ref: 7641ce9babf2604fdca74bd75360d53ea5b31266
parent: 748d4249805c19399b3c72c0f60d0f1a6ffe43ad
parent: 0aac0f9cfc5bc95b378d0c33cb047f136cd361b7
author: Rangi <35663410+Rangi42@users.noreply.github.com>
date: Fri Jul 27 08:06:46 EDT 2018
Merge pull request #545 from mid-kid/master bugs_and_glitches fixes
--- a/docs/bugs_and_glitches.md
+++ b/docs/bugs_and_glitches.md
@@ -2,7 +2,14 @@
These are known bugs and glitches in the original Pokémon Crystal game: code that clearly does not work as intended, or that only works in limited circumstances but has the possibility to fail or crash.
+Fixes are written in the `diff` format. If you're familiar with git, this should look farmiliar:
+```diff
+ this is some code
+-delete red - lines
++add green + lines
+```
+
## Contents
- [Thick Club and Light Ball can decrease damage done with boosted (Special) Attack](#thick-club-and-light-ball-can-decrease-damage-done-with-boosted-special-attack)
@@ -55,7 +62,6 @@
- [`LoadSpriteGFX` does not limit the capacity of `UsedSprites`](#loadspritegfx-does-not-limit-the-capacity-of-usedsprites)
- [`ChooseWildEncounter` doesn't really validate the wild Pokémon species](#choosewildencounter-doesnt-really-validate-the-wild-pokémon-species)
- [`TryObjectEvent` arbitrary code execution](#tryobjectevent-arbitrary-code-execution)
-- [`CheckBugContestContestantFlag` can read beyond its data table](#checkbugcontestcontestantflag-can-read-beyond-its-data-table)
- [`ClearWRAM` only clears WRAM bank 1](#clearwram-only-clears-wram-bank-1)
@@ -67,12 +73,6 @@
This is a bug with `SpeciesItemBoost` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm):
-```asm
-; Double the stat
- sla l
- rl h
- ret
-```
**Fix:**
@@ -103,24 +103,7 @@
This is a bug with `DittoMetalPowder` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm):
-```asm
- ld a, c
- srl a
- add c
- ld c, a
- ret nc
- srl b
- ld a, b
- and a
- jr nz, .done
- inc b
-.done
- scf
- rr c
- ret
-```
-
**Fix:**
```diff
@@ -161,35 +144,27 @@
This is a bug with `BattleCommand_BellyDrum` in [engine/battle/move_effects/belly_drum.asm](/engine/battle/move_effects/belly_drum.asm):
-```asm
-BattleCommand_BellyDrum:
-; bellydrum
-; This command is buggy because it raises the user's attack
-; before checking that it has enough HP to use the move.
-; Swap the order of these two blocks to fix.
- call BattleCommand_AttackUp2
- ld a, [wAttackMissed]
- and a
- jr nz, .failed
- callfar GetHalfMaxHP
- callfar CheckUserHasEnoughHP
- jr nc, .failed
-```
-
**Fix:**
-```asm
+```diff
BattleCommand_BellyDrum:
; bellydrum
- callfar GetHalfMaxHP
- callfar CheckUserHasEnoughHP
- jr nc, .failed
-
+-; This command is buggy because it raises the user's attack
+-; before checking that it has enough HP to use the move.
+-; Swap the order of these two blocks to fix.
++ callfar GetHalfMaxHP
++ callfar CheckUserHasEnoughHP
++ jr nc, .failed
++
call BattleCommand_AttackUp2
ld a, [wAttackMissed]
and a
jr nz, .failed
+-
+- callfar GetHalfMaxHP
+- callfar CheckUserHasEnoughHP
+- jr nc, .failed
```
@@ -212,6 +187,9 @@
This is a bug with `DefenseDownHit` in [data/moves/effects.asm](/data/moves/effects.asm):
+
+**Fix:**
+
```asm
DefenseDownHit:
checkobedience
@@ -231,15 +209,13 @@
supereffectivetext
checkdestinybond
buildopponentrage
- effectchance ; bug: duplicate effectchance shouldn't be here
+- effectchance ; bug: duplicate effectchance shouldn't be here
defensedown
statdownmessage
endmove
```
-**Fix:** Delete the second `effectchance`.
-
## Counter and Mirror Coat still work if the opponent uses an item
*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*
@@ -248,17 +224,11 @@
This is a bug with `BattleCommand_Counter` in [engine/battle/move_effects/counter.asm](/engine/battle/move_effects/counter.asm) and `BattleCommand_MirrorCoat` in [engine/battle/move_effects/mirror_coat.asm](/engine/battle/move_effects/mirror_coat.asm):
-```asm
- ; BUG: Move should fail with all non-damaging battle actions
- ld hl, wCurDamage
- ld a, [hli]
- or [hl]
- ret z
-```
**Fix:**
```diff
+- ; BUG: Move should fail with all non-damaging battle actions
ld hl, wCurDamage
ld a, [hli]
or [hl]
@@ -285,10 +255,14 @@
This is a bug with `CheckPlayerHasUsableMoves` in [engine/battle/core.asm](/engine/battle/core.asm):
-```asm
+
+**Fix:**
+
+```diff
.done
- ; Bug: this will result in a move with PP Up confusing the game.
- and a ; should be "and PP_MASK"
+- ; Bug: this will result in a move with PP Up confusing the game.
+- and a ; should be "and PP_MASK"
++ and PP_MASK
ret nz
.force_struggle
@@ -300,9 +274,7 @@
ret
```
-**Fix:** Change `and a` to `and PP_MASK`.
