Use more hardware and graphics constants (#532)

- Use `OBJ_SIZE` and `TILE_SIZE` from hardware.inc.
- `SPRITESTATEDATA1_LENGTH`, `NUM_SPRITESTATEDATA_STRUCTS`
  and `TILE_1BPP_SIZE` are used in some places.
- Highlight an oversight in `OakSpeech` where several
  direct MBC bank switches are requested.
- Remove redundant comments in home/overworld.asm.
- Add unreferenced `FillBgMap` function to avoid a byte
  of dead code.
- Some constants added in wram.asm.
- Correctly separate the commented code in `SaveMainData`.

4 files changed, 12 insertions, 11 deletions

diff --git a/engine/menus/display_text_id_init.asm b/engine/menus/display_text_id_init.asm
index f8bd6512..7ffdf7c3 100644
--- a/engine/menus/display_text_id_init.asm
+++ b/engine/menus/display_text_id_init.asm
@@ -43,8 +43,8 @@ DisplayTextIDInit::
 ; this is done because when you talk to an NPC, they turn to look your way
 ; the original direction they were facing must be restored after the dialogue is over
 	ld hl, wSprite01StateData1FacingDirection
-	ld c, $0f
-	ld de, $10
+	ld c, NUM_SPRITESTATEDATA_STRUCTS - 1
+	ld de, SPRITESTATEDATA1_LENGTH
 .spriteFacingDirectionCopyLoop
 	ld a, [hl] ; x#SPRITESTATEDATA1_FACINGDIRECTION
 	inc h
@@ -56,7 +56,8 @@ DisplayTextIDInit::
 ; loop to force all the sprites in the middle of animation to stand still
 ; (so that they don't like they're frozen mid-step during the dialogue)
 	ld hl, wSpritePlayerStateData1ImageIndex
-	ld de, $10
+	ld de, SPRITESTATEDATA1_LENGTH
+	ASSERT NUM_SPRITESTATEDATA_STRUCTS == SPRITESTATEDATA1_LENGTH
 	ld c, e
 .spriteStandStillLoop
 	ld a, [hl]
diff --git a/engine/menus/naming_screen.asm b/engine/menus/naming_screen.asm
index fda482e3..9c0cd0a8 100644
--- a/engine/menus/naming_screen.asm
+++ b/engine/menus/naming_screen.asm
@@ -327,7 +327,7 @@ LoadEDTile:
 	ld de, ED_Tile
 	ld hl, vFont tile $70
 	; BUG: BANK("Home") should be BANK(ED_Tile), although it coincidentally works as-is
-	lb bc, BANK("Home"), (ED_TileEnd - ED_Tile) / $8
+	lb bc, BANK("Home"), (ED_TileEnd - ED_Tile) / TILE_1BPP_SIZE
 	jp CopyVideoDataDouble
 
 ED_Tile:
diff --git a/engine/menus/save.asm b/engine/menus/save.asm
index 9dfdd949..3fab0d01 100644
--- a/engine/menus/save.asm
+++ b/engine/menus/save.asm
@@ -225,15 +225,15 @@ SaveMainData:
 	ld de, sSpriteData
 	ld bc, wSpriteDataEnd - wSpriteDataStart
 	call CopyData
-	ld hl, wBoxDataStart
 
 ; this part is redundant, SaveCurrentBoxData is always called next
+	ld hl, wBoxDataStart
 	ld de, sCurBoxData
 	ld bc, wBoxDataEnd - wBoxDataStart
 	call CopyData
+
 	ldh a, [hTileAnimations]
 	ld [sTileAnimations], a
-
 	ld hl, sGameData
 	ld bc, sGameDataEnd - sGameData
 	call CalcCheckSum
diff --git a/engine/menus/start_sub_menus.asm b/engine/menus/start_sub_menus.asm
index 8ba05b3f..c27e58a9 100644
--- a/engine/menus/start_sub_menus.asm
+++ b/engine/menus/start_sub_menus.asm
@@ -511,7 +511,7 @@ DrawTrainerInfo:
 	ld de, 13 tiles
 	add hl, de ; hl = colon tile pattern
 	ld de, vChars1 tile $56
-	ld bc, 1 tiles
+	ld bc, TILE_SIZE
 	ld a, BANK(TextBoxGraphics)
 	push bc
 	call FarCopyData2
@@ -677,13 +677,13 @@ SwitchPartyMon_ClearGfx:
 	dec c
 	jr nz, .clearMonBGLoop
 	pop af
-	ld hl, wShadowOAM
-	ld bc, $10
+	ld hl, wShadowOAMSprite00YCoord
+	ld bc, OBJ_SIZE * 4
 	call AddNTimes
-	ld de, $4
+	ld de, OBJ_SIZE
 	ld c, e
 .clearMonOAMLoop
-	ld [hl], $a0
+	ld [hl], SCREEN_HEIGHT_PX + OAM_Y_OFS
 	add hl, de
 	dec c
 	jr nz, .clearMonOAMLoop