add_sub_0sh.tdf

8*8位的先入先出（fifo）数据缓冲器的vhdl源程序

--lpm_add_sub CARRY_CHAIN="MANUAL" CARRY_CHAIN_LENGTH=70 DEVICE_FAMILY="Stratix" LPM_DIRECTION="ADD" LPM_REPRESENTATION="UNSIGNED" LPM_WIDTH=3 ONE_INPUT_IS_CONSTANT="YES" cin dataa datab result
--VERSION_BEGIN 5.0 cbx_cycloneii 2004:12:20:14:28:52:SJ cbx_lpm_add_sub 2005:04:12:13:30:42:SJ cbx_mgl 2005:04:13:17:26:48:SJ cbx_stratix 2005:03:14:17:09:02:SJ cbx_stratixii 2004:12:22:13:27:12:SJ  VERSION_END


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--  without limitation, that your use is for the sole purpose of 
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FUNCTION carry_sum (cin, sin)
RETURNS ( cout, sout);

--synthesis_resources = lut 4 
SUBDESIGN add_sub_0sh
( 
	cin	:	input;
	dataa[2..0]	:	input;
	datab[2..0]	:	input;
	result[2..0]	:	output;
) 
VARIABLE 
	add_sub_cella[2..0] : carry_sum;
	external_cin_cell : carry_sum;
	datab_node[2..0]	: WIRE;
	main_cin_wire	: WIRE;

BEGIN 
	add_sub_cella[0].cin = ((dataa[0..0] & datab_node[0..0]) # ((dataa[0..0] # datab_node[0..0]) & main_cin_wire));
	add_sub_cella[1].cin = ((dataa[1..1] & datab_node[1..1]) # ((dataa[1..1] # datab_node[1..1]) & add_sub_cella[0].cout));
	add_sub_cella[2].cin = ((dataa[2..2] & datab_node[2..2]) # ((dataa[2..2] # datab_node[2..2]) & add_sub_cella[1].cout));
	add_sub_cella[0].sin = ((dataa[0..0] $ datab_node[0..0]) $ main_cin_wire);
	add_sub_cella[1].sin = ((dataa[1..1] $ datab_node[1..1]) $ add_sub_cella[0].cout);
	add_sub_cella[2].sin = ((dataa[2..2] $ datab_node[2..2]) $ add_sub_cella[1].cout);
	external_cin_cell.cin = cin;
	external_cin_cell.sin = B"0";
	datab_node[] = datab[];
	main_cin_wire = external_cin_cell.cout;
	result[] = add_sub_cella[].sout;
END;
--VALID FILE