Answers Database

Are there counter modules in the xdw (xblox designware) libraries?


Record #2992

Product Family:  Software

Product Line:  Synopsys

Problem Title:
Are there counter modules in the xdw (xblox designware) libraries?


Problem Description:
Keywords: synopsys

Urgency: Standard

General Description:  Why are there not COUNTER modules added to the xdw
(xblox designware) library ?


Solution 1:

Synopsys (DesignWare) is incapable of inferring a COUNTER from the construct
"count <= count + 1", for example. The only operators that it can key off are:
+/-, muxes, * ; and the corresponding registers. So the construct:
count <= count + 1 only implies some form of an adder/incrementer to Synopsys.

In the M1 flow, 'counters' in HDL should be created by Logiblox, unless
the counters are 6-bits or smaller.

If you use the traditional method of describing a counter in
VHDL:

process(CLOCK)
	begin
	if(CLOCK'event and CLOCK='1') then
	A <= A + 1;
	end if;
end process;

or in Verilog:

always@(posedge CLOCK)
	A = A + 1;

Synopsys will pull a inc_dec and place registers in front
of it (The old xblox implementation of a counter, a registered
inc_dec). The old xblox DesignWare libraries have been renamed
to xdw_xc4000ex.  See Xilinx Solution 2991




End of Record #2992