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//可直接透過synthesis tool用於PLD，FPGA不可 LUT delay則要採其他方式。5 C, \# t* f Q, \+ P5 o$ d ]
//所有註解都要保留
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2 @% i! D: F0 Q. P; m`timescale 1 ns / 1 ns/ C& }- n& K8 p# o4 Q
module xclk(sclk,ena,set,outp);
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% {0 j& x; ?$ ~/ O, b0 O# T/ e
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' W5 P* _: Q) s' n7 \input sclk,ena;
E$ t+ w6 N/ vinput [1:0]set;/ Z; D! J" B) |3 a& r6 L3 F0 E
output outp;
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wire outp;
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/**** Node preservation for nodeA **************/% f2 }' d% R* h2 i- ~: R
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//exemplar attribute nodeA_5 preserve_signal true& x* i. N4 [- {+ B6 z
6 L, ]4 J; Q' ]! P! e//exemplar attribute nodeA_4 opt keep9 F" e) T3 s& m0 o1 C& |9 Y
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/**** The following comment form also works ****/5 P( z2 e( W& N- D
1 h9 C# q9 ?# a% x! d; W//exemplar attribute nodeA_3 preserve_signal true* A- T$ i3 t& @: e4 T
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//exemplar attribute nodeA_3 opt keep
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. z1 G; `! ^) X- D$ c/**** The following comment form also works ****/
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//exemplar attribute nodeA_2 preserve_signal true6 O! s ~: W7 R- W8 _3 u
4 o* z% l( \+ A* X. L//exemplar attribute nodeA_2 opt keep
# G; p- M* L7 e+ g, E9 f4 M+ T; N! `( v/ ?
/**** The following comment form also works ****/
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//exemplar attribute nodeA_1 preserve_signal true
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//exemplar attribute nodeA_1 opt keep
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2 V( u& S2 H) z$ @. r G: N" d7 j, a. w% I+ B7 y
/**** The following comment form also works ****/
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/*exemplar attribute nodeA_0 preserve_signal true( j- ~$ R; Y: s" b
w: o4 ^& Y3 C3 E9 [& G! O) ?exemplar attribute nodeA_0 opt keep*/ , X p: F2 Y6 M# ~# X7 z" c6 U0 w
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# y1 ~4 J; x2 U: n! q% d5 k# Gwire nodeA/* synthesis syn_keep=1 opt="keep"*/;
- P1 x' q! x* L2 m! E! Ywire nodeA_0/* synthesis syn_keep=1 opt="keep"*/;
+ M4 w; E' q) l6 T" ^wire nodeA_1/* synthesis syn_keep=1 opt="keep"*/;4 [. U I+ b4 L
wire nodeA_2/* synthesis syn_keep=1 opt="keep"*/;
/ U5 S, o; `5 O' b+ }# k& pwire nodeA_3/* synthesis syn_keep=1 opt="keep"*/;
8 D! R" e5 Z% ?" @/ kwire nodeA_4/* synthesis syn_keep=1 opt="keep"*/;; U- L1 c+ l+ j9 T! D: A
5 G# o7 D7 l6 P' _# Z, l% l0 y2 \assign#1 nodeA_0 = sclk & ena;
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assign#1 nodeA_1 = ~ nodeA_0;
( M8 T3 t/ e' `% J/ jassign#1 nodeA_2 = ~ nodeA_1;
G8 w Y; n9 D; A& u2 x' @assign#1 nodeA_3 = ~ nodeA_2;
% j4 B7 \9 [$ G4 Z# k2 Kassign#1 nodeA_4 = ~ nodeA_3;
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% c0 g: s; P+ Y; d, K7 D: }reg xout;
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always@(nodeA_1,nodeA_2,nodeA_3,nodeA_4,set)
: I5 [- X7 i8 p9 e3 ~* T casez(set)
/ c5 F3 ?% @; W1 |& }, g 1: xout =#1 nodeA_2;. G6 y0 O3 }' C
2: xout =#1 nodeA_3;
- q( d) E! `4 g* [) K8 y# h1 K* L 3: xout =#1 nodeA_4;$ t5 q4 Q: N5 c; A+ H% ^' D+ B
default: xout =#1 nodeA_1;
, t0 x* p* q' r# T4 ?. I( y endcase0 n8 g. W8 T, J3 p: k8 y
: I4 F' k% T* b. Nassign#1 nodeA = xout;
: ~& I. g8 n% _assign#1 outp = ena ? nodeA^sclk : 1'bz;. n2 o! C' v* d# h' n+ v/ e1 t3 w
6 G: k, u% t5 O/ H' oendmodule
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6 g# [4 o% ]) f0 T4 p# {`timescale 1 ns / 1 ns" N G! v8 a7 l
module xclk_tf();
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* k. p& ], \- D// Inputs
: S$ L$ }/ i, L6 o; S8 J* m reg sclk;0 L( N# p, f" r6 c
reg ena;
9 [7 c; M' t0 ]1 f4 h" _: U q reg [1:0] set;+ \ u1 J8 \" C$ z- ^
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// Outputs' H' y6 P: D' T
wire outp;
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xclk UUT ($ K4 ]- N# s1 G7 @$ Z( I5 p% d) a
.sclk(sclk), ! h8 F! | j- {2 c7 v' w( H
.ena(ena),
/ b; F8 n* T0 ~1 n" y- j1 l .set(set), 1 Y u `' C( ^: j
.outp(outp)2 ^6 y4 k' k0 R0 B- ?% p- Q! |$ j
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l- d: J0 G% a$ n initial begin, c& X2 q3 o+ C, L1 a/ D9 A
sclk = 0;5 O. g; `5 L' s. x) Y1 z+ ~; U+ |& U
ena = 0;% q% \ u# U; w! U5 E
set = 0;
0 F( ?/ N2 R& ], x: H2 [3 \- Z end
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always# 5 sclk = !sclk;6 ?1 g e1 A F& B
: b% B% z* r, i( b6 i" l. W$ @initial begin
! Z/ h! _, N* E #100
6 R- J4 Q/ l4 o8 d! ^9 D5 C' {7 {" | ena = 1; W; y7 x/ h8 J
#2000
& a) f j i+ C4 W7 h ` o5 p3 T set = 2;7 B5 a2 f! ? I$ i. x2 ?
#2000 $ T' ~) B( _9 O, d2 g7 }
set = 3;5 v9 P Q! i0 \1 b) P
#2000
1 K* n$ r E. d, L8 A6 P9 D+ P3 U $finish;+ V. {' w O/ m) A2 q
end" u. \# a4 ?) r. I4 T& Y( \/ o+ c
endmodule // xclk_tf |
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發表於 2007-3-17 11:29:24
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