ncverilog warning issue

[leeguoxian]

scheduled event for delayed signal

Dear all :

I'm running ncverilog with sdf annotated . Than the following message came up :

Scheduled event for delayed signal of net "D" at time xxxx PS was canceld
File: xxx/xxx/xxx/std.v , line = 8569 ;
Scope test.u0.xxx.xxxx
Time : xxxx PS

What does it meas ?? Is there anything wrong with the std cell behavior model ??

Following is the definition of the DFF cell :

module DFFPETX1 (Q, QN, D, CK, E, RN);
output Q, QN;
input D, CK, E, RN;
reg NOSIFIER;
supply1 xSN;
supply1 dSN;
buf XX1 (xRN, RN);

udp_edfft I0 (n0, D, CK, xRN, xSN, E, NOSIFIER);
buf I1 (Q, n0);
not I2 (QN, n0);
and I3 (Deff, xRN, D);
and I4 (Dcheck,E,xRN);
and I5 (check,E, D);
specify
specparam
tplh$CK$Q = 1.0,
tphl$CK$Q = 1.0,
tplh$CK$QN = 1.0,
tphl$CK$QN = 1.0,
tsetup$D$CK = 1.0,
thold$D$CK = 0.5,
tsetup$CK$CK = 1.0,
thold$CK$CK = 0.5,
tsetup$E$CK = 1.0,
thold$E$CK = 0.5,
tsetup$RN$CK = 1.0,
thold$RN$CK = 0.5,
tminpwl$CK = 1.0,
tminpwh$CK = 1.0,
tperiod$CK = 1.0;
// path delays
(posedge CK *> (Q +: Deff)) = (tplh$CK$Q, tphl$CK$Q);
(posedge CK *> (QN -: Deff)) = (tplh$CK$QN, tphl$CK$QN);
// timing checks
$setuphold(posedge CK &&& (Dcheck == 1), posedge D, tsetup$D$CK, thold$D$CK, NOSIFIER);
$setuphold(posedge CK &&& (Dcheck == 1), negedge D, tsetup$D$CK, thold$D$CK, NOSIFIER);
$setuphold(posedge CK, posedge E &&& (RN == 1), tsetup$E$CK, thold$E$CK, NOSIFIER);
$setuphold(posedge CK, negedge E &&& (RN == 1), tsetup$E$CK, thold$E$CK, NOSIFIER);
$setuphold(posedge CK, posedge RN, tsetup$RN$CK, thold$RN$CK, NOSIFIER);
$setuphold(posedge CK, negedge RN, tsetup$RN$CK, thold$RN$CK, NOSIFIER);
$width(negedge CK, tminpwl$CK, 0, NOSIFIER);
$width(posedge CK, tminpwh$CK, 0, NOSIFIER);
$period(posedge CK, tperiod$CK, NOSIFIER);
endspecify
endmodule

 

[ljxpjpjljx]

scheduled event for delayed signal of net

it seems a sdf syntax problem!