Add fix for possible crash when decompressing trainer back pics

src/battle_gfx_sfx_util.c

@@ -710,9 +710,17 @@ void DecompressTrainerFrontPic(u16 frontPicId, u8 battlerId)
 void DecompressTrainerBackPic(u16 backPicId, u8 battlerId)
 {
     u8 position = GetBattlerPosition(battlerId);
+#ifdef BUGFIX
+    CpuCopy32(gTrainerBackPicTable[backPicId].data, gMonSpritesGfxPtr->sprites.ptr[position], gTrainerBackPicTable[backPicId].size);
+#else
+    // Trainer back pics aren't compressed!
+    // Attempting to decompress the uncompressed data can softlock or crash the game.
+    // This is ok in vanilla by chance, because the pixels in the trainer back sprites that correspond
+    // to the compressed data's header are all 0, so the decompression does nothing.
     DecompressPicFromTable_2(&gTrainerBackPicTable[backPicId],
                              gMonSpritesGfxPtr->sprites.ptr[position],
                              SPECIES_NONE);
+#endif
     LoadCompressedPalette(gTrainerBackPicPaletteTable[backPicId].data,
                           OBJ_PLTT_ID(battlerId), PLTT_SIZE_4BPP);
 }

src/trainer_pokemon_sprites.c

@@ -57,10 +57,11 @@ bool16 ResetAllPicSprites(void)
     return FALSE;
 }
 
-static bool16 DecompressPic(u16 species, u32 personality, bool8 isFrontPic, u8 *dest, bool8 isTrainer, bool8 ignoreDeoxys)
+static bool16 DecompressPic(u16 picId, u32 personality, bool8 isFrontPic, u8 *dest, bool8 isTrainer, bool8 ignoreDeoxys)
 {
     if (!isTrainer)
     {
+        u16 species = picId;
         if (isFrontPic)
         {
             if (!ignoreDeoxys)
@@ -78,10 +79,23 @@ static bool16 DecompressPic(u16 species, u32 personality, bool8 isFrontPic, u8 *
     }
     else
     {
+        u16 trainerPicId = picId;
         if (isFrontPic)
-            DecompressPicFromTable(&gTrainerFrontPicTable[species], dest, species);
+        {
+            DecompressPicFromTable(&gTrainerFrontPicTable[trainerPicId], dest, trainerPicId);
+        }
         else
-            DecompressPicFromTable(&gTrainerBackPicTable[species], dest, species);
+        {
+#ifdef BUGFIX
+            CpuCopy32(gTrainerBackPicTable[trainerPicId].data, dest, gTrainerBackPicTable[trainerPicId].size);
+#else
+            // Trainer back pics aren't compressed!
+            // Attempting to decompress the uncompressed data can softlock or crash the game.
+            // This is ok in vanilla by chance, because the pixels in the trainer back sprites that correspond
+            // to the compressed data's header are all 0, so the decompression does nothing.
+            DecompressPicFromTable(&gTrainerBackPicTable[trainerPicId], dest, trainerPicId);
+#endif
+        }
     }
     return FALSE;
 }