Identify more flag bits (#464)

53 files changed, 267 insertions, 193 deletions

diff --git a/audio/engine_1.asm b/audio/engine_1.asm
index 99d47f37..e9642b32 100644
--- a/audio/engine_1.asm
+++ b/audio/engine_1.asm
@@ -15,9 +15,9 @@ Audio1_UpdateMusic::
 	ld a, [wMuteAudioAndPauseMusic]
 	and a
 	jr z, .applyAffects
-	bit 7, a
+	bit BIT_MUTE_AUDIO, a
 	jr nz, .nextChannel
-	set 7, a
+	set BIT_MUTE_AUDIO, a
 	ld [wMuteAudioAndPauseMusic], a
 	xor a ; disable all channels' output
 	ldh [rNR51], a
@@ -197,7 +197,7 @@ Audio1_sound_ret:
 .dontDisable
 	jr .afterDisable
 .returnFromCall
-	res 1, [hl]
+	res BIT_SOUND_CALL, [hl]
 	ld d, $0
 	ld a, c
 	add a
@@ -377,8 +377,8 @@ Audio1_toggle_perfect_pitch:
 	ld hl, wChannelFlags1
 	add hl, bc
 	ld a, [hl]
-	xor $1
-	ld [hl], a ; flip bit 0 of wChannelFlags1
+	xor 1 << BIT_PERFECT_PITCH
+	ld [hl], a
 	jp Audio1_sound_ret
 
 Audio1_vibrato:
diff --git a/audio/engine_2.asm b/audio/engine_2.asm
index bcaab694..2f11c027 100644
--- a/audio/engine_2.asm
+++ b/audio/engine_2.asm
@@ -17,9 +17,9 @@ Audio2_UpdateMusic::
 	ld a, [wMuteAudioAndPauseMusic]
 	and a
 	jr z, .applyAffects
-	bit 7, a
+	bit BIT_MUTE_AUDIO, a
 	jr nz, .nextChannel
-	set 7, a
+	set BIT_MUTE_AUDIO, a
 	ld [wMuteAudioAndPauseMusic], a
 	xor a ; disable all channels' output
 	ldh [rNR51], a
@@ -163,8 +163,8 @@ Audio2_PlayNextNote:
 	ld a, c
 	cp CHAN5
 	jr nz, .beginChecks
-	ld a, [wLowHealthAlarm] ; low health alarm enabled?
-	bit 7, a
+	ld a, [wLowHealthAlarm]
+	bit BIT_LOW_HEALTH_ALARM, a
 	ret nz
 .beginChecks
 	; ---
@@ -208,7 +208,7 @@ Audio2_sound_ret:
 .dontDisable
 	jr .afterDisable
 .returnFromCall
-	res 1, [hl]
+	res BIT_SOUND_CALL, [hl]
 	ld d, $0
 	ld a, c
 	add a
@@ -388,8 +388,8 @@ Audio2_toggle_perfect_pitch:
 	ld hl, wChannelFlags1
 	add hl, bc
 	ld a, [hl]
-	xor $1
-	ld [hl], a ; flip bit 0 of wChannelFlags1
+	xor 1 << BIT_PERFECT_PITCH
+	ld [hl], a
 	jp Audio2_sound_ret
 
 Audio2_vibrato:
@@ -978,7 +978,7 @@ Audio2_ResetCryModifiers:
 	cp CHAN5
 	jr nz, .skip
 	ld a, [wLowHealthAlarm]
-	bit 7, a
+	bit BIT_LOW_HEALTH_ALARM, a
 	jr z, .skip
 	xor a
 	ld [wFrequencyModifier], a
diff --git a/audio/engine_3.asm b/audio/engine_3.asm
index e5d285a3..f524875f 100644
--- a/audio/engine_3.asm
+++ b/audio/engine_3.asm
@@ -15,9 +15,9 @@ Audio3_UpdateMusic::
 	ld a, [wMuteAudioAndPauseMusic]
 	and a
 	jr z, .applyAffects
-	bit 7, a
+	bit BIT_MUTE_AUDIO, a
 	jr nz, .nextChannel
-	set 7, a
+	set BIT_MUTE_AUDIO, a
 	ld [wMuteAudioAndPauseMusic], a
 	xor a ; disable all channels' output
 	ldh [rNR51], a
@@ -197,7 +197,7 @@ Audio3_sound_ret:
 .dontDisable
 	jr .afterDisable
 .returnFromCall
-	res 1, [hl]
+	res BIT_SOUND_CALL, [hl]
 	ld d, $0
 	ld a, c
 	add a
@@ -377,8 +377,8 @@ Audio3_toggle_perfect_pitch:
 	ld hl, wChannelFlags1
 	add hl, bc
 	ld a, [hl]
-	xor $1
-	ld [hl], a ; flip bit 0 of wChannelFlags1
+	xor 1 << BIT_PERFECT_PITCH
+	ld [hl], a
 	jp Audio3_sound_ret
 
 Audio3_vibrato:
diff --git a/audio/low_health_alarm.asm b/audio/low_health_alarm.asm
index 35fe1815..728f5f65 100644
--- a/audio/low_health_alarm.asm
+++ b/audio/low_health_alarm.asm
@@ -1,12 +1,12 @@
 Music_DoLowHealthAlarm::
 	ld a, [wLowHealthAlarm]
-	cp $ff
+	cp DISABLE_LOW_HEALTH_ALARM
 	jr z, .disableAlarm
 
-	bit 7, a  ;alarm enabled?
-	ret z     ;nope
+	bit BIT_LOW_HEALTH_ALARM, a
+	ret z
 
-	and $7f   ;low 7 bits are the timer.
+	and LOW_HEALTH_TIMER_MASK
 	jr nz, .notToneHi ;if timer > 0, play low tone.
 
 	call .playToneHi
@@ -19,15 +19,15 @@ Music_DoLowHealthAlarm::
 	call .playToneLo ;actually set the sound registers.
 
 .noTone
-	ld a, $86
+	ld a, CRY_SFX_END
 	ld [wChannelSoundIDs + CHAN5], a ;disable sound channel?
 	ld a, [wLowHealthAlarm]
-	and $7f ;decrement alarm timer.
+	and LOW_HEALTH_TIMER_MASK
 	dec a
 
 .resetTimer
 	; reset the timer and enable flag.
-	set 7, a
+	set BIT_LOW_HEALTH_ALARM, a
 	ld [wLowHealthAlarm], a
 	ret
 
diff --git a/constants/audio_constants.asm b/constants/audio_constants.asm
index a8903052..99b899d1 100644
--- a/constants/audio_constants.asm
+++ b/constants/audio_constants.asm
@@ -66,3 +66,11 @@ DEF HW_CH4_DISABLE_MASK EQU (~HW_CH4_ENABLE_MASK & $ff)
 
 ; wChannelFlags2 constant (only has one flag)
 DEF BIT_EXECUTE_MUSIC EQU 0 ; if in execute music
+
+; wMuteAudioAndPauseMusic
+DEF BIT_MUTE_AUDIO EQU 7
+
+; wLowHealthAlarm
+DEF BIT_LOW_HEALTH_ALARM EQU 7
+DEF LOW_HEALTH_TIMER_MASK EQU %01111111
+DEF DISABLE_LOW_HEALTH_ALARM EQU $ff
diff --git a/constants/battle_constants.asm b/constants/battle_constants.asm
index 9349bb75..cde50b4d 100644
--- a/constants/battle_constants.asm
+++ b/constants/battle_constants.asm
@@ -72,6 +72,10 @@ DEF MAX_STAT_VALUE EQU 999
 DEF ATKDEFDV_TRAINER EQU $98
 DEF SPDSPCDV_TRAINER EQU $88
 
+; wDamageMultipliers
+DEF BIT_STAB_DAMAGE EQU 7
+DEF EFFECTIVENESS_MASK EQU %01111111
+
 ; wPlayerBattleStatus1 or wEnemyBattleStatus1 bit flags
 	const_def
 	const STORING_ENERGY           ; 0 ; Bide
diff --git a/constants/gfx_constants.asm b/constants/gfx_constants.asm
index c6268208..79d9647f 100644
--- a/constants/gfx_constants.asm
+++ b/constants/gfx_constants.asm
@@ -29,6 +29,12 @@ DEF TRANSFERBOTTOM EQU 2
 DEF REDRAW_COL EQU 1
 DEF REDRAW_ROW EQU 2
 
+; hUILayoutFlags
+	const_def
+	const BIT_PARTY_MENU_HP_BAR   ; 0
+	const BIT_DOUBLE_SPACED_MENU  ; 1
+	const BIT_SINGLE_SPACED_LINES ; 2
+
 ; tile list ids
 ; TileIDListPointerTable indexes (see data/tilemaps.asm)
 	const_def
diff --git a/constants/map_object_constants.asm b/constants/map_object_constants.asm
index 377edcea..3b17c6ae 100644
--- a/constants/map_object_constants.asm
+++ b/constants/map_object_constants.asm
@@ -40,9 +40,16 @@ DEF SPRITESTATEDATA2_LENGTH EQU const_value
 
