Battle formulas — decompiled from FF8_EN.exe

Battle formulas — decompiled from FF8_EN.exe

Exact integer arithmetic as compiled in the PC executable (function addresses given; image base 0x400000). Where the code differs from commonly circulated formulas, the difference is flagged. Notation: rand255 = uniform 0..255, randVar = rand%33 + 240 (the ±6% damage variance factor, applied as dmg × randVar / 256).

Character stats (`Stat_ComputeCharaStat`)

Kernel growth curve bytes A, B, C, D per stat; J_val = junctioned magic’s junction value, count = magic quantity (0–100):

STR/VIT/MAG/SPR: stat = weaponBonus(STR only) + (C + lvl·A/10 + lvl/B − (lvl²/D)/2)/4 + savedBonus + J_val·count/100, capped 255
SPD/LUCK: stat = bonus + lvl·A + lvl/B − lvl/D + savedBonus + J_val·count/100 (no /10, no level², no /4)
Max HP (Stat_ComputeCharaMaxHP): HP = savedBonus + C + lvl·A − 10·lvl²/B + hpJ_val·count — ⚠ the HP junction term has no /100 divisor
HIT (Stat_ComputeCharaHit): weapon.attackParameter + hitJ·count/100; EVA (Stat_ComputeCharaEva): SPD/4 + evaJ·count/100
All stats are then scaled by the Stat+X% ability multiplier (× mult/100, base 100); HP caps at 9999.

Monster stats (`Stat_ComputeMonsterStats` / `Stat_ComputeMonsterStatCurve` / `Stat_ComputeMonsterMaxHP`)

From the .dat info_stat 4-byte curves: STR/MAG = (C + lvl·A/10 + lvl/B − (lvl²/D)/2)/4; VIT/SPR/SPD/EVA = C + lvl·A + lvl/B − lvl/D; each is then scaled by the AI-controllable stat variable (× var/10), capped 255. HP = HP1·lvl²/20 + (HP1 + 100·HP3)·lvl + 10·HP2 + 1000·HP4.

Physical damage (`Damage_ComputePhysicalCore`)

dmg = [ P × ((265 − VIT) × (STR + STR²/16) / 256) / 16 ] × randVar / 256

Vit 0 sets VIT = 0. Hit roll (Damage_RollPhysicalHit): 255×(HIT + LUCK_atk/2 − EVA_tgt − LUCK_tgt)/100 ≥ rand255 (attacker Darkness quarters HIT); Sleep/Stop on target or accuracy 255 = auto-hit. Crit roll (Damage_RollCrit): LUCK + critBonus ≥ rand255 → damage ×2. Modifiers (Damage_ApplyPhysicalModifiers): Protect ÷2, back attack ×2, zombie target ÷2; attack element: dmg += dmg × elem% × (800 − elemDef)/10000.

⚠ Defend fully nullifies physical damage (returns 0, not a ÷2). Every physical attack type is gated before the formula: the dispatcher (Damage_DispatchByAttackType, cases Attack / %-physical / Renzokuken finisher) and the built-in-roll variant (Damage_ComputePhysicalWithHitCritRoll, Everyone’s Grudge / ignore-VIT) both bail out with return 0 if the target has Defend (status_2 bit 19), Invincible, Immune Physical attack (status_2 bit 20), or Petrify (status_1). It is the same immunity gate for all four statuses — Defend behaves identically to Immune-Physical/Invincible here — and only the “ignore immunity” hit flag (STATUS2_LINK_DRAIN_MAYBE_IGNORE_IMMUNITY) bypasses it. Defend does not protect against magic/GF, where it only halves — see below.

Gunblade (Damage_ComputeGunblade): dmg = [(CRIT_BONUS/20 + 2) × 4·P × ((265−VIT)×(STR + STR²/16)/256) / 128] × randVar/256; the trigger gives a flat ×1.5-style boost via that leading term and no crit roll happens.

Magic damage (`Damage_ComputeMagicAndGF`)

dmg = [ P × ((265 − SPR) × (P + MAG) / 4) / 256 ] × randVar / 256

⚠ Enemy-cast magic is halved: if the caster slot is ≥ 3 (a monster), dmg >>= 1 — confirmed in the PC code. Shell ÷2, Defend ÷2. Element: dmg × (900 − elemDef)/100 where 800 = neutral (so 100 % absorb → negative); a zombie target treats Holy at 700 (×2). Drain spells heal dmg × (acc − drainResist)/100, inverted on zombies. Cap 9999.

