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發表於 2009-1-10 22:11:05
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- ------------------------------------------------------------------------------------$ f' n! P/ ^. a: c- A1 D
- library IEEE;5 T3 }4 |6 F+ @' e
- use IEEE.std_logic_1164.all;
! C$ h4 r/ u- J# o - entity fifo is
! ?; |* Q) B# _5 r - generic (- ^3 y; k7 z7 k3 l @6 S- m
- depth : positive := 168 o4 t* \* z. ^6 ~: o
- ); 7 @! @+ P5 X3 W( q7 O& S
- port(: n9 P' l2 E6 n* a( b1 h
- CLR : in std_logic;: T9 l) R/ d6 N6 l5 E; R2 A- m
- WCLK : in std_logic;
+ ~4 w; A5 ?! m/ F$ X - WE : in std_logic;
$ l, n! M9 M, ?0 u- M - RCLK : in std_logic;
+ @5 x' D" h: w& T: R& b - RE : in std_logic;9 k0 f; C9 S% P6 k h
- DATA : in std_logic_vector(7 downto 0);2 X) o: {: }. {8 w. [6 B+ N
- EMPTY : out std_logic;- n5 X6 o( O7 ^' o
- FULL : out std_logic;3 _( U ^/ [- _9 H/ I
- Q : out std_logic_vector(7 downto 0)9 i6 g9 V7 M" U% S0 l, e/ _6 A- l' u+ k
- );
1 {. |( C. D* f1 g" Z( n; {! A - end entity;7 p3 x0 `& D& Q; N( {
- library IEEE;
* i# ~% u( k. ~: C) y& w9 I/ C - use IEEE.std_logic_unsigned.all;) V/ C+ |- S' h/ m; a6 ~
- architecture behavior of fifo is
: Z% C* V4 h; m0 H, l- c - constant fmax : positive := depth-1;
8 ]2 A+ q0 C3 c$ ~# f' B# S6 i - type fifo_array_type is array (fmax downto 0) of std_logic_vector(7 downto 0);
7 E4 B6 B7 K0 O1 q - signal fifo_array : fifo_array_type;6 F) o, {: ~4 C- M S2 O
- signal WR_PTR : INTEGER range 0 to fmax;2 `3 k+ U, x8 I- ~# M
- signal RD_PTR : INTEGER range 0 to fmax;" p$ |9 b" R0 Y
- signal count : INTEGER range 0 to depth;
4 N; p7 {' I+ O - begin4 o# V/ @7 N' f
- CNT: process(CLR, WR_PTR, RD_PTR)
% i7 D" J% ~9 z! Q, p- c - variable change : integer;
i" J% o% j3 D' |- V. ^# a - begin
( V; m% g- W. @8 e/ Z x0 J - if CLR = '1' then i, r) |" i* F8 l
- count <= 0;
# G/ u4 U. W0 z) @! y1 l4 w - change := 0;4 M' B( V! D2 ^5 @- R9 T9 j6 R
- else
$ _1 q" P# V, \4 A* W6 O! } - change := 0;
4 @( @+ O" J: k: I - if WR_PTR'event then
( [- |! s/ O' | - change := 1;
. \ M7 ^$ F* t; n9 S2 @ - end if;. j6 F( N/ n9 @9 A
- if RD_PTR'event then- G' V6 l- U$ J/ G0 N1 A* x
- change := change - 1;" _! O0 B$ ~. k# `9 F
- end if; R( y- x/ S* |4 U' n9 G
- count <= count + change;7 |! ~2 Q4 a. |2 o# ~/ S8 y
- end if;. M. P" M' i$ l6 y# ] V
- end process; ) {! V- Z! i1 n' c2 ~ r' J
- STATUS: process(count)
) _* e! x8 P+ h$ O4 [3 v - begin
' V/ q9 z: E9 c5 u; {# V' x: v- ?0 ` - if count=0 then
0 v6 |0 s' n9 r3 x8 ]9 ]. G - FULL <= '0';3 \& m7 i, T6 v
- EMPTY <= '1';
: o( O0 l# W. H; {( O* J1 T) \ - elsif count=depth then- L- B2 v( E! H0 U% U
- FULL <= '1'; 2 \$ ~, N* F6 ]+ M3 B; z/ V
- EMPTY <= '0'; * s$ S; a' j( o# i4 S
- else
' Z6 r) ?2 {; }, o - FULL <= '0';
9 S) \, l- A8 l0 J f - EMPTY <= '0';
) g( }; A- W. B# I5 g9 [: J3 w$ E - end if;
3 I4 D' x; Q# J' j$ g - end process;
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