Merge pull request #1531 from GriffinRichards/fix-statoverflow

Restore ModifyStatByNature bug notes

1 files changed, 17 insertions, 8 deletions

diff --git a/src/pokemon.c b/src/pokemon.c
index 6e3d37ae3..0f943734b 100644
--- a/src/pokemon.c
+++ b/src/pokemon.c
@@ -5775,27 +5775,36 @@ u8 GetTrainerEncounterMusicId(u16 trainerOpponentId)
         return TRAINER_ENCOUNTER_MUSIC(trainerOpponentId);
 }
 
-u16 ModifyStatByNature(u8 nature, u16 n, u8 statIndex)
-{
+u16 ModifyStatByNature(u8 nature, u16 stat, u8 statIndex)
+{
+// Because this is a u16 it will be unable to store the
+// result of the multiplication for any stat > 595 for a
+// positive nature and > 728 for a negative nature.
+// Neither occur in the base game, but this can happen if
+// any Nature-affected base stat is increased to a value
+// above 248. The closest by default is Shuckle at 230.
+#ifdef BUGFIX
+    u32 retVal;
+#else
     u16 retVal;
+#endif
+
     // Don't modify HP, Accuracy, or Evasion by nature
     if (statIndex <= STAT_HP || statIndex > NUM_NATURE_STATS)
-    {
-        return n;
-    }
+        return stat;
 
     switch (gNatureStatTable[nature][statIndex - 1])
     {
     case 1:
-        retVal = n * 110;
+        retVal = stat * 110;
         retVal /= 100;
         break;
     case -1:
-        retVal = n * 90;
+        retVal = stat * 90;
         retVal /= 100;
         break;
     default:
-        retVal = n;
+        retVal = stat;
         break;
     }