1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
-- Copyright (C) 2002 Morgan Kaufmann Publishers, Inc
-- This file is part of VESTs (Vhdl tESTs).
-- VESTs is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at
-- your option) any later version.
-- VESTs is distributed in the hope that it will be useful, but WITHOUT
-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
-- for more details.
-- You should have received a copy of the GNU General Public License
-- along with VESTs; if not, write to the Free Software Foundation,
-- Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package bit_vector_signed_arithmetic is
function "+" ( bv1, bv2 : bit_vector ) return bit_vector;
function "-" ( bv : bit_vector ) return bit_vector;
function "*" ( bv1, bv2 : bit_vector ) return bit_vector;
-- . . .
end package bit_vector_signed_arithmetic;
--------------------------------------------------
-- not in book
library ieee; use ieee.numeric_bit.all;
-- end not in book
package body bit_vector_signed_arithmetic is
function "+" ( bv1, bv2 : bit_vector ) return bit_vector is -- . . .
-- not in book
begin
return bit_vector( "+"(signed(bv1), signed(bv2)) );
end function "+";
-- end not in book
function "-" ( bv : bit_vector ) return bit_vector is -- . . .
-- not in book
begin
return bit_vector( "-"(signed(bv)) );
end function "-";
-- end not in book
function mult_unsigned ( bv1, bv2 : bit_vector ) return bit_vector is
-- . . .
begin
-- not in book
-- . . .
return bit_vector( "*"(unsigned(bv1), unsigned(bv2)) );
-- end not in book
end function mult_unsigned;
function "*" ( bv1, bv2 : bit_vector ) return bit_vector is
begin
if bv1(bv1'left) = '0' and bv2(bv2'left) = '0' then
return mult_unsigned(bv1, bv2);
elsif bv1(bv1'left) = '0' and bv2(bv2'left) = '1' then
return -mult_unsigned(bv1, -bv2);
elsif bv1(bv1'left) = '1' and bv2(bv2'left) = '0' then
return -mult_unsigned(-bv1, bv2);
else
return mult_unsigned(-bv1, -bv2);
end if;
end function "*";
-- . . .
end package body bit_vector_signed_arithmetic;
|
