LOL: fix long standing bugs in the battle system (hit chance, damage, etc) by adapting original style random number generator

svn-id: r42269

6 files changed, 60 insertions, 33 deletions

diff --git a/engines/kyra/lol.cpp b/engines/kyra/lol.cpp
index 7c4b073f29..8f00708e43 100644
--- a/engines/kyra/lol.cpp
+++ b/engines/kyra/lol.cpp
@@ -214,8 +214,6 @@ LoLEngine::LoLEngine(OSystem *system, const GameFlags &flags) : KyraEngine_v1(sy
 	_compassBroken = _drainMagic = 0;
 	_dialogueField = false;
 
-	_rndSpecial = 0x12349876;
-
 	_buttonData = 0;
 	_activeButtons = 0;
 	gui_resetButtonList();
@@ -1082,7 +1080,7 @@ bool LoLEngine::addCharacter(int id) {
 
 	loadCharFaceShapes(numChars, id);
 
-	_characters[numChars].nextAnimUpdateCountdown = (int16) _rnd.getRandomNumberRng(1, 12) + 6;
+	_characters[numChars].nextAnimUpdateCountdown = (int16) generateRandomNumber(1, 12) + 6;
 
 	for (i = 0; i < 11; i++) {
 		if (_characters[numChars].items[i]) {
@@ -1176,7 +1174,7 @@ void LoLEngine::updatePortraitSpeechAnim() {
 		}
 	}
 
-	int f = _rnd.getRandomNumberRng(1, 6) - 1;
+	int f = generateRandomNumber(1, 6) - 1;
 	if (f == _characters[_updateCharNum].curFaceFrame)
 		f++;
 	if (f > 5)
@@ -1404,24 +1402,24 @@ void LoLEngine::increaseExperience(int charNum, int skill, uint32 points) {
 		switch (skill) {
 		case 0:
 			_txt->printMessage(0x8003, getLangString(0x4023), _characters[charNum].name);
-			inc = _rnd.getRandomNumberRng(4, 6);
+			inc = generateRandomNumber(4, 6);
 			_characters[charNum].hitPointsCur += inc;
 			_characters[charNum].hitPointsMax += inc;
 			break;
 
 		case 1:
 			_txt->printMessage(0x8003, getLangString(0x4025), _characters[charNum].name);
-			inc = _rnd.getRandomNumberRng(2, 6);
+			inc = generateRandomNumber(2, 6);
 			_characters[charNum].hitPointsCur += inc;
 			_characters[charNum].hitPointsMax += inc;
 			break;
 
 		case 2:
 			_txt->printMessage(0x8003, getLangString(0x4024), _characters[charNum].name);
-			inc = (_characters[charNum].defaultModifiers[6] * (_rnd.getRandomNumberRng(1, 8) + 17)) >> 8;
+			inc = (_characters[charNum].defaultModifiers[6] * (generateRandomNumber(1, 8) + 17)) >> 8;
 			_characters[charNum].magicPointsCur += inc;
 			_characters[charNum].magicPointsMax += inc;
-			inc = _rnd.getRandomNumberRng(1, 6);
+			inc = generateRandomNumber(1, 6);
 			_characters[charNum].hitPointsCur += inc;
 			_characters[charNum].hitPointsMax += inc;
 			break;
@@ -1874,6 +1872,29 @@ void LoLEngine::delay(uint32 millis, bool doUpdate, bool) {
 	}
 }
 
+int LoLEngine::generateRandomNumber(int min, int max) {
+	// The output produced by this random number generator
+	// differs a lot from _rnd.getRandomNumberRng(). Using
+	// _rnd.getRandomNumberRng() instead of this function
+	// here will break the fighting system!
+
+	if (min <= 0 || max <= 0)
+		return 0;
+
+	int res = 0;
+	int d = 0;
+
+	do {
+		int val = (((int)_rnd.getRandomNumber(0x7fff) * max) / 0x8000) + 1;
+		if (val > max)
+			val -= max;
+		res += val;
+		d++;
+	} while (d < min);
+
+	return res;
+}
+
 void LoLEngine::updateEnvironmentalSfx(int soundId) {
 	snd_processEnvironmentalSoundEffect(soundId, _currentBlock);
 }
@@ -2260,7 +2281,7 @@ int LoLEngine::processMagicIce(int charNum, int spellLevel) {
 	} else {
 		uint16 o = _levelBlockProperties[calcNewBlockPosition(_currentBlock, _currentDirection)].assignedObjects;
 		while (o & 0x8000) {
-			int might = _rnd.getRandomNumberRng(iceDamageMin[spellLevel], iceDamageMax[spellLevel]) + iceDamageAdd[spellLevel];
+			int might = generateRandomNumber(iceDamageMin[spellLevel], iceDamageMax[spellLevel]) + iceDamageAdd[spellLevel];
 			int dmg = calcInflictableDamagePerItem(charNum, 0, might, 3, 2);
 