-
## A Pokémon that fainted from Pursuit will have its old status condition when revived
*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*
@@ -320,24 +292,21 @@
This is a bug with `CheckHiddenOpponent` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm):
-```asm
-CheckHiddenOpponent:
-; BUG: This routine should account for Lock-On and Mind Reader.
- ld a, BATTLE_VARS_SUBSTATUS3_OPP
- call GetBattleVar
- and 1 << SUBSTATUS_FLYING | 1 << SUBSTATUS_UNDERGROUND
- ret
-```
-Fix:
+**Fix:**
-```asm
-CheckHiddenOpponent: ; 37daa
+```diff
+CheckHiddenOpponent:
+-; BUG: This routine is completely redundant and introduces a bug, since BattleCommand_CheckHit does these checks properly.
+- ld a, BATTLE_VARS_SUBSTATUS3_OPP
+- call GetBattleVar
+- and 1 << SUBSTATUS_FLYING | 1 << SUBSTATUS_UNDERGROUND
ret
```
-The code in `CheckHiddenOpponent` is completely redundant as `CheckHit` already does what this code is doing. Another option is to remove `CheckHiddenOpponent` completely, the calls to `CheckHiddenOpponent`, and the jump afterwards.
+The code in `CheckHiddenOpponent` is completely redundant as `BattleCommand_CheckHit` already does what this code is doing. Another option is to remove `CheckHiddenOpponent` completely, the calls to `CheckHiddenOpponent`, and the jump afterwards.
+
## Beat Up can desynchronize link battles
*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*
@@ -346,7 +315,10 @@
This is a bug with `BattleCommand_BeatUp` in [engine/battle/move_effects/beat_up.asm](/engine/battle/move_effects/beat_up.asm):
-```asm
+
+**Fix:**
+
+```diff
.got_mon
ld a, [wd002]
ld hl, wPartyMonNicknames
@@ -359,9 +331,10 @@
ld a, [wd002]
ld c, a
ld a, [wCurBattleMon]
- ; BUG: this can desynchronize link battles
- ; Change "cp [hl]" to "cp c" to fix
- cp [hl]
+- ; BUG: this can desynchronize link battles
+- ; Change "cp [hl]" to "cp c" to fix
+- cp [hl]
++ cp c
ld hl, wBattleMonStatus
jr z, .active_mon
ld a, MON_STATUS
@@ -372,9 +345,7 @@
jp nz, .beatup_fail
```
-**Fix:** Change `cp [hl]` to `cp c`.
-
## Beat Up may fail to raise substitute
*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*
@@ -384,20 +355,37 @@
It prevents the substitute from being raised and the King's Rock from working.
-```asm
+
+**Fix (breaking):**
+
+```diff
.only_one_beatup
ld a, BATTLE_VARS_SUBSTATUS3
call GetBattleVarAddr
res SUBSTATUS_IN_LOOP, [hl]
+- call BattleCommand_BeatUpFailText
+- jp EndMoveEffect
++ ret
+```
+
+**Fix (cosmetics):**
+
+```diff
+.only_one_beatup
+ ld a, BATTLE_VARS_SUBSTATUS3
+ call GetBattleVarAddr
+ res SUBSTATUS_IN_LOOP, [hl]
call BattleCommand_BeatUpFailText
++ call BattleCommand_RaiseSub
jp EndMoveEffect
```
-**Fix (breaking):** Replace the last two lines with `ret`.
-**Fix (cosmetics):** Call `BattleCommand_RaiseSub` before the `jp`.
There's a similar oversight in `BattleCommand_FailureText` in [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm) that will prevent the substitute from being raised if Beat Up is protected against.
+
+**Fix (cosmetics):**
+
```asm
cp EFFECT_MULTI_HIT
jr z, .multihit
@@ -405,6 +393,8 @@
jr z, .multihit
cp EFFECT_POISON_MULTI_HIT
jr z, .multihit
++ cp EFFECT_BEAT_UP
++ jr z, .multihit
jp EndMoveEffect
.multihit
@@ -412,9 +402,7 @@
jp EndMoveEffect
```
-**Fix:** Check for `EFFECT_BEAT_UP` as well.
-
## Beat Up may trigger King's Rock even if it failed
*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*
@@ -423,17 +411,7 @@
This bug can be fixed in a plethora of ways, but the most straight-forward would be in `BattleCommand_BeatUpFailText` in [engine/battle/move_effects/beat_up.asm](/engine/battle/move_effects/beat_up.asm), as that's always ran before the king's rock effect.
-```asm
-BattleCommand_BeatUpFailText:
-; beatupfailtext
- ld a, [wBeatUpHitAtLeastOnce]
- and a
- ret nz
-
- jp PrintButItFailed
-```
-
**Fix:**
```diff
@@ -461,38 +439,28 @@
This is a bug with `BattleCommand_Present` in [engine/battle/move_effects/present.asm](/engine/battle/move_effects/present.asm):
-```asm
-BattleCommand_Present:
-; present
- ld a, [wLinkMode]
- cp LINK_COLOSSEUM
- jr z, .colosseum_skippush
- push bc
- push de
-.colosseum_skippush
-
- call BattleCommand_Stab
-
- ld a, [wLinkMode]
- cp LINK_COLOSSEUM
- jr z, .colosseum_skippop
- pop de
- pop bc
-.colosseum_skippop
-```
-
**Fix:**
-```asm
+```diff
BattleCommand_Present:
; present
+- ld a, [wLinkMode]
+- cp LINK_COLOSSEUM
+- jr z, .colosseum_skippush
push bc
push de
+-.colosseum_skippush
+-
call BattleCommand_Stab
+-
+- ld a, [wLinkMode]
+- cp LINK_COLOSSEUM
+- jr z, .colosseum_skippop
pop de
pop bc
+-.colosseum_skippop
```
@@ -502,17 +470,20 @@
This is a bug with `AI_Smart_MeanLook` in [engine/battle/ai/scoring.asm](/engine/battle/ai/scoring.asm):
-```asm
-; 80% chance to greatly encourage this move if the enemy is badly poisoned (buggy).
