pokedex/struct/__init__.py

   1 # encoding: utf8
   2 u"""
   3 Handles reading and encryption/decryption of Pokémon save file data.
   4
   5 See: http://projectpokemon.org/wiki/Pokemon_NDS_Structure
   6
   7 Kudos to LordLandon for his pkmlib.py, from which this module was originally
   8 derived.
   9 """
  10
  11 import struct
  12
  13 from pokedex.db import tables
  14 from pokedex.formulae import calculated_hp, calculated_stat
  15 from pokedex.util import namedtuple, permutations
  16 from pokedex.struct._pokemon_struct import pokemon_struct
  17
  18 def pokemon_prng(seed):
  19     u"""Creates a generator that simulates the main Pokémon PRNG."""
  20     while True:
  21         seed = 0x41C64E6D * seed + 0x6073
  22         seed &= 0xFFFFFFFF
  23         yield seed >> 16
  24
  25
  26 class SaveFilePokemon(object):
  27     u"""Represents an individual Pokémon, from the game's point of view.
  28
  29     Handles translating between the on-disk encrypted form, the in-RAM blob
  30     (also used by pokesav), and something vaguely intelligible.
  31     """
  32
  33     Stat = namedtuple('Stat', ['stat', 'base', 'gene', 'exp', 'calc'])
  34
  35     def __init__(self, blob, encrypted=False):
  36         u"""Wraps a Pokémon save struct in a friendly object.
  37
  38         If `encrypted` is True, the blob will be decrypted as though it were an
  39         on-disk save.  Otherwise, the blob is taken to be already decrypted and
  40         is left alone.
  41
  42         `session` is an optional database session.
  43         """
  44
  45         if encrypted:
  46             # Decrypt it.
  47             # Interpret as one word (pid), followed by a bunch of shorts
  48             struct_def = "I" + "H" * ((len(blob) - 4) / 2)
  49             shuffled = list( struct.unpack(struct_def, blob) )
  50
  51             # Apply standard Pokémon decryption, undo the block shuffling, and
  52             # done
  53             self.reciprocal_crypt(shuffled)
  54             words = self.shuffle_chunks(shuffled, reverse=True)
  55             self.blob = struct.pack(struct_def, *words)
  56
  57         else:
  58             # Already decrypted
  59             self.blob = blob
  60
  61         self.structure = pokemon_struct.parse(self.blob)
  62
  63     @property
  64     def as_struct(self):
  65         u"""Returns a decrypted struct, aka .pkm file."""
  66         return self.blob
  67
  68     @property
  69     def as_encrypted(self):
  70         u"""Returns an encrypted struct the game expects in a save file."""
  71
  72         # Interpret as one word (pid), followed by a bunch of shorts
  73         struct_def = "I" + "H" * ((len(self.blob) - 4) / 2)
  74         words = list( struct.unpack(struct_def, self.blob) )
  75
  76         # Apply the block shuffle and standard Pokémon encryption
  77         shuffled = self.shuffle_chunks(words)
  78         self.reciprocal_crypt(shuffled)
  79
  80         # Stuff back into a string, and done
  81         return struct.pack(struct_def, *shuffled)
  82
  83     ### Delicious data
  84     @property
  85     def is_shiny(self):
  86         u"""Returns true iff this Pokémon is shiny."""
  87         # See http://bulbapedia.bulbagarden.net/wiki/Personality#Shininess
  88         # But don't see it too much, because the above is super over
  89         # complicated.  Do this instead!
  90         personality_msdw = self.structure.personality >> 16
  91         personality_lsdw = self.structure.personality & 0xffff
  92         return (
  93             self.structure.original_trainer_id
  94             ^ self.structure.original_trainer_secret_id
  95             ^ personality_msdw
  96             ^ personality_lsdw
  97         ) < 8
  98
  99     def use_database_session(self, session):
 100         """Remembers the given database session, and prefetches a bunch of
 101         database stuff.  Gotta call this before you use the database properties
 102         like `species`, etc.