 DEF NUM_SPRITESTATEDATA_STRUCTS EQU 16
 
+	const_def 6
+	const BIT_TRAINER ; 6
+	const BIT_ITEM    ; 7
+
 ; different kinds of people events
-DEF ITEM    EQU $80
-DEF TRAINER EQU $40
+DEF TRAINER EQU 1 << BIT_TRAINER
+DEF ITEM    EQU 1 << BIT_ITEM
+
+; movement status
+DEF BIT_FACE_PLAYER EQU 7
 
 DEF WALK EQU $FE
 DEF STAY EQU $FF
diff --git a/constants/menu_constants.asm b/constants/menu_constants.asm
index f1f0d417..a6e035e7 100644
--- a/constants/menu_constants.asm
+++ b/constants/menu_constants.asm
@@ -44,6 +44,9 @@ DEF PC_ITEM_CAPACITY  EQU 50
 	const NO_YES_MENU       ; 7
 DEF NUM_TWO_OPTION_MENUS EQU const_value
 
+; wTwoOptionMenuID
+DEF BIT_SECOND_MENU_OPTION_DEFAULT EQU 7
+
 ; menu exit method constants for list menus and the buy/sell/quit menu
 DEF CHOSE_MENU_ITEM   EQU 1 ; pressed A
 DEF CANCELLED_MENU    EQU 2 ; pressed B
diff --git a/constants/oam_constants.asm b/constants/oam_constants.asm
index 8c5e6be8..e87e54a0 100644
--- a/constants/oam_constants.asm
+++ b/constants/oam_constants.asm
@@ -1,14 +1,20 @@
-; OAM flags used by this game
-DEF OAMFLAG_ENDOFDATA   EQU %00000001 ; pseudo OAM flag, only used by game logic
-DEF OAMFLAG_CANBEMASKED EQU %00000010 ; pseudo OAM flag, only used by game logic
+; Pseudo-OAM flags used by game logic
+	const_def
+	const BIT_END_OF_OAM_DATA    ; 0
+	const BIT_SPRITE_UNDER_GRASS ; 1
+
+; Used in SpriteFacingAndAnimationTable (see data/sprites/facings.asm)
+DEF FACING_END  EQU 1 << BIT_END_OF_OAM_DATA
+DEF UNDER_GRASS EQU 1 << BIT_SPRITE_UNDER_GRASS
 
 ; OAM attribute flags
-DEF OAM_PALETTE   EQU %111
-DEF OAM_TILE_BANK EQU 3
-DEF OAM_OBP_NUM   EQU 4 ; Non CGB Mode Only
-DEF OAM_X_FLIP    EQU 5
-DEF OAM_Y_FLIP    EQU 6
-DEF OAM_PRIORITY  EQU 7 ; 0: OBJ above BG, 1: OBJ behind BG (colors 1-3)
+DEF OAM_PALETTE EQU %111
+	const_def 3
+	const OAM_TILE_BANK ; 3
+	const OAM_OBP_NUM   ; 4 ; Non CGB Mode Only
+	const OAM_X_FLIP    ; 5
+	const OAM_Y_FLIP    ; 6
+	const OAM_PRIORITY  ; 7 ; 0: OBJ above BG, 1: OBJ behind BG (colors 1-3)
 
 ; OAM attribute masks
 DEF OAM_OBP1      EQU 1 << OAM_OBP_NUM  ; OBJ palette 1
diff --git a/constants/ram_constants.asm b/constants/ram_constants.asm
index 42956cc6..8102cc7e 100644
--- a/constants/ram_constants.asm
+++ b/constants/ram_constants.asm
@@ -1,3 +1,8 @@
+; wSlotMachineFlags
+	const_def 6
+	const BIT_SLOTS_CAN_WIN               ; 6
+	const BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR ; 7
+
 ; wMiscFlags
 	const_def
 	const BIT_SEEN_BY_TRAINER      ; 0
@@ -9,6 +14,15 @@
 	const BIT_TRIED_PUSH_BOULDER   ; 6
 	const BIT_PUSHED_BOULDER       ; 7
 
+; wAutoTextBoxDrawingControl
+DEF BIT_NO_AUTO_TEXT_BOX EQU 0
+
+; wTextPredefFlag
+DEF BIT_TEXT_PREDEF EQU 0
+
+; wFontLoaded
+DEF BIT_FONT_LOADED EQU 0
+
 ; wOptions
 DEF TEXT_DELAY_MASK EQU %111
 	const_def 6
@@ -24,6 +38,12 @@ DEF TEXT_DELAY_SLOW   EQU %101 ; 5
 	const BIT_FAST_TEXT_DELAY ; 0
 	const BIT_TEXT_DELAY      ; 1
 
+; wCurMapTileset
+DEF BIT_NO_PREVIOUS_MAP EQU 7
+
+; wCurrentBoxNum
+DEF BIT_HAS_CHANGED_BOXES EQU 7
+
 ; wObtainedBadges, wBeatGymFlags
 	const_def
 	const BIT_BOULDERBADGE ; 0
@@ -117,3 +137,13 @@ DEF NUM_BADGES EQU const_value
 	const_skip 3               ; 3-5 ; unused
 	const BIT_LEDGE_OR_FISHING ; 6
 	const BIT_SPINNING         ; 7
+
+; hFindPathFlags
+	const_def
+	const BIT_PATH_FOUND_Y ; 0
+	const BIT_PATH_FOUND_X ; 1
+
+; hNPCPlayerRelativePosFlags
+	const_def
+	const BIT_PLAYER_LOWER_Y ; 0
+	const BIT_PLAYER_LOWER_X ; 1
diff --git a/data/sprites/facings.asm b/data/sprites/facings.asm
index eb583d53..54fd7ed0 100644
--- a/data/sprites/facings.asm
+++ b/data/sprites/facings.asm
@@ -48,12 +48,12 @@ SpriteFacingAndAnimationTable:
 	; y, x, attributes
 	db 0, 0, $00 ; top left
 	db 0, 8, $00 ; top right
-	db 8, 0, OAMFLAG_CANBEMASKED ; bottom left
-	db 8, 8, OAMFLAG_CANBEMASKED | OAMFLAG_ENDOFDATA ; bottom right
+	db 8, 0, UNDER_GRASS ; bottom left
+	db 8, 8, UNDER_GRASS | FACING_END ; bottom right
 
 .FlippedOAM:
 	; y, x, attributes
 	db 0, 8, OAM_HFLIP ; top left
 	db 0, 0, OAM_HFLIP ; top right
-	db 8, 8, OAM_HFLIP | OAMFLAG_CANBEMASKED ; bottom left
-	db 8, 0, OAM_HFLIP | OAMFLAG_CANBEMASKED | OAMFLAG_ENDOFDATA ; bottom right
+	db 8, 8, OAM_HFLIP | UNDER_GRASS ; bottom left
+	db 8, 0, OAM_HFLIP | UNDER_GRASS | FACING_END ; bottom right
diff --git a/engine/battle/animations.asm b/engine/battle/animations.asm
index 3e077d2b..3ccbf7c4 100644
--- a/engine/battle/animations.asm
+++ b/engine/battle/animations.asm
@@ -114,13 +114,13 @@ DrawFrameBlock:
 	ld [de], a ; store tile ID
 	inc de
 	ld a, [hli]
-	bit 5, a ; is horizontal flip enabled?
+	bit OAM_X_FLIP, a
 	jr nz, .disableHorizontalFlip
 .enableHorizontalFlip
-	set 5, a
+	set OAM_X_FLIP, a
 	jr .storeFlags2
 .disableHorizontalFlip
-	res 5, a
+	res OAM_X_FLIP, a
 .storeFlags2
 	ld [de], a
 	inc de
diff --git a/engine/battle/battle_transitions.asm b/engine/battle/battle_transitions.asm
index 5956d875..85d2177e 100644
--- a/engine/battle/battle_transitions.asm
+++ b/engine/battle/battle_transitions.asm
@@ -64,6 +64,12 @@ BattleTransition:
 	ld l, a
 	jp hl
 
+	const_def
+	const BIT_TRAINER_BATTLE_TRANSITION  ; 0
+	const BIT_STRONGER_BATTLE_TRANSITION ; 1
+	const BIT_DUNGEON_BATTLE_TRANSITION  ; 2
+DEF NUM_BATTLE_TRANSITION_BITS EQU const_value
+
 ; the three GetBattleTransitionID functions set the first
 ; three bits of c, which determines what transition animation
 ; to play at the beginning of a battle
@@ -71,6 +77,7 @@ BattleTransition:
 ; bit 1: set if enemy is at least 3 levels higher than player
 ; bit 2: set if dungeon map
 BattleTransitions:
+	table_width 2, BattleTransitions
 	dw BattleTransition_DoubleCircle      ; %000
 	dw BattleTransition_Spiral            ; %001
 	dw BattleTransition_Circle            ; %010
@@ -79,15 +86,16 @@ BattleTransitions:
 	dw BattleTransition_Shrink            ; %101
 	dw BattleTransition_VerticalStripes   ; %110
 	dw BattleTransition_Split             ; %111
+	assert_table_length 1 << NUM_BATTLE_TRANSITION_BITS
 
