1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- S Y S T E M . V A L _ U N S --
9 -- Copyright (C) 1992-1997 Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
32 ------------------------------------------------------------------------------
34 with System
.Unsigned_Types
; use System
.Unsigned_Types
;
35 with System
.Val_Util
; use System
.Val_Util
;
37 package body System
.Val_Uns
is
43 function Scan_Unsigned
50 -- Local copy of the pointer
53 -- Accumulated unsigned integer result
58 Minus
: Boolean := False;
59 -- Set to True if minus sign is present, otherwise to False. Note that
60 -- a minus sign is permissible for the singular case of -0, and in any
61 -- case the pointer is left pointing past a negative integer literal.
63 Overflow
: Boolean := False;
64 -- Set True if overflow is detected at any point
67 -- Save location of first non-blank character
69 Base_Char
: Character;
70 -- Base character (# or :) in based case
72 Base
: Unsigned
:= 10;
73 -- Base value (reset in based case)
79 Scan_Sign
(Str
, Ptr
, Max
, Minus
, Start
);
81 if Str
(Ptr
.all) not in '0' .. '9' then
83 raise Constraint_Error
;
87 Uval
:= Character'Pos (Str
(P
)) - Character'Pos ('0');
90 -- Scan out digits of what is either the number or the base.
91 -- In either case, we are definitely scanning out in base 10.
94 Umax
: constant := (Unsigned
'Last - 9) / 10;
95 -- Max value which cannot overflow on accumulating next digit
97 Umax10
: constant := Unsigned
'Last / 10;
98 -- Numbers bigger than Umax10 overflow if multiplied by 10
101 -- Loop through decimal digits
105 Digit
:= Character'Pos (Str
(P
)) - Character'Pos ('0');
107 -- Non-digit encountered
110 if Str
(P
) = '_' then
111 Scan_Underscore
(Str
, P
, Ptr
, Max
, False);
116 -- Accumulate result, checking for overflow
120 Uval
:= 10 * Uval
+ Digit
;
122 elsif Uval
> Umax10
then
126 Uval
:= 10 * Uval
+ Digit
;
128 if Uval
< Umax10
then
140 -- Deal with based case
142 if P
< Max
and then (Str
(P
) = ':' or else Str
(P
) = '#') then
143 Base_Char
:= Str
(P
);
148 -- Check base value. Overflow is set True if we find a bad base, or
149 -- a digit that is out of range of the base. That way, we scan out
150 -- the numeral that is still syntactically correct, though illegal.
151 -- We use a safe base of 16 for this scan, to avoid zero divide.
153 if Base
not in 2 .. 16 then
158 -- Scan out based integer
161 Umax
: constant Unsigned
:= (Unsigned
'Last - Base
+ 1) / Base
;
162 -- Max value which cannot overflow on accumulating next digit
164 UmaxB
: constant Unsigned
:= Unsigned
'Last / Base
;
165 -- Numbers bigger than UmaxB overflow if multiplied by base
168 -- Loop to scan out based integer value
171 -- We require a digit at this stage
173 if Str
(P
) in '0' .. '9' then
174 Digit
:= Character'Pos (Str
(P
)) - Character'Pos ('0');
176 elsif Str
(P
) in 'A' .. 'F' then
178 Character'Pos (Str
(P
)) - (Character'Pos ('A') - 10);
180 elsif Str
(P
) in 'a' .. 'f' then
182 Character'Pos (Str
(P
)) - (Character'Pos ('a') - 10);
184 -- If we don't have a digit, then this is not a based number
185 -- after all, so we use the value we scanned out as the base
186 -- (now in Base), and the pointer to the base character was
187 -- already stored in Ptr.all.
194 -- If digit is too large, just signal overflow and continue.
195 -- The idea here is to keep scanning as long as the input is
196 -- syntactically valid, even if we have detected overflow
198 if Digit
>= Base
then
201 -- Here we accumulate the value, checking overflow
203 elsif Uval
<= Umax
then
204 Uval
:= Base
* Uval
+ Digit
;
206 elsif Uval
> UmaxB
then
210 Uval
:= Base
* Uval
+ Digit
;
217 -- If at end of string with no base char, not a based number
218 -- but we signal Constraint_Error and set the pointer past
219 -- the end of the field, since this is what the ACVC tests
220 -- seem to require, see CE3704N, line 204.
226 raise Constraint_Error
;
229 -- If terminating base character, we are done with loop
231 if Str
(P
) = Base_Char
then
235 -- Deal with underscore
237 elsif Str
(P
) = '_' then
238 Scan_Underscore
(Str
, P
, Ptr
, Max
, True);
245 -- Come here with scanned unsigned value in Uval. The only remaining
246 -- required step is to deal with exponent if one is present.
248 Expon
:= Scan_Exponent
(Str
, Ptr
, Max
);
250 if Expon
/= 0 and then Uval
/= 0 then
252 -- For non-zero value, scale by exponent value. No need to do this
253 -- efficiently, since use of exponent in integer literals is rare,
254 -- and in any case the exponent cannot be very large.
257 UmaxB
: constant Unsigned
:= Unsigned
'Last / Base
;
258 -- Numbers bigger than UmaxB overflow if multiplied by base
261 for J
in 1 .. Expon
loop
272 -- Return result, dealing with sign and overflow
274 if Overflow
or else (Minus
and then Uval
/= 0) then
275 raise Constraint_Error
;
285 function Value_Unsigned
(Str
: String) return Unsigned
is
287 P
: aliased Integer := Str
'First;
290 V
:= Scan_Unsigned
(Str
, P
'Access, Str
'Last);
291 Scan_Trailing_Blanks
(Str
, P
);