Rewrite array handling, save 175 bytes

2 files changed, 99 insertions, 50 deletions

diff --git a/arrayutils.s b/arrayutils.s
index 188ace4..4e3babf 100644
--- a/arrayutils.s
+++ b/arrayutils.s
@@ -14,47 +14,95 @@
 ; the function, or around 1/3 the size of the for loop, or under 1/4
 ; the size of bzero() plus its function call.
 
- .import _ships_on_screen
- .export _have_ships_on_screen, _clear_ships_on_screen
+; we also have clear_hkw() and clear_hold().
+
+ .import _ships_on_screen, _hkw_, _hold_
+ .export _no_ships_on_screen
+ .export _hold_is_empty, _hkw_is_empty, _have_no_cargo
+ .export _clear_hkw, _clear_hold, _clear_ships_on_screen
 
  .include "atari.inc"
 
- .proc _clear_ships_on_screen
- ldx #$14
+ .code
+_clear_ships_on_screen:
+ lda #<(_ships_on_screen-1)
+ ldx #>(_ships_on_screen-1)
+ ldy #$14
+ ; fall thru
+
+clr_array:
+ ; AX is array address minus one!
+ ; Y is sizeof(array)
+ sta FR0
+ stx FR0+1
  lda #0
 @l:
- sta _ships_on_screen-1,x
- dex
+ sta (FR0),y
+ dey
  bne @l
  rts
- .endproc
 
-; extern char have_ships_on_screen(void);
+_clear_hkw:
+ lda #<(_hkw_-1)
+ ldx #>(_hkw_-1)
+ ldy #$08
+ bne clr_array
+
+_clear_hold:
+ lda #<(_hold_-1)
+ ldx #>(_hold_-1)
+ ldy #$10
+ bne clr_array
 
-; optimized (both size and speed) replacement for:
+;;;;;
 
-; if ((ships_on_screen[0] == 0) && (ships_on_screen[1] == 0) &&
-;    (ships_on_screen[2] == 0) && (ships_on_screen[3] == 0) &&
-;    (ships_on_screen[4] == 0) && (ships_on_screen[5] == 0) &&
-;    (ships_on_screen[6] == 0) && (ships_on_screen[7] == 0) &&
-;    (ships_on_screen[8] == 0) && (ships_on_screen[9] == 0))
+; Several places in the Taipan C code we have to check whether an
+; array is all zero. A for loop in C takes up quite a bit of space,
+; so write an array-checker in asm.
 
-; ...which compiles to ~100 bytes of code. a for loop would be
-; around 64 bytes (like the clearing loop above). this is 3 bytes
-; for the function call plus 11 bytes for the function, plus a
-; couple more bytes for the ! in front of the function call (since
-; the result is opposite what the original code did).
-; I could save the 3 bytes by inlining this as asm() in the C code,
-; but it would be more fragile than making a separate function.
+; Wrappers for array_is_empty():
+; no_ships_on_screen()
+; hold_is_empty()
+; hkw_is_empty()
+; have_no_cargo();
 
- .proc _have_ships_on_screen
- ldx #$14   ; sizeof(ships_on_screen)
+_no_ships_on_screen:
+ lda #<(_ships_on_screen-1)
+ ldx #>(_ships_on_screen-1)
+ ldy #$14
+ ; fall thru
+
+array_is_empty:
+ ; AX is array address minus one!
+ ; Y is sizeof(array)
+ sta FR0
+ stx FR0+1
 @l:
- lda _ships_on_screen-1,x
- bne @done ; found a non-0 byte, A and X are both non-zero
- dex
+ lda (FR0),y
+ bne ret0
+ dey
  bne @l
- ; end of loop. if we get here, A and X are both zero
-@done:
+@ret1:
+ lda #1
  rts
- .endproc
+ret0:
+ lda #0
+ tax ; need this or not?
+ rts
+
+_hkw_is_empty:
+ lda #<(_hkw_-1)
+ ldx #>(_hkw_-1)
+ ldy #$08
+ bne array_is_empty
+
+_hold_is_empty:
+ lda #<(_hold_-1)
+ ldx #>(_hold_-1)
+ ldy #$10
+ bne array_is_empty
+
+_have_no_cargo:
+ jsr _hkw_is_empty
+ beq ret0
+ bne _hold_is_empty
diff --git a/taipan.c b/taipan.c
index 367c7be..8221cc1 100644
--- a/taipan.c
+++ b/taipan.c
@@ -378,6 +378,17 @@ unsigned long __fastcall__ strtonum(const char* nptr);
 