 GetBattleTransitionID_WildOrTrainer:
 	ld a, [wCurOpponent]
 	cp OPP_ID_OFFSET
 	jr nc, .trainer
-	res 0, c
+	res BIT_TRAINER_BATTLE_TRANSITION, c
 	ret
 .trainer
-	set 0, c
+	set BIT_TRAINER_BATTLE_TRANSITION, c
 	ret
 
 GetBattleTransitionID_CompareLevels:
@@ -108,12 +116,12 @@ GetBattleTransitionID_CompareLevels:
 	ld a, [wCurEnemyLevel]
 	sub e
 	jr nc, .highLevelEnemy
-	res 1, c
+	res BIT_STRONGER_BATTLE_TRANSITION, c
 	ld a, 1
 	ld [wBattleTransitionSpiralDirection], a
 	ret
 .highLevelEnemy
-	set 1, c
+	set BIT_STRONGER_BATTLE_TRANSITION, c
 	xor a
 	ld [wBattleTransitionSpiralDirection], a
 	ret
@@ -129,7 +137,7 @@ GetBattleTransitionID_IsDungeonMap:
 	cp e
 	jr nz, .loop1
 .match
-	set 2, c
+	set BIT_DUNGEON_BATTLE_TRANSITION, c
 	ret
 .noMatch1
 	ld hl, DungeonMaps2
@@ -145,7 +153,7 @@ GetBattleTransitionID_IsDungeonMap:
 	cp d
 	jr nc, .match
 .noMatch2
-	res 2, c
+	res BIT_DUNGEON_BATTLE_TRANSITION, c
 	ret
 
 INCLUDE "data/maps/dungeon_maps.asm"
diff --git a/engine/battle/core.asm b/engine/battle/core.asm
index 428bc78a..5e93393c 100644
--- a/engine/battle/core.asm
+++ b/engine/battle/core.asm
@@ -1007,12 +1007,12 @@ RemoveFaintedPlayerMon:
 	ld b, FLAG_RESET
 	predef FlagActionPredef ; clear gain exp flag for fainted mon
 	ld hl, wEnemyBattleStatus1
-	res 2, [hl]   ; reset "attacking multiple times" flag
+	res ATTACKING_MULTIPLE_TIMES, [hl]
 	ld a, [wLowHealthAlarm]
-	bit 7, a      ; skip sound flag (red bar (?))
+	bit BIT_LOW_HEALTH_ALARM, a
 	jr z, .skipWaitForSound
-	ld a, $ff
-	ld [wLowHealthAlarm], a ;disable low health alarm
+	ld a, DISABLE_LOW_HEALTH_ALARM
+	ld [wLowHealthAlarm], a
 	call WaitForSoundToFinish
 .skipWaitForSound
 ; a is 0, so this zeroes the enemy's accumulated damage.
@@ -1305,7 +1305,7 @@ EnemySendOutFirstMon:
 	dec a
 	ld [wAICount], a
 	ld hl, wPlayerBattleStatus1
-	res 5, [hl]
+	res USING_TRAPPING_MOVE, [hl]
 	hlcoord 18, 0
 	ld a, 8
 	call SlideTrainerPicOffScreen
@@ -1860,15 +1860,15 @@ DrawPlayerHUDAndHPBar:
 	jr z, .setLowHealthAlarm
 .fainted
 	ld hl, wLowHealthAlarm
-	bit 7, [hl] ;low health alarm enabled?
-	ld [hl], $0
+	bit BIT_LOW_HEALTH_ALARM, [hl]
+	ld [hl], 0
 	ret z
 	xor a
 	ld [wChannelSoundIDs + CHAN5], a
 	ret
 .setLowHealthAlarm
 	ld hl, wLowHealthAlarm
-	set 7, [hl] ;enable low health alarm
+	set BIT_LOW_HEALTH_ALARM, [hl]
 	ret
 
 DrawEnemyHUDAndHPBar:
@@ -2121,7 +2121,7 @@ DisplayBattleMenu::
 	ld a, D_LEFT | A_BUTTON
 	ld [hli], a ; wMenuWatchedKeys
 	call HandleMenuInput
-	bit 5, a ; check if left was pressed
+	bit BIT_D_LEFT, a
 	jr nz, .leftColumn ; if left was pressed, jump
 	ld a, [wCurrentMenuItem]
 	add $2 ; if we're in the right column, the actual id is +2
@@ -2473,11 +2473,11 @@ MoveSelectionMenu:
 .writemoves
 	ld de, wMovesString
 	ldh a, [hUILayoutFlags]
-	set 2, a
+	set BIT_SINGLE_SPACED_LINES, a
 	ldh [hUILayoutFlags], a
 	call PlaceString
 	ldh a, [hUILayoutFlags]
-	res 2, a
+	res BIT_SINGLE_SPACED_LINES, a
 	ldh [hUILayoutFlags], a
 	ret
 
@@ -2604,10 +2604,10 @@ SelectMenuItem:
 	ld [hl], "▷"
 .select
 	ld hl, hUILayoutFlags
-	set 1, [hl]
+	set BIT_DOUBLE_SPACED_MENU, [hl]
 	call HandleMenuInput
 	ld hl, hUILayoutFlags
-	res 1, [hl]
+	res BIT_DOUBLE_SPACED_MENU, [hl]
 	bit BIT_D_UP, a
 	jp nz, SelectMenuItem_CursorUp
 	bit BIT_D_DOWN, a
@@ -2652,7 +2652,7 @@ SelectMenuItem:
 	cp c
 	jr z, .disabled
 	ld a, [wPlayerBattleStatus3]
-	bit 3, a ; transformed
+	bit TRANSFORMED, a
 	jr nz, .transformedMoveSelected
 .transformedMoveSelected ; pointless
 	; Allow moves copied by Transform to be used.
@@ -3850,7 +3850,7 @@ PrintMoveFailureText:
 .playersTurn
 	ld hl, DoesntAffectMonText
 	ld a, [wDamageMultipliers]
-	and $7f
+	and EFFECTIVENESS_MASK
 	jr z, .gotTextToPrint
 	ld hl, AttackMissedText
 	ld a, [wCriticalHitOrOHKO]
@@ -5248,7 +5248,7 @@ AdjustDamageForMoveType:
 	ld a, l
 	ld [wDamage + 1], a
 	ld hl, wDamageMultipliers
-	set 7, [hl]
+	set BIT_STAB_DAMAGE, [hl]
 .skipSameTypeAttackBonus
 	ld a, [wMoveType]
 	ld b, a
@@ -5271,7 +5271,7 @@ AdjustDamageForMoveType:
 	push bc
 	inc hl
 	ld a, [wDamageMultipliers]
-	and $80
+	and 1 << BIT_STAB_DAMAGE
 	ld b, a
 	ld a, [hl] ; a = damage multiplier
 	ldh [hMultiplier], a
diff --git a/engine/battle/effects.asm b/engine/battle/effects.asm
index 6fba347f..95c8706f 100644
--- a/engine/battle/effects.asm
+++ b/engine/battle/effects.asm
@@ -194,7 +194,7 @@ ExplodeEffect:
 FreezeBurnParalyzeEffect:
 	xor a
 	ld [wAnimationType], a
-	call CheckTargetSubstitute ; test bit 4 of d063/d068 flags [target has substitute flag]
+	call CheckTargetSubstitute
 	ret nz ; return if they have a substitute, can't effect them
 	ldh a, [hWhoseTurn]
 	and a
diff --git a/engine/battle/experience.asm b/engine/battle/experience.asm
index 57d37f01..a8ee6747 100644
--- a/engine/battle/experience.asm
+++ b/engine/battle/experience.asm
@@ -224,7 +224,7 @@ GainExperience:
 	call CopyData
 	pop hl
 	ld a, [wPlayerBattleStatus3]
-	bit 3, a ; is the mon transformed?
+	bit TRANSFORMED, a
 	jr nz, .recalcStatChanges
 ; the mon is not transformed, so update the unmodified stats
 	ld de, wPlayerMonUnmodifiedLevel
diff --git a/engine/battle/trainer_ai.asm b/engine/battle/trainer_ai.asm
index 5eed1ae5..ccd4e804 100644
--- a/engine/battle/trainer_ai.asm
+++ b/engine/battle/trainer_ai.asm
@@ -632,27 +632,27 @@ AICureStatus:
 	ld [hl], a ; clear status in enemy team roster
 	ld [wEnemyMonStatus], a ; clear status of active enemy
 	ld hl, wEnemyBattleStatus3
-	res 0, [hl]
+	res BADLY_POISONED, [hl]
 	ret
 
 AIUseXAccuracy: ; unused
 	call AIPlayRestoringSFX
 	ld hl, wEnemyBattleStatus2
-	set 0, [hl]
+	set USING_X_ACCURACY, [hl]
 	ld a, X_ACCURACY
 	jp AIPrintItemUse
 