-; Should check wPlayerSubStatus5 instead.
- ld a, [wEnemySubStatus5]
+
+**Fix:**
+
+```diff
+-; 80% chance to greatly encourage this move if the enemy is badly poisoned (buggy).
+-; Should check wPlayerSubStatus5 instead.
+- ld a, [wEnemySubStatus5]
++; 80% chance to greatly encourage this move if the player is badly poisoned
++ ld a, [wPlayerSubStatus5]
bit SUBSTATUS_TOXIC, a
jr nz, .asm_38e26
```
-**Fix:** Change `wEnemySubStatus5` to `wPlayerSubStatus5`.
-
## AI makes a false assumption about `CheckTypeMatchup`
In [engine/battle/effect_commands.asm](/engine/battle/effect_commands.asm):
@@ -548,7 +519,10 @@
This is a bug with `AI_HealStatus` in [engine/battle/ai/items.asm](/engine/battle/ai/items.asm):
-```asm
+
+**Fix:**
+
+```diff
AI_HealStatus:
ld a, [wCurOTMon]
ld hl, wOTPartyMon1Status
@@ -557,18 +531,18 @@
xor a
ld [hl], a
ld [wEnemyMonStatus], a
- ; Bug: this should reset SUBSTATUS_NIGHTMARE too
- ; Uncomment the lines below to fix
- ; ld hl, wEnemySubStatus1
- ; res SUBSTATUS_NIGHTMARE, [hl]
+- ; Bug: this should reset SUBSTATUS_NIGHTMARE too
+- ; Uncomment the lines below to fix
+- ; ld hl, wEnemySubStatus1
+- ; res SUBSTATUS_NIGHTMARE, [hl]
++ ld hl, wEnemySubStatus1
++ res SUBSTATUS_NIGHTMARE, [hl]
ld hl, wEnemySubStatus5
res SUBSTATUS_TOXIC, [hl]
ret
```
-**Fix:** Uncomment `ld hl, wEnemySubStatus1` and `res SUBSTATUS_NIGHTMARE, [hl]`.
-
## HP bar animation is slow for high HP
([Video](https://www.youtube.com/watch?v=SE-BfsFgZVM))
@@ -575,17 +549,21 @@
This is a bug with `LongAnim_UpdateVariables` in [engine/battle/anim_hp_bar.asm](/engine/battle/anim_hp_bar.asm):
-```asm
- ; This routine is buggy. The result from ComputeHPBarPixels is stored
- ; in e. However, the pop de opcode deletes this result before it is even
- ; used. The game then proceeds as though it never deleted that output.
- ; To fix, uncomment the line below.
+
+**Fix:**
+
+```diff
+- ; This routine is buggy. The result from ComputeHPBarPixels is stored
+- ; in e. However, the pop de opcode deletes this result before it is even
+- ; used. The game then proceeds as though it never deleted that output.
+- ; To fix, uncomment the line below.
call ComputeHPBarPixels
- ; ld a, e
+- ; ld a, e
++ ld a, e
pop bc
pop de
pop hl
- ld a, e ; Comment or delete this line to fix the above bug.
+- ld a, e ; Comment or delete this line to fix the above bug.
ld hl, wCurHPBarPixels
cp [hl]
jr z, .loop
@@ -594,9 +572,7 @@
ret
```
-**Fix:** Move `ld a, e` to right after `call ComputeHPBarPixels`.
-
## HP bar animation off-by-one error for low HP
([Video](https://www.youtube.com/watch?v=9KyNVIZxJvI))
@@ -603,11 +579,14 @@
This is a bug with `ShortHPBar_CalcPixelFrame` in [engine/battle/anim_hp_bar.asm](/engine/battle/anim_hp_bar.asm):
-```asm
+
+**Fix:**
+
+```diff
ld b, 0
-; This routine is buggy. If [wCurHPAnimMaxHP] * [wCurHPBarPixels] is
-; divisible by HP_BAR_LENGTH_PX, the loop runs one extra time.
-; To fix, uncomment the line below.
+-; This routine is buggy. If [wCurHPAnimMaxHP] * [wCurHPBarPixels] is
+-; divisible by HP_BAR_LENGTH_PX, the loop runs one extra time.
+-; To fix, uncomment the line below.
.loop
ld a, l
sub HP_BAR_LENGTH_PX
@@ -615,15 +594,14 @@
ld a, h
sbc $0
ld h, a
- ; jr z, .done
+- ; jr z, .done
++ jr z, .done
jr c, .done
inc b
jr .loop
```
-**Fix:** Uncomment `jr z, .done`.
