|
5#
樓主 |
發表於 2009-1-10 22:11:05
|
只看該作者
- ------------------------------------------------------------------------------------
( J. C" B1 `, V5 ] - library IEEE;1 _$ a$ i( u, A1 I
- use IEEE.std_logic_1164.all;0 E* X. k, J) ^3 K& \
- entity fifo is
4 f& a! l. b8 Q6 D6 P - generic (# W0 e6 F' z. M2 P( k" P6 B6 N
- depth : positive := 16( H+ |( g2 @& b; J. n- `) u
- ); 3 G8 A0 A4 J' p, [! m# y1 A, o
- port(
- @- o( Q$ f/ g5 b- d - CLR : in std_logic;- K% q' |+ X- c
- WCLK : in std_logic;- m1 {" ]# x/ K& g% N
- WE : in std_logic;
) ` D, a, w1 }0 |1 `" m - RCLK : in std_logic;; r* x; w: S4 V( B
- RE : in std_logic;
; t/ s9 [1 v1 [* w# N - DATA : in std_logic_vector(7 downto 0);) j2 b a* B7 U7 `! a; u- h
- EMPTY : out std_logic;8 @# R; Q; Z" c7 l
- FULL : out std_logic;$ w2 D0 g3 u- X( M+ F, B) ~
- Q : out std_logic_vector(7 downto 0)( `) A5 d/ S+ ?
- );: Y- c0 p( Z+ ?
- end entity;
" \# Q9 K% Z9 X+ f6 h3 {6 @% |0 U - library IEEE;
7 J; S# M; K1 c j. J8 P0 D - use IEEE.std_logic_unsigned.all;" }" T3 E% L# _( P; H
- architecture behavior of fifo is7 z+ O1 ?) F& @
- constant fmax : positive := depth-1; 8 q7 F/ l* ]& m+ T c
- type fifo_array_type is array (fmax downto 0) of std_logic_vector(7 downto 0);
# ?1 @5 k# U9 i" r$ U' A - signal fifo_array : fifo_array_type;
3 I, N5 r) G. q7 [. P( c$ x2 G - signal WR_PTR : INTEGER range 0 to fmax;
0 C/ L5 l0 h# v - signal RD_PTR : INTEGER range 0 to fmax;
1 l; @0 h, x$ z/ p4 u+ o d5 P - signal count : INTEGER range 0 to depth;
t! M" Q7 c% G9 Y2 `; x. D - begin( m9 d* ?' G7 E
- CNT: process(CLR, WR_PTR, RD_PTR)4 j: y" P& C3 e. @
- variable change : integer;
. {1 l6 b% l3 |0 E; s/ y/ q) r: m - begin
: {6 P" \; ]! ^+ w - if CLR = '1' then
3 m7 p. d2 k% {+ L: j5 b5 m - count <= 0;6 w& N3 |# S0 S; M( Z* \
- change := 0;
. K4 b3 U4 g3 M% ?2 E - else- ^8 a' h) z' W. |9 d' C$ R% H
- change := 0;
& _# x' b! [: G' H. L9 D - if WR_PTR'event then
- z2 Y( T# d. f- p1 f - change := 1;% X5 r, d/ G! S E
- end if;
% O$ v1 @0 ^6 @% y1 |8 I' p5 G - if RD_PTR'event then
0 V/ t! q& f2 }: G& h' b - change := change - 1;, }7 |- v3 L6 f4 V/ r( I7 |7 R
- end if;5 @ G+ ^, C0 |1 V- K
- count <= count + change;
8 ?) [7 ?! Q' a$ b& h9 A' o3 c - end if;
# I, G y& r; ^1 U1 E% A - end process; 3 b% C: {) n/ x7 ?6 ^
- STATUS: process(count)
& r Q1 f3 t% D - begin
# b2 |& O+ W% ` - if count=0 then* j$ |- D' c4 V$ K& i& Q
- FULL <= '0';
: N/ B, s7 o& S8 m( W3 g - EMPTY <= '1';
# _5 ~8 g2 F3 z+ y3 @' M0 y - elsif count=depth then" r& z, A. l8 t5 O" ~' i; l& C
- FULL <= '1'; 3 {- I, U9 i& i: ]/ V
- EMPTY <= '0';
9 ]/ e" W7 Q- s# j7 R. { - else
9 `* }& G3 i" o9 y1 R3 r - FULL <= '0';
5 V, @+ m; O$ A: v1 X4 Z8 U7 c - EMPTY <= '0'; " N" n4 u+ I$ Q3 g4 g+ V
- end if; ; E0 G/ N1 f/ N
- end process;
複製代碼 |
|