1 |
6 |
mgeng |
----------------------------------------------------------------------
|
2 |
|
|
---- ----
|
3 |
|
|
---- Single port asynchronous RAM simulation model ----
|
4 |
|
|
---- ----
|
5 |
|
|
---- This file is part of the single_port project ----
|
6 |
|
|
---- ----
|
7 |
|
|
---- Description ----
|
8 |
|
|
---- This package implements functions to allocate, write, read ----
|
9 |
|
|
---- and deallocate a linked list based memory. ----
|
10 |
|
|
---- ----
|
11 |
|
|
---- Authors: ----
|
12 |
|
|
---- - Robert Paley, rpaley_yid@yahoo.com ----
|
13 |
|
|
---- - Michael Geng, vhdl@MichaelGeng.de ----
|
14 |
|
|
---- ----
|
15 |
|
|
---- References: ----
|
16 |
|
|
---- 1. The Designer's Guide to VHDL by Peter Ashenden ----
|
17 |
|
|
---- ISBN: 1-55860-270-4 (pbk.) ----
|
18 |
|
|
---- 2. Writing Testbenches - Functional Verification of HDL ----
|
19 |
|
|
---- models by Janick Bergeron | ISBN: 0-7923-7766-4 ----
|
20 |
|
|
---- ----
|
21 |
|
|
----------------------------------------------------------------------
|
22 |
|
|
---- ----
|
23 |
|
|
---- Copyright (C) 2005 Authors and OPENCORES.ORG ----
|
24 |
|
|
---- ----
|
25 |
|
|
---- This source file may be used and distributed without ----
|
26 |
|
|
---- restriction provided that this copyright statement is not ----
|
27 |
|
|
---- removed from the file and that any derivative work contains ----
|
28 |
|
|
---- the original copyright notice and the associated disclaimer. ----
|
29 |
|
|
---- ----
|
30 |
|
|
---- This source file is free software; you can redistribute it ----
|
31 |
|
|
---- and/or modify it under the terms of the GNU Lesser General ----
|
32 |
|
|
---- Public License as published by the Free Software Foundation; ----
|
33 |
|
|
---- either version 2.1 of the License, or (at your option) any ----
|
34 |
|
|
---- later version. ----
|
35 |
|
|
---- ----
|
36 |
|
|
---- This source is distributed in the hope that it will be ----
|
37 |
|
|
---- useful, but WITHOUT ANY WARRANTY; without even the implied ----
|
38 |
|
|
---- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ----
|
39 |
|
|
---- PURPOSE. See the GNU Lesser General Public License for more ----
|
40 |
|
|
---- details. ----
|
41 |
|
|
---- ----
|
42 |
|
|
---- You should have received a copy of the GNU Lesser General ----
|
43 |
|
|
---- Public License along with this source; if not, download it ----
|
44 |
|
|
---- from http://www.opencores.org/lgpl.shtml ----
|
45 |
|
|
---- ----
|
46 |
|
|
----------------------------------------------------------------------
|
47 |
2 |
rpaley_yid |
--
|
48 |
6 |
mgeng |
-- CVS Revision History
|
49 |
2 |
rpaley_yid |
--
|
50 |
6 |
mgeng |
-- $Log: not supported by cvs2svn $
|
51 |
8 |
mgeng |
-- Revision 1.2 2005/10/12 19:39:27 mgeng
|
52 |
|
|
-- Buses unconstrained, LGPL header added
|
53 |
|
|
--
|
54 |
6 |
mgeng |
-- Revision 1.1.1.1 2003/01/14 21:48:10 rpaley_yid
|
55 |
|
|
-- initial checkin
|
56 |
2 |
rpaley_yid |
--
|
57 |
6 |
mgeng |
-- Revision 1.1 2003/01/14 17:47:32 Default
|
58 |
|
|
-- Initial revision
|
59 |
|
|
--
|
60 |
|
|
-- Revision 1.1 2002/12/24 18:03:50 Default
|
61 |
|
|
-- Initial revision
|
62 |
|
|
--
|
63 |
2 |
rpaley_yid |
LIBRARY IEEE;
|
64 |
|
|
LIBRARY WORK;
|
65 |
|
|
USE IEEE.STD_LOGIC_1164.ALL;
|
66 |
|
|
USE WORK.single_port_pkg.all;
|
67 |
|
|
|
68 |
|
|
PACKAGE linked_list_mem_pkg IS
|
69 |
8 |
mgeng |
CONSTANT PAGEDEPTH : INTEGER := 256; -- memory page depth
|
70 |
6 |
mgeng |
-- pointer to one data word in the memory
|
71 |
|
|
-- The reason for using a pointer here is that it seems to be the only way to keep the model
|
72 |
|
|
-- independent of the data width
|
73 |
|
|
TYPE data_ptr IS ACCESS BIT_VECTOR;
|
74 |
2 |
rpaley_yid |
-- data memory array type definition
|
75 |
6 |
mgeng |
TYPE mem_array_typ IS ARRAY (0 TO PAGEDEPTH-1) OF data_ptr;
|
76 |
8 |
mgeng |
-- Define memory page linked list cell. This cell contains
|
77 |
|
|
-- the mem_array, starting page address, valid data array and
|
78 |
2 |
rpaley_yid |
-- the pointer to the next element in the linked list.
