shithub: pokecrystal

--- 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