames rendered, reset every second
logic_count = number of game loops processed, reset every second

--- a/src/main.c
+++ b/src/main.c
@@ -280,7 +280,7 @@
 		if (keypressed()) kp = 1;
 		if (is_fire(&ctrl) || is_jump(&ctrl)) kp = 1;
 		if (got_sound && dp != NULL) al_poll_duh(dp);
-		while(!cycle_count);
+                rest(20);
 	}
 }
 
@@ -322,7 +322,7 @@
 		cycle_count = 0;
 		if (got_sound && duh_player != NULL) al_poll_duh(duh_player);
 		i ++;
-		while(!cycle_count)	yield_timeslice();
+		while(!cycle_count)	rest(1);
 	}
 }
 
@@ -1127,6 +1127,10 @@
 
 	cycle_count = 0;
 	while(mode != 3) {
+		// Let other processes play
+		while(cycle_count == 0)
+			rest(1);
+
 		// do logic
 		while(cycle_count > 0) {
 			logic_count ++;
@@ -1152,9 +1156,6 @@
 			cycle_count --;
 		}
 
-		// let other processes play
-		yield_timeslice();
-
 		// draw stuff
 		draw_frame(swap_screen, 1);
 		draw_sprite(swap_screen, go, x, 35);
@@ -1174,6 +1175,10 @@
 
 	cycle_count = 0;
 	while(mode != 3) {
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
+
 		// do logic
 		while(cycle_count > 0) {
 			logic_count ++;
@@ -1194,9 +1199,6 @@
 			cycle_count --;
 		}
 
-		// let other processes play
-		yield_timeslice();
-
 		// draw stuff
 		draw_frame(swap_screen, 1);
 		draw_sprite(swap_screen, go, x, 35);
@@ -1237,6 +1239,10 @@
 
 	cycle_count = 0;
 	while(!done) {
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
+
 		// do logic
 		while(cycle_count > 0) {
 			logic_count ++;
@@ -1256,9 +1262,6 @@
 			cycle_count --;
 		}
 
-		// let other processes play
-		yield_timeslice();
-
 		// draw stuff
 		draw_custom_ending(swap_screen);
 		blit_to_screen(swap_screen);
@@ -1334,6 +1337,10 @@
 	clear_keybuf();
 	cycle_count = 0;
 	while(mode != 3) {
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
+
 		// do logic
 		while(cycle_count > 0) {
 			logic_count ++;
@@ -1372,9 +1379,6 @@
 			cycle_count --;
 		}
 
-		// let other processes play
-		yield_timeslice();
-
 		// draw stuff
 		blit(swap2, swap_screen, 0, 0, 0, 0, 160, 120);
 		draw_status_bar(swap_screen, 110);
@@ -1488,6 +1492,10 @@
 
 	cycle_count = 0;
 	while(!done) {
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
+
 		// do logic
 		while(cycle_count > 0) {
 			logic_count ++;
@@ -2343,7 +2351,7 @@
 		if (is_fire(&ctrl) || is_jump(&ctrl)) done = 1;
 		if (keypressed()) done = 1;
 		if (key[KEY_ESC]) done = -1;
-		yield_timeslice();
+		rest(20);
 	}
 
 	if (done == -1) {
@@ -2369,6 +2377,9 @@
 	game_status = GS_OK;
 	cycle_count = 0;
 	while(game_status == GS_OK) {
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
 
 		//  do logic
 		while(cycle_count > 0) {
@@ -2492,9 +2503,6 @@
 			cycle_count --;
 		}
 		
-		// let other processes play
-		yield_timeslice();
-
 		// draw 
 		frame_count ++;
 		draw_frame(swap_screen, 1);
@@ -2658,7 +2666,7 @@
 
 		}
 
-		while(!cycle_count);
+		while(!cycle_count) rest(1);
 
     }
 }
@@ -2693,6 +2701,9 @@
 	clear_keybuf();
 	cycle_count = 0;
 	while(status == GS_OK) {
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
 
 		//  do logic
 		while(cycle_count > 0) {
@@ -2774,9 +2785,6 @@
 			cycle_count --;
 		}
 
-		// let other processes play
-		yield_timeslice();
-
 		// draw 
 		frame_count ++;
 		draw_title(swap_screen, tick);
@@ -3021,7 +3029,8 @@
 		blit_to_screen(swap_screen);
 		fade_in_pal(100);
 		cycle_count = 0;
-		while(!key[KEY_ESC] && cycle_count < 200);
+		while(!key[KEY_ESC] && cycle_count < 200)
+			rest(50);
 		fade_out_pal(100);
 		clear(screen);
 	}
--- a/src/script.c
+++ b/src/script.c
@@ -102,8 +102,8 @@
 		cycle_count = 0;
 		poll_music();
 		count ++;
-		while(!cycle_count);
-		yield_timeslice();
+		while(!cycle_count)
+			rest(20);
 	}
     if (key[KEY_ESC]) script_done = -1;
 }
@@ -498,6 +498,10 @@
 	cycle_count = 0;
 	while(loops && !script_done) {
 
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
+
 		while(cycle_count > 0 && loops && !script_done) {
 			logic_count ++;
 
@@ -520,9 +524,6 @@
 			cycle_count --;
 		}
 
-		// let other processes play
-		yield_timeslice();
-
 		// blit buffer to swap buffer
 		blit(buffer, swap_buffer, 0, 0, 0, 0, 160, 120);
 		
--- a/src/shooter.c
+++ b/src/shooter.c
@@ -1131,7 +1131,10 @@
 	game_count = 0;
 	s_activate_sign(0, -1);
 	while(playing || s_sign.alive) {
-		
+		// let other processes play
+		while(cycle_count == 0)
+			rest(1);
+
 		//  do logic
 		while(cycle_count > 0) {
 			logic_count ++;
@@ -1266,10 +1269,6 @@
 			cycle_count --;
 		}
 		
-		
-		// let other processes play
-		yield_timeslice();
-		
 		// draw 
 		frame_count ++;
 		s_draw_frame(s_buffer);