FF7/Battle/Battle Scenes/Battle AI Addresses

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Revision as of 23:48, 23 October 2012 by my_wiki>NFITC1

In this page, an "actor" is defined as an entity instance in a battle (scene). The "current actor" is an actor that is executing a script or performing an action. An "active actor" is one that can perform actions. An "action" is defined as an event with a visual representation in battle (eg. an attack or a position change).

Most of the complexities of AI scripts use different memory addresses to make decisions based on the actor performing an action or the target of an action. There are three categories of address each spanning a separate useable1 address ranges.

Range Usage
0x0000 - 0x03FF Random Access Variables. No initial value or significance to battle.
0x2000 - 0x21DF Globally accessible values. Values are the same for all actors.
0x4000 - 0x433F Actor specific values. Contains information such as HP, MP, Level, stats, etc. One for each Actor, 10 in all.

Each address references a specific bit of memory rather than a byte which means individual bits can be manipulated without using BIT-wise operations in script. Every 8 address values is the beginning of a byte (ie. 0x0000, 0x0008, etc.). The code used to access an address determines whether a bit, byte, word, or dword is being read/written.
Addresses must be accessed directly. There is no pointer support to these values accessible in AI scripts.


Random Access Variables

These values are used between scripts and not automatically set/cleared at any time during battle. If an address is set to a specific value in one script, it will retain that value when the next script begins. The initial value is 0. Going beyond 3FFh as an address will result in memory leaks.

Global Values

Generally these contain information about the battle itself. These values are the same when any actor accesses them, although they do change to reflect the battle's events.

Address Value
0x2000 Command Index of last action performed
0x2008 Action Index of last action performed
0x2010 Memory 1/2 Bank access value
0x2018 DUMMY. Used in one script in a test enemy.
0x2020 Battle Formation (side, pincer, pre-emptive, etc.)
0x2038 Limit Level. Only used by Vincent during transformation.
0x2050 Active Actor List. A bit mask of all active (scripts enabled) actors.
0x2060 Single bit indicating which actor owns the script that is currently executing. Changes as scripts are triggered.
0x2070 Bit mask of actors indicating targets of the current action. Should be set prior to any action.
0x2080 Bit mask of actors indicating actors the current actor considers as allies. Changes as scripts are triggered.
0x2090 Bit mask of active actors indicating actors the current actor considers as allies. Changes as scripts are triggered.
0x20A0 Bit mask of actors indicating actors the current actor considers as enemies. Changes as scripts are triggered.
0x20B0 Bit mask of active actors indicating actors the current actor considers as enemies. Changes as scripts are triggered.
0x20C0 Bit mask of active player's characters
0x20E0 Bit mask of all active and inactive actors present in the battle.
0x2110 Set of flags indicating battle rewards (functions unknown).
0x2120 Elements of last performed action.
0x2140 Formation Index of the current battle.
0x2150 Index of last performed action.
0x2160 Some sort of flags (unknown effect).
0x2170 Special Attack Flags.
0x2180 Unknown
0x21A0 Something to do with String display (not sure what).
0x21C0 Party's Gil

Actor Specific

These values are reflections of a given actor's status. They include some obvious things like Statuses, Level, HP, MP, etc and a few abstract things like Animation IDs for reactions. Every actor has their own copy of these values that reflects their instance. These values are accessed by masking the address with a specific actor(s) in the script. Using the mask will let the script interpreter know which set of physical addresses to use.

Address Value
0x4000 Bitmask of current Statuses
0x4020 Set of flags relating to situation (defending, backrow, etc.).
0x4040 Unknown
0x4048 Level
0x4058 Greatest Elemental Damage modifier (No damage, half, normal, etc.)
0x4060 Unknown
0x4068 Physical Attack Power
0x4070 Magic Attack Power
0x4078 Physical Evade
0x4080 Idle Animation ID
0x4088 Damaged Animation ID
0x4090 Back Damage Multiplier
0x4098 Model Size (default is 16)
0x40A0 Dexterity
0x40A8 Luck
0x40B0 Unknown
0x40B8 Set to equal 0x4060 under unknown condition
0x40C0 Target(s) of last action performed by actor
0x40D0 Previous Attacker
0x40E0 Previous Physical Attacker
0x40F0 Previous Magical Attacker
0x4100 Physical Defense Rating
0x4110 Magical Defense Rating
0x4120 Index of actor
0x4130 Absorbed Elements
0x4140 Current MP
0x4150 Max MP
0x4160 Current HP
0x4180 Max HP
0x4220 Initial Statuses
0x4268 Magic Evade
0x4270 Row
0x4278 Unknown
0x4280 Gil stolen (Enemies only)
0x4290 Item stolen (Enemies only)
0x42A0 Unknown
0x42B0 AP actor is worth
0x42C0 Gil actor is worth
0x42E0 EXP actor is worth


Thanks to unchecked memory leaks1, any actor can directly access another actor's script values. The following table is to be read across to show what address should be used to access another actor's values starting at 4000. For example, Actor 2 can use 4D00 to access Actor6's values. Also, Actor 8 can use 2540 to access Actor 1's values.

Actors2 Actor 0 Actor 1 Actor 2 Actor 3 Actor 4 Actor 5 Actor 6 Actor 7 Actor 8 Actor 9 RAVs3
Actor 0 * 4340 4680 49C0 4D00 5040 5380 56C0 5A00 5D40 6080
Actor 1 2220 * 4340 4680 49C0 4D00 5040 5380 56C0 5A00 5D40
Actor 2 2220 2540 * 4340 4680 49C0 4D00 5040 5380 56C0 5A00
Actor 3 2220 2540 2880 * 4340 4680 49C0 4D00 5040 5380 56C0
Actor 4 2220 2540 2880 2BC0 * 4340 4680 49C0 4D00 5040 5380
Actor 5 2220 2540 2880 2BC0 2F00 * 4340 4680 49C0 4D00 5040
Actor 6 2220 2540 2880 2BC0 2F00 3240 * 4340 4680 49C0 4D00
Actor 7 2220 2540 2880 2BC0 2F00 3240 3580 * 4340 4680 49C0
Actor 8 2220 2540 2880 2BC0 2F00 3240 3580 38C0 * 4340 4680
Actor 9 2220 2540 2880 2BC0 2F00 3240 3580 38C0 3C00 * 4340

This is mostly unhelpful as formations can vary greatly and actors can still indirectly access each other's values based on controllable conditions. There are lots of examples of indirect access, the memory leak trick is just interesting.


NOTES:
1 - Address values are only checked by the minimum value and stored accordingly. The structure in memory stores the Global Variables first, the Actor Variables second, and the Random Access Variables last. Technically, a value of 0xFFFF could be used as an address, but that would result in a memory leak producing erratic results.
2 - Actors 0-2 are player controlled characters, Actors 4-9 are enemies. Actor 3 is a omnipresent battle actor that holds formation AI, if it exists. It does nothing on its own and is only used in a few boss battles.
3 - This will access the Random Access Variables starting at 0x0000. This is stupid as it requires more work to get to them. Don't do it this way!