|
//可直接透過synthesis tool用於PLD,FPGA不可 LUT delay則要採其他方式。
0 V/ F/ @) e/ f/ K; m, i8 Z//所有註解都要保留$ z0 a5 I* P% h( Q4 c
' Z1 x6 y. C+ v8 t`timescale 1 ns / 1 ns1 { z! Z: e6 H9 C, B0 N. o
module xclk(sclk,ena,set,outp);
# }& ]+ X" o; {
1 G( g- F% {- s; E$ b" J $ A+ K8 x, r( @/ d, I1 _/ L& Z6 H
' h" S4 U. ^- q2 I
input sclk,ena;( v" k2 M# n2 L
input [1:0]set;& I2 n, j1 P& N: I4 s& x3 q; B- ]
output outp;
2 V1 T6 h5 n3 j* X5 \7 V7 Y3 U
) L1 G d ` q& j, j% ?; _( Rwire outp;- g3 q& t. @1 h, K; M* a& T" I3 o
, k' e0 J2 o" `: _7 A
3 @" p, V" e- N! r2 c( _
2 C! @0 v1 O- F* X3 ^( w# x! s/ M
/**** Node preservation for nodeA **************/. G, z. M, p' ]( m: N8 Q
! W- C5 O5 I# R: E7 d
4 N( ^; |) Y( b3 A* u1 {//exemplar attribute nodeA_5 preserve_signal true; A( d( @0 {; t$ j4 \" M! l
+ e* M0 G! x {* r& u, R
//exemplar attribute nodeA_4 opt keep
+ Z# Z' k; Y$ n( [0 u
& H) Q& I! Q2 A* h$ {; t$ v! K/**** The following comment form also works ****/
' r1 C% Z3 I0 w9 k( z) m5 [
4 Z( t: d, H7 E1 A' G% r: N3 I6 V//exemplar attribute nodeA_3 preserve_signal true9 W1 w" `& j% y$ N; ?: k
q# P. ~5 x w5 G# R6 }! l# e4 ~//exemplar attribute nodeA_3 opt keep
& R2 e, Z, u% X7 G. k/ b3 S: O1 G0 `" k6 Z! W- U
/**** The following comment form also works ****/
& ~, o! u2 h' o+ @. G2 w9 O
" M6 g9 @9 M. b//exemplar attribute nodeA_2 preserve_signal true
8 h, u9 @) O" j/ K
/ } p: J0 w9 R- I, S! @0 e1 ~//exemplar attribute nodeA_2 opt keep
, T+ W5 V& [3 o
6 h& a* L4 z3 L; S4 X/**** The following comment form also works ****/
( W. s: V: R- o9 F0 Y% I* B. \9 U1 l
//exemplar attribute nodeA_1 preserve_signal true
: |5 T* z* R$ g$ ~* @2 p
8 V3 n3 ]* L$ }& Q//exemplar attribute nodeA_1 opt keep
; ?/ A3 e1 Z6 W( f* M& w4 {3 p
! R% m0 P1 r3 D5 {( J0 [0 w/ i
1 e4 {2 P& d/ l" b, x! ^7 i. _/**** The following comment form also works ****/
7 p I4 n' o' j f4 K# a6 c# V+ i2 A+ g! q+ I! L# M$ j0 {
/*exemplar attribute nodeA_0 preserve_signal true
: k. B% w7 \8 N% X1 @6 f R8 B
exemplar attribute nodeA_0 opt keep*/ # Y6 F+ r5 w0 O' C' \: P' k
`) l, \( Z ~" C2 `" _0 ~% J& L A0 {8 E2 e' b1 q
( T9 u" f' L9 y, M* v5 S9 _. T
1 q0 K4 H( d. d1 |
! h# u9 o: M" X7 @
- a/ C, r- }2 P" Y Q; u! D1 ]
) m. S" b, }% \& l. |# G. D3 |5 |/ ]# s$ y! w7 f# l. M0 |2 \8 Q
: |0 R3 \3 S8 U$ A9 P- R; w4 i
' I" h0 U4 E3 Y5 qwire nodeA/* synthesis syn_keep=1 opt="keep"*/;
* j1 }: N6 L2 H9 [wire nodeA_0/* synthesis syn_keep=1 opt="keep"*/;% R- l7 U1 a+ A) {1 ?$ s% `" m. c
wire nodeA_1/* synthesis syn_keep=1 opt="keep"*/;
' B; U7 @3 ]7 r0 i5 N" k% t* ^- lwire nodeA_2/* synthesis syn_keep=1 opt="keep"*/;* S& v; {3 p. H* r