GF damage (same function)

dmg = [ (SumMag+100)/100 × Boost/100 × P × ((265−SPR) × (LvlMod·GFLvl/10 + P + PwrMod) / 8) / 256 ] × randVar/256

SumMag = SumMag+% ability, Boost = boost value (up to 250). Diablos instead does GFLvl × maxHP / (PwrMod − LvlMod + 100); Demi does P × curHP/16.

Healing

Cure line (Damage_ComputeCurativeMagic): heal = P × randVar × ((P + MAG)/2) / 256. Item in battle: 50 × P. White Wind: caster’s maxHP − curHP. Revive: target maxHP/8 (from item Med data: maxHP/4). Angelo Recover: P × maxHP/16.

Status attacks (`Battle_ApplyStatusWithResistRoll`)

chance = accuracy + atkStat/4 − tgtStat/4 − mentalResist (must be > 0; resist ≥ 100 = immune). Accuracy < 250: succeed when 255·chance/100 ≥ rand255; accuracy 250–254: automatic unless resist zeroes it; accuracy 255: bypasses the resist check entirely (rarely documented).

How a computed result becomes what the player sees. The formula functions do not write to the targets directly — they fill a staging FF8BattleTargetData at 0x1D27ADD − 2 = 0x1D27ADB (the loose globals BATTLE_ACTION_STATE_RESULT, HIT_TYPE_2 @0x1D27ADE, DAMAGE_DEAL… are its fields), which computeTargetData copies into the per-target TARGET_DATA ring. Later, ApplyActionResultToTarget (0x506690) consumes one ring entry: applies statuses to the entity, queues the hit reaction, fires the crit screen flash, spawns the eject/death FX, and calls BattleFx_DamageNumbers_Spawn.

`HitType2` (staging +3) — how the number is displayed

Bit	Name	Set by (verified)	Display effect
0x01	`HIT_TYPE_RESTORATIVE`	curative magic, resurrection, negative final damage (elemental absorb); cleared when a Zombie flips a heal into damage	green number, steady-rise animation
0x02	`HIT_TYPE_CRIT`	the crit rolls	white screen flash in `ApplyActionResultToTarget`; damage already ×2
0x04	`HIT_TYPE_MISS`	evade roll, gravity-immune, dead/invincible targets, earth-vs-Float, reflected-away, zero-power attacks whose statuses all failed	single glyph 16 (the “Miss” icon) instead of digits
0x08	`HIT_TYPE_REACTION_NEEDED`	(consumer not yet traced)	—
0x10	`HIT_TYPE_CERBERUS_POPUP`	one site in the whole exe (0x491E62): the Cerberus ability, when it didn’t miss	stacked glyph pair 69+70, and overrides the no-number suppression — Cerberus deals no damage, so without this bit its popup would never show

`BattleActionResultFlag` (staging +2) — side effects on the target

Bit	Name	Meaning
0x01	`NO_DAMAGE_NUMBER`	action resolved without a visible HP change (status landed with 0 power, or spell reflected) → popup suppressed (unless 0x10 above)
0x04	`REVIVAL_SUCCESSFUL`	Life landed
0x10	`PROTECT_TRIGGERED`	Protect halved the damage → shimmer effect 39
0x20	`SHELL_TRIGGERED`	Shell halved the damage or healing → shimmer effect 40
0x30	both = Reflect	reflection sets `0x31` → flash effect 38 on the original target
0x40	`NORMAL_MONSTER_DIED`	monster death vanish animation + the two death SFX

The 39/40/38 effect dispatch is the switch (flags & 0x30) in ApplyActionResultToTarget — this is where the Protect / Shell / Reflect shimmers actually come from.

The popup itself (`BattleFx_DamageNumbers_Spawn` / `_TaskTick`)

A 32-byte task (TaskNodeDamageNumber) living 10 frames. Digits are glyphs 56+d; the text is built most-significant-first with a computed half-width for centering. Frame 0 resolves the target’s head anchor (bone 0xF0, +0x1000 up), projects it through the GTE and clamps to x∈[32,288], y∈[32,152]; each frame y moves by BattleFx_DamageNumbers_AnimTable[frame + 10×isHeal] — damage numbers bounce, heals rise steadily — and the last two frames fade via a palette scale + semi-transparent blend. Colours are plain RGB dwords: white 0x808080 (neutral modulate) for damage, green 0x408040 for heals. A drain attack spawns a second popup on the attacker from the drain-back half of the same ring entry.

