+/* values for change events for custom elements (stored in level file) */
+#define CE_DELAY 0
+#define CE_TOUCHED_BY_PLAYER 1
+#define CE_PRESSED_BY_PLAYER 2
+#define CE_PUSHED_BY_PLAYER 3
+#define CE_DROPPED_BY_PLAYER 4
+#define CE_HITTING_SOMETHING 5
+#define CE_IMPACT 6
+#define CE_SMASHED 7
+#define CE_TOUCHING_X 8
+#define CE_CHANGE_OF_X 9
+#define CE_EXPLOSION_OF_X 10
+#define CE_PLAYER_TOUCHES_X 11
+#define CE_PLAYER_PRESSES_X 12
+#define CE_PLAYER_PUSHES_X 13
+#define CE_PLAYER_COLLECTS_X 14
+#define CE_PLAYER_DROPS_X 15
+#define CE_VALUE_GETS_ZERO 16
+#define CE_VALUE_GETS_ZERO_OF_X 17
+#define CE_BY_OTHER_ACTION 18
+#define CE_BY_DIRECT_ACTION 19
+#define CE_PLAYER_DIGS_X 20
+#define CE_ENTERED_BY_PLAYER 21
+#define CE_LEFT_BY_PLAYER 22
+#define CE_PLAYER_ENTERS_X 23
+#define CE_PLAYER_LEAVES_X 24
+#define CE_SWITCHED 25
+#define CE_SWITCH_OF_X 26
+#define CE_HIT_BY_SOMETHING 27
+#define CE_HITTING_X 28
+#define CE_HIT_BY_X 29
+#define CE_BLOCKED 30
+#define CE_SWITCHED_BY_PLAYER 31
+#define CE_PLAYER_SWITCHES_X 32
+#define CE_SNAPPED_BY_PLAYER 33
+#define CE_PLAYER_SNAPS_X 34
+#define CE_MOVE_OF_X 35
+#define CE_DIGGING_X 36
+#define CE_CREATION_OF_X 37
+#define CE_SCORE_GETS_ZERO 38
+#define CE_SCORE_GETS_ZERO_OF_X 39
+#define CE_VALUE_CHANGES 40
+#define CE_VALUE_CHANGES_OF_X 41
+#define CE_SCORE_CHANGES 42
+#define CE_SCORE_CHANGES_OF_X 43
+
+#define NUM_CHANGE_EVENTS 44
+
+#define NUM_CE_BITFIELDS ((NUM_CHANGE_EVENTS + 31) / 32)
+
+#define CE_BITMASK_DEFAULT 0
+
+#define CH_EVENT_BITFIELD_NR(e) (e / 32)
+#define CH_EVENT_BIT(e) (1 << ((e) % 32))
+
+#define CH_EVENT_VAR(e,c) (element_info[e].change->has_event[c])
+#define CH_ANY_EVENT_VAR(e,c) (element_info[e].has_change_event[c])
+
+#define PAGE_HAS_CHANGE_EVENT(p,c) ((p)->has_event[c])
+#define HAS_CHANGE_EVENT(e,c) (IS_CUSTOM_ELEMENT(e) && \
+ CH_EVENT_VAR(e,c))
+#define HAS_ANY_CHANGE_EVENT(e,c) (IS_CUSTOM_ELEMENT(e) && \
+ CH_ANY_EVENT_VAR(e,c))
+
+#define SET_CHANGE_EVENT(e,c,v) (IS_CUSTOM_ELEMENT(e) ? \
+ CH_EVENT_VAR(e,c) = (v) : 0)
+#define SET_ANY_CHANGE_EVENT(e,c,v) (IS_CUSTOM_ELEMENT(e) ? \
+ CH_ANY_EVENT_VAR(e,c) = (v) : 0)
+
+/* values for player bitmasks */
+#define PLAYER_BITS_NONE 0
+#define PLAYER_BITS_1 (1 << 0)
+#define PLAYER_BITS_2 (1 << 1)
+#define PLAYER_BITS_3 (1 << 2)
+#define PLAYER_BITS_4 (1 << 3)
+#define PLAYER_BITS_ANY (PLAYER_BITS_1 | \
+ PLAYER_BITS_2 | \
+ PLAYER_BITS_3 | \
+ PLAYER_BITS_4)
+#define PLAYER_BITS_TRIGGER (1 << 4)
+#define PLAYER_BITS_ACTION (1 << 5)
+
+/* values for move directions (bits 0 - 3: basic move directions) */
+#define MV_BIT_PREVIOUS 4