 AIUseGuardSpec:
 	call AIPlayRestoringSFX
 	ld hl, wEnemyBattleStatus2
-	set 1, [hl]
+	set PROTECTED_BY_MIST, [hl]
 	ld a, GUARD_SPEC
 	jp AIPrintItemUse
 
 AIUseDireHit: ; unused
 	call AIPlayRestoringSFX
 	ld hl, wEnemyBattleStatus2
-	set 2, [hl]
+	set GETTING_PUMPED, [hl]
 	ld a, DIRE_HIT
 	jp AIPrintItemUse
 
diff --git a/engine/events/hidden_objects/pokecenter_pc.asm b/engine/events/hidden_objects/pokecenter_pc.asm
index f20f40ed..59867d1a 100644
--- a/engine/events/hidden_objects/pokecenter_pc.asm
+++ b/engine/events/hidden_objects/pokecenter_pc.asm
@@ -3,7 +3,7 @@ OpenPokemonCenterPC:
 	cp SPRITE_FACING_UP
 	ret nz
 	call EnableAutoTextBoxDrawing
-	ld a, TRUE
+	ld a, 1 << BIT_NO_AUTO_TEXT_BOX
 	ld [wAutoTextBoxDrawingControl], a
 	tx_pre_jump PokemonCenterPCText
 
diff --git a/engine/events/poison.asm b/engine/events/poison.asm
index 752899f7..5a7bed7c 100644
--- a/engine/events/poison.asm
+++ b/engine/events/poison.asm
@@ -1,7 +1,7 @@
 ApplyOutOfBattlePoisonDamage:
 	ld a, [wStatusFlags5]
 	assert BIT_SCRIPTED_MOVEMENT_STATE == 7
-	add a ; overflows bit 7 into carry flag
+	add a ; overflows scripted movement state bit into carry flag
 	jp c, .noBlackOut ; no black out if joypad states are being simulated
 	ld a, [wPartyCount]
 	and a
diff --git a/engine/gfx/hp_bar.asm b/engine/gfx/hp_bar.asm
index d848a337..c1ae598e 100644
--- a/engine/gfx/hp_bar.asm
+++ b/engine/gfx/hp_bar.asm
@@ -214,7 +214,7 @@ UpdateHPBar_PrintHPNumber:
 	ld [wHPBarTempHP], a
 	push hl
 	ldh a, [hUILayoutFlags]
-	bit 0, a
+	bit BIT_PARTY_MENU_HP_BAR, a
 	jr z, .hpBelowBar
 	ld de, $9
 	jr .next
diff --git a/engine/gfx/sprite_oam.asm b/engine/gfx/sprite_oam.asm
index 3916c0db..737443a6 100644
--- a/engine/gfx/sprite_oam.asm
+++ b/engine/gfx/sprite_oam.asm
@@ -124,7 +124,7 @@ PrepareOAMData::
 	inc hl
 	inc e
 	ld a, [hl]
-	bit 1, a ; is the tile allowed to set the sprite priority bit?
+	bit BIT_SPRITE_UNDER_GRASS, a
 	jr z, .skipPriority
 	ldh a, [hSpritePriority]
 	or [hl]
@@ -132,7 +132,7 @@ PrepareOAMData::
 	inc hl
 	ld [de], a
 	inc e
-	bit 0, a ; OAMFLAG_ENDOFDATA
+	bit BIT_END_OF_OAM_DATA, a
 	jr z, .tileLoop
 
