Digimon World damage formula

calculateDamage.c

int calculateDamage(DigimonEntity *attacker,DigimonEntity *defender,int moveId)
{
  byte factors [4];
  int damage;
  
  Special attackSpecial = MOVE_PARAM[moveId].special;
  for (int i = 0; i < 3; i += 1) {
    Special victimSpecial = DIGIMON_PARA[(defender->entity).type].special[i];
    factors[i] = victimSpecial == 0xff ? 10 : TYPE_FACTORS[attackSpecial][victimSpecial];
  }
  
  int offense = (int)attacker->offense;
  int defense = (int)defender->defense;
  
  // counter
  if (moveId == 0x2d) 
    defense = defense * 0.3;
  
  int typeFactor = factors[0] + factors[1] + factors[2];
  
  // regular attacks
  if ((moveId < 0x3a) || (0x70 < moveId)) {
    int offenseDifference = offense - defense;
    
    // make sure diff isn't bigger than 500
    if (500 < offenseDifference)
      offenseDifference = 500;
    if (offenseDifference < -500)
      offenseDifference = -500;
      
    int randomFactor = random(21);
    
    damage = (((int)(typeFactor * (MOVE_PARAM[moveId].power + (offenseDifference * MOVE_PARAM[moveId].power) / 500)) / 30) * (randomFactor + 90)) / 100;
  }
  else {
    // finisher
    damage = (int)((offense + MOVE_PARAM[moveId].power) * typeFactor) / 0x1e;
  }
  
  // finisher
  if ((0x39 < moveId) && (moveId < 0x71)) {
    // when partner, take chargeup factor
    if (attacker == ENTITY_TABLE.partner) {
      int chargeupValue = (uint)*(byte *)&(COMBAT_DATA_PTR->player).finisherChargeup;
      if (40 < chargeupValue)
        damage = (int)(damage * chargeupValue) / 40;
    }
    // when NPC, take random factor
    else {
      int chargeupValue = random(101);
      damage = (damage * (chargeupValue + 100)) / 100;
    }
    roll2 = random(21);
    damage = (damage * (roll2 + 90)) / 100;
  }
  
  // verify boundaries
  if (damage < 1)
    damage = 1;
  if (9999 < damage)
    damage = 9999;
    
  return damage;
}