|
79 |
|
|
TYPE mem_page_typ;
|
80 |
|
|
-- pointer to next item in the linked list.
|
81 |
6 |
mgeng |
TYPE mem_page_ptr IS ACCESS mem_page_typ;
|
82 |
2 |
rpaley_yid |
TYPE mem_page_typ IS RECORD
|
83 |
6 |
mgeng |
mem_array : mem_array_typ; -- data memory
|
84 |
2 |
rpaley_yid |
page_address : addr_typ;
|
85 |
6 |
mgeng |
next_cell : mem_page_ptr;
|
86 |
2 |
rpaley_yid |
END RECORD mem_page_typ;
|
87 |
|
|
PROCEDURE rw_mem (
|
88 |
6 |
mgeng |
VARIABLE data : INOUT STD_LOGIC_VECTOR;
|
89 |
|
|
VARIABLE addr : IN addr_typ;
|
90 |
|
|
VARIABLE next_cell : INOUT mem_page_ptr;
|
91 |
|
|
CONSTANT write_flag : IN BOOLEAN);
|
92 |
2 |
rpaley_yid |
PROCEDURE deallocate_mem (
|
93 |
6 |
mgeng |
VARIABLE next_cell : INOUT mem_page_ptr);
|
94 |
2 |
rpaley_yid |
|
95 |
|
|
END PACKAGE linked_list_mem_pkg;
|
96 |
|
|
|
97 |
8 |
mgeng |
PACKAGE BODY linked_list_mem_pkg IS
|
98 |
2 |
rpaley_yid |
-- --------------------------------------------------
|
99 |
|
|
-- The purpose of this procedure is to write a memory location from
|
100 |
|
|
-- the linked list, if the particular page does not exist, create it.
|
101 |
|
|
-- --------------------------------------------------
|
102 |
|
|
PROCEDURE rw_mem (
|
103 |
6 |
mgeng |
VARIABLE data : INOUT STD_LOGIC_VECTOR;
|
104 |
|
|
VARIABLE addr : IN addr_typ;
|
105 |
|
|
VARIABLE next_cell : INOUT mem_page_ptr;
|
106 |
|
|
CONSTANT write_flag : IN BOOLEAN) IS
|
107 |
|
|
VARIABLE current_cell_v : mem_page_ptr; -- current page pointer
|
108 |
|
|
VARIABLE page_address_v : addr_typ; -- calculated page address
|
109 |
|
|
VARIABLE index_v : INTEGER; -- address within the memory page
|
110 |
|
|
VARIABLE mem_array_v : mem_array_typ;
|
111 |
2 |
rpaley_yid |
BEGIN
|
112 |
|
|
-- Copy the top of the linked list pointer to a working pointer
|
113 |
|
|
current_cell_v := next_cell;
|
114 |
|
|
-- Calculate the index within the page from the given address
|
115 |
|
|
index_v := addr MOD PAGEDEPTH;
|
116 |
|
|
-- Calculate the page address from the given address
|
117 |
|
|
page_address_v := addr - index_v;
|
118 |
|
|
-- Search through the memory to determine if the calculated
|
119 |
|
|
-- memory page exists. Stop searching when reach the end of
|
120 |
|
|
-- the linked list.
