Added 48 test routines to miscInstrs.

* Added some comments to the functions include.
    * Flag bits are now included in defines.
    * Removed unused HeaderEnd define.
    * Added clearFlags and drawGrid library functions.

common/defines.inc

@@ -18,11 +18,15 @@ OverrideIntJoypad SET 0
 
 OverrideHeaderJump SET 0
 
-;
-; Memory Locations
-;
-HeaderEnd EQU $0150
-
+; Flags
+ZeroFlag SET 7
+SubtractFlag SET 6
+HalfCarryFlag SET 5
+CarryFlag SET 4
+
+; ===========
+; HEADER DEFS
+; ===========
 ;
 ; CGB Flag
 ;

common/functions.inc

@@ -1,5 +1,7 @@
 SECTION "functions", ROMX[$4000]
 
+; Disables the LCD during the next vblank period.
+; Clobbers HL.
 _lcdDisable: MACRO
 	call waitVBlank
 	ld hl, $ff40
@@ -8,6 +10,8 @@ _lcdDisable: MACRO
 	ld [hl], a
 	ENDM
 
+; Enables the LCD immediately.
+; Clobbers HL.
 _lcdEnable: MACRO
 	ld hl, $ff40
 	ld a, [hl]
@@ -15,6 +19,18 @@ _lcdEnable: MACRO
 	ld [hl], a
 	ENDM
 
+; Completely the flags register.
+; Modifies:
+;     F - End result: 0
+clearFlags:
+	push bc
+	ld b, a
+	ld c, 0
+	push bc
+	pop af
+	pop bc
+	ret
+
 ; 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:
@@ -43,6 +59,53 @@ clearLogo:
 	pop hl
 	ret
 
+; Draws an inverted grid over where the Nintendo logo tile data normally
+; resides. This is useful for tests that use a grid output, as it will make the
+; tile number more obvious. This should be called after the tests are performed,
+; as fillTile and fillTileEx will draw over the grid.
+drawGrid:
+	push hl
+	push de
+	push bc
+	ld hl, $8010  ; Start address.
+	ld de, $8190  ; End address.
+	ld b, $f      ; Used to find the top of each file.
+_gridLoop:
+	ld a, l       ; Check for the top of the tiles.
+	and b
+	jr z, _handleTop
+
+	; Invert the right side of the tile.
+	ld c, $01
+	ld a, [hl]
+	xor c
+	ld [hli], a
+
+	; See if we've reached the end.
+	ld a, h
+	cp d
+	jr nz, _gridLoop
+	ld a, l
+	cp e
+	jr nz, _gridLoop
+
+	; Fin.
+	pop bc
+	pop de
+	pop hl
+	ret
+
+_handleTop:
+	; Each row is stuffed into two bytes, so two writes are required to fully
+	; invert the top row.
+	ld a, [hl]
+	cpl
+	ld [hli], a
+	ld a, [hl]
+	cpl
+	ld [hli], a
+	jr _gridLoop
+
 ; Writes a value across 16 bytes, starting at HL. Intended to fill a single tile.
 ; Parameters:
 ;     B - The value to set the bytes to.