 103         """
 104         self._session = session
 105
 106         st = self.structure
 107         self._pokemon = session.query(tables.Pokemon).get(st.national_id)
 108         self._ability = self._session.query(tables.Ability).get(st.ability_id)
 109
 110         growth_rate = self._pokemon.evolution_chain.growth_rate
 111         self._experience_rung = session.query(tables.Experience) \
 112             .filter(tables.Experience.growth_rate == growth_rate) \
 113             .filter(tables.Experience.experience <= st.exp) \
 114             .order_by(tables.Experience.level.desc()) \
 115             [0]
 116         level = self._experience_rung.level
 117
 118         self._next_experience_rung = None
 119         if level < 100:
 120             self._next_experience_rung = session.query(tables.Experience) \
 121                 .filter(tables.Experience.growth_rate == growth_rate) \
 122                 .filter(tables.Experience.level == level + 1) \
 123                 .one()
 124
 125         self._held_item = None
 126         if st.held_item_id:
 127             self._held_item = session.query(tables.ItemInternalID) \
 128                 .filter_by(generation_id = 4, internal_id = st.held_item_id).one().item
 129
 130         self._stats = []
 131         for pokemon_stat in self._pokemon.stats:
 132             structure_name = pokemon_stat.stat.name.lower().replace(' ', '_')
 133             gene = st.ivs['iv_' + structure_name]
 134             exp  = st['effort_' + structure_name]
 135
 136             if pokemon_stat.stat.name == u'HP':
 137                 calc = calculated_hp
 138             else:
 139                 calc = calculated_stat
 140
 141             stat_tup = self.Stat(
 142                 stat = pokemon_stat.stat,
 143                 base = pokemon_stat.base_stat,
 144                 gene = gene,
 145                 exp  = exp,
 146                 calc = calc(
 147                     pokemon_stat.base_stat,
 148                     level = level,
 149                     iv = gene,
 150                     effort = exp,
 151                 ),
 152             )
 153
 154             self._stats.append(stat_tup)
 155
 156
 157         move_ids = (
 158             self.structure.move1_id,
 159             self.structure.move2_id,
 160             self.structure.move3_id,
 161             self.structure.move4_id,
 162         )
 163         move_rows = self._session.query(tables.Move).filter(tables.Move.id.in_(move_ids))
 164         moves_dict = dict((move.id, move) for move in move_rows)
 165
 166         self._moves = [moves_dict.get(move_id, None) for move_id in move_ids]
 167
 168         if st.hgss_pokeball >= 17:
 169             pokeball_id = st.hgss_pokeball - 17 + 492
 170         else:
 171             pokeball_id = st.dppt_pokeball
 172         self._pokeball = session.query(tables.ItemInternalID) \
 173             .filter_by(generation_id = 4, internal_id = pokeball_id).one().item
 174
 175         egg_loc_id = st.pt_egg_location_id or st.dp_egg_location_id
 176         met_loc_id = st.pt_met_location_id or st.dp_met_location_id
 177
 178         self._egg_location = None
 179         if egg_loc_id:
 180             self._egg_location = session.query(tables.LocationInternalID) \
 181                 .filter_by(generation_id = 4, internal_id = egg_loc_id).one().location
 182
 183         self._met_location = session.query(tables.LocationInternalID) \
 184             .filter_by(generation_id = 4, internal_id = met_loc_id).one().location
 185
 186     @property
 187     def species(self):
 188         # XXX forme!
 189         return self._pokemon
 190
 191     @property
 192     def pokeball(self):
 193         return self._pokeball
 194
 195     @property
 196     def egg_location(self):
 197         return self._egg_location
 198
 199     @property
 200     def met_location(self):
 201         return self._met_location
 202
 203     @property
 204     def shiny_leaves(self):
 205         return (
 206             self.structure.shining_leaves.leaf1,
 207             self.structure.shining_leaves.leaf2,
 208             self.structure.shining_leaves.leaf3,
 209             self.structure.shining_leaves.leaf4,
 210             self.structure.shining_leaves.leaf5,
 211         )
 212
 213     @property
 214     def level(self):
 215         return self._experience_rung.level
 216
 217     @property
 218     def exp_to_next(self):
 219         if self._next_experience_rung:
 220             return self._next_experience_rung.experience - self.structure.exp
 221         else:
 222             return 0
 223
 224     @property
 225     def progress_to_next(self):
 226         if self._next_experience_rung:
 227             return 1.0 \
 228                 * (self.structure.exp - self._experience_rung.experience) \
 229                 / (self._next_experience_rung.experience - self._experience_rung.experience)
 230         else:
 231             return 0.0
 232
 233     @property
 234     def ability(self):
 235         return self._ability
 236
 237     @property
 238     def held_item(self):
 239         return self._held_item
 240
 241     @property
 242     def stats(self):
 243         return self._stats
 244
 245     @property
 246     def moves(self):
 247         return self._moves
 248
 249     @property
 250     def move_pp(self):
 251         return (
 252             self.structure.move1_pp,
 253             self.structure.move2_pp,
 254             self.structure.move3_pp,
 255             self.structure.move4_pp,
 256         )
 257
 258
 259     ### Utility methods
 260
 261     shuffle_orders = list( permutations(range(4)) )
 262
 263     @classmethod
 264     def shuffle_chunks(cls, words, reverse=False):
 265         """The main 128 encrypted bytes (or 64 words) in a save block are split
 266         into four chunks and shuffled around in some order, based on
 267         personality.  The actual order of shuffling is a permutation of four
 268         items in order, indexed by the shuffle index.  That is, 0 yields 0123,
 269         1 yields 0132, 2 yields 0213, etc.
 270
 271         Given a list of words (the first of which should be the pid), this
 272         function returns the words in shuffled order.  Pass reverse=True to
 273         unshuffle instead.
 274         """
 275
 276         pid = words[0]
 277         shuffle_index = (pid >> 0xD & 0x1F) % 24
 278
 279         shuffle_order = cls.shuffle_orders[shuffle_index]
 280         if reverse:
 281             # Decoding requires going the other way; invert the order
 282             shuffle_order = [shuffle_order.index(i) for i in range(4)]
 283
 284         shuffled = words[:3]  # skip the unencrypted stuff
 285         for chunk in shuffle_order:
 286             shuffled += words[ chunk * 16 + 3 : chunk * 16 + 19 ]
 287         shuffled += words[67:]  # extra bytes are also left alone
 288
 289         return shuffled
 290
 291     @classmethod
 292     def reciprocal_crypt(cls, words):
 293         u"""Applies the reciprocal Pokémon save file cipher to the provided
 294         list of words.
 295
 296         Returns nothing; the list is changed in-place.
 297         """
 298         # Apply regular Pokémon "encryption": xor everything with the output of
 299         # the PRNG.  First three items are pid/unused/checksum and are not
 300         # encrypted.
 301
 302         # Main data is encrypted using the checksum as a seed
 303         prng = pokemon_prng(words[2])
 304         for i in range(3, 67):
 305             words[i] ^= next(prng)
 306
 307         if len(words) > 67:
 308             # Extra bytes are encrypted using the pid as a seed
 309             prng = pokemon_prng(words[0])
 310             for i in range(67, len(words)):
 311                 words[i] ^= next(prng)
 312
 313         return