ref: 0d48d829d407524fa4edd45cc012f4e7d935e9b4
parent: e3e0bcd653f8d671f6fd1390fa922e3b644f4a34
author: bbbbbbbbba <[email protected]>
date: Sun Oct 20 14:25:34 EDT 2019
Document Special Defense badge boost glitch (#651) Document Special Defense badge boost glitch
--- a/docs/bugs_and_glitches.md
+++ b/docs/bugs_and_glitches.md
@@ -18,6 +18,7 @@
- [Thick Club and Light Ball can make (Special) Attack wrap around above 1024](#thick-club-and-light-ball-can-make-special-attack-wrap-around-above-1024)
- [Metal Powder can increase damage taken with boosted (Special) Defense](#metal-powder-can-increase-damage-taken-with-boosted-special-defense)
- [Reflect and Light Screen can make (Special) Defense wrap around above 1024](#reflect-and-light-screen-can-make-special-defense-wrap-around-above-1024)
+- [Glacier Badge may not boost Special Defense depending on the value of Special Attack](#glacier-badge-may-not-boost-special-defense-depending-on-the-value-of-special-attack)
- [Moves with a 100% secondary effect chance will not trigger it in 1/256 uses](#moves-with-a-100-secondary-effect-chance-will-not-trigger-it-in-1256-uses)
- [Belly Drum sharply boosts Attack even with under 50% HP](#belly-drum-sharply-boosts-attack-even-with-under-50-hp)
- [Confusion damage is affected by type-boosting items and Explosion/Self-Destruct doubling](#confusion-damage-is-affected-by-type-boosting-items-and-explosionself-destruct-doubling)
@@ -165,6 +166,34 @@
```
(This fix also affects Thick Club, Light Ball, and Metal Powder, as described above, but their specific fixes in the above bugs allow more accurate damage calculations.)
+
+
+## Glacier Badge may not boost Special Defense depending on the value of Special Attack
+
+As Pryce's dialog ("That BADGE will raise the SPECIAL stats of POKéMON.") implies, Glacier Badge is intended to boost both Special Attack and Special Defense. However, due to BoostStat overwriting `a` when boosting Special Attack, the Special Defense boost will not happen if the unboosted Special Attack stat is either 0-205 or 433-660.+
+**Fix:** Edit `BadgeStatBoosts.CheckBadge` in [engine/battle/core.asm](https://github.com/pret/pokecrystal/blob/master/engine/battle/core.asm):
+
+```diff
+ .CheckBadge:
+ ld a, b
+ srl b
++ push af
+ call c, BoostStat
++ pop af
+ inc hl
+ inc hl
+ ; Check every other badge.
+ srl b
+ dec c
+ jr nz, .CheckBadge
+ ; Check GlacierBadge again for Special Defense.
+-; This check is buggy because it assumes that a is set by the "ld a, b" in the above loop,
+-; but it can actually be overwritten by the call to BoostStat.
+ srl a
+ call c, BoostStat
+ ret
+```
## Moves with a 100% secondary effect chance will not trigger it in 1/256 uses
--- a/engine/battle/core.asm
+++ b/engine/battle/core.asm
@@ -6758,12 +6758,12 @@
; depending on which badges have been obtained.
; Every other badge boosts a stat, starting from the first.
+; GlacierBadge also boosts Special Defense, although the relevant code is buggy (see below).
; ZephyrBadge: Attack
; PlainBadge: Speed
; MineralBadge: Defense
-; GlacierBadge: Special Attack
-; RisingBadge: Special Defense
+; GlacierBadge: Special Attack and Special Defense
; The boosted stats are in order, except PlainBadge and MineralBadge's boosts are swapped.
@@ -6806,7 +6806,9 @@
srl b
dec c
jr nz, .CheckBadge
-; And the last one (RisingBadge) too.
+; Check GlacierBadge again for Special Defense.
+; This check is buggy because it assumes that a is set by the "ld a, b" in the above loop,
+; but it can actually be overwritten by the call to BoostStat.
srl a
call c, BoostStat
ret