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321 lines
10 KiB
Python
321 lines
10 KiB
Python
# encoding: utf8
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u"""
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Handles reading and encryption/decryption of Pokémon save file data.
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See: http://projectpokemon.org/wiki/Pokemon_NDS_Structure
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Kudos to LordLandon for his pkmlib.py, from which this module was originally
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derived.
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"""
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import struct
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from pokedex.db import tables
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from pokedex.formulae import calculated_hp, calculated_stat
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from pokedex.util import namedtuple, permutations
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from pokedex.struct._pokemon_struct import pokemon_struct
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def pokemon_prng(seed):
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u"""Creates a generator that simulates the main Pokémon PRNG."""
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while True:
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seed = 0x41C64E6D * seed + 0x6073
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seed &= 0xFFFFFFFF
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yield seed >> 16
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class SaveFilePokemon(object):
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u"""Represents an individual Pokémon, from the game's point of view.
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Handles translating between the on-disk encrypted form, the in-RAM blob
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(also used by pokesav), and something vaguely intelligible.
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"""
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Stat = namedtuple('Stat', ['stat', 'base', 'gene', 'exp', 'calc'])
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def __init__(self, blob, encrypted=False):
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u"""Wraps a Pokémon save struct in a friendly object.
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If `encrypted` is True, the blob will be decrypted as though it were an
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on-disk save. Otherwise, the blob is taken to be already decrypted and
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is left alone.
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`session` is an optional database session.
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"""
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if encrypted:
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# Decrypt it.
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# Interpret as one word (pid), followed by a bunch of shorts
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struct_def = "I" + "H" * ((len(blob) - 4) / 2)
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shuffled = list( struct.unpack(struct_def, blob) )
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# Apply standard Pokémon decryption, undo the block shuffling, and
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# done
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self.reciprocal_crypt(shuffled)
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words = self.shuffle_chunks(shuffled, reverse=True)
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self.blob = struct.pack(struct_def, *words)
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else:
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# Already decrypted
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self.blob = blob
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self.structure = pokemon_struct.parse(self.blob)
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@property
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def as_struct(self):
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u"""Returns a decrypted struct, aka .pkm file."""
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return self.blob
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@property
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def as_encrypted(self):
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u"""Returns an encrypted struct the game expects in a save file."""
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# Interpret as one word (pid), followed by a bunch of shorts
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struct_def = "I" + "H" * ((len(self.blob) - 4) / 2)
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words = list( struct.unpack(struct_def, self.blob) )
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# Apply the block shuffle and standard Pokémon encryption
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shuffled = self.shuffle_chunks(words)
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self.reciprocal_crypt(shuffled)
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# Stuff back into a string, and done
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return struct.pack(struct_def, *shuffled)
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### Delicious data
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@property
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def is_shiny(self):
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u"""Returns true iff this Pokémon is shiny."""
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# See http://bulbapedia.bulbagarden.net/wiki/Personality#Shininess
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# But don't see it too much, because the above is super over
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# complicated. Do this instead!
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personality_msdw = self.structure.personality >> 16
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personality_lsdw = self.structure.personality & 0xffff
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return (
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self.structure.original_trainer_id
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^ self.structure.original_trainer_secret_id
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^ personality_msdw
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^ personality_lsdw
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) < 8
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def use_database_session(self, session):
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"""Remembers the given database session, and prefetches a bunch of
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database stuff. Gotta call this before you use the database properties
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like `species`, etc.