 	ld a, e
diff --git a/engine/items/item_effects.asm b/engine/items/item_effects.asm
index 91462478..9643412c 100644
--- a/engine/items/item_effects.asm
+++ b/engine/items/item_effects.asm
@@ -691,7 +691,7 @@ ItemUseSurfboard:
 	ldh [hSpriteIndex], a
 	ld d, 16 ; talking range in pixels (normal range)
 	call IsSpriteInFrontOfPlayer2
-	res 7, [hl]
+	res BIT_FACE_PLAYER, [hl]
 	ldh a, [hSpriteIndex]
 	and a ; is there a sprite in the way?
 	jr nz, .cannotStopSurfing
@@ -1052,13 +1052,13 @@ ItemUseMedicine:
 	ld a, SFX_HEAL_HP
 	call PlaySoundWaitForCurrent
 	ldh a, [hUILayoutFlags]
-	set 0, a
+	set BIT_PARTY_MENU_HP_BAR, a
 	ldh [hUILayoutFlags], a
 	ld a, $02
 	ld [wHPBarType], a
 	predef UpdateHPBar2 ; animate HP bar decrease of pokemon that used Softboiled
 	ldh a, [hUILayoutFlags]
-	res 0, a
+	res BIT_PARTY_MENU_HP_BAR, a
 	ldh [hUILayoutFlags], a
 	pop af
 	ld b, a ; store heal amount (1/5 of max HP)
@@ -1202,13 +1202,13 @@ ItemUseMedicine:
 	ld a, SFX_HEAL_HP
 	call PlaySoundWaitForCurrent
 	ldh a, [hUILayoutFlags]
-	set 0, a
+	set BIT_PARTY_MENU_HP_BAR, a
 	ldh [hUILayoutFlags], a
 	ld a, $02
 	ld [wHPBarType], a
 	predef UpdateHPBar2 ; animate the HP bar lengthening
 	ldh a, [hUILayoutFlags]
-	res 0, a
+	res BIT_PARTY_MENU_HP_BAR, a
 	ldh [hUILayoutFlags], a
 	ld a, REVIVE_MSG
 	ld [wPartyMenuTypeOrMessageID], a
diff --git a/engine/items/town_map.asm b/engine/items/town_map.asm
index a9840268..6f2c050c 100644
--- a/engine/items/town_map.asm
+++ b/engine/items/town_map.asm
@@ -75,9 +75,9 @@ DisplayTownMap:
 	jr z, .inputLoop
 	ld a, SFX_TINK
 	call PlaySound
-	bit 6, b
+	bit BIT_D_UP, b
 	jr nz, .pressedUp
-	bit 7, b
+	bit BIT_D_DOWN, b
 	jr nz, .pressedDown
 	xor a
 	ld [wTownMapSpriteBlinkingEnabled], a
@@ -196,13 +196,13 @@ LoadTownMap_Fly::
 	pop hl
 	and A_BUTTON | B_BUTTON | D_UP | D_DOWN
 	jr z, .inputLoop
-	bit 0, b
+	bit BIT_A_BUTTON, b
 	jr nz, .pressedA
 	ld a, SFX_TINK
 	call PlaySound
-	bit 6, b
+	bit BIT_D_UP, b
 	jr nz, .pressedUp
-	bit 7, b
+	bit BIT_D_DOWN, b
 	jr nz, .pressedDown
 	jr .pressedB
 .pressedA
diff --git a/engine/link/cable_club.asm b/engine/link/cable_club.asm
index cbb8a358..8ae192b8 100644
--- a/engine/link/cable_club.asm
+++ b/engine/link/cable_club.asm
@@ -282,7 +282,7 @@ CableClub_DoBattleOrTradeAgain:
 	call ClearScreen
 	call Delay3
 	ld hl, wOptions
-	res 7, [hl]
+	res BIT_BATTLE_ANIMATION, [hl]
 	predef InitOpponent
 	predef HealParty
 	jp ReturnToCableClubRoom
@@ -342,10 +342,10 @@ TradeCenter_SelectMon:
 	ld [wTopMenuItemX], a
 .enemyMonMenu_HandleInput
 	ld hl, hUILayoutFlags
-	set 1, [hl]
+	set BIT_DOUBLE_SPACED_MENU, [hl]
 	call HandleMenuInput
 	ld hl, hUILayoutFlags
-	res 1, [hl]
+	res BIT_DOUBLE_SPACED_MENU, [hl]
 	and a
 	jp z, .getNewInput
 	bit BIT_A_BUTTON, a
@@ -407,10 +407,10 @@ TradeCenter_SelectMon:
 	call ClearScreenArea
 .playerMonMenu_HandleInput
 	ld hl, hUILayoutFlags
-	set 1, [hl]
+	set BIT_DOUBLE_SPACED_MENU, [hl]
 	call HandleMenuInput
 	ld hl, hUILayoutFlags
-	res 1, [hl]
+	res BIT_DOUBLE_SPACED_MENU, [hl]
 	and a ; was anything pressed?
 	jr nz, .playerMonMenu_SomethingPressed
 	jp .getNewInput
@@ -489,7 +489,7 @@ TradeCenter_SelectMon:
 	ld a, 1
 	ld [wTopMenuItemX], a
 	call HandleMenuInput
-	bit 4, a ; Right pressed?
+	bit BIT_D_RIGHT, a
 	jr nz, .selectTradeMenuItem
 	bit BIT_B_BUTTON, a
 	jr z, .displayPlayerMonStats
@@ -585,7 +585,7 @@ ReturnToCableClubRoom:
 	ld a, [hl]
 	push af
 	push hl
-	res 0, [hl]
+	res BIT_FONT_LOADED, [hl]
 	xor a
 	ld [wStatusFlags3], a ; clears BIT_INIT_TRADE_CENTER_FACING
 	dec a
diff --git a/engine/menus/display_text_id_init.asm b/engine/menus/display_text_id_init.asm
index a89696fb..2ef1cfb1 100644
--- a/engine/menus/display_text_id_init.asm
+++ b/engine/menus/display_text_id_init.asm
@@ -3,7 +3,7 @@ DisplayTextIDInit::
 	xor a
 	ld [wListMenuID], a
 	ld a, [wAutoTextBoxDrawingControl]
-	bit 0, a
+	bit BIT_NO_AUTO_TEXT_BOX, a
 	jr nz, .skipDrawingTextBoxBorder
 	ldh a, [hTextID]
 	and a
@@ -31,7 +31,7 @@ DisplayTextIDInit::
 	call TextBoxBorder
 .skipDrawingTextBoxBorder
 	ld hl, wFontLoaded
-	set 0, [hl]
+	set BIT_FONT_LOADED, [hl]
 	ld hl, wMiscFlags
 	bit BIT_NO_SPRITE_UPDATES, [hl]
 	res BIT_NO_SPRITE_UPDATES, [hl]
diff --git a/engine/menus/league_pc.asm b/engine/menus/league_pc.asm
index 17d58c55..03b1de6d 100644
--- a/engine/menus/league_pc.asm
+++ b/engine/menus/league_pc.asm
@@ -44,7 +44,7 @@ PKMNLeaguePC:
 	pop af
 	ld [wUpdateSpritesEnabled], a
 	pop hl
-	res 6, [hl]
+	res BIT_NO_TEXT_DELAY, [hl]
 	call GBPalWhiteOutWithDelay3
 	call ClearScreen
 	call RunDefaultPaletteCommand
@@ -57,7 +57,7 @@ LeaguePCShowTeam:
 	call LeaguePCShowMon
 	call WaitForTextScrollButtonPress
 	ldh a, [hJoyHeld]
-	bit 1, a
+	bit BIT_B_BUTTON, a
 	jr nz, .exit
 	ld hl, wHallOfFame + HOF_MON
 	ld de, wHallOfFame
diff --git a/engine/menus/party_menu.asm b/engine/menus/party_menu.asm
index 6c8cd6eb..e6388b5f 100644
--- a/engine/menus/party_menu.asm
+++ b/engine/menus/party_menu.asm
@@ -70,12 +70,12 @@ RedrawPartyMenu_::
 	push hl
 	ld bc, SCREEN_WIDTH + 1 ; down 1 row and right 1 column
 	ldh a, [hUILayoutFlags]
-	set 0, a
+	set BIT_PARTY_MENU_HP_BAR, a
 	ldh [hUILayoutFlags], a
 	add hl, bc
 	predef DrawHP2 ; draw HP bar and prints current / max HP
 	ldh a, [hUILayoutFlags]
-	res 0, a
+	res BIT_PARTY_MENU_HP_BAR, a
 	ldh [hUILayoutFlags], a
 	call SetPartyMenuHPBarColor ; color the HP bar (on SGB)
 	pop hl
diff --git a/engine/menus/players_pc.asm b/engine/menus/players_pc.asm
index 9e1553dd..402275b5 100644
--- a/engine/menus/players_pc.asm
+++ b/engine/menus/players_pc.asm
@@ -50,7 +50,7 @@ PlayerPCMenu:
 	ld hl, WhatDoYouWantText
 	call PrintText
 	call HandleMenuInput
-	bit 1, a
+	bit BIT_B_BUTTON, a
 	jp nz, ExitPlayerPC
 	call PlaceUnfilledArrowMenuCursor
 	ld a, [wCurrentMenuItem]
diff --git a/engine/menus/save.asm b/engine/menus/save.asm
index 2f61b678..eeb4b9e8 100644
--- a/engine/menus/save.asm
+++ b/engine/menus/save.asm
@@ -66,7 +66,7 @@ LoadSAV0:
 	ld bc, wMainDataEnd - wMainDataStart
 	call CopyData
 	ld hl, wCurMapTileset
-	set 7, [hl]
+	set BIT_NO_PREVIOUS_MAP, [hl]
 	ld hl, sSpriteData
 	ld de, wSpriteDataStart
 	ld bc, wSpriteDataEnd - wSpriteDataStart
@@ -349,15 +349,15 @@ ChangeBox::
 	and a
 	ret nz ; return if No was chosen
 	ld hl, wCurrentBoxNum
-	bit 7, [hl] ; is it the first time player is changing the box?
+	bit BIT_HAS_CHANGED_BOXES, [hl] ; is it the first time player is changing the box?
 	call z, EmptyAllSRAMBoxes ; if so, empty all boxes in SRAM
 	call DisplayChangeBoxMenu
 	call UpdateSprites
 	ld hl, hUILayoutFlags
-	set 1, [hl]
+	set BIT_DOUBLE_SPACED_MENU, [hl]
 	call HandleMenuInput
 	ld hl, hUILayoutFlags
-	res 1, [hl]
+	res BIT_DOUBLE_SPACED_MENU, [hl]
 	bit BIT_B_BUTTON, a
 	ret nz
 	call GetBoxSRAMLocation
@@ -366,7 +366,7 @@ ChangeBox::
 	ld hl, wBoxDataStart
 	call CopyBoxToOrFromSRAM ; copy old box from WRAM to SRAM
 	ld a, [wCurrentMenuItem]
-	set 7, a
+	set BIT_HAS_CHANGED_BOXES, a
 	ld [wCurrentBoxNum], a
 	call GetBoxSRAMLocation
 	ld de, wBoxDataStart
@@ -448,12 +448,12 @@ DisplayChangeBoxMenu:
 	ld c, 7
 	call TextBoxBorder
 	ld hl, hUILayoutFlags
-	set 2, [hl]
+	set BIT_SINGLE_SPACED_LINES, [hl]
 	ld de, BoxNames
 	hlcoord 13, 1
 	call PlaceString
 	ld hl, hUILayoutFlags
-	res 2, [hl]
+	res BIT_SINGLE_SPACED_LINES, [hl]
 	ld a, [wCurrentBoxNum]
 	and $7f
 	cp 9
diff --git a/engine/menus/text_box.asm b/engine/menus/text_box.asm
index 3c1b5233..1c078693 100644
--- a/engine/menus/text_box.asm
+++ b/engine/menus/text_box.asm
@@ -227,8 +227,8 @@ DisplayTwoOptionMenu:
