immextend.pat

i need of vhdl code for 32-bit risc processor

in bitv1 B;
in bitv2 B;
in bitv3 B;
out outvector (7 to 0) B;

begin
pat_0 :0 0 0 ?00000000;
pat_1 :0 1 0 ?00000010;
pat_2 :1 0 0 ?00000100;
pat_3 :1 1 1 ?00000111;
pat_4 :0 1 1 ?00000011;

end;