Replaced various "limit" functions with LIMIT and LIMIT_ADD macros.

This is mainly because the old "limit" functions were all restricted
to certain types, which is incredibly silly given how simple they are.
Macros are much simpler, and a warning gets raised if they're used
improperly with multiple types, anyway.

In the process, I also found and fixed a bug: it seems the original
author intended for escaping enemies to gradually accelerate to
fleeing speed, but the low value was indicated as the max value, and
the way limitFloat was written, that caused the max value to be used
(it was supposed to reduce the speed to a minimum of -15, but it
instead effectively assigned the speed to -15). It might be a good
idea to re-implement the old buggy behavior intentionally; depends
on whether the acceleration of jumping looks better or worse than
just immediately going to jump speed.

src/alien.cpp

@@ -813,7 +813,7 @@ bool alien_add()
 	aliens[index].deathCounter = 0 - (aliens[index].maxShield * 3);
 	aliens[index].hit = 0;
 
-	limitInt(&aliens[index].deathCounter, -250, 0);
+	LIMIT(aliens[index].deathCounter, -250, 0);
 
 	// Attempts to place an alien. If it fails, the alien is deactivated.
 	for (int i = 0 ; i < 100 ; i++)

src/bullet.cpp

@@ -200,7 +200,7 @@ char checkPlayerShockDamage(float x, float y)
 
 		player.shield -= (int)(10 - distX);
 		player.shield -= (int)(10 - distY);
-		limitInt(&player.shield, 0, player.maxShield);
+		LIMIT(player.shield, 0, player.maxShield);
 		player.hit = 10;
 
 		return 1;
@@ -278,18 +278,18 @@ void doBullets()
 			if (bullet->target != NULL)
 			{
 				if (bullet->x < bullet->target->x)
-					limitFloat(&(bullet->dx += homingMissileSpeed), -15, 15);
+					LIMIT_ADD(bullet->dx, homingMissileSpeed, -15, 15);
-				if (bullet->x > bullet->target->x)
+				else if (bullet->x > bullet->target->x)
-					limitFloat(&(bullet->dx -= homingMissileSpeed), -15, 15);
+					LIMIT_ADD(bullet->dx, -homingMissileSpeed, -15, 15);
 
 				//Rocket is (more or less) inline with target. Fly straight
 				if ((bullet->x > bullet->target->x - 1) && (bullet->x < bullet->target->x + 5))
 					bullet->dx = 0;
 
 				if (bullet->y < bullet->target->y)
-					limitFloat(&(bullet->dy += homingMissileSpeed), -15, 15);
+					LIMIT_ADD(bullet->dy, homingMissileSpeed, -15, 15);
-				if (bullet->y > bullet->target->y)
+				else if (bullet->y > bullet->target->y)
-					limitFloat(&(bullet->dy -= homingMissileSpeed), -15, 15);
+					LIMIT_ADD(bullet->dy, -homingMissileSpeed, -15, 15);
 
 				//Rocket is (more or less) inline with target. Fly straight
 				if ((bullet->y > bullet->target->y - 1) && (bullet->y < bullet->target->y + 5))
@@ -388,7 +388,7 @@ void doBullets()
 							setInfoLine("!!! WARNING: SHIELD LOW !!!", FONT_RED);
 
 						player.shield -= bullet->damage;
-						limitInt(&player.shield, 0, player.maxShield);
+						LIMIT(player.shield, 0, player.maxShield);
 						player.hit = 5;
 					}
 

src/cargo.cpp

@@ -101,8 +101,8 @@ void doCargo()
 			cargo[i].x += engine.ssx + engine.smx;
 			cargo[i].y += engine.ssy + engine.smy;
 
-			limitFloat(&cargo[i].x, cargo[i].owner->x - 50, cargo[i].owner->x + 50);
+			LIMIT(cargo[i].x, cargo[i].owner->x - 50, cargo[i].owner->x + 50);
-			limitFloat(&cargo[i].y, cargo[i].owner->y - 50, cargo[i].owner->y + 50);
+			LIMIT(cargo[i].y, cargo[i].owner->y - 50, cargo[i].owner->y + 50);
 
 			dx = (cargo[i].x - cargo[i].owner->x) / 10;
 			dy = (cargo[i].y - cargo[i].owner->y) / 10;

src/collectable.cpp

@@ -329,7 +329,7 @@ void doCollectables()
 						break;
 
