Cache canister updates and make huge scrubbers use power; add movable version

code/modules/atmospherics/machinery/components/unary_devices/thermomachine.dm

@@ -6,6 +6,7 @@
 	var/icon_state_open = "cold_off"
 	density = TRUE
 	anchored = TRUE
+	idle_power_usage = 25
 
 	var/on = FALSE
 	var/min_temperature = 0

code/modules/atmospherics/machinery/portable/canister.dm

@@ -21,7 +21,7 @@
 	pressure_resistance = 7 * ONE_ATMOSPHERE
 	var/temperature_resistance = 1000 + T0C
 
-	var/update_flag = 0
+	var/update = 0
 	var/static/list/label2types = list(
 		"n2" = /obj/machinery/portable_atmospherics/canister/nitrogen,
 		"o2" = /obj/machinery/portable_atmospherics/canister/oxygen,
@@ -90,26 +90,57 @@
 	air_contents.gases["o2"][MOLES] = (O2STANDARD * maximum_pressure * filled) * air_contents.volume / (R_IDEAL_GAS_EQUATION * air_contents.temperature)
 	air_contents.gases["n2"][MOLES] = (N2STANDARD * maximum_pressure * filled) * air_contents.volume / (R_IDEAL_GAS_EQUATION * air_contents.temperature)
 
+#define HOLDING 1
+#define CONNECTED 2
+#define EMPTY 4
+#define LOW 8
+#define FULL 16
+#define DANGER 32
 /obj/machinery/portable_atmospherics/canister/update_icon()
 	if(destroyed)
-		overlays = 0
+		overlays.Cut()
 		icon_state = "[initial(icon_state)]-1"
 		return
 
-	overlays.Cut()
+	var/last_update = update
+	update = 0
+
 	if(holding)
-		overlays += "can-open"
+		update |= HOLDING
 	if(connected_port)
-		overlays += "can-connector"
+		update |= CONNECTED
 	var/pressure = air_contents.return_pressure()
 	if(pressure < 10)
-		overlays += "can-o0"
+		update |= EMPTY
 	else if(pressure < ONE_ATMOSPHERE)
-		overlays += "can-o1"
+		update |= LOW
 	else if(pressure < 15 * ONE_ATMOSPHERE)
-		overlays += "can-o2"
+		update |= FULL
 	else
+		update |= DANGER
+
+	if(update == last_update)
+		return
+
+	overlays.Cut()
+	if(update & HOLDING)
+		overlays += "can-open"
+	if(update & CONNECTED)
+		overlays += "can-connector"
+	if(update & EMPTY)
+		overlays += "can-o0"
+	else if(update & LOW)
+		overlays += "can-o1"
+	else if(update & FULL)
+		overlays += "can-o2"
+	else if(update & DANGER)
 		overlays += "can-o3"
+#undef HOLDING
+#undef CONNECTED
+#undef EMPTY
+#undef LOW
+#undef FULL
+#undef DANGER
 
 /obj/machinery/portable_atmospherics/canister/temperature_expose(datum/gas_mixture/air, exposed_temperature, exposed_volume)
 	if(exposed_temperature > temperature_resistance)

code/modules/atmospherics/machinery/portable/scrubber.dm

@@ -97,18 +97,26 @@
 /obj/machinery/portable_atmospherics/scrubber/huge
 	name = "huge air scrubber"
 	icon_state = "scrubber:0"
-	anchored = 1
+	anchored = TRUE
+	active_power_usage = 500
+	idle_power_usage = 10
 
 	volume_rate = 1500
 	volume = 50000
 
+	var/movable = FALSE
+
+/obj/machinery/portable_atmospherics/scrubber/huge/movable
+	movable = TRUE
+
 /obj/machinery/portable_atmospherics/scrubber/huge/update_icon()
 	icon_state = "scrubber:[on]"
 
 /obj/machinery/portable_atmospherics/scrubber/huge/process_atmos()
-	if(!anchored)
+	if((!anchored && !movable) || !is_operational())
 		on = FALSE
 		update_icon()
+	use_power = 1 + on
 	if(!on)
 		return
 
@@ -120,6 +128,7 @@
 
 /obj/machinery/portable_atmospherics/scrubber/huge/attackby(obj/item/weapon/W, mob/user)
 	if(default_unfasten_wrench(user, W))
-		on = FALSE
+		if(!movable)
+			on = FALSE
 	else
 		..()

code/modules/power/power.dm

@@ -50,10 +50,8 @@
 // returns true if the area has power on given channel (or doesn't require power).
 // defaults to power_channel
 /obj/machinery/proc/powered(var/chan = -1) // defaults to power_channel
-
-	if(!src.loc)
+	if(!loc)
 		return 0
-
 	if(!use_power)
 		return 1