1 --------------------------------------------------------------------------
2 --
3 -- Copyright (C) 1993, Peter J. Ashenden
4 -- Mail: Dept. Computer Science
5 -- University of Adelaide, SA 5005, Australia
6 -- e-mail: petera@cs.adelaide.edu.au
7 --
8 -- This program is free software; you can redistribute it and/or modify
9 -- it under the terms of the GNU General Public License as published by
10 -- the Free Software Foundation; either version 1, or (at your option)
11 -- any later version.
12 --
13 -- This program is distributed in the hope that it will be useful,
14 -- but WITHOUT ANY WARRANTY; without even the implied warranty of
15 -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 -- GNU General Public License for more details.
17 --
18 -- You should have received a copy of the GNU General Public License
19 -- along with this program; if not, write to the Free Software
20 -- Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 --
22 --------------------------------------------------------------------------
23 --
24 -- $RCSfile: images-body.vhdl,v $ $Revision: 1.1 $ $Date: 2000/05/08 14:36:48 $
25 --
26 --------------------------------------------------------------------------
27 --
28 -- Images package body.
29 --
30 -- Functions that return the string image of values.
31 -- Each image is a correctly formed literal according to the
32 -- rules of VHDL-93.
33 --
34 --------------------------------------------------------------------------
35
36 package body images is
37
38
39 -- Image of bit vector as binary bit string literal
40 -- (in the format B"...")
41 -- Length of result is bv'length + 3
42
43 function image (bv : in bit_vector) return string is
44
45 alias bv_norm : bit_vector(1 to bv'length) is bv;
46 variable result : string(1 to bv'length + 3);
47
48 begin
49 result(1) := 'B';
50 result(2) := '"';
51 for index in bv_norm'range loop
52 if bv_norm(index) = '0' then
53 result(index + 2) := '0';
54 else
55 result(index + 2) := '1';
56 end if;
57 end loop;
58 result(bv'length + 3) := '"';
59 return result;
60 end image;
61
62 ----------------------------------------------------------------
63
64 -- Image of bit vector as octal bit string literal
65 -- (in the format O"...")
66 -- Length of result is (bv'length+2)/3 + 3
67
68 function image_octal (bv : in bit_vector) return string is
69
70 constant nr_digits : natural := (bv'length + 2) / 3;
71 variable result : string(1 to nr_digits + 3);
72 variable bits : bit_vector(0 to 3*nr_digits - 1) := (others => '0');
73 variable three_bits : bit_vector(0 to 2);
74 variable digit : character;
75
76 begin
77 result(1) := 'O';
78 result(2) := '"';
79 bits(bits'right - bv'length + 1 to bits'right) := bv;
80 for index in 0 to nr_digits - 1 loop
81 three_bits := bits(3*index to 3*index + 2);
82 case three_bits is
83 when b"000" =>
84 digit := '0';
85 when b"001" =>
86 digit := '1';
87 when b"010" =>
88 digit := '2';
89 when b"011" =>
90 digit := '3';
91 when b"100" =>
92 digit := '4';
93 when b"101" =>
94 digit := '5';
95 when b"110" =>
96 digit := '6';
97 when b"111" =>
98 digit := '7';
99 end case;
100 result(index + 3) := digit;
101 end loop;
102 result(nr_digits + 3) := '"';
103 return result;
104 end image_octal;
105
106 ----------------------------------------------------------------
107
108 -- Image of bit vector as hex bit string literal
109 -- (in the format X"...")
110 -- Length of result is (bv'length+3)/4 + 3
111
112 function image_hex (bv : in bit_vector) return string is
113
114 constant nr_digits : natural := (bv'length + 3) / 4;
115 variable result : string(1 to nr_digits + 3);
116 variable bits : bit_vector(0 to 4*nr_digits - 1) := (others => '0');
117 variable four_bits : bit_vector(0 to 3);
118 variable digit : character;
119
120 begin
121 result(1) := 'X';
122 result(2) := '"';
123 bits(bits'right - bv'length + 1 to bits'right) := bv;
124 for index in 0 to nr_digits - 1 loop
125 four_bits := bits(4*index to 4*index + 3);
126 case four_bits is
127 when b"0000" =>
128 digit := '0';
129 when b"0001" =>
130 digit := '1';
131 when b"0010" =>
132 digit := '2';
133 when b"0011" =>
134 digit := '3';
135 when b"0100" =>
136 digit := '4';
137 when b"0101" =>
138 digit := '5';
139 when b"0110" =>
140 digit := '6';
141 when b"0111" =>
142 digit := '7';
143 when b"1000" =>
144 digit := '8';
145 when b"1001" =>
146 digit := '9';
147 when b"1010" =>
148 digit := 'A';
149 when b"1011" =>
150 digit := 'B';
151 when b"1100" =>
152 digit := 'C';
153 when b"1101" =>
154 digit := 'D';
155 when b"1110" =>
156 digit := 'E';
157 when b"1111" =>
158 digit := 'F';
159 end case;
160 result(index + 3) := digit;
161 end loop;
162 result(nr_digits + 3) := '"';
163 return result;
164 end image_hex;
165
166
167 end images;
168
This page was generated using GHDL 0.14 (20040829) [Sokcho edition], a program written by Tristan Gingold