|
5#
樓主 |
發表於 2009-1-10 22:11:05
|
只看該作者
- ------------------------------------------------------------------------------------4 `9 T& z2 G6 p$ Q9 f
- library IEEE;
) r. O" }: [8 y" z- O# o( x - use IEEE.std_logic_1164.all;
! ]1 @0 H6 ]% c - entity fifo is7 h1 M" b5 N; I \* s3 }& @6 t
- generic (
" y" {+ w# m$ P& x8 Z - depth : positive := 16- c1 y$ o6 s, N5 ~$ O
- );
5 F0 E8 n( X5 I& O! Q2 D - port(" E# i$ W/ e" _. B* q* r
- CLR : in std_logic; p% ?4 u) c2 K
- WCLK : in std_logic;
! L. v" [) e+ v4 f* t - WE : in std_logic;
- v7 _5 n2 _0 `, T - RCLK : in std_logic;# J! p: P" G6 o
- RE : in std_logic;0 P) U0 F2 N% L1 W2 _; R
- DATA : in std_logic_vector(7 downto 0);
9 y1 G' X0 L3 j# K9 U { - EMPTY : out std_logic;. ]5 |! ?3 M- N2 w$ `* i
- FULL : out std_logic;9 v0 O8 N" _" K, ]
- Q : out std_logic_vector(7 downto 0)/ \) g! B9 p0 Y6 y4 N1 }
- );
3 H4 k- T: {4 v4 `! a - end entity;
$ B' T- F3 @, q o - library IEEE;* L; b3 n! S2 a$ N
- use IEEE.std_logic_unsigned.all;
( a0 C! X1 m( S - architecture behavior of fifo is* g0 S! X3 I T/ C/ k
- constant fmax : positive := depth-1; 3 B+ z+ A- a5 J" w6 G: P
- type fifo_array_type is array (fmax downto 0) of std_logic_vector(7 downto 0);
, k- W0 _* ]2 }0 Q - signal fifo_array : fifo_array_type;
! t$ T2 t8 z" j - signal WR_PTR : INTEGER range 0 to fmax;+ T4 \# n9 B. n& B, f3 E
- signal RD_PTR : INTEGER range 0 to fmax;# t" V/ ?) P$ G4 l
- signal count : INTEGER range 0 to depth;9 x( D* C" M) A2 f# A
- begin
, E8 x- r1 }9 Y3 @% A& C - CNT: process(CLR, WR_PTR, RD_PTR)
; f( Y8 \7 m6 a, @ - variable change : integer;
: M, G* @- a+ L - begin + {1 U$ {. |9 j; |* }; O# i4 ^
- if CLR = '1' then& Y+ q1 s6 H4 E* o; e
- count <= 0;. W! e1 V$ R( t9 g! Y
- change := 0;
! }; F- N$ V3 R( Q - else8 @3 `: T$ A! P7 Z* ?
- change := 0; E9 Q4 T4 R4 F9 |1 N0 r/ Z
- if WR_PTR'event then8 N* Z' j1 T |5 k+ b" O
- change := 1;
4 l% D) r L( W i4 T% l; C' X - end if;
" a2 o# g6 v4 l4 D9 I5 N4 X2 ] - if RD_PTR'event then
5 t! O6 P2 n! Z3 r" A; H1 k } - change := change - 1;4 q* u ^: U$ g8 M& X) D! D
- end if;) `9 g$ x- b- |
- count <= count + change;
9 N0 O6 B# G7 {8 w% W - end if;9 ^8 i4 w/ j$ w- B2 Z
- end process;
3 \$ p' I- o. @; D - STATUS: process(count)
; E: F) Q. S! y9 A - begin / b% g, k$ {3 l/ n
- if count=0 then3 W8 v {& u* U3 k0 q! h D
- FULL <= '0';. u! }- h1 s' s7 m. }' L
- EMPTY <= '1';+ j+ R% X! b) f$ ~7 H( }' k2 P
- elsif count=depth then: _5 n/ Q+ ~4 p6 c$ k& z5 V
- FULL <= '1'; ) k+ O" W2 o) r+ H+ Y
- EMPTY <= '0';
5 r6 P7 k# b2 l, p - else 3 R3 W" H, ~( x3 H1 M* t
- FULL <= '0'; / D$ G# B4 K3 n) u5 ^
- EMPTY <= '0'; ( v& r; M! v$ a- f) r
- end if; # `2 \ `+ a6 x$ p7 y6 S4 d8 Y$ C
- end process;
複製代碼 |
|