 					case P_ROCKET:
-						limitCharAdd(&player.ammo[1], collectable->value, 0,
+						LIMIT_ADD(player.ammo[1], collectable->value, 0,
 							currentGame.maxRocketAmmo);
 						if (player.ammo[1] == currentGame.maxRocketAmmo)
 							sprintf(temp, "Rocket Ammo at Maximum");
@@ -344,7 +344,7 @@ void doCollectables()
 						break;
 
 					case P_SHIELD:
-						limitInt(&(player.shield += 10), 0, player.maxShield);
+						LIMIT_ADD(player.shield, 10, 0, player.maxShield);
 						currentGame.shieldPickups ++;
 						sprintf(temp, "Restored 10 shield points");
 						break;
@@ -405,7 +405,8 @@ void doCollectables()
 							sprintf(temp, "Plasma cells already at Maximum");
 						else
 						{
-							limitCharAdd(&player.ammo[0], collectable->value, 0, currentGame.maxPlasmaAmmo);
+							LIMIT_ADD(player.ammo[0], collectable->value,
+								0, currentGame.maxPlasmaAmmo);
 							if (collectable->value > 1)
 							{
 								sprintf(temp, "Got %d plasma cells", collectable->value);

src/debris.cpp

@@ -29,7 +29,7 @@ void addDebris(int x, int y, int amount)
 	object *debris;
 	
 	amount = rrand(3, rand() % amount);
-	limitInt(&amount, 3, 8);
+	LIMIT(amount, 3, 8);
 
 	for (int i = 0 ; i < amount ; i++)
 	{

src/defs.h

@@ -22,6 +22,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define LIMIT(x, a, b) x = ((x) < (b) ? ((x) > (a) ? (x) : (a)) : (b))
+#define LIMIT_ADD(x, y, a, b) x = (((x) + (y)) < (b) ? \
+	(((x) + (y)) > (a) ? \
+		((x) + (y)) : (a)) : (b))
 
 // ALL
 #define NONE 0

src/game.cpp

@@ -395,7 +395,7 @@ int mainGameLoop()
 	{
 		aliens[i].systemPower = aliens[i].maxShield;
 		aliens[i].deathCounter = 0 - (aliens[i].maxShield * 3);
-		limitInt(&aliens[i].deathCounter, -350, 0);
+		LIMIT(aliens[i].deathCounter, -350, 0);
 	}
 
 	// Set target energy meter
@@ -536,7 +536,7 @@ int mainGameLoop()
 					}
 					else if ((currentGame.area == 26) && (engine.musicVolume > 0))
 					{
-						limitFloat(&(engine.musicVolume -= 0.2), 0, 100);
+						LIMIT_ADD(engine.musicVolume, -0.2, 0, 100);
 						audio_setMusicVolume((int)engine.musicVolume);
 					}
 					else
@@ -551,7 +551,7 @@ int mainGameLoop()
 			}
 			else
 			{
-				limitFloat(&(engine.musicVolume -= 0.2), 0, 100);
+				LIMIT_ADD(engine.musicVolume, -0.2, 0, 100);
 				audio_setMusicVolume((int)engine.musicVolume);
 				if (SDL_GetTicks() >= engine.missionCompleteTimer)
 				{
@@ -615,7 +615,7 @@ int mainGameLoop()
 
 					canFire = true; // The alien is allowed to fire
 
-					limitInt(&--alien->thinktime, 0, 250);
+					LIMIT_ADD(alien->thinktime, -1, 0, 250);
 
 					if (alien->target->shield < 1)
 						alien->target = alien;
@@ -659,8 +659,8 @@ int mainGameLoop()
 							alien->face = (alien->dx > 0);
 						}
 
-						limitFloat(&alien->dx, 0 - alien->speed, alien->speed);
+						LIMIT(alien->dx, -alien->speed, alien->speed);
-						limitFloat(&alien->dy, 0 - alien->speed, alien->speed);
+						LIMIT(alien->dy, -alien->speed, alien->speed);
 