⚠ Both colour constants are valid .text addresses, so IDA renders them as bogus function offsets (0x808080 collected hundreds of false xrefs). They are numbers.

Specials

Formula	Code
Kamikaze	`5 × attacker maxHP`
Everyone’s Grudge	`P × character NumKills`
LV Up/Down	`newLvl = clamp(P×lvl/8, 1, 100)`, gated by `acc > rand255`
Devour	success when `atkHP ≥ tgtHP` and `rand255 ≤ 255×(atkHP−tgtHP)/atkHP`; heal `HPHeal × maxHP/16`
Card	success when `256 − 255×curHP/maxHP ≥ rand255` (≈1/256 at full HP, never 0 below max); rare card when `rand255 < 16`
Draw quantity	`((atkLvl − tgtLvl + 10)/2 − drawResist + rand(1..32) + MAG)/5 − stockAmount`, clamp 0–9
Draw-cast damage	`dmg × (rand255 + 10)/150`
Mug	success when `rand255 ≤ MugRate + SPD/2`
Drop/Mug slots	weights 178/51/15/12 (community docs often say /1 — the last slot spans rand 244–255)
Rare Item bug	with Rare Item, the 4th-slot compare compiles to `rand ≥ 261` — impossible for a byte, so weights become 128/114/14/0
EXP	`(damage share of HP) × (5·Exp·enemyLvl/avgPartyLvl − Exp)`, clamp 1..60000; killer gets the same with own level; Card/Devour/Doom kills give 0
GF XP	character XP / number of junctioned GFs; compatibility per cast: `+= tableByte − 100`, clamped 1000..6000
Multipliers	Darkside ×3, Angel Wing ×5, Berserk ×1.5, Cover ÷2; damage cap 9999 (60000 with Break Damage Limit flag)

Notable code-vs-community differences

Enemy magic ÷2 is real and unconditional for caster slots ≥ 3.
Drop/mug fourth slot weight is 12, not 1.
Rare Item makes the rarest slot unreachable (rand ≥ 261 bug).
HP junction is hpJ × count with no /100.
Crit chance is exactly (LUCK + bonus)/256 — the compiled 255·x/255 is a no-op.
Status accuracy 250–254 vs 255 behave differently (auto-success vs full resist bypass).

Key functions: Damage_DispatchByAttackType · Damage_ComputePhysicalWithHitCritRoll · Damage_ApplyPhysicalModifiers · Battle_RollDropItem · Battle_RollMugItem · Battle_ComputeDrawQuantity · Battle_RollCardCommand · Battle_ComputeExpDistribution · Stat_RefreshCharaBattleStats.

Two ID spaces: command type vs attack type

An action carries two independent IDs, easy to confuse:

Command type (commandType, byte +1 of each BattleTask68Data action slot; the live copy is CURRENT_COMMAND_TYPE_ID). This is the command — Attack, Magic, GF, Item, Mug, Darkside, and the synthetic gunblade/Renzokuken variants. It selects animation, on-hit text and recoil behaviour, not the damage formula. (This field was mislabelled commandTypeWIthGunblade in an earlier pass — it holds the plain command type; the gunblade logic only reads it.)
Attack type (p_attack_type, from the kernel Attack Type field of the magic/ability). This is what Damage_DispatchByAttackType switches on to pick the damage formula.

Attack-type → formula dispatch (`Damage_DispatchByAttackType`)

