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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。4 B# M& ?$ Q8 ^; J( c2 [
//所有註解都要保留* r" f/ L, d* T' B. o7 H3 I* Z
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`timescale 1 ns / 1 ns
' {* g: v! k2 ~: x# H; Gmodule xclk(sclk,ena,set,outp);0 f2 T+ d+ z1 A( I: D) Y- l
$ n; ]. t' \. ^+ `
! }7 J9 ^1 q" c" r7 P' }; l( H
4 o. R8 ^7 P+ s1 a/ f% Q* ]input sclk,ena;
7 i$ @% C# z7 M6 o2 Uinput [1:0]set;
/ u/ C& L( w+ L4 m1 K6 t& U1 Woutput outp; : r" ^7 S: L, ~5 A, p, \
9 K9 F3 e% v& y. P- {9 I9 Swire outp;
% N$ H- y1 g. n6 ]+ w6 X. E/ r5 n6 K6 o& E+ F$ u* q0 N% d
- r- S! N8 n% U8 J0 L6 ?% a8 w' {9 R# J, F% H# J; N! c
/**** Node preservation for nodeA **************/( ^8 a' i& |3 [+ r2 Z, R' C
7 Y6 y' T/ W" `
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//exemplar attribute nodeA_5 preserve_signal true' Y1 J( L" E/ D/ j x [) R) i
8 l" F! h4 w$ A5 M4 L* Z- z//exemplar attribute nodeA_4 opt keep
0 o! F r$ _5 g7 y
2 m) F$ a# v H" }/**** The following comment form also works ****/; ^) Q6 T" n+ f1 H9 B% [
' A6 J& G* M0 s \6 Z$ o
//exemplar attribute nodeA_3 preserve_signal true
6 Z- k' ]2 ~, b! s5 ~5 J8 W: {* H, x. v$ D/ m; o/ c
//exemplar attribute nodeA_3 opt keep {7 ^. }4 U: k$ O9 n
! ?! S3 p8 M; c& ^$ l
/**** The following comment form also works ****/! |( Q% \# ]( V }/ @5 U
: | v, i+ G7 o2 _* f) M) R) P% t
//exemplar attribute nodeA_2 preserve_signal true
; ]" e2 v3 B1 _0 V# j8 K$ q$ l
3 ?% G" `9 i, {: }" J. F( t/ N# I( f//exemplar attribute nodeA_2 opt keep r2 D6 O" N( T$ X/ X3 E
; Y6 m. W$ E+ O3 b4 m# l/**** The following comment form also works ****/* h8 j# f, Y/ v, F) \
& }" S* @. B+ v: }# }! K5 W//exemplar attribute nodeA_1 preserve_signal true2 D9 a: U4 p; l# y
3 s# k f9 {/ I! ^- M7 n
//exemplar attribute nodeA_1 opt keep
7 i% p1 P" Q! j; j+ w ; Z% `/ N) m, H% y6 N4 j
4 {# J# o4 K. c8 ]* o- p: T
/**** The following comment form also works ****/
9 s* V/ i: p! ^1 O
$ M# g6 e' X3 D: G+ M% H/*exemplar attribute nodeA_0 preserve_signal true
t$ H0 k% Q, w9 i6 |9 S6 y- O. i6 n4 [3 _
exemplar attribute nodeA_0 opt keep*/
1 @+ X+ p" F8 m. v9 E
& j0 k, `* H7 U( Z3 p( m1 m6 t. N& B) b
7 s, F& ]9 K) A
/ A7 A G6 A8 m2 x l B( ~3 r9 w M' G
7 ^0 o7 ~; u; |
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5 @5 `! A, d; J& Q0 X. [8 ]+ \3 L
) ~# L5 _% p2 A7 K B" }$ E! swire nodeA/* synthesis syn_keep=1 opt="keep"*/;; A8 f1 L/ N4 d1 J& ~
wire nodeA_0/* synthesis syn_keep=1 opt="keep"*/;
. `( R+ A, ^$ r& \wire nodeA_1/* synthesis syn_keep=1 opt="keep"*/;7 d; k& z5 d" n; N
wire nodeA_2/* synthesis syn_keep=1 opt="keep"*/;
( o6 ?0 z8 t. n( Qwire nodeA_3/* synthesis syn_keep=1 opt="keep"*/;. V- F4 u4 B5 `9 ?
