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AR# 44499

XST - Severity change for XST message "WARNING:HDLCompiler:1128" beginning in ISE 13.3 software

Description

Themessage"WARNING:HDLCompiler:1128" produced by the XST new parser prior to 13.3 iswill change to"ERROR:HDLCompiler:1128" starting from version 13.3 of XSTfor cases where there are multiple signal edgesin the sensitive list, but not all of the signals are used in the process/always block.

Solution

Takethe following piece of code as an example:

always @(posedge clk or posedge reset) begin

/*
if (reset)
out <= 1'b0;
else
*/
out <= d;
end

The XST new parser (prior to version 13.3) would have given the following warning message for the above piece of code:
"WARNING:HDLCompiler:1128 - "multiple_clocks_1128.v" Line 16: Assignment under multiple single edges is not supported for synthesis."


Starting with version 13.3 of XST, this warning is modified to an error without any change to the actual information or message as follows:
"ERROR:HDLCompiler:1128 - "multiple_clocks_1128.v" Line 16: Assignment under multiple single edges is not supported for synthesis."

In the above example, with the if-else clause commented,the toolis unable to unambiguously pick the clock signal from clk and reset.The HDLCompiler errors out with the above message in similar scenarios, as mentioned in the above example.

AR# 44499
Date Created 10/17/2011
Last Updated 05/16/2012
Status Active
Type Error Message
Tools
  • ISE Design Suite - 13.3