 					}
 
@@ -678,7 +678,11 @@ int mainGameLoop()
 
 					if (alien->flags & FL_LEAVESECTOR)
 					{
-						limitFloat(&(alien->dx -= 0.5), 0, -15);
+						// Note: The original version of this line incorrectly
+						// specified -15 as the *maximum* instead of the
+						// *minimum*, which at the time was equivalent to
+						// ``alien->dx = -15``.
+						LIMIT_ADD(alien->dx, -0.5, -15, 0);
 						alien->dy = 0;
 						alien->thinktime = 999;
 						alien->face = 0;
@@ -728,12 +732,12 @@ int mainGameLoop()
 
 					if (alien->classDef == CD_MOBILESHIELD)
 					{
-						limitInt(&(++aliens[ALIEN_BOSS].shield), 0,
+						LIMIT_ADD(aliens[ALIEN_BOSS].shield, 1, 0,
 							aliens[ALIEN_BOSS].maxShield);
 					}
 
-					limitCharAdd(&alien->reload[0], -1, 0, 999);
+					LIMIT_ADD(alien->reload[0], -1, 0, 999);
-					limitCharAdd(&alien->reload[1], -1, 0, 999);
+					LIMIT_ADD(alien->reload[1], -1, 0, 999);
 
 					if ((!(alien->flags & FL_DISABLED)) &&
 						(!(alien->flags & FL_NOFIRE)))
@@ -788,7 +792,7 @@ int mainGameLoop()
 					}
 					else
 					{
-						limitCharAdd(&alien->ammo[0], 1, 0, 250);
+						LIMIT_ADD(alien->ammo[0], 1, 0, 250);
 					}
 
 					if (alien->flags & FL_FIRELASER)
@@ -818,7 +822,7 @@ int mainGameLoop()
 					if (alien->hit)
 						shapeToUse += SHIP_HIT_INDEX;
 
-					limitCharAdd(&alien->hit, -1, 0, 100);
+					LIMIT_ADD(alien->hit, -1, 0, 100);
 
 					if ((alien->x + alien->image[0]->w > 0) &&
 						(alien->x < screen->w) &&

src/intermission.cpp

@@ -33,8 +33,8 @@ static void doCursor()
 {
 	getPlayerInput();
 
-	limitInt(&engine.cursor_x, 10, screen->w - 10 - shape[0]->w);
+	LIMIT(engine.cursor_x, 10, screen->w - 10 - shape[0]->w);
-	limitInt(&engine.cursor_y, 10, screen->h - 10 - shape[0]->h);
+	LIMIT(engine.cursor_y, 10, screen->h - 10 - shape[0]->h);
 	blit(shape[0], engine.cursor_x, engine.cursor_y);
 }
 

src/math.h

@@ -20,58 +20,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #ifndef MATH_H
 #define MATH_H
 
-static inline void limitChar(signed char *in, int low, int high)
-{
-	if (*in < low)
-		*in = low;
-	if (*in > high)
-		*in = high;
-}
-
-static inline void limitChar(unsigned char *in, int low, int high)
-{
-	if (*in < low)
-		*in = low;
-	if (*in > high)
-		*in = high;
-}
-
-static inline void limitCharAdd(signed char *in, int add, int low, int high)
-{
-	int tmp = (int)*in + add;
-	if (tmp < low)
-		tmp = low;
-	if (tmp > high)
-		tmp = high;
-	*in = tmp;
-}
-
-static inline void limitCharAdd(unsigned char *in, int add, int low, int high)
-{
-	int tmp = (int)*in + add;
-	if (tmp < low)
-		tmp = low;
-	if (tmp > high)
-		tmp = high;
-	*in = tmp;
-}
-
-static inline void limitInt(int *in, int low, int high)
-{
-	if (*in < low)
-		*in = low;
-	if (*in > high)
-		*in = high;
-}
-
-static inline void limitFloat(float *in, float low, float high)
-{
-	if (*in < low)
-		*in = low;
-	if (*in > high)
-		*in = high;
-}
-
 static inline void wrapChar(signed char *in, signed char low, signed char high)
 {
 	if (*in < low)

src/misc.cpp

@@ -389,7 +389,7 @@ void doInfo()
 		return;
 
 	if ((!engine.keyState[KEY_ALTFIRE]) && (player.weaponType[1] == W_LASER) && (engine.eventTimer % 8 == 1))
-		limitCharAdd(&player.ammo[1], -1, 1, 255);
+		LIMIT_ADD(player.ammo[1], -1, 1, 255);
 
 	if ((engine.eventTimer < 30) && (player.shield <= engine.lowShield))
 		return;

src/player.cpp

@@ -133,7 +133,7 @@ void doPlayer()
 				{
 					if (!charger_fired)
 					{
-						limitCharAdd(&player.ammo[1], 1, 0, 150);
+						LIMIT_ADD(player.ammo[1], 1, 0, 150);
 						if (player.ammo[1] >= 150)
 						{
 							ship_fireBullet(&player, 1);
@@ -171,8 +171,8 @@ void doPlayer()
 				engine.keyState[KEY_SWITCH] = 0;
 			}
 
