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
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
-- GHDL Run Time (GRT) - support for exp
-- Copyright (C) 2022 Tristan Gingold
--
-- This program 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.
--
-- This program 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 this program. If not, see <gnu.org/licenses>.
--
-- As a special exception, if other files instantiate generics from this
-- unit, or you link this unit with other files to produce an executable,
-- this unit does not by itself cause the resulting executable to be
-- covered by the GNU General Public License. This exception does not
-- however invalidate any other reasons why the executable file might be
-- covered by the GNU Public License.
package body Grt.Arith is
function Hi (V : Ghdl_U64) return Ghdl_U32 is
begin
return Ghdl_U32 (Shift_Right (V, 32) and 16#ffff_ffff#);
end Hi;
pragma Inline (Hi);
function Lo (V : Ghdl_U64) return Ghdl_U32 is
begin
return Ghdl_U32 (V and 16#ffff_ffff#);
end Lo;
pragma Inline (Lo);
function Hi (V : Ghdl_I64) return Ghdl_U32 is
begin
return Hi (To_Ghdl_U64 (V));
end Hi;
function Lo (V : Ghdl_I64) return Ghdl_U32 is
begin
return Lo (To_Ghdl_U64 (V));
end Lo;
procedure Mul_I32_Ovf (L, R : Ghdl_I32;
Res : out Ghdl_I32;
Ovf : out Boolean)
is
T : Ghdl_I64;
begin
T := Ghdl_I64 (L) * Ghdl_I64 (R);
if Hi (T) /= Shift_Right_Arithmetic (Lo (T), 31) then
Ovf := True;
else
Ovf := False;
Res := Ghdl_I32 (T);
end if;
end Mul_I32_Ovf;
procedure Mul_U64_Ovf (L, R : Ghdl_U64;
Res : out Ghdl_U64;
Ovf : out Boolean)
is
Ll : constant Ghdl_U32 := Lo (L);
Lh : constant Ghdl_U32 := Hi (L);
Rl : constant Ghdl_U32 := Lo (R);
Rh : constant Ghdl_U32 := Hi (R);
-- Result is:
-- Ll * Rl
-- Lh * Rl
-- Ll * Rh
-- Lh * Rh
Vll, Vhl, Vhh : Ghdl_U64;
begin
Vhh := Ghdl_U64 (Lh) * Ghdl_U64 (Rh);
if Vhh /= 0 then
Ovf := True;
return;
end if;
-- Note: no overflow in the addition because either Rh = 0 or Lh = 0.
Vhl := Ghdl_U64 (Lh) * Ghdl_U64 (Rl) + Ghdl_U64 (Ll) * Ghdl_U64 (Rh);
Vll := Ghdl_U64 (Ll) * Ghdl_U64 (Rl);
Vhl := Vhl + Ghdl_U64 (Hi (Vll));
if Hi (Vhl) /= 0 then
Ovf := True;
else
Ovf := False;
Res := Shift_Left (Vhl, 32) or Ghdl_U64 (Lo (Vll));
end if;
end Mul_U64_Ovf;
procedure Exp_I64 (V : Ghdl_I64;
E : Std_Integer;
Res : out Ghdl_I64;
Ovf : out Boolean)
is
R : Std_Integer;
P : Ghdl_U64;
Ures : Ghdl_U64;
begin
if E < 0 then
Ovf := True;
return;
elsif E = 1 then
Res := V;
Ovf := False;
return;
end if;
P := To_Ghdl_U64 (V);
if V < 0 then
-- Avoid overflow.
P := (not P) + 1;
end if;
Ures := 1;
R := E;
loop
if R mod 2 = 1 then
Mul_U64_Ovf (Ures, P, Ures, Ovf);
if Ovf then
return;
end if;
end if;
R := R / 2;
exit when R = 0;
Mul_U64_Ovf (P, P, P, Ovf);
if Ovf then
return;
end if;
end loop;
if V < 0 and (E mod 2) = 1 then
-- Need to negate the result.
if Shift_Right (Ures, 63) = 1 then
if Shift_Left (Ures, 1) = 0 then
Res := To_Ghdl_I64 (Ures);
Ovf := False;
else
Ovf := True;
end if;
return;
end if;
Res := To_Ghdl_I64 ((not Ures) + 1);
else
if Shift_Right (Ures, 63) = 1 then
Ovf := True;
return;
end if;
Ovf := False;
Res := To_Ghdl_I64 (Ures);
end if;
Ovf := False;
end Exp_I64;
procedure Exp_I32 (V : Ghdl_I32;
E : Std_Integer;
Res : out Ghdl_I32;
Ovf : out Boolean)
is
R : Std_Integer;
P : Ghdl_I32;
begin
if E < 0 then
Ovf := True;
return;
end if;
Res := 1;
P := V;
R := E;
loop
if R mod 2 = 1 then
Mul_I32_Ovf (Res, P, Res, Ovf);
if Ovf then
return;
end if;
end if;
R := R / 2;
exit when R = 0;
Mul_I32_Ovf (P, P, P, Ovf);
if Ovf then
return;
end if;
end loop;
Ovf := False;
end Exp_I32;
end Grt.Arith;
|
