Scaffolded a file to test misc opcodes.

* No tests current being run in it.
    * Moved LCD disable/enable into macros.
    * Created memset function, modified fillTile to use it.
    * Changed the stack pointer in callRet to $e000 to ensure that LD SP
      functions as expected.

Makefile

@@ -24,6 +24,7 @@ dirs:
 cpu: cpuDirs \
 	${BIN_DIR}/cpu/callRet.gb \
 	${BIN_DIR}/cpu/memcpy.gb \
+	${BIN_DIR}/cpu/miscInstrs.gb \
 	${BIN_DIR}/cpu/rst.gb
 
 cpuDirs:
@@ -40,6 +41,11 @@ ${BIN_DIR}/cpu/memcpy.gb: dirs cpu/memcpy.asm
 	${LD} -o ${BIN_DIR}/cpu/memcpy.gb ${OBJ_DIR}/cpu/memcpy.o
 	${FIX} ${BIN_DIR}/cpu/memcpy.gb
 
+${BIN_DIR}/cpu/miscInstrs.gb: dirs cpu/miscInstrs.asm
+	${AS} -o ${OBJ_DIR}/cpu/miscInstrs.o cpu/miscInstrs.asm
+	${LD} -o ${BIN_DIR}/cpu/miscInstrs.gb ${OBJ_DIR}/cpu/miscInstrs.o
+	${FIX} ${BIN_DIR}/cpu/miscInstrs.gb
+
 ${BIN_DIR}/cpu/rst.gb: dirs cpu/rst.asm
 	${AS} -o ${OBJ_DIR}/cpu/rst.o cpu/rst.asm
 	${LD} -o ${BIN_DIR}/cpu/rst.gb ${OBJ_DIR}/cpu/rst.o

common/functions.inc

@@ -1,5 +1,20 @@
 SECTION "functions", ROM0[$2000]
 
+_lcdDisable: MACRO
+	call waitVBlank
+	ld hl, $ff40
+	ld a, [hl]
+	res 7, a
+	ld [hl], a
+	ENDM
+
+_lcdEnable: MACRO
+	ld hl, $ff40
+	ld a, [hl]
+	set 7, a
+	ld [hl], a
+	ENDM
+
 ; Clears the Nintendo logo tile data. This is intended to leave the screen open
 ; for simple (i.e. a bunch of boxes drawn with fillTile) test output.
 clearLogo:
@@ -7,11 +22,7 @@ clearLogo:
 	push hl
 
 	; disable the LCD
-	call waitVBlank
-	ld hl, $ff40
-	ld a, [hl]
-	res 7, a
-	ld [hl], a
+	_lcdDisable
 
 	; wipe the logo
 	ld hl, $81A0
@@ -26,10 +37,7 @@ clearLogo:
 	jr nz, .loop
 
 	; enable the LCD and return
-	ld hl, $ff40
-	ld a, [hl]
-	set 7, a
-	ld [hl], a
+	_lcdEnable
 
 	pop af
 	pop hl
@@ -41,16 +49,10 @@ clearLogo:
 ; Modifies:
 ;     HL - End result: HL + 16
 fillTile:
-	push af
 	push de
 	ld d, 16
-	ld a, b
-.loop:
-	ld [hli], a
-	dec d
-	jr nz, .loop
+	call memset
 	pop de
-	pop af
 	ret
 
 ; Copies up to 256 bytes of memory to another location.
@@ -70,6 +72,24 @@ memcpy:
 	ret z
 	jr memcpy
 
+; Fills up to 256 bytes of memory with a set value, starting at HL.
+; Parameters:
+;     B  - The value to set the bytes to.
+;     D  - The number of bytes to modify.
+;     HL - Destination location.
+; Modifies:
+;     D  - End result: 0
+;     HL - End result: HL + D
+memset:
+	push af
+	ld a, b
+.loop:
+	ld [hli], a
+	dec d
+	jr nz, .loop
+	pop af
+	ret
+
 ; Wait for vblank without using interrupts.
 waitVBlank:
 	push af

cpu/callRet.asm

@@ -19,6 +19,7 @@ ProgramStart:
 	call waitVBlank
 
 	ld b, $ff  ; Fill pattern.
+	ld sp, $e000
 
 	call clearLogo
 
@@ -76,10 +77,10 @@ ProgramStart:
 	; Stack pointer validation.
 	ld hl, sp+$00
 	ld a, h
-	cp $ff
+	cp $e0
 	jr nz, loop
 	ld a, l
-	cp $fe
+	cp $00
 	jr nz, loop
 	ld hl, $8180
 	call waitVBlank

cpu/miscInstrs.asm

@@ -0,0 +1,35 @@
+HeaderTitle EQUS "\"MISCINSTRS\""
+
+include "common/defines.inc"
+include "common/header.inc"
+include "common/functions.inc"
+
+SECTION "home", ROM0
+ProgramStart:
+	call clearLogo
+
+	_lcdDisable
+
+	; Set a proper grayscale palette.
+	ld a, %11100100
+	ldh [$ff47], a
+
+	; TODO: Write actual tests. :)
+	ld a, $ff
+	ld hl, $8014
+	ld [hl], a
+	ld hl, $8016
+	ld [hl], a
+	ld hl, $8019
+	ld [hl], a
+	ld hl, $801b
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	ld [hli], a
+	call memset
+	_lcdEnable
+
+.loop:
+	jr .loop