 			MonsterInPlay *m = &_monsters[o & 0x7fff];
@@ -3192,7 +3213,7 @@ int LoLEngine::battleHitSkillTest(int16 attacker, int16 target, int skill) {
 		evadeChanceModifier = _characters[target].defaultModifiers[3];
 	}
 
-	int r = _rnd.getRandomNumberRng(1, 100);
+	int r = generateRandomNumber(1, 100);
 	if (r >= sk)
 		return 2;
 
@@ -3230,9 +3251,9 @@ int LoLEngine::inflictDamage(uint16 target, int damage, uint16 attacker, int ski
 			m->hitPoints -= damage;
 			m->damageReceived = 0x8000 | damage;
 			m->flags |= 0x10;
-			m->hitOffsX = _rnd.getRandomNumberRng(1, 24);
+			m->hitOffsX = generateRandomNumber(1, 24);
 			m->hitOffsX -= 12;
-			m->hitOffsY = _rnd.getRandomNumberRng(1, 24);
+			m->hitOffsY = generateRandomNumber(1, 24);
 			m->hitOffsY -= 12;
 			m->hitPoints = CLIP<int16>(m->hitPoints, 0, m->properties->hitPoints);
 
@@ -3436,7 +3457,7 @@ void LoLEngine::checkForPartyDeath() {
 }
 
 void LoLEngine::applyMonsterAttackSkill(MonsterInPlay *monster, int16 target, int16 damage) {
-	if (_rnd.getRandomNumberRng(1, 100) > monster->properties->attackSkillChance)
+	if (generateRandomNumber(1, 100) > monster->properties->attackSkillChance)
 		return;
 
 	int t = 0;
@@ -3506,7 +3527,7 @@ void LoLEngine::applyMonsterAttackSkill(MonsterInPlay *monster, int16 target, in
 }
 
 void LoLEngine::applyMonsterDefenseSkill(MonsterInPlay *monster, int16 attacker, int flags, int skill, int damage) {
-	if (_rnd.getRandomNumberRng(1, 100) > monster->properties->defenseSkillChance)
+	if (generateRandomNumber(1, 100) > monster->properties->defenseSkillChance)
 		return;
 
 	int itm = 0;
@@ -3593,7 +3614,7 @@ int LoLEngine::paralyzePoisonCharacter(int charNum, int typeFlag, int immunityFl
 	if (!(_characters[charNum].flags & 1) || (_characters[charNum].flags & immunityFlags))
 		return 0;
 
-	if ((int)_rnd.getRandomNumberRng(1, 100) > hitChance)
+	if ((int)generateRandomNumber(1, 100) > hitChance)
 		return 0;
 
 	int r = 0;
@@ -3711,7 +3732,7 @@ void LoLEngine::launchMagicViper() {
 	_screen->copyPage(12, 0);
 	_screen->copyPage(12, 2);
 
-	int t = _rnd.getRandomNumberRng(1, 4);
+	int t = generateRandomNumber(1, 4);
 
 	for (int i = 0; i < 4; i++) {
 		if (!(_characters[i].flags & 1)) {
diff --git a/engines/kyra/lol.h b/engines/kyra/lol.h
index 12000c31fa..8fafa450b3 100644
--- a/engines/kyra/lol.h
+++ b/engines/kyra/lol.h
@@ -642,6 +642,7 @@ private:
 	int olol_setWallType(EMCState *script);
 	int olol_getWallType(EMCState *script);
 	int olol_drawScene(EMCState *script);
+	int olol_getRand(EMCState *script);
 	int olol_moveParty(EMCState *script);
 	int olol_delay(EMCState *script);
 	int olol_setGameFlag(EMCState *script);
@@ -1313,6 +1314,7 @@ private:
 