Attack type	Damage function	Notes
Physical attack	`Damage_ComputePhysicalCore(…,0)`	hit + crit roll first
Magic attack	`Damage_ComputeMagicAndGF` (unmissable)
Magic ignoring target SPR	`Damage_ComputeMagicAndGF` (ignore SPR)
GF	`Damage_ComputeMagicAndGF` (GF)
GF ignoring target SPR	`Damage_ComputeMagicAndGF` (GF, ignore SPR)
Percent magic damage	`Damage_ComputeMagicAndGF` (% current HP)	Demi
Percent GF damage	`Damage_ComputeMagicAndGF` (Diablos)
Squall gunblade attack	`Damage_ComputeGunblade`
Renzokuken finisher	`Damage_ComputePhysicalCore(…,0)`
Percent physical damage	`Damage_ComputePhysicalCore(…,1)`
Kamikaze	`Damage_ComputePhysicalCore(…,3)`	5 × attacker maxHP
Everyone’s Grudge	`Damage_ComputePhysicalWithHitCritRoll(…,16)`	× NumKills
Physical, ignore VIT	`Damage_ComputePhysicalWithHitCritRoll(…,19)`
Curative magic	`Damage_ComputeCurativeMagic(…,7)`
Curative item	`Damage_ComputeCurativeItemSpecial(…,14)`
White Wind	`Damage_ComputeCurativeItemSpecial(…,9)`
Angelo Recover	`Damage_ComputeCurativeItemSpecial(…,15)`	give % HP
Revive / Revive at full HP	`Damage_ComputeReviveHP` / resurrection
Fixed / target HP−1 / GF-level fixed / 1 HP	`Damage_ComputeFixedSpecial(…,11/12/13/18)`
LV Down / LV Up	`computeLvlUpDown(…,0/1)`	LV Up also restores HP
Scan	scan flag + text	sets abbreviated-repeat flag
Card	eject + card-obtained text	miss if no card
Devour	HP-ratio success roll
Angelo Search	random item find
Moogle Dance (Moomba)	GF revive

Before the switch, sleep/confusion are cleared on the target (unless the attack is a medicine item or shelled magic); after it, back-attack status is cleared.

The command-type ID space (complete)

Battle_applyDamage dispatches on commandType twice via two-level jump tables (cmp id, 0xFE; ja default): stage 1 (damage-formula fields) through BATTLE_COMMAND_SWITCH_REMAP1, stage 2 (semantic handler) through BATTLE_COMMAND_SWITCH_REMAP2. The IDs fall into two disjoint bands.

Real kernel battle commands (0x00–0x26) — indices into the kernel battle-command ability list:

ID	Command	ID	Command	ID	Command
0x00	none / Kamikaze / Phoenix Pinion (fail sentinel)	0x0E	Shot (Irvine)	0x1A	Recover
0x01	Attack	0x0F	Blue Magic (Quistis)	0x1B	Revive
0x02	Magic	0x10	Slot (Selphie)	0x1C	Darkside
0x04	Item	0x11	No Mercy (Seifer)	0x1D	Card
0x05	Renzokuken launch, no finisher	0x12	Sorcery (Edea)	0x1E	Doom
0x06	Draw	0x13	Combine (Selphie “The End”)	0x1F	(unknown 0x1F)
0x07	Devour	0x14–0x16	Slot/No-Mercy/Sorcery item variants (base \| 0x04)	0x20	Absorb
0x08	Monster attack	0x17	Defend	0x21	LV Down
0x0B	Zell Duel link (launch)	0x18	Mad Rush	0x22	LV Up
0x0C	Mug	0x19	Treatment	0x26	MiniMog
0x0D	Item sub-link

Synthetic pseudo-commands (0xEC–0xFE) — injected at runtime for the multi-stage limit and gunblade sequences (0x27–0xEB, 0xF2, and 0xFF are unused and route to the generic handler):

ID	Command	Character / mechanic
0xEC	Seifer link	Seifer
0xED / 0xEE	Shot on-hit / expire	Irvine
0xEF	Zell Duel link (secondary)	Zell
0xF0	Angelo auto-move	Rinoa
0xF1	Duel (main)	Zell
0xF3	Darkside + gunblade trigger	Squall/Seifer
0xF4	Angelo / Chocobo (Invincible Moon…)	Rinoa
0xF5	Odin / Gilgamesh	GF
0xF6	Doom countdown reached 0	—
0xF7	Reflected-spell variant	—
0xF8	Mug + gunblade trigger	Squall
0xF9	Renzokuken finisher (Rough Divide … Lion Heart)	Squall
0xFA	Renzokuken launch / sequence marker	Squall
0xFB	Renzokuken on-hit (each initial hit)	Squall
0xFC	Special action (generic)	—
0xFD	Gunblade on-hit (Attack + trigger)	Squall
0xFE	G-Force (GF summon)	GF

The gunblade variants (0xF3/0xF8/0xFD) and the Renzokuken launch pair (0x05/0xFA) collapse to shared handlers in stage 2; the gunblade forms are produced by Battle_ApplyGunbladeTriggerHit from the base command in commandType. computeDamageEndOfAction then queues Darkside’s self-damage recoil after a Darkside hit (0x1C or its gunblade form 0xF3) via the internal command 0 — the same path as the poison end-of-turn tick.