+#define MV_BIT_TRIGGER 5
+#define MV_BIT_TRIGGER_BACK 6
+#define MV_BIT_NORMAL MV_BIT_TRIGGER
+#define MV_BIT_REVERSE MV_BIT_TRIGGER_BACK
+
+#define MV_PREVIOUS (1 << MV_BIT_PREVIOUS)
+#define MV_TRIGGER (1 << MV_BIT_TRIGGER)
+#define MV_TRIGGER_BACK (1 << MV_BIT_TRIGGER_BACK)
+#define MV_NORMAL (1 << MV_BIT_NORMAL)
+#define MV_REVERSE (1 << MV_BIT_REVERSE)
+
+/* values for move stepsize */
+#define STEPSIZE_NOT_MOVING 0
+#define STEPSIZE_VERY_SLOW 1
+#define STEPSIZE_SLOW 2
+#define STEPSIZE_NORMAL 4
+#define STEPSIZE_FAST 8
+#define STEPSIZE_VERY_FAST 16
+#define STEPSIZE_EVEN_FASTER 32
+#define STEPSIZE_SLOWER 50 /* (symbolic value only) */
+#define STEPSIZE_FASTER 200 /* (symbolic value only) */
+#define STEPSIZE_RESET 100 /* (symbolic value only) */
+
+/* values for change side for custom elements */
+#define CH_SIDE_NONE MV_NONE
+#define CH_SIDE_LEFT MV_LEFT
+#define CH_SIDE_RIGHT MV_RIGHT
+#define CH_SIDE_TOP MV_UP
+#define CH_SIDE_BOTTOM MV_DOWN
+#define CH_SIDE_LEFT_RIGHT MV_HORIZONTAL
+#define CH_SIDE_TOP_BOTTOM MV_VERTICAL
+#define CH_SIDE_ANY MV_ANY_DIRECTION
+
+/* values for change player for custom elements */
+#define CH_PLAYER_NONE PLAYER_BITS_NONE
+#define CH_PLAYER_1 PLAYER_BITS_1
+#define CH_PLAYER_2 PLAYER_BITS_2
+#define CH_PLAYER_3 PLAYER_BITS_3
+#define CH_PLAYER_4 PLAYER_BITS_4
+#define CH_PLAYER_ANY PLAYER_BITS_ANY
+
+/* values for change page for custom elements */
+#define CH_PAGE_ANY_FILE (0xff)
+#define CH_PAGE_ANY (0xffffffff)
+
+/* values for change power for custom elements */
+#define CP_WHEN_EMPTY 0
+#define CP_WHEN_DIGGABLE 1
+#define CP_WHEN_DESTRUCTIBLE 2
+#define CP_WHEN_COLLECTIBLE 3
+#define CP_WHEN_REMOVABLE 4
+#define CP_WHEN_WALKABLE 5
+
+/* values for change actions for custom elements (stored in level file) */
+#define CA_NO_ACTION 0
+#define CA_EXIT_PLAYER 1
+#define CA_KILL_PLAYER 2
+#define CA_MOVE_PLAYER 3
+#define CA_RESTART_LEVEL 4
+#define CA_SHOW_ENVELOPE 5
+#define CA_SET_LEVEL_TIME 6
+#define CA_SET_LEVEL_GEMS 7
+#define CA_SET_LEVEL_SCORE 8
+#define CA_SET_LEVEL_WIND 9
+#define CA_SET_PLAYER_GRAVITY 10
+#define CA_SET_PLAYER_KEYS 11
+#define CA_SET_PLAYER_SPEED 12
+#define CA_SET_PLAYER_SHIELD 13
+#define CA_SET_PLAYER_ARTWORK 14
+#define CA_SET_CE_SCORE 15
+#define CA_SET_CE_VALUE 16
+#define CA_SET_ENGINE_SCAN_MODE 17
+#define CA_SET_PLAYER_INVENTORY 18
+#define CA_SET_CE_ARTWORK 19
+#define CA_SET_LEVEL_RANDOM_SEED 20
+
+#define CA_HEADLINE_LEVEL_ACTIONS 250
+#define CA_HEADLINE_PLAYER_ACTIONS 251
+#define CA_HEADLINE_CE_ACTIONS 252
+#define CA_HEADLINE_ENGINE_ACTIONS 253
