ERROR:NgdBuild:604 - logical block 'u0' with type 'viterbi_v7_0' could not be resolved. A pin name misspelling can cause this, a missing edif or ngc file, case mismatch between the block name and the edif or ngc file name, or the misspelling of a type name. Symbol 'viterbi_v7_0' is not supported in target 'virtex6'.
WARNING: the Core Generator generated file 'viterbi_v7_0.ngc' was not found in 'C:/p4workspace/NRRT/Xilinx Projects/Viterbi_Decoder_w_Tail_Biting/tail_biting/ipcore_dir/'.
WARNING: the Core Generator generated file 'viterbi_v7_0.ngc' was not found in 'C:/p4workspace/NRRT/Xilinx Projects/Viterbi_Decoder_w_Tail_Biting/tail_biting/ipcore_dir'.
WARNING:HDLCompiler:89 - "C:\p4workspace\NRRT\Xilinx Projects\Viterbi_Decoder_w_Tail_Biting\tail_biting\vitdec_top.vhd" Line 49: <viterbi_v7_0> remains a black-box since it has no binding entity.