wire nodeA_3/* synthesis syn_keep=1 opt="keep"*/;
* W) j! p2 P' x7 W% ^/ F6 U1 Z: k0 ?0 R- |wire nodeA_4/* synthesis syn_keep=1 opt="keep"*/;
- X: }8 f5 X# l# F5 X- E- ~
3 U9 e/ e* E4 fassign#1 nodeA_0 = sclk & ena;- F3 I7 ?. w4 R3 G. L7 _7 Z6 Y
+ v7 k4 t, i2 }* u; u5 U
assign#1 nodeA_1 = ~ nodeA_0;
9 e1 T4 I7 x" |1 ?assign#1 nodeA_2 = ~ nodeA_1;
3 d1 o, e g: tassign#1 nodeA_3 = ~ nodeA_2;- Y- V" U- h6 q( e: R" ^
assign#1 nodeA_4 = ~ nodeA_3;
8 `; k+ }7 j4 [" M& c
% `" Y/ a, J7 g: m4 Xreg xout;
z& ?; ^4 R* X/ c7 @( { | L
9 s' @* K$ H& s# T0 Y$ Xalways@(nodeA_1,nodeA_2,nodeA_3,nodeA_4,set)
8 H" [. ^/ X% {7 z4 B7 f# p& e/ E casez(set)
$ r, C" M# s# Y6 z 1: xout =#1 nodeA_2;8 N" q' {, _& |2 q4 I
2: xout =#1 nodeA_3;5 B( V1 H/ h! m2 f3 M6 U) y
3: xout =#1 nodeA_4;
3 X" t- `7 e7 E2 A' j5 a default: xout =#1 nodeA_1;0 F) Q7 a7 |5 L" B3 A: w
endcase
" ], b Y/ U) b. M! A
) _; j' x/ V% N# ]- T: r% {5 passign#1 nodeA = xout;
; C3 S U9 `; B0 I$ @ z$ {5 G5 Gassign#1 outp = ena ? nodeA^sclk : 1'bz;9 C" B: _( I* [1 Q4 |, P' x) g
/ r# c+ A0 ~" H
endmodule
* p4 V+ j- w0 C) D+ ]5 Y2 x% }% ] `* Z' E
0 B9 c4 ]5 \4 x- }& P/ M
! C! x2 o# h9 }! r
`timescale 1 ns / 1 ns
9 P1 ]4 `; Q8 [module xclk_tf();! M4 f' C3 \9 _" W$ [- l3 l
: W, J- ]1 [4 o- ?% b, r0 g6 Z1 D// Inputs
0 i- z1 N- e, R# @& |- E, l) p) o d reg sclk;3 m5 V, O* T' g
reg ena;
! i/ D8 K. f7 Y, X8 T reg [1:0] set;$ R) ~/ w; R- _7 K% b5 S; {
5 G* x8 ?" `1 h! {9 ]
7 T/ \) E5 a1 \! n. a// Outputs5 e0 |/ S7 M+ B* ~$ b8 J
wire outp;5 j# G `! |! ]% {
! @& m. [ p6 t& L) }
& V# I0 ~0 ]& s6 d" ~+ z; t, M
/ \5 k# o5 \6 G xclk UUT ( {) K" Q: ~" w \ `4 G* M
.sclk(sclk), . T$ p" c: i. {) H3 e* g7 s2 }6 A) `
.ena(ena),
' r; w& s% y3 B( y9 a( V .set(set),
3 v$ H7 E$ N- d4 Q! D+ D .outp(outp)
, `6 @7 v' P: l+ z( M4 z( @" O );
/ Y0 T: J, h( {5 j' ^& n8 b8 R7 p0 p6 l% d% L
# R6 l$ W; h2 V) d4 [# t' [( h J' l' G9 J4 p& w0 D
initial begin
0 Q/ l, @" {' K$ I' L& x sclk = 0;* \ l! K& `* @
ena = 0;
6 A9 M7 x# c$ Q set = 0;
# Z! h9 ?: T4 r' C3 b) k end
4 ] u/ t% E! P T! v) l0 @7 U
: z& E- d5 p, e+ Q! e n+ ~8 P0 ]! N0 Z5 J t$ ]6 v
always# 5 sclk = !sclk;4 v% ]8 U- L1 s1 T3 F
) B8 V, B1 j2 q3 `, U7 z
initial begin5 @/ ]1 n* {; L0 N9 P
#100
, l. F; M; I0 E y- q! K! f ena = 1;
$ I) V4 V8 u! ]- r: _# b #2000 ' E# m* V( f6 r% z& G
set = 2;: L# G4 a9 ~2 f3 X. C6 A t
#2000
6 h9 ~$ o0 b$ A set = 3;2 N8 V/ n8 _# I1 y% J, ?
#2000
. I6 h3 {( ~- ?# n" b8 C7 w $finish;4 ?1 J0 L! k* D9 N
end
6 J3 q$ H$ O) z; q) A" Tendmodule // xclk_tf |
|