-
## Experience underflow for level 1 Pokémon with Medium-Slow growth rate
([Video](https://www.youtube.com/watch?v=SXH8u0plHrE))
@@ -632,17 +610,6 @@
This is a bug with `CalcExpAtLevel` in [engine/pokemon/experience.asm](/engine/pokemon/experience.asm):
-```asm
-CalcExpAtLevel:
-; (a/b)*n**3 + c*n**2 + d*n - e
- ld a, [wBaseGrowthRate]
- add a
- add a
- ld c, a
- ld b, 0
- ld hl, GrowthRates
- add hl, bc
-```
**Fix:**
@@ -678,12 +645,16 @@
This is a bug with `Text_ABoostedStringBuffer2ExpPoints` and `Text_StringBuffer2ExpPoints` in [data/text/common_2.asm](/data/text/common_2.asm):
-```asm
+
+**Fix:**
+
+```diff
Text_ABoostedStringBuffer2ExpPoints::
text_start
line "a boosted"
cont "@"
- deciram wStringBuffer2, 2, 4
+- deciram wStringBuffer2, 2, 4
++ deciram wStringBuffer2, 2, 5
text " EXP. Points!"
prompt
@@ -690,30 +661,33 @@
Text_StringBuffer2ExpPoints::
text_start
line "@"
- deciram wStringBuffer2, 2, 4
+- deciram wStringBuffer2, 2, 4
++ deciram wStringBuffer2, 2, 5
text " EXP. Points!"
prompt
```
-**Fix:** Change both `deciram wStringBuffer2, 2, 4` to `deciram wStringBuffer2, 2, 5`.
-
## BRN/PSN/PAR do not affect catch rate
This is a bug with `PokeBallEffect` in [engine/items/item_effects.asm](/engine/items/item_effects.asm):
-```asm
-; This routine is buggy. It was intended that SLP and FRZ provide a higher
-; catch rate than BRN/PSN/PAR, which in turn provide a higher catch rate than
-; no status effect at all. But instead, it makes BRN/PSN/PAR provide no
-; benefit.
-; Uncomment the line below to fix this.
+
+**Fix:**
+
+```diff
+-; This routine is buggy. It was intended that SLP and FRZ provide a higher
+-; catch rate than BRN/PSN/PAR, which in turn provide a higher catch rate than
+-; no status effect at all. But instead, it makes BRN/PSN/PAR provide no
+-; benefit.
+-; Uncomment the line below to fix this.
ld b, a
ld a, [wEnemyMonStatus]
and 1 << FRZ | SLP
ld c, 10
jr nz, .addstatus
- ; ld a, [wEnemyMonStatus]
+- ; ld a, [wEnemyMonStatus]
++ ld a, [wEnemyMonStatus]
and a
ld c, 5
jr nz, .addstatus
@@ -726,83 +700,70 @@
.max_1
```
-**Fix:** Uncomment `ld a, [wEnemyMonStatus]`.
-
## Moon Ball does not boost catch rate
This is a bug with `MoonBallMultiplier` in [items/item_effects.asm](/items/item_effects.asm):
-```asm
-MoonBallMultiplier:
-; This function is buggy.
-; Intent: multiply catch rate by 4 if mon evolves with moon stone
-; Reality: no boost
-...
+**Fix:**
-; Moon Stone's constant from Pokémon Red is used.
-; No Pokémon evolve with Burn Heal,
-; so Moon Balls always have a catch rate of 1×.
+```diff
+-; Moon Stone's constant from Pokémon Red is used.
+-; No Pokémon evolve with Burn Heal,
+-; so Moon Balls always have a catch rate of 1×.
push bc
ld a, BANK("Evolutions and Attacks")call GetFarByte
- cp MOON_STONE_RED ; BURN_HEAL
+- cp MOON_STONE_RED ; BURN_HEAL
++ cp MOON_STONE
pop bc
ret nz
```
-**Fix:** Change `MOON_STONE_RED` to `MOON_STONE`.
-
## Love Ball boosts catch rate for the wrong gender
This is a bug with `LoveBallMultiplier` in [items/item_effects.asm](/items/item_effects.asm):
-```asm
-LoveBallMultiplier:
-; This function is buggy.
-; Intent: multiply catch rate by 8 if mons are of same species, different sex
-; Reality: multiply catch rate by 8 if mons are of same species, same sex
-...
+**Fix:**
+```diff
+.wildmale
+
ld a, d
pop de
cp d
pop bc
- ret nz ; for the intended effect, this should be "ret z"
+- ret nz ; for the intended effect, this should be "ret z"
++ ret z
```
-**Fix:** Change `ret nz` to `ret z`.
-
## Fast Ball only boosts catch rate for three Pokémon
This is a bug with `FastBallMultiplier` in [items/item_effects.asm](/items/item_effects.asm):
-```asm
-FastBallMultiplier:
-; This function is buggy.
-; Intent: multiply catch rate by 4 if enemy mon is in one of the three
-; FleeMons tables.
-; Reality: multiply catch rate by 4 if enemy mon is one of the first three in
-; the first FleeMons table.
-...
+**Fix:**
+```diff
+.loop
+ ld a, BANK(FleeMons)
+ call GetFarByte
+
inc hl
cp -1
jr z, .next
cp c
- jr nz, .next ; for the intended effect, this should be "jr nz, .loop"
+- jr nz, .next ; for the intended effect, this should be "jr nz, .loop"
++ jr nz, .loop
sla b
jr c, .max
```
-**Fix:** Change `jr nz, .next` to `jr nz, .loop`.
