Sir, am getting this message when using RC.After showing this message tool is not responding.My other designs are working fine.But for this program sad1.vhd am getting correct output in NCSIM (also I was able to synthesize the design in xilinx ISE) so what may be the problem.
Elaborating top-level block 'SAD' from file 'sad1.vhd'.
Done elaborating 'SAD'.
Trying carrysave optimization (configuration 1 of 1) on module 'SAD_csa_cluster_104'...
Info : Done carrysave optimization. [RTLOPT-20]
: There are 2 CSA groups in module 'SAD_csa_cluster_104'... Rejected.
Trying carrysave optimization (configuration 1 of 2) on module 'SAD_csa_cluster'...
Info : Done carrysave optimization. [RTLOPT-20]
: There are 16 CSA groups in module 'SAD_csa_cluster'... Rejected.
Trying carrysave optimization (configuration 2 of 2) on module 'SAD_csa_cluster'...
Info : Done carrysave optimization. [RTLOPT-20]
: There are 17 CSA groups in module 'SAD_csa_cluster'... Rejected.
Trying carrysave optimization (configuration 1 of 2) on module 'SAD_csa_cluster'...
Info : Done carrysave optimization. [RTLOPT-20]
: There are 2 CSA groups in module 'SAD_csa_cluster'... Accepted.
Trying carrysave optimization (configuration 2 of 2) on module 'SAD_csa_cluster'...
Info : Done carrysave optimization. [RTLOPT-20]
: There are 10 CSA groups in module 'SAD_csa_cluster'... Accepted.
Mapping SAD to gates.