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"""
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self._session = session
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st = self.structure
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self._pokemon = session.query(tables.Pokemon).get(st.national_id)
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self._pokemon_form = session.query(tables.PokemonForm) \
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.with_parent(self._pokemon) \
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.filter_by(name=st.alternate_form) \
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.one()
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self._ability = self._session.query(tables.Ability).get(st.ability_id)
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growth_rate = self._pokemon.evolution_chain.growth_rate
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self._experience_rung = session.query(tables.Experience) \
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.filter(tables.Experience.growth_rate == growth_rate) \
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.filter(tables.Experience.experience <= st.exp) \
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.order_by(tables.Experience.level.desc()) \
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[0]
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level = self._experience_rung.level
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self._next_experience_rung = None
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if level < 100:
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self._next_experience_rung = session.query(tables.Experience) \
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.filter(tables.Experience.growth_rate == growth_rate) \
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.filter(tables.Experience.level == level + 1) \
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.one()
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self._held_item = None
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if st.held_item_id:
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self._held_item = session.query(tables.ItemGameIndex) \
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.filter_by(generation_id = 4, game_index = st.held_item_id).one().item
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self._stats = []
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for pokemon_stat in self._pokemon.stats:
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structure_name = pokemon_stat.stat.name.lower().replace(' ', '_')
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gene = st.ivs['iv_' + structure_name]
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exp = st['effort_' + structure_name]
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if pokemon_stat.stat.name == u'HP':
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calc = calculated_hp
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else:
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calc = calculated_stat
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stat_tup = self.Stat(
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stat = pokemon_stat.stat,
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base = pokemon_stat.base_stat,
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gene = gene,
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exp = exp,
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calc = calc(
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pokemon_stat.base_stat,
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level = level,
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iv = gene,
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effort = exp,
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),
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)
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self._stats.append(stat_tup)
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move_ids = (
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self.structure.move1_id,
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self.structure.move2_id,
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self.structure.move3_id,
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self.structure.move4_id,
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)
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move_rows = self._session.query(tables.Move).filter(tables.Move.id.in_(move_ids))
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moves_dict = dict((move.id, move) for move in move_rows)
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self._moves = [moves_dict.get(move_id, None) for move_id in move_ids]
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if st.hgss_pokeball >= 17:
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pokeball_id = st.hgss_pokeball - 17 + 492
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else:
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pokeball_id = st.dppt_pokeball
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self._pokeball = session.query(tables.ItemGameIndex) \
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.filter_by(generation_id = 4, game_index = pokeball_id).one().item
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egg_loc_id = st.pt_egg_location_id or st.dp_egg_location_id
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met_loc_id = st.pt_met_location_id or st.dp_met_location_id
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self._egg_location = None
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if egg_loc_id:
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self._egg_location = session.query(tables.LocationGameIndex) \
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.filter_by(generation_id = 4, game_index = egg_loc_id).one().location
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self._met_location = session.query(tables.LocationGameIndex) \
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.filter_by(generation_id = 4, game_index = met_loc_id).one().location
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@property
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def species(self):
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# XXX forme!
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return self._pokemon
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@property
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def species_form(self):
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return self._pokemon_form
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@property
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def pokeball(self):
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return self._pokeball
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@property
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def egg_location(self):
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return self._egg_location
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@property
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def met_location(self):
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return self._met_location
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@property
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def shiny_leaves(self):
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return (
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self.structure.shining_leaves.leaf1,
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self.structure.shining_leaves.leaf2,
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self.structure.shining_leaves.leaf3,
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self.structure.shining_leaves.leaf4,
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self.structure.shining_leaves.leaf5,
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)
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@property
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def level(self):
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return self._experience_rung.level
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@property
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def exp_to_next(self):
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if self._next_experience_rung:
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return self._next_experience_rung.experience - self.structure.exp
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else:
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return 0
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@property
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def progress_to_next(self):
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if self._next_experience_rung:
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return 1.0 \
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* (self.structure.exp - self._experience_rung.experience) \
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/ (self._next_experience_rung.experience - self._experience_rung.experience)
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else:
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return 0.0
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@property
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def ability(self):
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return self._ability
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@property
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def held_item(self):
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return self._held_item
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@property
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def stats(self):
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return self._stats
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@property
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def moves(self):
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return self._moves
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@property
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def move_pp(self):
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return (
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self.structure.move1_pp,
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self.structure.move2_pp,
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self.structure.move3_pp,
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self.structure.move4_pp,
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)
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### Utility methods
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shuffle_orders = list( permutations(range(4)) )
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@classmethod
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def shuffle_chunks(cls, words, reverse=False):
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"""The main 128 encrypted bytes (or 64 words) in a save block are split
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into four chunks and shuffled around in some order, based on
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personality. The actual order of shuffling is a permutation of four
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items in order, indexed by the shuffle index. That is, 0 yields 0123,
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1 yields 0132, 2 yields 0213, etc.
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Given a list of words (the first of which should be the pid), this
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function returns the words in shuffled order. Pass reverse=True to
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unshuffle instead.
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"""
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pid = words[0]
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shuffle_index = (pid >> 0xD & 0x1F) % 24
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shuffle_order = cls.shuffle_orders[shuffle_index]
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if reverse:
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# Decoding requires going the other way; invert the order
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shuffle_order = [shuffle_order.index(i) for i in range(4)]
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shuffled = words[:3] # skip the unencrypted stuff
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for chunk in shuffle_order:
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shuffled += words[ chunk * 16 + 3 : chunk * 16 + 19 ]
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shuffled += words[67:] # extra bytes are also left alone
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return shuffled
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@classmethod
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def reciprocal_crypt(cls, words):
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u"""Applies the reciprocal Pokémon save file cipher to the provided
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list of words.
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Returns nothing; the list is changed in-place.
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"""
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# Apply regular Pokémon "encryption": xor everything with the output of
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# the PRNG. First three items are pid/unused/checksum and are not
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# encrypted.
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# Main data is encrypted using the checksum as a seed
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prng = pokemon_prng(words[2])
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for i in range(3, 67):
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words[i] ^= next(prng)
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if len(words) > 67:
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# Extra bytes are encrypted using the pid as a seed
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prng = pokemon_prng(words[0])
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for i in range(67, len(words)):
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words[i] ^= next(prng)
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return
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