-
## Dragon Scale, not Dragon Fang, boosts Dragon-type moves
*Fixing this bug will break compatibility with standard Pokémon Crystal for link battles.*
@@ -809,19 +770,24 @@
This is a bug with `ItemAttributes` in [data/items/attributes.asm](/data/items/attributes.asm):
-```asm
+
+**Fix:**
+
+```diff
; DRAGON_FANG
- item_attribute 100, 0, 0, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE
+- item_attribute 100, HELD_NONE, 0, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE
++ item_attribute 100, HELD_DRAGON_BOOST, 0, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE
+```
-...
+And:
+```diff
; DRAGON_SCALE
- item_attribute 2100, HELD_DRAGON_BOOST, 10, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE
+- item_attribute 2100, HELD_DRAGON_BOOST, 10, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE
++ item_attribute 2100, HELD_NONE, 10, CANT_SELECT, ITEM, ITEMMENU_NOUSE, ITEMMENU_NOUSE
```
-**Fix:** Move `HELD_DRAGON_BOOST` to the `DRAGON_FANG` attributes and `0` to `DRAGON_SCALE`.
-
## Daisy's grooming doesn't always increase happiness
This is a bug with `HaircutOrGrooming` in [engine/events/haircut.asm](/engine/events/haircut.asm):
@@ -863,10 +829,6 @@
In [data/events/happiness_probabilities.asm](/data/events/happiness_probabilities.asm):
-```asm
-HappinessData_DaisysGrooming:
- db $ff, 2, HAPPINESS_GROOMING ; 99.6% chance
-```
**Fix:**
@@ -882,37 +844,43 @@
This is a bug with `LoadEnemyMon.CheckMagikarpArea` in [engine/battle/core.asm](/engine/battle/core.asm):
-```asm
-.CheckMagikarpArea:
-; The "jr z" checks are supposed to be "jr nz".
-; Instead, all maps in GROUP_LAKE_OF_RAGE (Mahogany area)
-; and Routes 20 and 44 are treated as Lake of Rage.
+**Fix:**
-; This also means Lake of Rage Magikarp can be smaller than ones
-; caught elsewhere rather than the other way around.
-
-; Intended behavior enforces a minimum size at Lake of Rage.
-; The real behavior prevents a minimum size in the Lake of Rage area.
-
-; Moreover, due to the check not being translated to feet+inches, all Magikarp
-; smaller than 4'0" may be caught by the filter, a lot more than intended.
+```diff
+.CheckMagikarpArea:
+-; The "jr z" checks are supposed to be "jr nz".
+-
+-; Instead, all maps in GROUP_LAKE_OF_RAGE (Mahogany area)
+-; and Routes 20 and 44 are treated as Lake of Rage.
+-
+-; This also means Lake of Rage Magikarp can be smaller than ones
+-; caught elsewhere rather than the other way around.
+-
+-; Intended behavior enforces a minimum size at Lake of Rage.
+-; The real behavior prevents a minimum size in the Lake of Rage area.
+-
+-; Moreover, due to the check not being translated to feet+inches, all Magikarp
+-; smaller than 4'0" may be caught by the filter, a lot more than intended.
ld a, [wMapGroup]
cp GROUP_LAKE_OF_RAGE
- jr z, .Happiness
+- jr z, .Happiness
++ jr nz, .Happiness
ld a, [wMapNumber]
cp MAP_LAKE_OF_RAGE
- jr z, .Happiness
+- jr z, .Happiness
++ jr nz, .Happiness
```
-**Fix:** Change both `jr z, .Happiness` to `jr nz, .Happiness`.
-
## Magikarp length limits have a unit conversion error
This is a bug with `LoadEnemyMon.CheckMagikarpArea` in [engine/battle/core.asm](/engine/battle/core.asm):
-```asm
+
+**Fix:**
+
+```diff
; Get Magikarp's length
ld de, wEnemyMonDVs
ld bc, wPlayerID
@@ -920,7 +888,8 @@
; No reason to keep going if length > 1536 mm (i.e. if HIGH(length) > 6 feet)
ld a, [wMagikarpLength]
- cp HIGH(1536) ; should be "cp 5", since 1536 mm = 5'0", but HIGH(1536) = 6
+- cp HIGH(1536) ; should be "cp 5", since 1536 mm = 5'0", but HIGH(1536) = 6
++ cp 5
jr nz, .CheckMagikarpArea
; 5% chance of skipping both size checks
@@ -929,7 +898,8 @@
jr c, .CheckMagikarpArea
; Try again if length >= 1616 mm (i.e. if LOW(length) >= 3 inches)
ld a, [wMagikarpLength + 1]
- cp LOW(1616) ; should be "cp 3", since 1616 mm = 5'3", but LOW(1616) = 80
+- cp LOW(1616) ; should be "cp 3", since 1616 mm = 5'3", but LOW(1616) = 80
++ cp 3
jr nc, .GenerateDVs
; 20% chance of skipping this check
@@ -938,33 +908,33 @@
jr c, .CheckMagikarpArea
; Try again if length >= 1600 mm (i.e. if LOW(length) >= 2 inches)
ld a, [wMagikarpLength + 1]
- cp LOW(1600) ; should be "cp 2", since 1600 mm = 5'2", but LOW(1600) = 64
+- cp LOW(1600) ; should be "cp 2", since 1600 mm = 5'2", but LOW(1600) = 64
++ cp 2
jr nc, .GenerateDVs
```
-**Fix:** Change the three `cp` instructions to use their commented values.
-
## Magikarp lengths can be miscalculated
This is a bug with `CalcMagikarpLength.BCLessThanDE` in [engine/events/magikarp.asm](/engine/events/magikarp.asm):
-```asm
+
+**Fix:**
+
+```diff
.BCLessThanDE:
-; Intention: Return bc < de.