+#define CA_UNDEFINED 255
+
+/* values for change action mode for custom elements */
+#define CA_MODE_UNDEFINED 0
+#define CA_MODE_SET 1
+#define CA_MODE_ADD 2
+#define CA_MODE_SUBTRACT 3
+#define CA_MODE_MULTIPLY 4
+#define CA_MODE_DIVIDE 5
+#define CA_MODE_MODULO 6
+
+/* values for change action parameters for custom elements */
+#define CA_ARG_MIN 0
+#define CA_ARG_0 0
+#define CA_ARG_1 1
+#define CA_ARG_2 2
+#define CA_ARG_3 3
+#define CA_ARG_4 4
+#define CA_ARG_5 5
+#define CA_ARG_6 6
+#define CA_ARG_7 7
+#define CA_ARG_8 8
+#define CA_ARG_9 9
+#define CA_ARG_10 10
+#define CA_ARG_100 100
+#define CA_ARG_1000 1000
+#define CA_ARG_MAX 9999
+#define CA_ARG_PLAYER 10000
+#define CA_ARG_PLAYER_1 (CA_ARG_PLAYER + PLAYER_BITS_1)
+#define CA_ARG_PLAYER_2 (CA_ARG_PLAYER + PLAYER_BITS_2)
+#define CA_ARG_PLAYER_3 (CA_ARG_PLAYER + PLAYER_BITS_3)
+#define CA_ARG_PLAYER_4 (CA_ARG_PLAYER + PLAYER_BITS_4)
+#define CA_ARG_PLAYER_ANY (CA_ARG_PLAYER + PLAYER_BITS_ANY)
+#define CA_ARG_PLAYER_TRIGGER (CA_ARG_PLAYER + PLAYER_BITS_TRIGGER)
+#define CA_ARG_PLAYER_ACTION (CA_ARG_PLAYER + PLAYER_BITS_ACTION)
+#define CA_ARG_PLAYER_HEADLINE (CA_ARG_PLAYER + 999)
+#define CA_ARG_NUMBER 11000
+#define CA_ARG_NUMBER_MIN (CA_ARG_NUMBER + 0)
+#define CA_ARG_NUMBER_MAX (CA_ARG_NUMBER + 1)
+#define CA_ARG_NUMBER_RESET (CA_ARG_NUMBER + 2)
+#define CA_ARG_NUMBER_CE_SCORE (CA_ARG_NUMBER + 3)
+#define CA_ARG_NUMBER_CE_VALUE (CA_ARG_NUMBER + 4)
+#define CA_ARG_NUMBER_CE_DELAY (CA_ARG_NUMBER + 5)
+#define CA_ARG_NUMBER_LEVEL_TIME (CA_ARG_NUMBER + 6)
+#define CA_ARG_NUMBER_LEVEL_GEMS (CA_ARG_NUMBER + 7)
+#define CA_ARG_NUMBER_LEVEL_SCORE (CA_ARG_NUMBER + 8)
+#define CA_ARG_NUMBER_HEADLINE (CA_ARG_NUMBER + 999)
+#define CA_ARG_ELEMENT 12000
+#define CA_ARG_ELEMENT_RESET (CA_ARG_ELEMENT + 0)
+#define CA_ARG_ELEMENT_TARGET (CA_ARG_ELEMENT + 1)
+#define CA_ARG_ELEMENT_TRIGGER (CA_ARG_ELEMENT + 2)
+#define CA_ARG_ELEMENT_ACTION (CA_ARG_ELEMENT + 7)
+#define CA_ARG_ELEMENT_HEADLINE (CA_ARG_ELEMENT + 997)
+#define CA_ARG_ELEMENT_CV_TARGET (CA_ARG_ELEMENT_TARGET)
+#define CA_ARG_ELEMENT_CV_TRIGGER (CA_ARG_ELEMENT_TRIGGER)
+#define CA_ARG_ELEMENT_CV_ACTION (CA_ARG_ELEMENT_ACTION)
+#define CA_ARG_ELEMENT_CV_HEADLINE (CA_ARG_ELEMENT_HEADLINE)
+#define CA_ARG_ELEMENT_NR_TARGET (CA_ARG_ELEMENT + 3)
+#define CA_ARG_ELEMENT_NR_TRIGGER (CA_ARG_ELEMENT + 4)
+#define CA_ARG_ELEMENT_NR_ACTION (CA_ARG_ELEMENT + 8)
+#define CA_ARG_ELEMENT_NR_HEADLINE (CA_ARG_ELEMENT + 998)
+#define CA_ARG_ELEMENT_CS_TARGET (CA_ARG_ELEMENT + 5)
+#define CA_ARG_ELEMENT_CS_TRIGGER (CA_ARG_ELEMENT + 6)
+#define CA_ARG_ELEMENT_CS_ACTION (CA_ARG_ELEMENT + 9)