wire nodeA_4/* synthesis syn_keep=1 opt="keep"*/;% h- q( N# A3 o, I+ L$ l
! z1 L0 o5 J" c' R9 j
assign#1 nodeA_0 = sclk & ena;
9 s: T& O- v1 P9 j" `& O/ a3 y1 T* L2 s. {0 q9 B$ W
assign#1 nodeA_1 = ~ nodeA_0;' u9 n! D8 K1 S g
assign#1 nodeA_2 = ~ nodeA_1;9 ^& p+ O$ G( F7 Q
assign#1 nodeA_3 = ~ nodeA_2;- Y, H# e" \2 K, N2 V& }" S0 u
assign#1 nodeA_4 = ~ nodeA_3;9 ]" R% S7 a* A! ]
v! {, g6 t( x R3 X. v
reg xout;
" @( [3 L) R: X" {4 B* g
" @( l j7 J! [: i8 T* ]4 Jalways@(nodeA_1,nodeA_2,nodeA_3,nodeA_4,set)% k+ b) W2 E N" {! J& R
casez(set)) I0 @; g/ O2 A( b( a1 g; l
1: xout =#1 nodeA_2;
3 x6 T/ c7 w9 D! Y& b 2: xout =#1 nodeA_3;
* C* u3 |: _0 p2 ?0 L 3: xout =#1 nodeA_4;/ _0 q8 X# H( H. X
default: xout =#1 nodeA_1;% b# ?* M4 p7 C! \7 D
endcase, g Y& R5 Y5 ?- `
$ x- H+ Q5 I- oassign#1 nodeA = xout;* V% H& K/ I! J0 l7 d6 v& K+ D
assign#1 outp = ena ? nodeA^sclk : 1'bz;7 h) o! c3 x3 G" }: \, C
& Y$ q: M! B1 p' U- [! ?
endmodule
4 u% N$ Z! x7 N4 E4 @( C# {" e! {* |# @" \) S
, V3 Y& i. g# ]8 j! L
7 n* g4 K' F, E: G7 m`timescale 1 ns / 1 ns) W# f8 H z& j0 k8 k% w
module xclk_tf();
4 y$ ^! s, K z3 ^; ^2 g% w- h, V0 H4 P9 k
// Inputs2 _8 G3 h1 C( i" Y8 I m+ K
reg sclk;
. v% u' O8 q6 g) h2 J reg ena;
; y( @ k$ {; [$ C reg [1:0] set;4 W7 a! V# C7 c* x
: g" X8 t/ A& l/ l5 f! \
" o1 s0 C0 k4 [0 {( h// Outputs$ l$ F$ w8 n9 E
wire outp;
! F5 G! a& h( b; U% M, Z+ {
# @- Q9 R% {' p* x% p& v
# x6 y% S. H9 W0 m2 d) [; t, v: C8 {; C
xclk UUT () n$ h5 r' X1 J2 y& |
.sclk(sclk), 5 _, u: {9 e' _% J
.ena(ena),
- p" c3 i+ B5 z0 p, O .set(set), 2 C: Q) h$ H. F6 r2 d- }
.outp(outp)
4 J# s$ n1 t; \5 ]6 D( Y* l5 o );
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initial begin
4 R. f4 m6 g1 N3 K3 M5 h8 R4 F7 { sclk = 0;
7 I/ L/ s" J( T; _ ena = 0;' p* V4 Q- R, c
set = 0;, U& h, k; I. A& r9 b
end
" j0 ^! Q& U& f$ A% V6 g, t: M( w: E% @% E! l2 X n
1 W# l3 }1 I7 m! Q5 |- f# M
always# 5 sclk = !sclk;3 ]: [6 O4 O x. f0 |% D/ s0 P
- d; u+ o# \9 ^* Y
initial begin
! t. Y+ D: y( \! `8 V #100) g0 I" P O' x$ }
ena = 1;
) f* F, i7 k3 I #2000 n* a/ H- Z6 o- I" A
set = 2;9 E+ m# d N- W$ Q' @, M/ ]
#2000
. r' c3 c- z C. n3 k- t set = 3;
" j' ^( [5 V+ I! @! ~ #2000
6 B0 H$ E' G/ A$ a0 r $finish;
. v7 o+ W1 ]3 x# c$ w2 G2 M, [4 Kend
9 p2 N' e }: H- mendmodule // xclk_tf |
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發表於 2007-3-17 11:29:24
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