87 lines
1.8 KiB
Coq
87 lines
1.8 KiB
Coq
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`timescale 100 ps / 10 ps
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module test;
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reg cdn, cp, d;
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wire qr, qp;
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initial begin
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$timeformat(-9, 2, " ns", 9);
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$monitor("%t - cdn=%b, cp=%b, d=%b, qr=%b, qp=%b",$time,cdn,cp,d,qr,qp);
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// Reset the FF.
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cp = 0; d = 1;
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#100 cdn = 0;
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#100 cdn = 1;
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// Toggle in some data.
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#100 cp = 1;
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#100 cp = 0; d = 0;
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#100 cp = 1;
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#100 cp = 0; d = 1;
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#100 cp = 1;
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end
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dff_rtl dutr(qr, d, cp, cdn); // This one works fine.
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dff_prm dutp(qp, d, cp, cdn); // This one has no delay.
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endmodule
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// The RTL version appears to work fine.
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module dff_rtl (q, d, cp, cdn);
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output q;
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input d;
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input cp;
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input cdn;
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reg qi;
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always @(posedge cp or negedge cdn) begin
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if (~cdn) qi <= 1'b0;
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else qi <= d;
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end
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buf (q, qi);
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specify
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specparam tpd_cp_q_lh = 6;
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specparam tpd_cp_q_hl = 7;
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specparam tpd_cdn_q_lh = 0;
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specparam tpd_cdn_q_hl = 3;
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if (cdn) (posedge cp => (q +: d)) = (tpd_cp_q_lh, tpd_cp_q_hl);
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(negedge cdn => (q +: 1'b0)) = (tpd_cdn_q_lh, tpd_cdn_q_hl);
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endspecify
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endmodule
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// The primitive version has no delay.
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module dff_prm (q, d, cp, cdn);
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output q;
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input d, cp, cdn;
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UDP_DFF G3(q, d, cp, cdn);
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specify
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specparam tpd_cp_q_lh = 6;
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specparam tpd_cp_q_hl = 7;
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specparam tpd_cdn_q_lh = 0;
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specparam tpd_cdn_q_hl = 3;
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if (cdn) (posedge cp => (q +: d)) = (tpd_cp_q_lh, tpd_cp_q_hl);
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(negedge cdn => (q +: 1'b0)) = (tpd_cdn_q_lh, tpd_cdn_q_hl);
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endspecify
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endmodule
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// This is overly simplistic, but it works for this example.
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primitive UDP_DFF(q, d, cp, cdn);
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output q;
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reg q;
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input d, cp, cdn;
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table
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// d cp cdn q0 q
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* ? ? : ? : - ;
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? n ? : ? : - ;
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0 r 1 : ? : 0 ;
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1 r 1 : ? : 1 ;
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? ? 0 : ? : 0 ;
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? ? p : ? : - ;
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endtable
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endprimitive
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