-; Reality: Return b < d.
+-; Intention: Return bc < de.
+-; Reality: Return b < d.
ld a, b
cp d
ret c
- ret nc ; whoops
+- ret nc ; whoops
ld a, c
cp e
ret
```
-**Fix:** Delete `ret nc`.
-
## Battle transitions fail to account for the enemy's level
([Video](https://www.youtube.com/watch?v=eij_1060SMc))
@@ -1017,9 +987,13 @@
This is a bug with `_HallOfFamePC.DisplayMonAndStrings` in [engine/events/halloffame.asm](/engine/events/halloffame.asm):
-```asm
+
+**Fix:**
+
+```diff
ld a, [wHallOfFameTempWinCount]
- cp HOF_MASTER_COUNT + 1 ; should be HOF_MASTER_COUNT
+- cp HOF_MASTER_COUNT + 1 ; should be HOF_MASTER_COUNT
++ cp HOF_MASTER_COUNT
jr c, .print_num_hof
ld de, .HOFMaster
hlcoord 1, 2
@@ -1028,9 +1002,7 @@
jr .finish
```
-**Fix:** Change `HOF_MASTER_COUNT + 1` to `HOF_MASTER_COUNT`.
-
## Slot machine payout sound effects cut each other off
([Video](https://www.youtube.com/watch?v=ojq3xqfRF6I))
@@ -1037,7 +1009,10 @@
This is a bug with `Slots_PayoutAnim` in [engine/games/slot_machine.asm](/engine/games/slot_machine.asm):
-```asm
+
+**Fix:**
+
+```diff
.okay
ld [hl], e
dec hl
@@ -1044,27 +1019,18 @@
ld [hl], d
ld a, [wSlotsDelay]
and $7
- ret z ; ret nz would be more appropriate
+- ret z ; ret nz would be more appropriate
++ ret nz
ld de, SFX_GET_COIN_FROM_SLOTS
call PlaySFX
ret
```
-**Fix:** Change `ret z` to `ret nz`.
-
## Team Rocket battle music is not used for Executives or Scientists
This is a bug with `PlayBattleMusic` in [engine/battle/start_battle.asm](/engine/battle/start_battle.asm):
-```asm
- ; They should have included EXECUTIVEM, EXECUTIVEF, and SCIENTIST too...
- ld de, MUSIC_ROCKET_BATTLE
- cp GRUNTM
- jr z, .done
- cp GRUNTF
- jr z, .done
-```
**Fix:**
@@ -1087,34 +1053,16 @@
This is a bug with `DoPlayerMovement.CheckWarp` in [engine/overworld/player_movement.asm](/engine/overworld/player_movement.asm):
-```asm
-; Bug: Since no case is made for STANDING here, it will check
-; [.edgewarps + $ff]. This resolves to $3e at $8035a.
-; This causes wd041 to be nonzero when standing on tile $3e,
-; making bumps silent.
- ld a, [wWalkingDirection]
- ; cp STANDING
- ; jr z, .not_warp
- ld e, a
- ld d, 0
- ld hl, .EdgeWarps
- add hl, de
- ld a, [wPlayerStandingTile]
- cp [hl]
- jr nz, .not_warp
-
- ld a, 1
- ld [wd041], a
- ld a, [wWalkingDirection]
- ; This is in the wrong place.
- cp STANDING
- jr z, .not_warp
-```
-
**Fix:**
```diff
+.CheckWarp:
+-; Bug: Since no case is made for STANDING here, it will check
+-; [.edgewarps + $ff]. This resolves to $3e at $8035a.
+-; This causes wd041 to be nonzero when standing on tile $3e,
+-; making bumps silent.
+-
ld a, [wWalkingDirection]
- ; cp STANDING
- ; jr z, .not_warp
@@ -1143,23 +1091,19 @@
The exact cause is unknown, but a workaround exists for `DexEntryScreen_MenuActionJumptable.Cry` in [engine/pokedex/pokedex.asm](/engine/pokedex/pokedex.asm):
-```asm
-.Cry:
- call Pokedex_GetSelectedMon
- ld a, [wd265]
- call GetCryIndex
- ld e, c
- ld d, b
- call PlayCry
- ret
-```
**Workaround:**
-```asm
+```diff
.Cry:
- ld a, [wCurPartySpecies]
- call PlayMonCry
+- call Pokedex_GetSelectedMon
+- ld a, [wd265]
+- call GetCryIndex
+- ld e, c
+- ld d, b
+- call PlayCry
++ ld a, [wCurPartySpecies]
++ call PlayMonCry
ret
```
@@ -1192,14 +1136,18 @@
In [home/map.asm](/home/map.asm):
-```asm
+
+**Fix:**
+
+```diff
; Set hl to the address of the current metatile data ([wTilesetBlocksAddress] + (a) tiles).
- ; This is buggy; it wraps around past 128 blocks.
- ; To fix, uncomment the line below.
- add a ; Comment or delete this line to fix the above bug.
+- ; This is buggy; it wraps around past 128 blocks.
+- ; To fix, uncomment the line below.
+- add a ; Comment or delete this line to fix the above bug.
ld l, a
ld h, 0
- ; add hl, hl
+- ; add hl, hl
++ add hl, hl
add hl, hl
add hl, hl
add hl, hl
@@ -1211,9 +1159,7 @@
ld h, a
```
-**Fix:** Delete `add a` and uncomment `add hl, hl`.