Function addresses

Function	Address	Description
`Stat_ComputeCharaStat`	0x496440	Character STR/VIT/MAG/SPR/SPD/LUCK stat formula
`Stat_ComputeCharaMaxHP`	0x496310	Character max HP formula
`Stat_ComputeCharaHit`	0x4967C0	Character HIT stat formula
`Stat_ComputeCharaEva`	0x4968A0	Character EVA stat formula
`Stat_ComputeMonsterStats`	0x48C1C0	Monster battle-stat curve dispatch/scaling
`Stat_ComputeMonsterStatCurve`	0x48C3F0	Monster STR/MAG/VIT/SPR/SPD/EVA curve
`Stat_ComputeMonsterMaxHP`	0x48C500	Monster max HP formula
`Damage_ComputePhysicalCore`	0x492C40	Base physical damage formula
`Damage_RollPhysicalHit`	0x492BA0	Physical hit-chance roll
`Damage_RollCrit`	0x492B30	Critical-hit roll
`Damage_ApplyPhysicalModifiers`	0x48F600	Protect/back-attack/zombie/element modifiers
`Damage_DispatchByAttackType`	0x4922B0	Attack Type → damage formula dispatcher
`Damage_ComputePhysicalWithHitCritRoll`	0x492E10	Physical damage variant with built-in hit/crit roll
`Damage_ComputeGunblade`	0x48F480	Squall gunblade-trigger damage formula
`Damage_ComputeMagicAndGF`	0x491AD0	Magic and GF damage formula
`Damage_ComputeCurativeMagic`	0x493280	Curative magic (Cure line) healing formula
`Battle_ApplyStatusWithResistRoll`	0x48F9F0	Status-attack accuracy/resist roll
`Battle_RollDropItem`	0x486650	Item drop roll
`Battle_RollMugItem`	0x4867C0	Mug item roll
`Battle_ComputeDrawQuantity`	0x48FD20	Draw quantity formula
`computeTargetData`	0x48EF80	copies the staging result struct into the `TARGET_DATA` ring
`ApplyActionResultToTarget`	0x506690	applies a ring entry: statuses, reaction anim, crit flash, Protect/Shell/Reflect shimmer, popup
`BattleFx_DamageNumbers_Spawn`	0x5068B0	builds the damage/heal popup task (`TaskNodeDamageNumber`)
`BattleFx_DamageNumbers_TaskTick`	0x5069B0	popup per-frame tick: project, bounce/rise, fade
`Damage_ComputeReviveHP`	0x491940	Life / Full-Life revive HP (zombie target → unmissable magic damage)
`computeResurrection`	0x4935A0	resurrection entry: sets restorative display, handles the resurrection map-seal
`Battle_RollCardCommand`	0x48FBA0	Card command capture roll
`Battle_ComputeExpDistribution`	0x494D40	EXP distribution formula
`Stat_RefreshCharaBattleStats`	0x495960	Recomputes battle stats from base + junction
`Battle_applyDamage`	0x48FE20	Command-type dispatcher (stage 1/2 jump tables)
`BATTLE_COMMAND_SWITCH_REMAP1`	0x491250	Global variable/data, not a function — stage-1 jump table
`BATTLE_COMMAND_SWITCH_REMAP2`	0x4913B8	Global variable/data, not a function — stage-2 jump table
`Battle_ApplyGunbladeTriggerHit`	0x485160	Produces gunblade pseudo-command IDs
`computeDamageEndOfAction`	0x484180	Queues Darkside recoil / end-of-action damage
`CURRENT_COMMAND_TYPE_ID`	0x1D27AD9	Global variable/data, not a function — live command-type slot

Battle formulas — decompiled from FF8_EN.exe

Character stats (Stat_ComputeCharaStat)

Monster stats (Stat_ComputeMonsterStats / Stat_ComputeMonsterStatCurve / Stat_ComputeMonsterMaxHP)

Physical damage (Damage_ComputePhysicalCore)

Magic damage (Damage_ComputeMagicAndGF)