|
121 |
6 |
mgeng |
WHILE ( current_cell_v /= NULL AND
|
122 |
|
|
current_cell_v.page_address /= page_address_v) LOOP
|
123 |
2 |
rpaley_yid |
current_cell_v := current_cell_v.next_cell;
|
124 |
|
|
END LOOP;
|
125 |
|
|
|
126 |
|
|
IF write_flag THEN
|
127 |
|
|
IF ( current_cell_v /= NULL AND -- Check if address exists in memory.
|
128 |
6 |
mgeng |
current_cell_v.page_address = page_address_v ) THEN
|
129 |
2 |
rpaley_yid |
-- Found the memory page the particular address belongs to
|
130 |
6 |
mgeng |
IF ( current_cell_v.mem_array(index_v) /= NULL ) THEN
|
131 |
|
|
current_cell_v.mem_array(index_v).ALL := TO_BITVECTOR(data);
|
132 |
|
|
ELSE
|
133 |
|
|
current_cell_v.mem_array(index_v) := NEW BIT_VECTOR'(TO_BITVECTOR(data));
|
134 |
|
|
END IF;
|
135 |
2 |
rpaley_yid |
ELSE
|
136 |
|
|
-- The memory page the address belongs to was not allocated in memory.
|
137 |
|
|
-- Allocate page here and assign data.
|
138 |
6 |
mgeng |
mem_array_v(index_v) := NEW BIT_VECTOR'(TO_BITVECTOR(data));
|
139 |
|
|
next_cell := NEW mem_page_typ'( mem_array => mem_array_v,
|
140 |
2 |
rpaley_yid |
page_address => page_address_v,
|
141 |
6 |
mgeng |
next_cell => next_cell);
|
142 |
2 |
rpaley_yid |
END IF;
|
143 |
|
|
ELSE -- Read memory
|
144 |
|
|
IF ( current_cell_v /= NULL AND -- Check if address exists in memory.
|
145 |
|
|
current_cell_v.page_address = page_address_v AND
|
146 |
6 |
mgeng |
current_cell_v.mem_array(index_v) /= NULL ) THEN
|
147 |
2 |
rpaley_yid |
-- Found the memory page the particular address belongs to,
|
148 |
|
|
-- and the memory location has valid data.
|
149 |
6 |
mgeng |
data := TO_STDLOGICVECTOR(current_cell_v.mem_array(index_v).ALL);
|
150 |
2 |
rpaley_yid |
ELSE
|
151 |
|
|
-- Trying to read from unwritten or unallocated
|
152 |
|
|
-- memory location, return 'U';
|
153 |
6 |
mgeng |
data := (data'RANGE => 'U');
|
154 |
2 |
rpaley_yid |
END IF;
|
155 |
|
|
END IF;
|
156 |
|
|
END PROCEDURE rw_mem;
|
157 |
|
|
|
158 |
|
|
PROCEDURE deallocate_mem (
|
159 |
6 |
mgeng |
VARIABLE next_cell : INOUT mem_page_ptr) IS
|
160 |
2 |
rpaley_yid |
VARIABLE delete_cell_v : mem_page_ptr;
|
161 |
|
|
BEGIN
|
162 |
|
|
-- Deallocate the linked link memory from work station memory.
|
163 |
|
|
WHILE next_cell /= NULL LOOP -- while not reached the end of the LL
|
164 |
|
|
delete_cell_v := next_cell; -- Copy pointer to record for deleting
|
165 |
6 |
mgeng |
FOR i IN 0 TO PAGEDEPTH-1 LOOP
|
166 |
|
|
IF delete_cell_v.mem_array(i) /= NULL THEN
|
167 |
|
|
deallocate(delete_cell_v.mem_array(i));
|
168 |
|
|
END IF;
|
169 |
|
|
END LOOP;
|
170 |
2 |
rpaley_yid |
next_cell := next_cell.next_cell; -- set pointer to next cell in LL
|
171 |
|
|
deallocate(delete_cell_v); -- Deallocate current cell from memory.
|
172 |
|
|
END LOOP;
|
173 |
|
|
END PROCEDURE deallocate_mem;
|
174 |
8 |
mgeng |
END PACKAGE BODY linked_list_mem_pkg;
|