 	// misc
 	void delay(uint32 millis, bool doUpdate = false, bool isMainLoop = false);
+	int generateRandomNumber(int min, int max);
 
 	uint8 _compassBroken;
 	uint8 _drainMagic;
@@ -1320,8 +1322,7 @@ private:
 
 	uint8 *_pageBuffer1;
 	uint8 *_pageBuffer2;
-	uint32 _rndSpecial;
-
+	
 	// spells
 	typedef Common::Functor1Mem<ActiveSpell*, int, LoLEngine> SpellProc;
 	Common::Array<const SpellProc*> _spellProcs;
diff --git a/engines/kyra/scene_lol.cpp b/engines/kyra/scene_lol.cpp
index 945495517f..403b4cc69c 100644
--- a/engines/kyra/scene_lol.cpp
+++ b/engines/kyra/scene_lol.cpp
@@ -552,14 +552,14 @@ void LoLEngine::updateLampStatus() {
 		if (_lampEffect == -1) {
 			if (_screen->_fadeFlag == 0)
 				setPaletteBrightness(_screen->getPalette(0), _brightness, newLampEffect);
-			_lampStatusTimer = _system->getMillis() + (10 + _rnd.getRandomNumberRng(1, 30)) * _tickLength;
+			_lampStatusTimer = _system->getMillis() + (10 + generateRandomNumber(1, 30)) * _tickLength;
 		} else {
 			if ((_lampEffect & 0xfe) == (newLampEffect & 0xfe)) {
 				if (_system->getMillis() <= _lampStatusTimer) {
 					newLampEffect = _lampEffect;
 				} else {
 					newLampEffect = _lampEffect ^ 1;
-					_lampStatusTimer = _system->getMillis() + (10 + _rnd.getRandomNumberRng(1, 30)) * _tickLength;
+					_lampStatusTimer = _system->getMillis() + (10 + generateRandomNumber(1, 30)) * _tickLength;
 				}
 			} else {
 				if (_screen->_fadeFlag == 0)
diff --git a/engines/kyra/script_lol.cpp b/engines/kyra/script_lol.cpp
index a606419722..18b8d81ef9 100644
--- a/engines/kyra/script_lol.cpp
+++ b/engines/kyra/script_lol.cpp
@@ -135,6 +135,11 @@ int LoLEngine::olol_drawScene(EMCState *script) {
 	return 1;
 }
 
+int LoLEngine::olol_getRand(EMCState *script) {
+	debugC(3, kDebugLevelScriptFuncs, "LoLEngine::olol_getRand(%p) (%d, %d)", (const void *)script, stackPos(0), stackPos(1));
+	return generateRandomNumber(stackPos(0), stackPos(1));
+}
+
 int LoLEngine::olol_moveParty(EMCState *script) {
 	debugC(3, kDebugLevelScriptFuncs, "LoLEngine::olol_moveParty(%p) (%d)", (const void *)script, stackPos(0));
 	int mode = stackPos(0);
@@ -831,10 +836,10 @@ int LoLEngine::olol_initMonster(EMCState *script) {
 		l->hitPoints = (l->properties->hitPoints * _monsterModifiers[_monsterDifficulty]) >> 8;
 
 		if (_currentLevel == 12 && l->type == 2)
-			l->hitPoints = (l->hitPoints * (_rnd.getRandomNumberRng(1, 128) + 192)) >> 8;
+			l->hitPoints = (l->hitPoints * (generateRandomNumber(1, 128) + 192)) >> 8;
 
 		l->numDistAttacks = l->properties->numDistAttacks;
-		l->distAttackTick = _rnd.getRandomNumberRng(1, calcMonsterSkillLevel(l->id | 0x8000, 8)) - 1;
+		l->distAttackTick = generateRandomNumber(1, calcMonsterSkillLevel(l->id | 0x8000, 8)) - 1;
 		l->flyingHeight = 2;
 		l->flags = stackPos(5);
 		l->assignedItems = 0;
@@ -1366,18 +1371,18 @@ int LoLEngine::olol_characterSkillTest(EMCState *script){
 	debugC(3, kDebugLevelScriptFuncs, "LoLEngine::olol_characterSkillTest(%p) (%d, %d)", (const void *)script, stackPos(0), stackPos(1));
 	int skill = stackPos(0);
 	int n = countActiveCharacters();
-	uint m = 0;
+	int m = 0;
 	int c = 0;
 
 	for	(int i = 0; i < n ; i++) {
-		uint v = _characters[i].skillModifiers[skill] + _characters[i].skillLevels[skill] + 25;
+		int v = _characters[i].skillModifiers[skill] + _characters[i].skillLevels[skill] + 25;
 		if (v > m) {
 			m = v;
 			c = i;
 		}
 	}
 
