YosysHQ.yosys/techlibs/ice40/spram.txt

ram huge $__ICE40_SPRAM_ {
	abits 14;
	width 16;
	cost 2048;
	byte 4;
	port srsw "A" {
		clock posedge;
		clken;
		wrbe_separate;
		rdwr no_change;
	}
}