-
## Surfing directly across a map connection does not load the new map
([Video](https://www.youtube.com/watch?v=XFOWvMNG-zw))
@@ -1227,16 +1173,18 @@
This is a bug with `CanObjectMoveInDirection` in [engine/overworld/npc_movement.asm](/engine/overworld/npc_movement.asm):
-```asm
+
+**Fix:**
+
+```diff
ld hl, OBJECT_FLAGS1
add hl, bc
bit NOCLIP_TILES_F, [hl] ; lost, uncomment next line to fix
- ; jr nz, .noclip_tiles
+- ; jr nz, .noclip_tiles
++ jr nz, .noclip_tiles
```
-**Fix:** Uncomment `jr nz, .noclip_tiles`.
-
## `CheckOwnMon` only checks the first five letters of OT names
([Video](https://www.youtube.com/watch?v=GVTTmReM4nQ))
@@ -1245,14 +1193,18 @@
In [engine/pokemon/search.asm](/engine/pokemon/search.asm):
-```asm
+
+**Fix:**
+
+```diff
; check OT
-; This only checks five characters, which is fine for the Japanese version,
-; but in the English version the player name is 7 characters, so this is wrong.
+-; This only checks five characters, which is fine for the Japanese version,
+-; but in the English version the player name is 7 characters, so this is wrong.
ld hl, wPlayerName
-rept NAME_LENGTH_JAPANESE + -2 ; should be PLAYER_NAME_LENGTH + -2
+-rept NAME_LENGTH_JAPANESE + -2 ; should be PLAYER_NAME_LENGTH + -2
++rept PLAYER_NAME_LENGTH + -2
ld a, [de]
cp [hl]
jr nz, .notfound
@@ -1267,9 +1219,7 @@
jr z, .found
```
-**Fix:** Change `rept NAME_LENGTH_JAPANESE + -2` to `rept PLAYER_NAME_LENGTH + -2`.
-
## Catching a Transformed Pokémon always catches a Ditto
This bug can affect Mew or Pokémon other than Ditto that used Transform via Mirror Move or Sketch.
@@ -1276,45 +1226,9 @@
This is a bug with `PokeBallEffect` in [engine/items/item_effects.asm](/engine/items/item_effects.asm):
-```asm
- ld hl, wEnemySubStatus5
- ld a, [hl]
- push af
- set SUBSTATUS_TRANSFORMED, [hl]
-; This code is buggy. Any wild Pokémon that has Transformed will be
-; caught as a Ditto, even if it was something else like Mew.
-; To fix, do not set [wTempEnemyMonSpecies] to DITTO.
- bit SUBSTATUS_TRANSFORMED, a
- jr nz, .ditto
- jr .not_ditto
+**Fix:**
-.ditto
- ld a, DITTO
- ld [wTempEnemyMonSpecies], a
- jr .load_data
-
-.not_ditto
- set SUBSTATUS_TRANSFORMED, [hl]
- ld hl, wEnemyBackupDVs
- ld a, [wEnemyMonDVs]
- ld [hli], a
- ld a, [wEnemyMonDVs + 1]
- ld [hl], a
-
-.load_data
- ld a, [wTempEnemyMonSpecies]
- ld [wCurPartySpecies], a
- ld a, [wEnemyMonLevel]
- ld [wCurPartyLevel], a
- farcall LoadEnemyMon
-
- pop af
- ld [wEnemySubStatus5], a
-```
-
-**Fix:**
-
```diff
ld hl, wEnemySubStatus5
ld a, [hl]
@@ -1360,14 +1274,6 @@
This is a bug with `PokeBallEffect` in [engine/items/item_effects.asm](/engine/items/item_effects.asm):
-```asm
-.room_in_party
- xor a
- ld [wWildMon], a
- ld a, [wCurItem]
- cp PARK_BALL
- call nz, ReturnToBattle_UseBall
-```
**Fix:**
@@ -1387,14 +1293,18 @@
This is a bug with `PokeBallEffect` in [engine/items/item_effects.asm](/engine/items/item_effects.asm):
-```asm
- ; BUG: farcall overwrites a, and GetItemHeldEffect takes b anyway.
- ; This is probably the reason the HELD_CATCH_CHANCE effect is never used.
- ; Uncomment the line below to fix.
+
+**Fix:**
+
+```diff
+- ; BUG: farcall overwrites a, and GetItemHeldEffect takes b anyway.
+- ; This is probably the reason the HELD_CATCH_CHANCE effect is never used.
+- ; Uncomment the line below to fix.
ld d, a
push de
ld a, [wBattleMonItem]
- ; ld b, a
+- ; ld b, a
++ ld b, a
farcall GetItemHeldEffect
ld a, b
cp HELD_CATCH_CHANCE
@@ -1407,14 +1317,15 @@
.max_2
```
-**Fix:** Uncomment `ld b, a`.
-
## Only the first three evolution entries can have Stone compatibility reported correctly
This is a bug with `PlacePartyMonEvoStoneCompatibility.DetermineCompatibility` in [engine/pokemon/party_menu.asm](/engine/pokemon/party_menu.asm):
-```asm
+
+**Workaround (supports up to six entries):**
+
+```diff
.DetermineCompatibility:
ld de, wStringBuffer1
ld a, BANK(EvosAttacksPointers)
@@ -1426,27 +1337,16 @@
ld l, a
ld de, wStringBuffer1
ld a, BANK("Evolutions and Attacks")- ld bc, 10
+- ld bc, 10
++ ld bc, wStringBuffer2 - wStringBuffer1
call FarCopyBytes
```
-**Fix:** Change `ld bc, 10` to `ld bc, wStringBuffer2 - wStringBuffer1` to support up to six Stone entries.
