Help me remove some XST warnings

[jadedfox]

WARNING:Xst:2042 - Unit dig_cntrl_osc: 5 internal tristates are replaced by logic (pull-up yes): cell4_in, DCO_OUT1Bs3, DCO_OUT2Bs1, DCO_OUTBs0, DCO_OUTBs2.
WARNING:Xst:2040 - Unit dig_cntrl_osc: 3 multi-source signals are replaced by logic (pull-up yes): cell1_in, cell2_in, cell3_in.
WARNING:Xst:2170 - Unit adpll : the following signal(s) form a combinatorial loop: DCO1/cell2_in.
WARNING:Xst:2170 - Unit adpll : the following signal(s) form a combinatorial loop: DCO1/DCO_OUT2Bs1.

module dig_cntrl_osc(enable, DCO_CONTRL, DCO_OUT);
	input enable;
	input [7:0] DCO_CONTRL;
	output DCO_OUT;
	
	
	not invsel0( CONTRL6b, DCO_CONTRL[6] );
	not invsel1( CONTRL7b, DCO_CONTRL[7] );
	and andsel0( sel0, CONTRL7b, CONTRL6b );
	and andsel1( sel1, CONTRL7b, DCO_CONTRL[6] );
	and andsel2( sel2, DCO_CONTRL[7], CONTRL6b );
	and andsel3( sel3, DCO_CONTRL[7], DCO_CONTRL[6] );
	nand nandout( DCO_OUTB, cell1_out, enable );
	not INV1( DCO_OUT1B, DCO_OUTB );
	bufif1 tmp1 (DCO_OUTBs0, DCO_OUTB, enable);//
	bufif1 tmp2 (DCO_OUT2Bs1, DCO_OUT2B, enable);//
	bufif1 tmp3 (DCO_OUTBs2, DCO_OUTB, enable);//
	bufif1 tmp4 (DCO_OUT1Bs3, DCO_OUT1B, enable);//
	bufif1 buf1( cell1_in, DCO_OUT1Bs3, sel3 );
	bufif0 buf2( cell1_in, cell2_out, sel3 );
	bufif1 buf3( cell2_in, DCO_OUTBs2, sel2 );
	bufif0 buf4( cell2_in, cell3_out, sel2 );
	not INV2( DCO_OUT2B, DCO_OUTB );
	bufif1 buf5( cell3_in, DCO_OUT2Bs1, sel1 );
	bufif0 buf6( cell3_in, cell4_out, sel1 );
	bufif1 buf7( cell4_in, DCO_OUTBs0, sel0 );
	not INV3( DCO_OUT, DCO_OUTB );
	DCO_CELL cell1( DCO_CONTRL[5:0], cell1_in, cell1_out );
	DCO_CELL cell2( DCO_CONTRL[5:0], cell2_in, cell2_out );
	DCO_CELL cell3( DCO_CONTRL[5:0], cell3_in, cell3_out );
	DCO_CELL cell4( DCO_CONTRL[5:0], cell4_in, cell4_out );
	

endmodule

how can i get rid of the above warnings??
any one...

 

[jadedfox]

xst:2042

WARNING:Xst:2042 - Unit dig_cntrl_osc: 5 internal tristates are replaced by logic (pull-up yes): cell4_in, DCO_OUT1Bs3, DCO_OUT2Bs1, DCO_OUTBs0, DCO_OUTBs2.
WARNING:Xst:2040 - Unit dig_cntrl_osc: 3 multi-source signals are replaced by logic (pull-up yes): cell1_in, cell2_in, cell3_in.
WARNING:Xst:2170 - Unit adpll : the following signal(s) form a combinatorial loop: DCO1/cell2_in.
WARNING:Xst:2170 - Unit adpll : the following signal(s) form a combinatorial loop: DCO1/DCO_OUT2Bs1.

how can i get rid of the above warnings??
any one...