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先给出代码
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module fsm (# @) X2 b3 e+ `% @& o/ f# E0 ]5 J
clk,# ^) R0 D: i4 {. ~
rst_n,
# R3 `; H- t5 {5 s* ^ w_i,
5 \; v* ?8 O6 _% S" F z_o
# G' F5 K, Z* n4 q: X, w);( y) Y! N7 B, q! B9 N% X8 d- N: T
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input clk;
2 |1 \6 z# |& c$ q% ` tinput rst_n;
0 [ @ i) W& {$ O' `input w_i;
1 B% M3 ~% k9 ioutput z_o;
4 L& X/ z' v3 Y o9 e5 o# r( L8 E
4 p; _2 {$ k4 a8 M* Y( E6 k7 I& mparameter IDLE = 2'b00;
0 E, A- H, ?* {2 Oparameter S0 = 2'b01;2 ~; Z4 W& Q; i, a' L% Y
parameter S1 = 2'b10;
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reg [1:0] curr_state;' y1 ]" v H2 V- v8 Y5 ~* a5 C
reg [1:0] next_state;: J* z+ O" b L7 |2 X
reg z_o;
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3 {, E: R' _6 w4 S// state reg+ d' u0 A2 i6 H5 E0 g" S% c
always@(posedge clk or negedge rst_n)
0 G2 j" L4 o$ ^& V2 [ if (~rst_n) curr_state <= IDLE;
! e3 M* s0 F6 b( l else curr_state <= next_state;$ N/ ^0 Y$ K7 Z" d; Z) \- }! X5 _
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// next state logic
6 I" r* H8 R) y" Walways@(*)
: X# u. e9 h, Q' v case (curr_state)% F; y# p: y0 a4 K; `, ^2 t
IDLE : if (w_i) next_state = S0;' [/ n" t; ]2 T
else next_state = IDLE;' A7 S/ F2 t( J( \, b
S0 : if (w_i) next_state = S1;
4 R) Y' K+ g% P% \; m else next_state = IDLE;
0 `" c2 d% `+ V! K& F8 K S1 : if (w_i) next_state = S1;( V c7 x% Z9 L3 Q Z. }4 d
else next_state = IDLE;) z" ?3 _" ~5 y
default : next_state = IDLE;6 V0 Y4 |# `; T
endcase 4 A& E, ^& H1 \* t
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// output logic9 b" ^5 F. Y' x- C4 m: v
always@(*)+ e4 S7 s; w5 V- z
case (curr_state)
% q$ @" t8 U6 s ]- F5 g- U IDLE : z_o = 1'b0;* D" P1 y% G; R( F: S1 e7 K9 V
S0 : z_o = 1'b0;; L( C& e% Z1 O- R( I5 r+ e
S1 : z_o = 1'b1;$ Z% N* L8 E& U, e
default : z_o = 1'b0;# ?! ~+ v+ ~+ ?% [4 h" c4 o
endcase# J0 Y# ?0 u5 O G
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endmodule
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# f+ [2 v0 \8 L& G9 Y然后是状态机的结构图:2 r2 F7 q7 r( Q
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然后再来一个时序图:
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6 i. w; ~6 Z( M可以发现状态机S0已被综合掉了。; e- B; | O0 A; N4 Y& P. x
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