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Pokemon index extension branch

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aaaaaa123456789 edited this page Mar 26, 2020 · 18 revisions

Pokémon index extension branch (expand-mon-ID)

This is the first feature branch of the repository, implementing an actual case of 16-bit extension. Pokémon species IDs are extended to 16 bits, updating the various subsystems that depend on the actual indexes to use the conversion table created by this branch.

(NOTE: this documentation page is a work in progress. Items below that don't link anywhere haven't been written yet.)

  • Conversion table definition
  • Affected subsystems
  • Map scripting changes
  • Evolutions and learnsets
  • Trainer data
  • Subsystems using full indexes
  • Saving and reloading
  • Indirection tables

Conversion table definition

An unused, suitably-aligned region of WRAM bank 2, starting at address $D200, was reserved for the Pokémon index conversion table, as well as any further conversion tables added by future branches.

The table itself is declared as wPokemonIndexTable, with a corresponding set of parameter constants prefixed by MON_TABLE; the values of those parameters are the following:

Constant Value
MON_TABLE_ENTRIES 100
MON_TABLE_LOCKED_ENTRIES 30
MON_TABLE_CACHE_SIZE 16
MON_TABLE_SAVED_RECENT_INDEXES 8
MON_TABLE_MINIMUM_RESERVED_INDEX $FD

The parameters defined above make the table fit exactly in $100 bytes with no padding. The minimum reserved ID is set to $FD so eggs can continue using that value: the EGG constant is redefined as -3, which will expand as $FD when used as an 8-bit value and $FFFD when used as a 16-bit value; since $FD is defined as a reserved ID, it will convert to $FFFD (and vice-versa), making the EGG constant valid both as an 8-bit ID and a 16-bit index.

The home bank functions needed to access this table are declared as GetPokemonIndexFromID, GetPokemonIDFromIndex, LockPokemonID and GetLockedPokemonID. The garbage collector function is also exposed as PokemonTableGarbageCollection.

The garbage collector will look for valid IDs in the following locations to consider them as "in use":

  • Party and currently-selected PC box
  • Opponent trainer's party and linked player's party
  • Roaming Pokémon
  • Pokémon left in the Day-Care
  • Bug-Catching Contest current Pokémon and results
  • Various temporary buffers (wBattleMon, wEnemyMon, wTempMon, wBufferMon, odd egg data, base stat data)
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