|
//可直接透過synthesis tool用於PLD,FPGA不可 LUT delay則要採其他方式。
, C1 i+ f J0 }//所有註解都要保留
7 q8 {. V1 p: o: V6 s
# U) v2 A8 b( l3 J$ v`timescale 1 ns / 1 ns- c+ d) B' i# s! a" H0 z$ B. m! L
module xclk(sclk,ena,set,outp);
$ ^/ R2 ?. ]6 e/ f* H9 z" D
0 v9 C9 I& e, A9 i) [- u/ f7 S
- d7 `' c7 }# e, J, k! h3 s4 C$ n$ b
input sclk,ena;
% S, ]1 F# Q; F5 w3 E% u2 Yinput [1:0]set;* C. F0 O% h" j! J
output outp;
9 H7 O/ P' q" A- w5 F3 C: W, R6 Q$ w: C( s
wire outp;
) F# J9 Z0 v* \' X- G+ u# K* @7 D7 t9 T: M
9 _7 l% I6 q' f$ j* }: K3 N. A/ r% m* }5 K# X
/**** Node preservation for nodeA **************/
. A" T% n( W, _! Q
9 G5 a! t6 ^ x* c' j" g( `3 s' w
# U8 Q$ _) L1 d//exemplar attribute nodeA_5 preserve_signal true& _, `+ Q# s+ o, J7 P9 I* G
! Z9 v7 g8 n% O F. z2 f' ?, d//exemplar attribute nodeA_4 opt keep2 C% l+ m' d q4 ]
& O1 @# ^! X) q. h: N( q7 P, l/**** The following comment form also works ****/- ^4 Q0 a! Y, B
; x# \$ E. F1 _+ q. a
//exemplar attribute nodeA_3 preserve_signal true
4 v! S% |# [5 s' o# [+ b. W2 t* m* K7 D) Q* K* @ N8 v& q2 v
//exemplar attribute nodeA_3 opt keep: s) A- q9 u+ _5 ^; r; X4 b. r& E) }
; @, Z0 y8 P7 s' y5 Z
/**** The following comment form also works ****/
* C& a, k3 ^$ X' F7 S+ r4 Q3 f) V& g- U& u& y+ U
//exemplar attribute nodeA_2 preserve_signal true* m9 P! K/ r, V' z# q1 N+ K
! Q* f7 m5 {% v$ r/ r" J//exemplar attribute nodeA_2 opt keep
9 ?" L6 k: E/ j2 p' v4 Y* C+ q) P+ q* i1 F8 r9 p3 p
/**** The following comment form also works ****/6 ?& y3 t5 e/ N# A0 S# C
5 ]# O2 N' ]6 f2 i2 y$ K//exemplar attribute nodeA_1 preserve_signal true% Z L% S& G% C% x0 \$ L: V" u. h
* e$ F5 f& x4 r+ ]
//exemplar attribute nodeA_1 opt keep/ S3 O+ X% Y1 g, Z- k$ E
5 y) \% \1 m% @ Z( l$ |# ^# j s% E
/**** The following comment form also works ****/5 x1 v9 w v; A. a" }1 E# T! r" o
. }: e% b; b Y
/*exemplar attribute nodeA_0 preserve_signal true
9 b: Y( n! F: f6 r
+ k: H) j# u% f$ [( s% D& f6 Rexemplar attribute nodeA_0 opt keep*/ , U$ ~ `( y1 K5 F5 D0 W
1 A3 ^9 T; N& l M' _
7 S( f5 \4 e2 w8 Z7 M) t 0 ~- p. u4 V; c- j
! ?# P8 R, e- M6 w5 H" H
[. F% c. s) F$ l# c
; X) i, u4 A- S4 g- p4 C0 I, b
" s8 r' D) p' k6 w0 q* \8 t" K/ E% x0 M* m' E8 U
2 v' ~0 ?* T& _/ ^ G, I1 R8 F1 j
1 t2 M0 n# z% x3 q( `0 swire nodeA/* synthesis syn_keep=1 opt="keep"*/; ~, I; {! z1 m) ]) n
wire nodeA_0/* synthesis syn_keep=1 opt="keep"*/;) ?+ ^2 d' s+ U/ a' O7 ~
wire nodeA_1/* synthesis syn_keep=1 opt="keep"*/;
9 U0 R, ^$ v' F& p4 G4 I# Uwire nodeA_2/* synthesis syn_keep=1 opt="keep"*/;5 n& n1 Y* j, l8 W" _8 C) m