-
## `EVOLVE_STAT` can break Stone compatibility reporting
This is a bug with `PlacePartyMonEvoStoneCompatibility.DetermineCompatibility` in [engine/pokemon/party_menu.asm](/engine/pokemon/party_menu.asm):
-```asm
-.loop2
- ld a, [hli]
- and a
- jr z, .nope
- inc hl
- inc hl
- cp EVOLVE_ITEM
- jr nz, .loop2
-```
**Fix:**
@@ -1510,11 +1410,14 @@
In [engine/overworld/overworld.asm](/engine/overworld/overworld.asm):
-```asm
-LoadSpriteGFX:
-; Bug: b is not preserved, so it's useless as a next count.
-; Uncomment the lines below to fix.
+**Fix:**
+
+```diff
+LoadSpriteGFX:
+-; Bug: b is not preserved, so it's useless as a next count.
+-; Uncomment the lines below to fix.
+-
ld hl, wUsedSprites
ld b, SPRITE_GFX_LIST_CAPACITY
.loop
@@ -1532,43 +1435,25 @@
ret
.LoadSprite:
- ; push bc
+- ; push bc
++ push bc
call GetSprite
- ; pop bc
+- ; pop bc
++ pop bc
ld a, l
ret
```
-**Fix:** Uncomment `push bc` and `pop bc`.
-
## `ChooseWildEncounter` doesn't really validate the wild Pokémon species
In [engine/overworld/wildmons.asm](/engine/overworld/wildmons.asm):
-```asm
-ChooseWildEncounter:
-...
- ld a, b
- ld [wCurPartyLevel], a
- ld b, [hl]
- ; ld a, b
- call ValidateTempWildMonSpecies
- jr c, .nowildbattle
- ld a, b ; This is in the wrong place.
- cp UNOWN
- jr nz, .done
-
-...
-
-ValidateTempWildMonSpecies:
-; Due to a development oversight, this function is called with the wild Pokemon's level, not its species, in a.
-```
-
**Fix:**
```diff
+.ok
ld a, b
ld [wCurPartyLevel], a
ld b, [hl]
@@ -1581,12 +1466,16 @@
jr nz, .done
```
+
## `TryObjectEvent` arbitrary code execution
In [engine/overworld/events.asm](/engine/overworld/events.asm):
-```asm
-; Bug: If IsInArray returns nc, data at bc will be executed as code.
+
+**Fix:**
+
+```diff
+-; Bug: If IsInArray returns nc, data at bc will be executed as code.
push bc
ld de, 3
ld hl, .pointers
@@ -1601,48 +1490,21 @@
jp hl
.nope_bugged
- ; pop bc
+- ; pop bc
++ pop bc
xor a
ret
```
-**Fix:** Uncomment `pop bc`.
-
-## `CheckBugContestContestantFlag` can read beyond its data table
-
-In [engine/events/bug_contest/contest_2.asm](/engine/events/bug_contest/contest_2.asm):
-
-```asm
-CheckBugContestContestantFlag:
-; Checks the flag of the Bug Catching Contestant whose index is loaded in a.
-
-; Bug: If a >= NUM_BUG_CONTESTANTS when this is called,
-; it will read beyond the table.
-
- ld hl, BugCatchingContestantEventFlagTable
- ld e, a
- ld d, 0
- add hl, de
- add hl, de
- ld e, [hl]
- inc hl
- ld d, [hl]
- ld b, CHECK_FLAG
- call EventFlagAction
- ret
-
-INCLUDE "data/events/bug_contest_flags.asm"
-```
-
-However, `a < NUM_BUG_CONTESTANTS` should always be true, so in practice this is not a problem.
-
-
## `ClearWRAM` only clears WRAM bank 1
In [home/init.asm](/home/init.asm):
-```asm
+
+**Fix:**
+
+```diff
ClearWRAM::
; Wipe swappable WRAM banks (1-7)
; Assumes CGB or AGB
@@ -1658,8 +1520,7 @@
pop af
inc a
cp 8
- jr nc, .bank_loop ; Should be jr c
+- jr nc, .bank_loop ; Should be jr c
++ jr c, .bank_loop
ret
```
-
-**Fix:** Change `jr nc, .bank_loop` to `jr c, .bank_loop`.
--- a/engine/battle/effect_commands.asm
+++ b/engine/battle/effect_commands.asm
@@ -6684,7 +6684,7 @@
INCLUDE "engine/battle/move_effects/thunder.asm"
CheckHiddenOpponent:
-; BUG: This routine should account for Lock-On and Mind Reader.
+; BUG: This routine is completely redundant and introduces a bug, since BattleCommand_CheckHit does these checks properly.
ld a, BATTLE_VARS_SUBSTATUS3_OPP
call GetBattleVar
and 1 << SUBSTATUS_FLYING | 1 << SUBSTATUS_UNDERGROUND
--- a/engine/events/bug_contest/contest_2.asm
+++ b/engine/events/bug_contest/contest_2.asm
@@ -58,9 +58,6 @@
CheckBugContestContestantFlag:
; Checks the flag of the Bug Catching Contestant whose index is loaded in a.
-; Bug: If a >= NUM_BUG_CONTESTANTS when this is called,
-; it will read beyond the table.
-
ld hl, BugCatchingContestantEventFlagTable
ld e, a
ld d, 0