+#define CA_ARG_ELEMENT_CS_HEADLINE (CA_ARG_ELEMENT + 999)
+#define CA_ARG_SPEED 13000
+#define CA_ARG_SPEED_NOT_MOVING (CA_ARG_SPEED + STEPSIZE_NOT_MOVING)
+#define CA_ARG_SPEED_VERY_SLOW (CA_ARG_SPEED + STEPSIZE_VERY_SLOW)
+#define CA_ARG_SPEED_SLOW (CA_ARG_SPEED + STEPSIZE_SLOW)
+#define CA_ARG_SPEED_NORMAL (CA_ARG_SPEED + STEPSIZE_NORMAL)
+#define CA_ARG_SPEED_FAST (CA_ARG_SPEED + STEPSIZE_FAST)
+#define CA_ARG_SPEED_VERY_FAST (CA_ARG_SPEED + STEPSIZE_VERY_FAST)
+#define CA_ARG_SPEED_EVEN_FASTER (CA_ARG_SPEED + STEPSIZE_EVEN_FASTER)
+#define CA_ARG_SPEED_SLOWER (CA_ARG_SPEED + STEPSIZE_SLOWER)
+#define CA_ARG_SPEED_FASTER (CA_ARG_SPEED + STEPSIZE_FASTER)
+#define CA_ARG_SPEED_RESET (CA_ARG_SPEED + STEPSIZE_RESET)
+#define CA_ARG_SPEED_HEADLINE (CA_ARG_SPEED + 999)
+#define CA_ARG_GRAVITY 14000
+#define CA_ARG_GRAVITY_OFF (CA_ARG_GRAVITY + 0)
+#define CA_ARG_GRAVITY_ON (CA_ARG_GRAVITY + 1)
+#define CA_ARG_GRAVITY_TOGGLE (CA_ARG_GRAVITY + 2)
+#define CA_ARG_GRAVITY_HEADLINE (CA_ARG_GRAVITY + 999)
+#define CA_ARG_DIRECTION 15000
+#define CA_ARG_DIRECTION_NONE (CA_ARG_DIRECTION + MV_NONE)
+#define CA_ARG_DIRECTION_LEFT (CA_ARG_DIRECTION + MV_LEFT)
+#define CA_ARG_DIRECTION_RIGHT (CA_ARG_DIRECTION + MV_RIGHT)
+#define CA_ARG_DIRECTION_UP (CA_ARG_DIRECTION + MV_UP)
+#define CA_ARG_DIRECTION_DOWN (CA_ARG_DIRECTION + MV_DOWN)
+#define CA_ARG_DIRECTION_TRIGGER (CA_ARG_DIRECTION + MV_TRIGGER)
+#define CA_ARG_DIRECTION_TRIGGER_BACK (CA_ARG_DIRECTION + MV_TRIGGER_BACK)
+#define CA_ARG_DIRECTION_HEADLINE (CA_ARG_DIRECTION + 999)
+#define CA_ARG_SHIELD 16000
+#define CA_ARG_SHIELD_OFF (CA_ARG_SHIELD + 0)
+#define CA_ARG_SHIELD_NORMAL (CA_ARG_SHIELD + 1)
+#define CA_ARG_SHIELD_DEADLY (CA_ARG_SHIELD + 2)
+#define CA_ARG_SHIELD_HEADLINE (CA_ARG_SHIELD + 999)
+#define CA_ARG_SCAN_MODE 17000
+#define CA_ARG_SCAN_MODE_NORMAL (CA_ARG_SCAN_MODE + MV_NORMAL)
+#define CA_ARG_SCAN_MODE_REVERSE (CA_ARG_SCAN_MODE + MV_REVERSE)
+#define CA_ARG_SCAN_MODE_HEADLINE (CA_ARG_SCAN_MODE + 999)
+#define CA_ARG_INVENTORY 18000
+#define CA_ARG_INVENTORY_RESET (CA_ARG_INVENTORY + 0)
+#define CA_ARG_INVENTORY_RM_TARGET (CA_ARG_INVENTORY + 1)
+#define CA_ARG_INVENTORY_RM_TRIGGER (CA_ARG_INVENTORY + 2)
+#define CA_ARG_INVENTORY_RM_ACTION (CA_ARG_INVENTORY + 3)
+#define CA_ARG_INVENTORY_RM_FIRST (CA_ARG_INVENTORY + 4)
+#define CA_ARG_INVENTORY_RM_LAST (CA_ARG_INVENTORY + 5)
+#define CA_ARG_INVENTORY_RM_ALL (CA_ARG_INVENTORY + 6)
+#define CA_ARG_INVENTORY_HEADLINE (CA_ARG_INVENTORY + 998)
+#define CA_ARG_INVENTORY_RM_HEADLINE (CA_ARG_INVENTORY + 999)
+#define CA_ARG_UNDEFINED 65535
