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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。
1 x7 o( g1 e0 H//所有註解都要保留* H# n1 ^+ ?/ ?% `5 L
' A& D, L# f9 Q7 x- G
`timescale 1 ns / 1 ns
; r7 g2 a3 L) P% ~module xclk(sclk,ena,set,outp);
' A3 N8 F& @ x4 P* G- {7 o' O3 `3 e6 _4 c& E# ^
0 I$ B7 J6 T" Y4 T3 ?* y
$ r+ W9 l& |0 x3 ^" ^! u ~$ dinput sclk,ena;8 }$ H7 {( y5 s7 i8 ]/ ~$ ^7 ~
input [1:0]set;
3 o0 c, y* L" E+ \output outp; 5 B5 ~# S5 J/ \
0 F5 P& f) U E5 b5 ?, g" }" Q( c+ jwire outp;
' k& f8 I, u) d( e1 _* I( h+ Z5 R+ u* z: E( N
' g! o, I9 o; ]; T! y1 I" \
+ ^; y$ _* B6 k8 u6 s
/**** Node preservation for nodeA **************/) Q! F! ^- } w" V- R
# [4 m( u' X% _' ?4 B5 }
( h5 u9 } M, H//exemplar attribute nodeA_5 preserve_signal true; \9 Q4 K" C' M" a8 E
0 z( T) B# M4 ?. \! i
//exemplar attribute nodeA_4 opt keep' `! L. q/ _9 G F2 W
* q) r/ O. K) l& ~$ r6 i' |* V/**** The following comment form also works ****/6 i! @. I4 C0 c- e4 j+ a
9 B% C0 G- F; @9 @6 b$ ?0 D$ _
//exemplar attribute nodeA_3 preserve_signal true
0 p7 v2 A E0 {3 j" b5 D' F o! { c0 V) i" k9 I$ v# q' V. ?
//exemplar attribute nodeA_3 opt keep, Y, }- D9 O# g, v6 r
. v' i) S( `( `5 a% q8 |
/**** The following comment form also works ****/
; m' X& Q% u$ {2 j; `1 p4 a# j1 i7 j) J
//exemplar attribute nodeA_2 preserve_signal true
9 s% u+ |9 ?) @- J6 G+ [0 d2 i5 k% Z/ P$ J, z* y
//exemplar attribute nodeA_2 opt keep0 H6 I! }$ K# P( h* R3 d7 F
; A! H9 l: J& @& `. [8 J+ W& E/**** The following comment form also works ****/: s5 R" v7 r0 A# U- I7 G' y
' X, _9 X F) {5 ]//exemplar attribute nodeA_1 preserve_signal true& L0 \" K3 g) ^/ i' r
# f' f9 `( F2 t4 y- |: D/ G) ^//exemplar attribute nodeA_1 opt keep
) {1 A7 B2 X+ h- _
H6 {" y/ J" t1 `+ K4 z
1 l2 L0 p5 }3 K. s/**** The following comment form also works ****/
; l! n \* M+ x9 y+ y8 d3 X. E8 S; Q3 ]0 r+ `1 F
/*exemplar attribute nodeA_0 preserve_signal true& D4 Q# m( S9 J& M: _6 M# E; R
8 W0 D) I2 u% e8 K* G) S& o, qexemplar attribute nodeA_0 opt keep*/ 7 L n" p2 e: h7 m
7 E- o$ G9 ~" T5 X6 l
7 t3 G I. ]2 M) V7 Z: O2 l0 W' {/ U
6 J2 L6 _; n. K6 o: _
9 x* H, i- K& p! P9 l# @& `: H; y; w
; ^2 C; m' Y5 ^( p& i: J* o, Y. `, U" z0 ~1 f0 T2 ]
, l0 K) H M( y; i9 r- C
8 G* |5 Q0 n) f
6 ~! X+ R! d( P, Q! ]wire nodeA/* synthesis syn_keep=1 opt="keep"*/;1 E4 a; _; b; B
wire nodeA_0/* synthesis syn_keep=1 opt="keep"*/;- t( Y- l% H# H
wire nodeA_1/* synthesis syn_keep=1 opt="keep"*/;# z+ y8 G- I# o! r" ^4 R% X
wire nodeA_2/* synthesis syn_keep=1 opt="keep"*/;
1 S& ]/ X7 F9 [wire nodeA_3/* synthesis syn_keep=1 opt="keep"*/;