 unsigned char firmpos;
 
+int ships_on_screen[10];
+
+/* arrayutils.s */
+extern char no_ships_on_screen(void);
+extern void clear_ships_on_screen(void);
+extern char have_no_cargo(void);
+extern char hold_is_empty(void);
+extern char hkw_is_empty(void);
+extern void clear_hold(void);
+extern void clear_hkw(void);
+
 /* use page 6 for these buffers, for .xex build. Otherwise they're BSS. */
 #ifdef CART_TARGET
 char firm[23];
@@ -637,14 +648,8 @@ void init_game(void) {
 #else
 	bank         = 0;
 #endif
-	hkw_[0]      = 0;
-	hkw_[1]      = 0;
-	hkw_[3]      = 0;
-	hkw_[4]      = 0;
-	hold_[0]     = 0;
-	hold_[1]     = 0;
-	hold_[2]     = 0;
-	hold_[3]     = 0;
+	clear_hkw();
+	clear_hold();
 	hold         = 0;
 	damage       = 0;
 	wu_warn      = 0;
@@ -1091,12 +1096,6 @@ void plus_or_space(unsigned char b) {
 #endif
 */
 
-int ships_on_screen[10];
-extern char have_ships_on_screen(void);
-extern void clear_ships_on_screen(void);
-
-char have_no_cargo(void);
-
 /* sea_battle only ever returns 1 to 4. making the
 	return type a char saved 61 bytes! */
 char sea_battle(char id, int num_ships) {
@@ -1212,7 +1211,7 @@ char sea_battle(char id, int num_ships) {
 			set_orders();
 
 			for(i = 1; i <= guns; i++) {
-				if(!have_ships_on_screen()) {
+				if(no_ships_on_screen()) {
 					static int j;
 
 					for (j = 0; j <= 9; j++) {
@@ -1332,7 +1331,7 @@ char sea_battle(char id, int num_ships) {
 			total = 0;
 			turbo = 0;
 
-			if(have_no_cargo()) {
+			if(hold_is_empty()) {
 				print_combat_msg(M_you_have_no_cargo);
 				cprint_taipan_bangbang();
 				bad_joss_sound();
@@ -1407,10 +1406,7 @@ char sea_battle(char id, int num_ships) {
 						hold += amount;
 						ok += (amount / 10);
 					} else {
-						hold_[0] = 0;
-						hold_[1] = 0;
-						hold_[2] = 0;
-						hold_[3] = 0;
+						clear_hold();
 						hold += total;
 						ok += (total / 10);
 					}
@@ -2179,12 +2175,15 @@ void final_stats(void)
 #endif
 }
 
+/*
+	// rewritten in asm (arrayutils.s)
 char have_no_cargo(void) {
 	char i;
 	for(i = 0; i < 4; ++i)
 		if(hkw_[i] || hold_[i]) return 0;
 	return 1;
 }
+*/
 
 /*
 #ifdef CART_TARGET
@@ -3550,9 +3549,11 @@ int main(void) {
          under_attack_timed_getch();
       }
 
+		/*
       if ((one_chance_in(50)) &&
           ((hkw_[0] + hkw_[1] + hkw_[2] + hkw_[3]) > 0))
-      {
+			 */
+      if(one_chance_in(50) && !hkw_is_empty()) {
          int i;
 
          for (i = 0; i < 4; i++)