+
+/* values for custom move patterns (bits 0 - 3: basic move directions) */
+#define MV_BIT_TOWARDS_PLAYER 4
+#define MV_BIT_AWAY_FROM_PLAYER 5
+#define MV_BIT_ALONG_LEFT_SIDE 6
+#define MV_BIT_ALONG_RIGHT_SIDE 7
+#define MV_BIT_TURNING_LEFT 8
+#define MV_BIT_TURNING_RIGHT 9
+#define MV_BIT_WHEN_PUSHED 10
+#define MV_BIT_MAZE_RUNNER 11
+#define MV_BIT_MAZE_HUNTER 12
+#define MV_BIT_WHEN_DROPPED 13
+#define MV_BIT_TURNING_LEFT_RIGHT 14
+#define MV_BIT_TURNING_RIGHT_LEFT 15
+#define MV_BIT_TURNING_RANDOM 16
+#define MV_BIT_WIND_DIRECTION 17
+
+/* values for custom move patterns */
+#define MV_TOWARDS_PLAYER (1 << MV_BIT_TOWARDS_PLAYER)
+#define MV_AWAY_FROM_PLAYER (1 << MV_BIT_AWAY_FROM_PLAYER)
+#define MV_ALONG_LEFT_SIDE (1 << MV_BIT_ALONG_LEFT_SIDE)
+#define MV_ALONG_RIGHT_SIDE (1 << MV_BIT_ALONG_RIGHT_SIDE)
+#define MV_TURNING_LEFT (1 << MV_BIT_TURNING_LEFT)
+#define MV_TURNING_RIGHT (1 << MV_BIT_TURNING_RIGHT)
+#define MV_WHEN_PUSHED (1 << MV_BIT_WHEN_PUSHED)
+#define MV_MAZE_RUNNER (1 << MV_BIT_MAZE_RUNNER)
+#define MV_MAZE_HUNTER (1 << MV_BIT_MAZE_HUNTER)
+#define MV_MAZE_RUNNER_STYLE (MV_MAZE_RUNNER | MV_MAZE_HUNTER)
+#define MV_WHEN_DROPPED (1 << MV_BIT_WHEN_DROPPED)
+#define MV_TURNING_LEFT_RIGHT (1 << MV_BIT_TURNING_LEFT_RIGHT)
+#define MV_TURNING_RIGHT_LEFT (1 << MV_BIT_TURNING_RIGHT_LEFT)
+#define MV_TURNING_RANDOM (1 << MV_BIT_TURNING_RANDOM)
+#define MV_WIND_DIRECTION (1 << MV_BIT_WIND_DIRECTION)
+
+/* values for initial move direction */
+#define MV_START_NONE (MV_NONE)
+#define MV_START_AUTOMATIC (MV_NONE)
+#define MV_START_LEFT (MV_LEFT)
+#define MV_START_RIGHT (MV_RIGHT)
+#define MV_START_UP (MV_UP)
+#define MV_START_DOWN (MV_DOWN)
+#define MV_START_RANDOM (MV_ALL_DIRECTIONS)
+#define MV_START_PREVIOUS (MV_PREVIOUS)
+
+/* values for elements left behind by custom elements */
+#define LEAVE_TYPE_UNLIMITED 0
+#define LEAVE_TYPE_LIMITED 1
+
+/* values for slippery property for custom elements */
+#define SLIPPERY_ANY_RANDOM 0
+#define SLIPPERY_ANY_LEFT_RIGHT 1
+#define SLIPPERY_ANY_RIGHT_LEFT 2
+#define SLIPPERY_ONLY_LEFT 3
+#define SLIPPERY_ONLY_RIGHT 4
+
+/* values for explosion type for custom elements */
+#define EXPLODES_3X3 0
+#define EXPLODES_1X1 1
+#define EXPLODES_CROSS 2
+
+/* macros for configurable properties */
+#define IS_DIGGABLE(e) HAS_PROPERTY(e, EP_DIGGABLE)
+#define IS_COLLECTIBLE_ONLY(e) HAS_PROPERTY(e, EP_COLLECTIBLE_ONLY)
+#define DONT_RUN_INTO(e) HAS_PROPERTY(e, EP_DONT_RUN_INTO)
+#define DONT_COLLIDE_WITH(e) HAS_PROPERTY(e, EP_DONT_COLLIDE_WITH)
+#define DONT_TOUCH(e) HAS_PROPERTY(e, EP_DONT_TOUCH)