 	ld [wMenuWatchMovingOutOfBounds], a
 	push hl
 	ld hl, wTwoOptionMenuID
-	bit 7, [hl] ; select second menu item by default?
-	res 7, [hl]
+	bit BIT_SECOND_MENU_OPTION_DEFAULT, [hl]
+	res BIT_SECOND_MENU_OPTION_DEFAULT, [hl]
 	jr z, .storeCurrentMenuItem
 	inc a
 .storeCurrentMenuItem
diff --git a/engine/overworld/map_sprites.asm b/engine/overworld/map_sprites.asm
index 8acbb04f..75c46474 100644
--- a/engine/overworld/map_sprites.asm
+++ b/engine/overworld/map_sprites.asm
@@ -162,7 +162,7 @@ LoadMapSpriteTilePatterns:
 	pop de
 	ld b, a
 	ld a, [wFontLoaded]
-	bit 0, a ; reloading upper half of tile patterns after displaying text?
+	bit BIT_FONT_LOADED, a ; reloading upper half of tile patterns after displaying text?
 	jr nz, .skipFirstLoad ; if so, skip loading data into the lower half
 	ld a, b
 	ld b, 0
@@ -183,7 +183,7 @@ LoadMapSpriteTilePatterns:
 	inc d
 .noCarry3
 	ld a, [wFontLoaded]
-	bit 0, a ; reloading upper half of tile patterns after displaying text?
+	bit BIT_FONT_LOADED, a ; reloading upper half of tile patterns after displaying text?
 	jr nz, .loadWhileLCDOn
 	pop af
 	pop hl
@@ -268,7 +268,7 @@ InitOutsideMapSprites:
 	call nc, GetSplitMapSpriteSetID ; if so, choose the appropriate one
 	ld b, a ; b = spriteSetID
 	ld a, [wFontLoaded]
-	bit 0, a ; reloading upper half of tile patterns after displaying text?
+	bit BIT_FONT_LOADED, a ; reloading upper half of tile patterns after displaying text?
 	jr nz, .loadSpriteSet ; if so, forcibly reload the sprite set
 	ld a, [wSpriteSetID]
 	cp b ; has the sprite set ID changed?
diff --git a/engine/overworld/movement.asm b/engine/overworld/movement.asm
index 1ca24f6a..5f95cf6c 100644
--- a/engine/overworld/movement.asm
+++ b/engine/overworld/movement.asm
@@ -57,7 +57,7 @@ UpdatePlayerSprite:
 .next
 	ld [wSpritePlayerStateData1FacingDirection], a
 	ld a, [wFontLoaded]
-	bit 0, a
+	bit BIT_FONT_LOADED, a
 	jr nz, .notMoving
 .moving
 	ld a, [wMovementFlags]
@@ -135,11 +135,11 @@ UpdateNPCSprite:
 	ld l, a
 	inc l
 	ld a, [hl]        ; x#SPRITESTATEDATA1_MOVEMENTSTATUS
-	bit 7, a ; is the face player flag set?
+	bit BIT_FACE_PLAYER, a
 	jp nz, MakeNPCFacePlayer
 	ld b, a
 	ld a, [wFontLoaded]
-	bit 0, a
+	bit BIT_FONT_LOADED, a
 	jp nz, notYetMoving
 	ld a, b
 	cp $2
@@ -412,7 +412,7 @@ MakeNPCFacePlayer:
 	ld a, [wStatusFlags3]
 	bit BIT_NO_NPC_FACE_PLAYER, a
 	jr nz, notYetMoving
-	res 7, [hl]
+	res BIT_FACE_PLAYER, [hl]
 	ld a, [wPlayerDirection]
 	bit PLAYER_DIR_BIT_UP, a
 	jr z, .notFacingDown
diff --git a/engine/overworld/pathfinding.asm b/engine/overworld/pathfinding.asm
index d067345e..58fa1da9 100644
--- a/engine/overworld/pathfinding.asm
+++ b/engine/overworld/pathfinding.asm
@@ -16,7 +16,7 @@ FindPathToPlayer:
 	and a
 	jr nz, .stillHasYProgress
 	ldh a, [hFindPathFlags]
-	set 0, a ; current end of path matches the player's Y coordinate
+	set BIT_PATH_FOUND_Y, a
 	ldh [hFindPathFlags], a
 .stillHasYProgress
 	ldh a, [hFindPathXProgress]
@@ -27,11 +27,11 @@ FindPathToPlayer:
 	and a
 	jr nz, .stillHasXProgress
 	ldh a, [hFindPathFlags]
-	set 1, a ; current end of path matches the player's X coordinate
+	set BIT_PATH_FOUND_X, a
 	ldh [hFindPathFlags], a
 .stillHasXProgress
 	ldh a, [hFindPathFlags]
-	cp $3 ; has the end of the path reached the player's position?
+	cp (1 << BIT_PATH_FOUND_X) | (1 << BIT_PATH_FOUND_Y)
 	jr z, .done
 ; Compare whether the X distance between the player and the current of the path
 ; is greater or if the Y distance is. Then, try to reduce whichever is greater.
@@ -40,7 +40,7 @@ FindPathToPlayer:
 	jr c, .yDistanceGreater
 ; x distance is greater
 	ldh a, [hNPCPlayerRelativePosFlags]
-	bit 1, a
+	bit BIT_PLAYER_LOWER_X, a
 	jr nz, .playerIsLeftOfNPC
 	ld d, NPC_MOVEMENT_RIGHT
 	jr .next1
@@ -53,7 +53,7 @@ FindPathToPlayer:
 	jr .storeDirection
 .yDistanceGreater
 	ldh a, [hNPCPlayerRelativePosFlags]
-	bit 0, a
+	bit BIT_PLAYER_LOWER_Y, a
 	jr nz, .playerIsAboveNPC
 	ld d, NPC_MOVEMENT_DOWN
 	jr .next2
@@ -97,15 +97,15 @@ CalcPositionOfPlayerRelativeToNPC:
 .NPCNorthOfPlayer
 	push hl
 	ld hl, hNPCPlayerRelativePosFlags
-	bit 0, [hl]
-	set 0, [hl]
+	bit BIT_PLAYER_LOWER_Y, [hl]
+	set BIT_PLAYER_LOWER_Y, [hl]
 	pop hl
 	jr .divideYDistance
 .NPCSouthOfOrAlignedWithPlayer
 	push hl
 	ld hl, hNPCPlayerRelativePosFlags
-	bit 0, [hl]
-	res 0, [hl]
+	bit BIT_PLAYER_LOWER_Y, [hl]
+	res BIT_PLAYER_LOWER_Y, [hl]
 	pop hl
 .divideYDistance
 	push hl
@@ -125,15 +125,15 @@ CalcPositionOfPlayerRelativeToNPC:
 .NPCWestOfPlayer
 	push hl
 	ld hl, hNPCPlayerRelativePosFlags
-	bit 1, [hl]
-	set 1, [hl]
+	bit BIT_PLAYER_LOWER_X, [hl]
+	set BIT_PLAYER_LOWER_X, [hl]
 	pop hl
 	jr .divideXDistance
 .NPCEastOfOrAlignedWithPlayer
 	push hl
 	ld hl, hNPCPlayerRelativePosFlags
-	bit 1, [hl]
-	res 1, [hl]
+	bit BIT_PLAYER_LOWER_X, [hl]
+	res BIT_PLAYER_LOWER_X, [hl]
 	pop hl
 .divideXDistance
 	ldh [hDividend2], a
diff --git a/engine/overworld/push_boulder.asm b/engine/overworld/push_boulder.asm
index ff481439..1773e818 100644
--- a/engine/overworld/push_boulder.asm
+++ b/engine/overworld/push_boulder.asm
@@ -18,7 +18,7 @@ TryPushingBoulder::
 	swap a
 	ld e, a
 	add hl, de
-	res 7, [hl]
+	res BIT_FACE_PLAYER, [hl]
 	call GetSpriteMovementByte2Pointer
 	ld a, [hl]
 	cp BOULDER_MOVEMENT_BYTE_2
diff --git a/engine/overworld/special_warps.asm b/engine/overworld/special_warps.asm
index 303415c1..b20d490e 100644
--- a/engine/overworld/special_warps.asm
+++ b/engine/overworld/special_warps.asm
@@ -52,7 +52,7 @@ LoadSpecialWarpData:
 	bit BIT_DEBUG_MODE, a
 	; warp to wLastMap (PALLET_TOWN) for StartNewGameDebug
 	jr nz, .notNewGameWarp
-	bit 2, a
+	bit BIT_FLY_OR_DUNGEON_WARP, a
 	jr nz, .notNewGameWarp
 	ld hl, NewGameWarp
 .copyWarpData
diff --git a/engine/pokemon/learn_move.asm b/engine/pokemon/learn_move.asm
index 2df9964e..819466a5 100644
--- a/engine/pokemon/learn_move.asm
+++ b/engine/pokemon/learn_move.asm
@@ -127,11 +127,11 @@ TryingToLearn:
 	hlcoord 6, 8
 	ld de, wMovesString
 	ldh a, [hUILayoutFlags]
-	set 2, a
+	set BIT_SINGLE_SPACED_LINES, a
 	ldh [hUILayoutFlags], a
 	call PlaceString
 	ldh a, [hUILayoutFlags]
-	res 2, a
+	res BIT_SINGLE_SPACED_LINES, a
 	ldh [hUILayoutFlags], a
 	ld hl, wTopMenuItemY
 	ld a, 8
@@ -147,10 +147,10 @@ TryingToLearn:
 	ld [hli], a ; wMenuWatchedKeys
 	ld [hl], 0 ; wLastMenuItem
 	ld hl, hUILayoutFlags
-	set 1, [hl]
+	set BIT_DOUBLE_SPACED_MENU, [hl]
 	call HandleMenuInput
 	ld hl, hUILayoutFlags
-	res 1, [hl]
+	res BIT_DOUBLE_SPACED_MENU, [hl]
 	push af
 	call LoadScreenTilesFromBuffer1
 	pop af
diff --git a/engine/pokemon/status_screen.asm b/engine/pokemon/status_screen.asm
index 8d377f79..447db8fd 100644
--- a/engine/pokemon/status_screen.asm
+++ b/engine/pokemon/status_screen.asm
@@ -41,7 +41,7 @@ DrawHP_:
 	call DrawHPBar
 	pop hl
 	ldh a, [hUILayoutFlags]
-	bit 0, a
+	bit BIT_PARTY_MENU_HP_BAR, a
 	jr z, .printFractionBelowBar
 	ld bc, $9 ; right of bar
 	jr .printFraction
diff --git a/engine/slots/slot_machine.asm b/engine/slots/slot_machine.asm
index 649f634c..1ed24a1a 100644
--- a/engine/slots/slot_machine.asm
+++ b/engine/slots/slot_machine.asm
@@ -1,8 +1,9 @@
 PromptUserToPlaySlots:
 	call SaveScreenTilesToBuffer2
-	ld a, BANK(DisplayTextIDInit) ; TRUE
-	ld [wAutoTextBoxDrawingControl], a
-	ld b, a
+	ld a, BANK(DisplayTextIDInit)
+	assert BANK(DisplayTextIDInit) == 1 << BIT_NO_AUTO_TEXT_BOX
+	ld [wAutoTextBoxDrawingControl], a ; 1 << BIT_NO_AUTO_TEXT_BOX
+	ld b, a ; BANK(DisplayTextIDInit)
 	ld hl, DisplayTextIDInit
 	call Bankswitch
 	ld hl, PlaySlotMachineText
@@ -173,7 +174,7 @@ OneMoreGoSlotMachineText:
 
