Fix monster damage potentially being off by 63/64th

Monster damage values from melee/missile hits could potentially add or subtract up to 63/64ths of damage over and above a monster's usual damage range

Co-authored-by: Stephen C. Wills <staphen@gmail.com>

Source/missiles.cpp

@@ -1177,7 +1177,7 @@ bool PlayerMHit(int pnum, Monster *monster, int dist, int mind, int maxd, missil
 		dam = player._pHitPoints / 3;
 	} else {
 		if (!shift) {
-			dam = (mind << 6) + GenerateRnd((maxd - mind + 1) << 6);
+			dam = (mind << 6) + GenerateRnd(((maxd - mind) << 6) + 1);
 			if (monster == nullptr)
 				if ((player._pIFlags & ISPL_ABSHALFTRAP) != 0)
 					dam /= 2;

Source/monster.cpp

@@ -1484,7 +1484,7 @@ void MonsterAttackPlayer(int i, int pnum, int hit, int minDam, int maxDam)
 		Direction dir = GetDirection(player.position.tile, monster.position.tile);
 		StartPlrBlock(pnum, dir);
 		if (pnum == MyPlayerId && player.wReflections > 0) {
-			int dam = GenerateRnd((maxDam - minDam + 1) << 6) + (minDam << 6);
+			int dam = GenerateRnd(((maxDam - minDam) << 6) + 1) + (minDam << 6);
 			dam = std::max(dam + (player._pIGetHit << 6), 64);
 			CheckReflect(i, pnum, dam);
 		}
@@ -1504,7 +1504,7 @@ void MonsterAttackPlayer(int i, int pnum, int hit, int minDam, int maxDam)
 			}
 		}
 	}
-	int dam = (minDam << 6) + GenerateRnd((maxDam - minDam + 1) << 6);
+	int dam = (minDam << 6) + GenerateRnd(((maxDam - minDam) << 6) + 1);
 	dam = std::max(dam + (player._pIGetHit << 6), 64);
 	if (pnum == MyPlayerId) {
 		if (player.wReflections > 0)