-	return (_rnd.getRandomNumberRng(1, 100) > m) ? -1 : c;
+	return (generateRandomNumber(1, 100) > m) ? -1 : c;
 }
 
 int LoLEngine::olol_countAllMonsters(EMCState *script){
@@ -1440,7 +1445,7 @@ int LoLEngine::olol_calcInflictableDamage(EMCState *script) {
 int LoLEngine::olol_getInflictedDamage(EMCState *script) {
 	debugC(3, kDebugLevelScriptFuncs, "LoLEngine::olol_getInflictedDamage(%p) (%d)", (const void *)script, stackPos(0));
 	int mx = stackPos(0);
-	return mx ? _rnd.getRandomNumberRng(2, mx) : 0;
+	return generateRandomNumber(2, mx);
 }
 
 int LoLEngine::olol_checkForCertainPartyMember(EMCState *script) {
@@ -2617,7 +2622,7 @@ void LoLEngine::setupOpcodeTable() {
 	Opcode(olol_setWallType);
 	Opcode(olol_getWallType);
 	Opcode(olol_drawScene);
-	Opcode(o1_getRand);
+	Opcode(olol_getRand);
 
 	// 0x04
 	Opcode(olol_moveParty);
diff --git a/engines/kyra/sprites_lol.cpp b/engines/kyra/sprites_lol.cpp
index 8cee1dc5fc..b1edecb318 100644
--- a/engines/kyra/sprites_lol.cpp
+++ b/engines/kyra/sprites_lol.cpp
@@ -1071,7 +1071,7 @@ void LoLEngine::updateMonster(MonsterInPlay *monster) {
 	monster->speedTick = 0;
 
 	if (monster->properties->flags & 0x40) {
-		monster->hitPoints += _rnd.getRandomNumberRng(1, 8);
+		monster->hitPoints += generateRandomNumber(1, 8);
 		if (monster->hitPoints > monster->properties->hitPoints)
 			monster->hitPoints = monster->properties->hitPoints;
 	}
@@ -1264,7 +1264,7 @@ bool LoLEngine::chasePartyWithDistanceAttacks(MonsterInPlay *monster) {
 	int s = 0;
 
 	if (monster->flags & 0x10) {
-		s = monster->properties->numDistWeapons ? _rnd.getRandomNumberRng(1, monster->properties->numDistWeapons) : 0;
+		s = monster->properties->numDistWeapons ? generateRandomNumber(1, monster->properties->numDistWeapons) : 0;
 	} else {
 		s = monster->curDistWeapon++;
 		if (monster->curDistWeapon >= monster->properties->numDistWeapons)
@@ -1344,7 +1344,7 @@ void LoLEngine::chasePartyWithCloseAttacks(MonsterInPlay *monster) {
 
 				if (hit) {
 					int mx = calcInflictableDamage(m, dst, hit);
-					int dmg = mx ? _rnd.getRandomNumberRng(2, mx) : 0;
+					int dmg = generateRandomNumber(2, mx );
 					inflictDamage(dst, dmg, m, 0, 0);
 					applyMonsterAttackSkill(monster, dst, dmg);
 				}
@@ -1364,7 +1364,7 @@ void LoLEngine::chasePartyWithCloseAttacks(MonsterInPlay *monster) {
 		walkMonster(monster);
 	} else {
 		setMonsterDirection(monster, monster->destDirection);
-		setMonsterMode(monster, (_rnd.getRandomNumberRng(1, 100) <= 50) ? 4 : 3);
+		setMonsterMode(monster, (generateRandomNumber(1, 100) <= 50) ? 4 : 3);
 	}
 }
 
diff --git a/engines/kyra/timer_lol.cpp b/engines/kyra/timer_lol.cpp
index 84c4f8b19d..0a17c0993c 100644
--- a/engines/kyra/timer_lol.cpp
+++ b/engines/kyra/timer_lol.cpp
@@ -147,7 +147,7 @@ void LoLEngine::timerSpecialCharacterUpdate(int timerNum) {
 				break;
 
 			case 3:
-				v = _rnd.getRandomNumberRng(1, 2);
+				v = generateRandomNumber(1, 2);
 				if (inflictDamage(i, v, 0x8000, 0, 0x80)) {
 					_txt->printMessage(2, getLangString(0x4022), _characters[i].name);
 					_characters[i].characterUpdateDelay[ii] = 10;
@@ -241,7 +241,7 @@ void LoLEngine::timerUpdatePortraitAnimations(int skipUpdate) {
 		} else {
 			_characters[i].curFaceFrame = 0;
 			gui_drawCharPortraitWithStats(i);
-			_characters[i].nextAnimUpdateCountdown = (int16) _rnd.getRandomNumberRng(1, 12) + 6;
+			_characters[i].nextAnimUpdateCountdown = (int16) generateRandomNumber(1, 12) + 6;
 		}
 	}
 }