[Reverse-engineering] [th04/th05] Clearing the playfield's text RAM area

master.lib's text_boxfillca() function would have been perfectly
suitable here…

Part of P0089, funded by [Anonymous] and Blue Bolt.

th02/main/playfld.h

@@ -13,5 +13,13 @@
 #define PLAYFIELD_VRAM_RIGHT (PLAYFIELD_RIGHT / 8)
 
 #define PLAYFIELD_TRAM_X (PLAYFIELD_X / 8)
+#define PLAYFIELD_TRAM_Y (PLAYFIELD_Y / 16)
 #define PLAYFIELD_TRAM_W (PLAYFIELD_W / 8)
 #define PLAYFIELD_TRAM_RIGHT (PLAYFIELD_RIGHT / 8)
+#define PLAYFIELD_TRAM_BOTTOM (PLAYFIELD_BOTTOM / 16)
+
+#if (GAME == 2)
+	// Fills the playfield's area on the text RAM with transparency.
+	// (Future games use a near function.)
+	void far playfield_tram_wipe(void);
+#endif

th02/main/playfld.inc

@@ -13,8 +13,64 @@ PLAYFIELD_VRAM_W = PLAYFIELD_W / 8
 PLAYFIELD_VRAM_RIGHT = PLAYFIELD_RIGHT / 8
 
 PLAYFIELD_TRAM_X = PLAYFIELD_X / 8
+PLAYFIELD_TRAM_Y = PLAYFIELD_Y / 16
 PLAYFIELD_TRAM_W = PLAYFIELD_W / 8
 PLAYFIELD_TRAM_RIGHT = PLAYFIELD_RIGHT / 8
+PLAYFIELD_TRAM_BOTTOM = PLAYFIELD_BOTTOM / 16
+
+if GAME eq 5
+	playfield_tram_x_loop	macro @@atrb:req
+		call	text_putsa pascal, PLAYFIELD_TRAM_X, si, _PLAYFIELD_BLANK_ROW, @@atrb
+	endm
+else
+	playfield_tram_x_loop	macro @@atrb:req
+	local @@x_loop, @@x_more?
+		mov	di, PLAYFIELD_TRAM_X
+		jmp	short @@x_more?
+	; ---------------------------------------------------------------------------
+
+	@@x_loop:
+		call	text_putca pascal, di, si, (' ' shl 16) + @@atrb
+		inc	di
+
+	@@x_more?:
+		cmp	di, PLAYFIELD_TRAM_RIGHT
+		jl	short @@x_loop
+	endm
+endif
+
+playfield_tram_loop	macro @@atrb:req
+	mov	si, PLAYFIELD_TRAM_Y
+	jmp	short @@y_more?
+; ---------------------------------------------------------------------------
+
+@@y_loop:
+	playfield_tram_x_loop	<@@atrb>
+	inc	si
+
+@@y_more?:
+	cmp	si, PLAYFIELD_TRAM_BOTTOM
+	jl	short @@y_loop
+endm
+
+playfield_tram_loop_func	macro @@funcname:req, @@dist:req, @@atrb:req
+	public @@funcname
+	@@funcname	proc @@dist
+		push	bp
+		mov	bp, sp
+		push	si
+		if GAME ne 5
+			push	di
+			playfield_tram_loop	<@@atrb>
+			pop	di
+		else
+			playfield_tram_loop	<@@atrb>
+		endif
+		pop	si
+		pop	bp
+		ret
+	@@funcname	endp
+endm
 