 SlotMachine_SetFlags:
 	ld hl, wSlotMachineFlags
-	bit 7, [hl]
+	bit BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR, [hl]
 	ret nz
 	ld a, [wSlotMachineAllowMatchesCounter]
 	and a
@@ -191,14 +192,14 @@ SlotMachine_SetFlags:
 	ld [hl], 0
 	ret
 .allowMatches
-	set 6, [hl]
+	set BIT_SLOTS_CAN_WIN, [hl]
 	ret
 .setAllowMatchesCounter
 	ld a, 60
 	ld [wSlotMachineAllowMatchesCounter], a
 	ret
 .allowSevenAndBarMatches
-	set 7, [hl]
+	set BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR, [hl]
 	ret
 
 SlotMachine_SpinWheels:
@@ -289,7 +290,7 @@ SlotMachine_StopWheel1Early:
 	call SlotMachine_GetWheel1Tiles
 	ld hl, wSlotMachineWheel1BottomTile
 	ld a, [wSlotMachineFlags]
-	and $80
+	and 1 << BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR
 	jr nz, .sevenAndBarMode
 ; Stop early if the middle symbol is not a cherry.
 	inc hl
@@ -317,7 +318,7 @@ SlotMachine_StopWheel1Early:
 SlotMachine_StopWheel2Early:
 	call SlotMachine_GetWheel2Tiles
 	ld a, [wSlotMachineFlags]
-	and $80
+	and 1 << BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR
 	jr nz, .sevenAndBarMode
 ; Stop early if any symbols are lined up in the first two wheels.
 	call SlotMachine_FindWheel1Wheel2Matches
@@ -401,7 +402,7 @@ SlotMachine_CheckForMatches:
 	call SlotMachine_CheckForMatch
 	jr z, .foundMatch
 	ld a, [wSlotMachineFlags]
-	and $c0
+	and (1 << BIT_SLOTS_CAN_WIN) | (1 << BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR)
 	jr z, .noMatch
 	ld hl, wSlotMachineRerollCounter
 	dec [hl]
@@ -421,9 +422,9 @@ SlotMachine_CheckForMatches:
 	jp SlotMachine_CheckForMatches
 .foundMatch
 	ld a, [wSlotMachineFlags]
-	and $c0
+	and (1 << BIT_SLOTS_CAN_WIN) | (1 << BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR)
 	jr z, .rollWheel3DownByOneSymbol ; roll wheel if player isn't allowed to win
-	and $80
+	and 1 << BIT_SLOTS_CAN_WIN_WITH_7_OR_BAR
 	jr nz, .acceptMatch
 ; if 7/bar matches aren't enabled and the match was a 7/bar symbol, roll wheel
 	ld a, [hl]
@@ -599,7 +600,7 @@ SlotReward300Func:
 	call PlaySound
 	call Random
 	cp $80
-	ld a, $0
+	ld a, 0
 	jr c, .skip
 	ld [wSlotMachineFlags], a
 .skip
@@ -654,7 +655,7 @@ SlotMachine_PrintPayoutCoins:
 	jp PrintNumber
 
 SlotMachine_PayCoinsToPlayer:
-	ld a, $1
+	ld a, TRUE
 	ld [wMuteAudioAndPauseMusic], a
 	call WaitForSoundToFinish
 
diff --git a/home/map_objects.asm b/home/map_objects.asm
index 342139dd..e200238a 100644
--- a/home/map_objects.asm
+++ b/home/map_objects.asm
@@ -227,7 +227,7 @@ SetSpriteMovementBytesToFF::
 
 ; returns the sprite movement byte 1 pointer for sprite [hSpriteIndex] in hl
 GetSpriteMovementByte1Pointer::
-	ld h, $C2
+	ld h, HIGH(wSpriteStateData2)
 	ldh a, [hSpriteIndex]
 	swap a
 	add 6
diff --git a/home/overworld.asm b/home/overworld.asm
index 1595fdf0..e43ebc81 100644
--- a/home/overworld.asm
+++ b/home/overworld.asm
@@ -121,7 +121,7 @@ OverworldLoopLessDelay::
 	ld a, [wCurMap]
 	call SwitchToMapRomBank ; switch to the ROM bank of the current map
 	ld hl, wCurMapTileset
-	set 7, [hl]
+	set BIT_NO_PREVIOUS_MAP, [hl]
 .changeMap
 	jp EnterMap
 .checkForOpponent
@@ -879,10 +879,10 @@ LoadTilesetTilePatternData::
 	ld a, [wTilesetBank]
 	jp FarCopyData2
 
-; this loads the current maps complete tile map (which references blocks, not individual tiles) to C6E8
+; this loads the current map's complete tile map (which references blocks, not individual tiles) to wOverworldMap
 ; it can also load partial tile maps of connected maps into a border of length 3 around the current map
 LoadTileBlockMap::
-; fill C6E8-CBFB with the background tile
+; fill wOverworldMap-wOverworldMapEnd with the background tile
 	ld hl, wOverworldMap
 	ld a, [wMapBackgroundTile]
 	ld d, a
@@ -1210,7 +1210,7 @@ IsSpriteInFrontOfPlayer2::
 	and $f0
 	inc a
 	ld l, a ; hl = x#SPRITESTATEDATA1_MOVEMENTSTATUS
-	set 7, [hl] ; set flag to make the sprite face the player
+	set BIT_FACE_PLAYER, [hl]
 	ld a, e
 	ldh [hTextID], a
 	ret
@@ -1303,7 +1303,7 @@ CheckForTilePairCollisions::
 	ld a, [wTileInFrontOfPlayer]
 	ld c, a
 .tilePairCollisionLoop
-	ld a, [wCurMapTileset] ; tileset number
+	ld a, [wCurMapTileset]
 	ld b, a
 	ld a, [hli]
 	cp $ff
@@ -1943,7 +1943,7 @@ CollisionCheckOnWater::
 	call PlayDefaultMusic
 	jr .noCollision
 .checkIfVermilionDockTileset
-	ld a, [wCurMapTileset] ; tileset
+	ld a, [wCurMapTileset]
 	cp SHIP_PORT ; Vermilion Dock tileset
 	jr nz, .noCollision ; keep surfing if it's not the boarding platform tile
 	jr .stopSurfing ; if it is the boarding platform tile, stop surfing
@@ -2015,10 +2015,10 @@ LoadMapHeader::
 	call SwitchToMapRomBank
 	ld a, [wCurMapTileset]
 	ld b, a
-	res 7, a
+	res BIT_NO_PREVIOUS_MAP, a
 	ld [wCurMapTileset], a
 	ldh [hPreviousTileset], a
-	bit 7, b
+	bit BIT_NO_PREVIOUS_MAP, b
 	ret nz
 	ld hl, MapHeaderPointers
 	ld a, [wCurMap]
@@ -2203,9 +2203,9 @@ LoadMapHeader::
 	ld [hl], a ; store text ID in byte 1 of sprite entry
 	pop hl
 	ldh a, [hLoadSpriteTemp1]
-	bit 6, a
+	bit BIT_TRAINER, a
 	jr nz, .trainerSprite
-	bit 7, a
+	bit BIT_ITEM, a
 	jr nz, .itemBallSprite
 	jr .regularSprite
 .trainerSprite
diff --git a/home/predef_text.asm b/home/predef_text.asm
index bdecd3cf..61e22fce 100644
--- a/home/predef_text.asm
+++ b/home/predef_text.asm
@@ -3,7 +3,7 @@ PrintPredefTextID::
 	ld hl, TextPredefs
 	call SetMapTextPointer
 	ld hl, wTextPredefFlag
-	set 0, [hl]
+	set BIT_TEXT_PREDEF, [hl]
 	call DisplayTextID
 