wire nodeA_3/* synthesis syn_keep=1 opt="keep"*/;
# i: O3 T3 B: `" Uwire nodeA_4/* synthesis syn_keep=1 opt="keep"*/;
0 t: P+ l2 y) s
9 [0 C; @& Z9 O$ s4 o- Fassign#1 nodeA_0 = sclk & ena;
) e9 {1 o0 Y& ~+ @( q2 l. P9 Z# I+ i# A' R1 L( ~. Q5 W
assign#1 nodeA_1 = ~ nodeA_0;9 U$ W# S, W. W1 Y2 D5 Y8 |- @
assign#1 nodeA_2 = ~ nodeA_1;
% [! n. f5 }- s/ R0 ?- wassign#1 nodeA_3 = ~ nodeA_2;' e: A0 t' I2 B& @
assign#1 nodeA_4 = ~ nodeA_3;" Z0 {' v& i) M0 {
K, o0 U, H" V: @reg xout;
( [+ X* O& p0 e( J" C( x6 ~+ U% Y4 c) a* c6 V$ S
always@(nodeA_1,nodeA_2,nodeA_3,nodeA_4,set)) F9 }0 \8 Q$ C* H
casez(set)
7 a6 F) P& J, ]* g) L 1: xout =#1 nodeA_2;
4 b W% a, M+ m# i9 i. h 2: xout =#1 nodeA_3;
7 K# K, \2 m+ w, u& |3 p5 p 3: xout =#1 nodeA_4;0 L6 t* x- A6 c6 D9 y x
default: xout =#1 nodeA_1;
* z7 r; r% b/ k' ^4 [/ n endcase' H1 |( b3 D) b5 S1 F2 G: \" X
8 D6 B5 h y+ M$ F& i: k2 Zassign#1 nodeA = xout;1 a5 k! I; ^* _2 D% O9 O! S
assign#1 outp = ena ? nodeA^sclk : 1'bz;. `8 \4 r& f' M: ^- }3 F: m
+ \- k# f) G: b7 N, V9 @# s0 \+ Wendmodule# d: u( A1 P/ `+ Y% _
$ |& A8 c4 T# ?( [8 D5 l
: j+ ~1 {# a! C2 ^( i' |
+ J# N: n: N- q9 n9 n4 c: b`timescale 1 ns / 1 ns
! X; _0 g/ m9 @& wmodule xclk_tf();
' ^: Q0 z; q1 O. v- k
9 }. A+ O, x1 c1 N: A! d8 J// Inputs
+ j; z# m6 c& q( q# b, y }9 b+ M! L. F reg sclk;. \+ Q2 D f/ @7 o: @
reg ena;. C1 E8 Z0 r; `# Z9 X7 G: i$ i
reg [1:0] set;$ ?, l# E$ f! f, B
& m# L% x6 _5 ?2 }# X4 b
8 |; @5 o X, s) p// Outputs
, X+ {' I! `. `1 J) u- ] wire outp;
0 D4 `8 G# Y0 f' m
- @! D, F/ i% K0 X5 L/ o0 t( w( p
. T4 Q( w S. D' ~% q. @3 e! U6 n8 E0 O* Q
xclk UUT (
$ b! m" |% h s; R .sclk(sclk),
* V8 C4 v: @, Q9 U .ena(ena), % m0 q9 X5 t* J( R- B. L3 W
.set(set), ; D1 g( ~* v# X/ L/ L; F
.outp(outp)) U" F: f9 d) V9 B$ M: r
);! x/ m. g E J1 `
) c& i- {% w0 k: _: o5 D( J, l8 E
4 T, ]$ p( [- S% _% J& A5 m$ Z4 G) Z3 C3 f
initial begin
$ b- d9 R& F' V9 J9 T$ U: w* C5 x sclk = 0;3 k: u0 m6 I, ~% e+ ~* N& A* g1 E. n, X9 j
ena = 0;
6 l9 Q' Z6 B& f set = 0;
, ] C7 d- H' w& ^1 j end) V6 F+ H! R; X I8 r
s: y! v7 e' G0 w5 [* i0 b/ s# ?- n9 l2 @ x+ }8 u
always# 5 sclk = !sclk;1 l( P. s* H" I+ |
8 j1 @+ R8 m6 V/ i& N
initial begin: J4 t* [1 L u0 J& P7 H! v8 c3 i
#1006 |- K8 G5 R" q& o7 h- w9 C
ena = 1;
" E# Y+ m+ [9 n! d6 J8 m" Y2 ` U #2000 . L ` H0 s$ A; ^3 M0 [
set = 2;+ _4 v( a* s9 q+ ~$ B* y+ n6 w
#2000
4 L. K7 }$ x& c0 k0 ^1 ] set = 3;1 p1 O) O1 D2 r& z: c: R# }
#2000
1 C4 @& h( H: |" [. p% H7 | $finish;
6 X! f4 l0 H$ nend1 Z( I' m; s1 T& k: l: k
endmodule // xclk_tf |
|