-			limitCharAdd(&player.reload[0], -1, 0, 999);
+			LIMIT_ADD(player.reload[0], -1, 0, 999);
-			limitCharAdd(&player.reload[1], -1, 0, 999);
+			LIMIT_ADD(player.reload[1], -1, 0, 999);
 
 			if (engine.keyState[KEY_UP])
 			{
@@ -299,7 +299,7 @@ void doPlayer()
 			if (player.hit)
 				shapeToUse += SHIP_HIT_INDEX;
 
-			limitCharAdd(&player.hit, -1, 0, 100);
+			LIMIT_ADD(player.hit, -1, 0, 100);
 
 			blit(shipShape[shapeToUse], (int)player.x, (int)player.y);
 			if ((player.maxShield > 1) && (player.shield <= engine.lowShield) &&
@@ -334,8 +334,8 @@ void doPlayer()
 		}
 	}
 
-	limitFloat(&engine.ssx, -cameraMaxSpeed, cameraMaxSpeed);
+	LIMIT(engine.ssx, -cameraMaxSpeed, cameraMaxSpeed);
-	limitFloat(&engine.ssy, -cameraMaxSpeed, cameraMaxSpeed);
+	LIMIT(engine.ssy, -cameraMaxSpeed, cameraMaxSpeed);
 
 	// Specific for the mission were you have to chase the Executive Transport
 	if ((currentGame.area == 18) && (aliens[ALIEN_BOSS].shield > 0) &&

src/shop.cpp

@@ -549,7 +549,7 @@ static void buy(int i)
 				shopSelectedItem = -4;
 				return;
 			}
-			limitCharAdd(&player.ammo[0], 10, 0, currentGame.maxPlasmaAmmo);
+			LIMIT_ADD(player.ammo[0], 10, 0, currentGame.maxPlasmaAmmo);
 			break;
 
 		case SHOP_ROCKET_AMMO:
@@ -668,7 +668,7 @@ static void buy(int i)
 			}
 			shop_sellSecondaryWeapon();
 			player.weaponType[1] = W_DOUBLE_ROCKETS;
-			limitChar(&currentGame.maxRocketAmmo, 5, 50);
+			LIMIT(currentGame.maxRocketAmmo, 5, 50);
 			shopSelectedItem = -1;
 			break;
 
@@ -680,7 +680,7 @@ static void buy(int i)
 			}
 			shop_sellSecondaryWeapon();
 			player.weaponType[1] = W_MICRO_ROCKETS;
-			limitChar(&currentGame.maxRocketAmmo, 5, 50);
+			LIMIT(currentGame.maxRocketAmmo, 5, 50);
 			shopSelectedItem = -1;
 			break;
 
@@ -713,7 +713,7 @@ static void buy(int i)
 			while (currentGame.maxRocketAmmo > maxHoming)
 				sell(SHOP_ROCKET_MAX_AMMO);
 
-			limitChar(&currentGame.maxRocketAmmo, 5, maxHoming);
+			LIMIT(currentGame.maxRocketAmmo, 5, maxHoming);
 			shopSelectedItem = -1;
 			break;
 
@@ -746,7 +746,7 @@ static void buy(int i)
 			while (currentGame.maxRocketAmmo > maxDoubleHoming)
 				sell(SHOP_ROCKET_MAX_AMMO);
 
-			limitChar(&currentGame.maxRocketAmmo, 5, maxDoubleHoming);
+			LIMIT(currentGame.maxRocketAmmo, 5, maxDoubleHoming);
 			shopSelectedItem = -1;
 			break;
 
@@ -762,7 +762,7 @@ static void buy(int i)
 			while (currentGame.maxRocketAmmo > maxMicroHoming)
 				sell(SHOP_ROCKET_MAX_AMMO);
 
-			limitChar(&currentGame.maxRocketAmmo, 5, maxMicroHoming);
+			LIMIT(currentGame.maxRocketAmmo, 5, maxMicroHoming);
 			shopSelectedItem = -1;
 			break;
 	}