 RestoreMapTextPointer::
diff --git a/home/print_bcd.asm b/home/print_bcd.asm
index 38aedd3c..57ec12a8 100644
--- a/home/print_bcd.asm
+++ b/home/print_bcd.asm
@@ -13,12 +13,12 @@
 ; their meaning at the beginning of the functions's execution.
 PrintBCDNumber::
 	ld b, c ; save flags in b
-	res 7, c
-	res 6, c
-	res 5, c ; c now holds the length
-	bit 5, b
+	res BIT_LEADING_ZEROES, c
+	res BIT_LEFT_ALIGN, c
+	res BIT_MONEY_SIGN, c ; c now holds the length
+	bit BIT_MONEY_SIGN, b
 	jr z, .loop
-	bit 7, b
+	bit BIT_LEADING_ZEROES, b
 	jr nz, .loop
 	ld [hl], "¥"
 	inc hl
@@ -31,14 +31,14 @@ PrintBCDNumber::
 	inc de
 	dec c
 	jr nz, .loop
-	bit 7, b ; were any non-zero digits printed?
+	bit BIT_LEADING_ZEROES, b
 	jr z, .done ; if so, we are done
 .numberEqualsZero ; if every digit of the BCD number is zero
-	bit 6, b ; left or right alignment?
+	bit BIT_LEFT_ALIGN, b
 	jr nz, .skipRightAlignmentAdjustment
 	dec hl ; if the string is right-aligned, it needs to be moved back one space
 .skipRightAlignmentAdjustment
-	bit 5, b
+	bit BIT_MONEY_SIGN, b
 	jr z, .skipCurrencySymbol
 	ld [hl], "¥"
 	inc hl
@@ -54,24 +54,24 @@ PrintBCDDigit::
 	and a
 	jr z, .zeroDigit
 .nonzeroDigit
-	bit 7, b ; have any non-space characters been printed?
+	bit BIT_LEADING_ZEROES, b
 	jr z, .outputDigit
 ; if bit 7 is set, then no numbers have been printed yet
-	bit 5, b ; print the currency symbol?
+	bit BIT_MONEY_SIGN, b
 	jr z, .skipCurrencySymbol
 	ld [hl], "¥"
 	inc hl
-	res 5, b
+	res BIT_MONEY_SIGN, b
 .skipCurrencySymbol
-	res 7, b ; unset 7 to indicate that a nonzero digit has been reached
+	res BIT_LEADING_ZEROES, b
 .outputDigit
 	add "0"
 	ld [hli], a
 	jp PrintLetterDelay
 .zeroDigit
-	bit 7, b ; either printing leading zeroes or already reached a nonzero digit?
+	bit BIT_LEADING_ZEROES, b
 	jr z, .outputDigit ; if so, print a zero digit
-	bit 6, b ; left or right alignment?
+	bit BIT_LEFT_ALIGN, b
 	ret nz
 	inc hl ; if right-aligned, "print" a space by advancing the pointer
 	ret
diff --git a/home/reload_sprites.asm b/home/reload_sprites.asm
index 8a08d64d..5cf5d458 100644
--- a/home/reload_sprites.asm
+++ b/home/reload_sprites.asm
@@ -4,7 +4,7 @@ ReloadMapSpriteTilePatterns::
 	ld hl, wFontLoaded
 	ld a, [hl]
 	push af
-	res 0, [hl]
+	res BIT_FONT_LOADED, [hl]
 	push hl
 	xor a
 	ld [wSpriteSetID], a
diff --git a/home/text.asm b/home/text.asm
index dc78b982..da884125 100644
--- a/home/text.asm
+++ b/home/text.asm
@@ -63,7 +63,7 @@ PlaceNextChar::
 	jr nz, .NotNext
 	ld bc, 2 * SCREEN_WIDTH
 	ldh a, [hUILayoutFlags]
-	bit 2, a
+	bit BIT_SINGLE_SPACED_LINES, a
 	jr z, .ok
 	ld bc, SCREEN_WIDTH
 .ok
diff --git a/home/text_script.asm b/home/text_script.asm
index d367683d..c1606371 100644
--- a/home/text_script.asm
+++ b/home/text_script.asm
@@ -6,8 +6,8 @@ DisplayTextID::
 	push af
 	farcall DisplayTextIDInit ; initialization
 	ld hl, wTextPredefFlag
-	bit 0, [hl]
-	res 0, [hl]
+	bit BIT_TEXT_PREDEF, [hl]
+	res BIT_TEXT_PREDEF, [hl]
 	jr nz, .skipSwitchToMapBank
 	ld a, [wCurMap]
 	call SwitchToMapRomBank
@@ -128,7 +128,7 @@ CloseTextDisplay::
 	ld [MBC1RomBank], a
 	call InitMapSprites ; reload sprite tile pattern data (since it was partially overwritten by text tile patterns)
 	ld hl, wFontLoaded
-	res 0, [hl]
+	res BIT_FONT_LOADED, [hl]
 	ld a, [wStatusFlags6]
 	bit BIT_FLY_WARP, a
 	call z, LoadPlayerSpriteGraphics
diff --git a/home/window.asm b/home/window.asm
index 01b52d41..48ab1d0e 100644
--- a/home/window.asm
+++ b/home/window.asm
@@ -137,12 +137,12 @@ PlaceMenuCursor::
 	jr z, .checkForArrow1
 	push af
 	ldh a, [hUILayoutFlags]
-	bit 1, a ; is the menu double spaced?
+	bit BIT_DOUBLE_SPACED_MENU, a
 	jr z, .doubleSpaced1
-	ld bc, 20
+	ld bc, SCREEN_WIDTH
 	jr .getOldMenuItemScreenPosition
 .doubleSpaced1
-	ld bc, 40
+	ld bc, SCREEN_WIDTH * 2
 .getOldMenuItemScreenPosition
 	pop af
 .oldMenuItemLoop
@@ -163,12 +163,12 @@ PlaceMenuCursor::
 	jr z, .checkForArrow2
 	push af
 	ldh a, [hUILayoutFlags]
-	bit 1, a ; is the menu double spaced?
+	bit BIT_DOUBLE_SPACED_MENU, a
 	jr z, .doubleSpaced2
-	ld bc, 20
+	ld bc, SCREEN_WIDTH
 	jr .getCurrentMenuItemScreenPosition
 .doubleSpaced2
-	ld bc, 40
+	ld bc, SCREEN_WIDTH * 2
 .getCurrentMenuItemScreenPosition
 	pop af
 .currentMenuItemLoop
@@ -272,7 +272,7 @@ EnableAutoTextBoxDrawing::
 	jr AutoTextBoxDrawingCommon
 
 DisableAutoTextBoxDrawing::
-	ld a, TRUE
+	ld a, 1 << BIT_NO_AUTO_TEXT_BOX
 
 AutoTextBoxDrawingCommon::
 	ld [wAutoTextBoxDrawingControl], a
diff --git a/ram/hram.asm b/ram/hram.asm
index e7c3ef3c..1be1dab6 100644
--- a/ram/hram.asm
+++ b/ram/hram.asm
@@ -388,6 +388,7 @@ hClearLetterPrintingDelayFlags:: db
 
 ; bit 0: draw HP fraction to the right of bar instead of below (for party menu)
 ; bit 1: menu is double spaced
+; bit 2: text is single spaced
 hUILayoutFlags:: db
 
 hFieldMoveMonMenuTopMenuItemX:: db
diff --git a/scripts/CeruleanBadgeHouse.asm b/scripts/CeruleanBadgeHouse.asm
index b1f6db7f..54186523 100644
--- a/scripts/CeruleanBadgeHouse.asm
+++ b/scripts/CeruleanBadgeHouse.asm
@@ -1,5 +1,5 @@
 CeruleanBadgeHouse_Script:
-	ld a, TRUE
+	ld a, 1 << BIT_NO_AUTO_TEXT_BOX
 	ld [wAutoTextBoxDrawingControl], a
 	dec a
 	ld [wDoNotWaitForButtonPressAfterDisplayingText], a
diff --git a/scripts/Museum1F.asm b/scripts/Museum1F.asm
index 600c03c7..465c72f8 100644
--- a/scripts/Museum1F.asm
+++ b/scripts/Museum1F.asm
@@ -1,5 +1,5 @@
 Museum1F_Script:
-	ld a, TRUE
+	ld a, 1 << BIT_NO_AUTO_TEXT_BOX
 	ld [wAutoTextBoxDrawingControl], a
 	xor a
 	ld [wDoNotWaitForButtonPressAfterDisplayingText], a
diff --git a/scripts/OaksLab.asm b/scripts/OaksLab.asm
index 89d6ef80..71704c5b 100644
--- a/scripts/OaksLab.asm
+++ b/scripts/OaksLab.asm
@@ -1,7 +1,7 @@
 OaksLab_Script:
 	CheckEvent EVENT_PALLET_AFTER_GETTING_POKEBALLS_2
 	call nz, OaksLabLoadTextPointers2Script
-	ld a, TRUE
+	ld a, 1 << BIT_NO_AUTO_TEXT_BOX
 	ld [wAutoTextBoxDrawingControl], a
 	xor a
 	ld [wDoNotWaitForButtonPressAfterDisplayingText], a
diff --git a/scripts/PewterMart.asm b/scripts/PewterMart.asm
index 0a5baac2..49a91977 100644
--- a/scripts/PewterMart.asm
+++ b/scripts/PewterMart.asm
@@ -1,6 +1,6 @@
 PewterMart_Script:
 	call EnableAutoTextBoxDrawing
-	ld a, TRUE
+	ld a, 1 << BIT_NO_AUTO_TEXT_BOX
 	ld [wAutoTextBoxDrawingControl], a
 	ret
 
diff --git a/scripts/SSAnne2FRooms.asm b/scripts/SSAnne2FRooms.asm
index e7b88b3f..3358759d 100644
--- a/scripts/SSAnne2FRooms.asm
+++ b/scripts/SSAnne2FRooms.asm
@@ -1,5 +1,5 @@
 SSAnne2FRooms_Script:
-	ld a, TRUE
+	ld a, 1 << BIT_NO_AUTO_TEXT_BOX
 	ld [wAutoTextBoxDrawingControl], a
 	xor a
 	ld [wDoNotWaitForButtonPressAfterDisplayingText], a