From a9bc3bfb963049cb8a4fa20b9830378144bde416 Mon Sep 17 00:00:00 2001
From: Ian Burgmyer <spectere@gmail.com>
Date: Mon, 7 Sep 2020 20:18:30 -0400
Subject: [PATCH] Split some common functions into an include.

---
 common/functions.inc | 28 ++++++++++++++++++++++++++
 cpu/callRet.asm      | 55 +++++++++++++++++-----------------------------------
 video/lcdToggle.asm  | 19 ++++--------------
 3 files changed, 50 insertions(+), 52 deletions(-)
 create mode 100644 common/functions.inc

diff --git a/common/functions.inc b/common/functions.inc
new file mode 100644
index 0000000..7c89098
--- /dev/null
+++ b/common/functions.inc
@@ -0,0 +1,28 @@
+SECTION "functions", ROM0[$2000]
+; Wait for vblank without using interrupts.
+waitVBlank:
+	push af
+.waitVBlankLoop:
+	ldh a, [$ff44]
+	cp $90
+	jr nz, .waitVBlankLoop
+	pop af
+	ret
+
+; Writes a value across 16 bytes, starting at HL. Intended to fill a single tile.
+; Parameters:
+;     B - The value to set the bytes to.
+; Modifies:
+;     HL - End result: HL + 16
+fillTile:
+	push af
+	push de
+	ld d, 16
+	ld a, b
+.fillTileLoop:
+	ld [hli], a
+	dec d
+	jr nz, .fillTileLoop
+	pop de
+	pop af
+	ret
diff --git a/cpu/callRet.asm b/cpu/callRet.asm
index dae1abf..fa90e3d 100644
--- a/cpu/callRet.asm
+++ b/cpu/callRet.asm
@@ -2,6 +2,7 @@ HeaderTitle EQUS "\"CALLRET\""
 
 include "common/defines.inc"
 include "common/header.inc"
+include "common/functions.inc"
 
 ; 1: call    / ret
 ; 2: call    / ret nz
@@ -17,6 +18,8 @@ SECTION "home", ROM0
 ProgramStart:
 	call waitVBlank
 
+	ld b, $ff  ; Fill color.
+
 	; disable the LCD while we clear the logo
 	ld hl, $ff40
 	ld a, [hl]
@@ -32,65 +35,57 @@ ProgramStart:
 
 	call waitVBlank
 	ld hl, $8010
-	call drawRect
+	call fillTile
 
 	call waitVBlank
 	call retNz
 	ld hl, $8040
-	call drawRect
+	call fillTile
 
 	call waitVBlank
 	call retZ
 	ld hl, $8060
-	call drawRect
+	call fillTile
 
 	call waitVBlank
 	call retNc
 	ld hl, $8080
-	call drawRect
+	call fillTile
 
 	call waitVBlank
 	call retC
 	ld hl, $80a0
-	call drawRect
+	call fillTile
 
 	call waitVBlank
 	ld a, 2
 	dec a
 	ld hl, $8110
-	call nz, drawRect
+	call nz, fillTile
 
 	call waitVBlank
 	ld a, 1
 	dec a
 	ld hl, $8130
-	call z, drawRect
+	call z, fillTile
 
 	call waitVBlank
-	ld a, 2
-	dec a
+	ld a, 200
+	add a, 55
 	ld hl, $8150
-	call nc, drawRect
+	call nc, fillTile
 
 	call waitVBlank
 	ld a, 255
 	add a, 1
 	ld hl, $8170
-	call c, drawRect
+	call c, fillTile
 
 loop:
 	jr loop
 
 
-SECTION "waitVBlank", ROM0[$200]
-waitVBlank:
-	ldh a, [$ff44]
-	cp $90
-	jr nz, waitVBlank
-	ret
-
-
-SECTION "clearLogo", ROM0[$220]
+SECTION "clearLogo", ROM0[$200]
 clearLogo:
 	ld hl, $81A0
 .clearLoop:
@@ -105,21 +100,7 @@ clearLogo:
 	ret
 
 
-SECTION "drawRect", ROM0[$240]
-drawRect:
-	push af
-	push de
-	ld d, 16
-	ld a, $ff
-.logoDraw:
-	ld [hli], a
-	dec d
-	jr nz, .logoDraw
-	pop de
-	pop af
-	ret
-
-SECTION "ret", ROM0[$300]
+SECTION "retTests", ROM0[$220]
 retError:
 	jr retError
 
@@ -136,8 +117,8 @@ retZ:
 	jr retError
 
 retNc:
-	ld a, 2
-	dec a
+	ld a, 200
+	add a, 55
 	ret nc
 	jr retError
 
diff --git a/video/lcdToggle.asm b/video/lcdToggle.asm
index bbb0c11..2ca550a 100644
--- a/video/lcdToggle.asm
+++ b/video/lcdToggle.asm
@@ -2,17 +2,11 @@ HeaderTitle EQUS "\"LCDTOGGLE\""
 
 include "common/defines.inc"
 include "common/header.inc"
+include "common/functions.inc"
 
 SECTION "home", ROM0
-vblankWait:
-	; Wait for vblank without interrupts.
-	ldh a, [$ff44]
-	cp $90
-	jr nz, vblankWait
-	ret
-
 wait:
-	call vblankWait
+	call waitVBlank
 	dec d
 	jr nz, wait
 	ret
@@ -28,18 +22,13 @@ reset:
 
 .loop:
 	; Disable the LCD
-	call vblankWait
+	call waitVBlank
 	ldh a, [$ff40]
 	res 7, a
 	ldh [$ff40], a
 
 	; Mess with the logo, as we often do.
-	ld d, 16
-	ld a, b
-.logoDraw:
-	ld [hli], a
-	dec d
-	jr nz, .logoDraw
+	call fillTile
 
 	; Enable the LCD
 	ldh a, [$ff40]