 TILE_W = 16
 TILE_H = 16

th02_main.asm

@@ -2124,7 +2124,7 @@ var_C		= byte ptr -0Ch
 		call	graph_clear
 		graph_showpage 0
 		call	hud_put
-		call	sub_FBE9
+		call	_playfield_tram_wipe
 		call	_pi_slot_palette_apply stdcall, 0
 		call	_pi_slot_palette_apply stdcall, 0
 		call	_pi_slot_put stdcall, 96, large 144
@@ -3396,9 +3396,9 @@ loc_C3FB:
 loc_C400:
 		cmp	_key_det, 0
 		jz	short loc_C3FB
-		call	sub_FBE9
+		call	_playfield_tram_wipe
 		call	sub_1C9FE
-		call	sub_FBE9
+		call	_playfield_tram_wipe
 		les	bx, _resident
 		cmp	es:[bx+mikoconfig_t.continues_used], 3
 		jnb	loc_C4F5
@@ -3504,7 +3504,7 @@ loc_C516:
 		mov	power_overflow_level, 10
 		mov	PaletteTone, 100
 		call	far ptr	palette_show
-		call	sub_FBE9
+		call	_playfield_tram_wipe
 		mov	ax, di
 		pop	di
 		pop	si
@@ -8208,7 +8208,7 @@ loc_EB5D:
 		inc	byte_21A55
 		cmp	byte_21A55, 12h
 		jb	short loc_EB7C
-		call	sub_FBE9
+		call	_playfield_tram_wipe
 		mov	word_218B6, 84h
 
 loc_EB7C:
@@ -9434,43 +9434,7 @@ loc_FBDF:
 		retn	0Ah
 sub_FB42	endp
 
-
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_FBE9	proc far
-		push	bp
-		mov	bp, sp
-		push	si
-		push	di
-		mov	si, 1
-		jmp	short loc_FC0C
-; ---------------------------------------------------------------------------
-
-loc_FBF3:
-		mov	di, 4
-		jmp	short loc_FC06
-; ---------------------------------------------------------------------------
-
-loc_FBF8:
-		call	text_putca pascal, di, si, (' ' shl 16) + TX_WHITE
-		inc	di
-
-loc_FC06:
-		cmp	di, 52
-		jl	short loc_FBF8
-		inc	si
-
-loc_FC0C:
-		cmp	si, 24
-		jl	short loc_FBF3
-		pop	di
-		pop	si
-		pop	bp
-		retf
-sub_FBE9	endp
-
+playfield_tram_loop_func	_playfield_tram_wipe, far, <TX_WHITE>
 
 ; =============== S U B	R O U T	I N E =======================================
 
@@ -9531,7 +9495,7 @@ var_4		= dword	ptr -4
 		push	offset gBONUS
 		mov	cx, 6
 		call	SCOPY@
-		call	sub_FBE9
+		call	_playfield_tram_wipe
 		mov	PaletteTone, 62
 		call	far ptr	palette_show
 		push	(24 shl 16) + 4
@@ -9693,7 +9657,7 @@ var_4		= dword	ptr -4
 		push	offset gBONUS_0
 		mov	cx, 6
 		call	SCOPY@
-		call	sub_FBE9
+		call	_playfield_tram_wipe
 		mov	PaletteTone, 62
 		call	far ptr	palette_show
 		push	(24 shl 16) + 4
@@ -15551,13 +15515,13 @@ var_2		= word ptr -2
 		push	si
 		push	di
 		mov	di, 32
-		nopcall	sub_FBE9
+		nopcall	_playfield_tram_wipe
 		call	sub_DE4E
 		call	graph_scrollup pascal, _scroll_line
 		mov	PaletteTone, 100
 		call	far ptr	palette_show
 		graph_accesspage _page_front
-		nopcall	sub_FBE9
+		nopcall	_playfield_tram_wipe
 		mov	si, 320
 		add	si, _scroll_line
 		cmp	si, RES_Y
@@ -15627,7 +15591,7 @@ var_2		= word ptr -2
 		push	si
 		push	di
 		mov	di, 20h	; ' '
-		nopcall	sub_FBE9
+		nopcall	_playfield_tram_wipe
 		mov	si, 320
 		add	si, _scroll_line
 		cmp	si, RES_Y
@@ -16431,7 +16395,7 @@ sub_13414	endp
 sub_13439	proc near
 		push	bp
 		mov	bp, sp
-		nopcall	sub_FBE9
+		nopcall	_playfield_tram_wipe
 		kajacall	KAJA_SONG_STOP
 		pop	cx
 		push	69h ; 'i'

th04/main/playfld.h

@@ -0,0 +1,7 @@
+#include "th02/main/playfld.h"
+
+// Fills the playfield area on the text RAM with transparent spaces.
+void near playfield_tram_wipe(void);
+// Fills the playfield area on the text RAM with black, effectively hiding the
+// playfield in the process.
+void near playfield_tram_black(void);