; P& L9 }+ \ Jwire nodeA_4/* synthesis syn_keep=1 opt="keep"*/;
* |' D* X# | r3 G2 J6 |' ?( A9 c( i
assign#1 nodeA_0 = sclk & ena;8 g+ V- M/ }# y3 J! s; @
1 z9 ]. `+ C: I# cassign#1 nodeA_1 = ~ nodeA_0;
: |. Y3 Y2 v# b: J. I5 Jassign#1 nodeA_2 = ~ nodeA_1;
3 v5 R' @# Y4 A% \% v& ?* a/ z" uassign#1 nodeA_3 = ~ nodeA_2;
: B- s$ w( A" h+ _assign#1 nodeA_4 = ~ nodeA_3;" n2 I% g' c! ]9 @/ {/ }
: F% ~. T. S: ^8 J$ w- r7 e
reg xout;
" { L s8 w' ^$ E3 u5 d8 e- l o0 G5 Z n# A% t0 i
always@(nodeA_1,nodeA_2,nodeA_3,nodeA_4,set)
3 V- l6 F! T1 B) g, U1 N casez(set)
& Y3 h, ?5 L$ S5 y 1: xout =#1 nodeA_2;
+ i. U+ N) p1 } 2: xout =#1 nodeA_3;
5 }6 V! ` M% _, z2 l! a# t 3: xout =#1 nodeA_4;
* Y8 |0 n) P# ^ default: xout =#1 nodeA_1;) ]1 P, z9 e0 Z4 E. g) x
endcase9 }1 p r. o/ ]4 C% C: W- L" l8 Z" E
9 p9 O1 D$ n0 ] h$ Fassign#1 nodeA = xout;5 F& Z+ \6 w/ W; X" y) ?, E
assign#1 outp = ena ? nodeA^sclk : 1'bz;
" B: ` ? d. L
) O2 \2 U5 T, s: A S) fendmodule
" U, L' {3 ?9 u# ^5 {
7 y8 i2 p6 ^) |5 l- T: G* h* z8 l& K, J8 [
! Z8 \; [' k W`timescale 1 ns / 1 ns
' k8 f9 |/ E$ g3 Xmodule xclk_tf();8 E% Z- I3 O' z1 r4 Q" g
/ n0 O/ t9 n- ~2 D
// Inputs
9 |* U, K+ b% Z; l" f7 M d3 g reg sclk;
( V3 Z4 [4 m( M, \4 h* V0 I! @ reg ena;
! X- C# d, {4 ^9 Z reg [1:0] set;3 y* ?& L. J: I* i, j0 S
1 h7 i! C) \1 J" N" c1 _
/ }, r9 f. W8 f& h! W/ E// Outputs
# j! R0 g$ U) }3 e. k' B wire outp;# H/ ^" z0 j& Q; C
" D, P1 q- K9 E1 ?) g, K
; l8 u, {3 f" u* R3 E a1 w3 p* q) {, n4 H) Z' k& _
xclk UUT (; a+ e4 E- U4 ^" t, V: C7 N/ E1 Z
.sclk(sclk),
' k8 y( O, D. ]2 p3 y# V0 q .ena(ena),
, @3 `9 U/ \6 K8 \: Y .set(set), 8 k! W9 q1 B, I3 O6 C* \ f1 b
.outp(outp)
( t5 G: z0 e- |) y2 [ );
# w: i* ~8 m& a& c; U$ q& j8 {
& |. _8 `+ y6 K1 o& H: a# d6 [
9 v6 ]6 U- T9 G, ^9 G) s9 D
7 ?1 @, p! v }7 D6 Q1 |0 s- c% W" ?3 H initial begin: i# U0 m0 ~% ]" I5 G# G5 s
sclk = 0;
2 b! }4 k9 O3 m& I9 z+ M; J% a. \ ena = 0;) K( G5 t: K& l/ S; q; x8 z0 a
set = 0;# Y- |0 o2 j# M3 Z% d
end+ W8 M2 i9 }1 R' q3 a
; j! H u3 d/ S5 j: B; W% w
* V: i( t" v$ l
always# 5 sclk = !sclk;% h( R9 T5 B7 \' A
1 t: u$ G: H* J- O0 V) T) G' Winitial begin
/ G( N2 T% F4 x0 L' E7 u7 `/ x #1003 i& f4 A6 r* E: w) U7 c
ena = 1;4 w7 k% g4 }5 P# L, ^
#2000 ( }, q. a/ k" [) c, V6 X
set = 2;/ L+ \& S( M6 @" R* W
#2000
# N. _0 W- k* q: k( X4 x" r, h- @5 q set = 3;3 M6 v; m5 f3 A- F- @
#20008 H# F. b' w3 C o% Y, a! Z0 ]+ K$ p
$finish;
# I5 t% x) D L" G4 cend/ L/ h% @! c+ q5 z& `# a4 {
endmodule // xclk_tf |
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發表於 2007-3-17 11:29:24
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