File : s-valllu.adb
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
5 -- S Y S T E M . V A L _ L L U --
-- --
-- S p e c --
-- --
-- $Revision: 1.12 $ --
10 -- --
-- Copyright (C) 1992-1997 Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
15 -- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT 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 --
20 -- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
25 -- 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. --
30 -- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
-- --
------------------------------------------------------------------------------
35
with System.Unsigned_Types; use System.Unsigned_Types;
with System.Val_Util; use System.Val_Util;
package body System.Val_LLU is
40
-----------------------------
-- Scan_Long_Long_Unsigned --
-----------------------------
45 function Scan_Long_Long_Unsigned
(Str : String;
Ptr : access Integer;
Max : Integer)
return Long_Long_Unsigned
50 is
P : Integer;
-- Local copy of the pointer
Uval : Long_Long_Unsigned;
55 -- Accumulated unsigned integer result
Expon : Integer;
-- Exponent value
60 Minus : Boolean := False;
-- Set to True if minus sign is present, otherwise to False. Note that
-- a minus sign is permissible for the singular case of -0, and in any
-- case the pointer is left pointing past a negative integer literal.
65 Overflow : Boolean := False;
-- Set True if overflow is detected at any point
Start : Positive;
-- Save location of first non-blank character
70
Base_Char : Character;
-- Base character (# or :) in based case
Base : Long_Long_Unsigned := 10;
75 -- Base value (reset in based case)
Digit : Long_Long_Unsigned;
-- Digit value
80 begin
Scan_Sign (Str, Ptr, Max, Minus, Start);
if Str (Ptr.all) not in '0' .. '9' then
Ptr.all := Start;
85 raise Constraint_Error;
end if;
P := Ptr.all;
Uval := Character'Pos (Str (P)) - Character'Pos ('0');
90 P := P + 1;
-- Scan out digits of what is either the number or the base.
-- In either case, we are definitely scanning out in base 10.
95 declare
Umax : constant := (Long_Long_Unsigned'Last - 9) / 10;
-- Max value which cannot overflow on accumulating next digit
Umax10 : constant := Long_Long_Unsigned'Last / 10;
100 -- Numbers bigger than Umax10 overflow if multiplied by 10
begin
-- Loop through decimal digits
loop
105 exit when P > Max;
Digit := Character'Pos (Str (P)) - Character'Pos ('0');
-- Non-digit encountered
110
if Digit > 9 then
if Str (P) = '_' then
Scan_Underscore (Str, P, Ptr, Max, False);
else
115 exit;
end if;
-- Accumulate result, checking for overflow
120 else
if Uval <= Umax then
Uval := 10 * Uval + Digit;
elsif Uval > Umax10 then
125 Overflow := True;
else
Uval := 10 * Uval + Digit;
130 if Uval < Umax10 then
Overflow := True;
end if;
end if;
135 P := P + 1;
end if;
end loop;
end;
140 Ptr.all := P;
-- Deal with based case
if P < Max and then (Str (P) = ':' or else Str (P) = '#') then
145 Base_Char := Str (P);
P := P + 1;
Base := Uval;
Uval := 0;
150 -- Check base value. Overflow is set True if we find a bad base, or
-- a digit that is out of range of the base. That way, we scan out
-- the numeral that is still syntactically correct, though illegal.
-- We use a safe base of 16 for this scan, to avoid zero divide.
155 if Base not in 2 .. 16 then
Overflow := True;
Base := 16;
end if;
160 -- Scan out based integer
declare
Umax : constant Long_Long_Unsigned :=
(Long_Long_Unsigned'Last - Base + 1) / Base;
165 -- Max value which cannot overflow on accumulating next digit
UmaxB : constant Long_Long_Unsigned :=
Long_Long_Unsigned'Last / Base;
-- Numbers bigger than UmaxB overflow if multiplied by base
170
begin
-- Loop to scan out based integer value
loop
175 -- We require a digit at this stage
if Str (P) in '0' .. '9' then
Digit := Character'Pos (Str (P)) - Character'Pos ('0');
180 elsif Str (P) in 'A' .. 'F' then
Digit :=
Character'Pos (Str (P)) - (Character'Pos ('A') - 10);
elsif Str (P) in 'a' .. 'f' then
185 Digit :=
Character'Pos (Str (P)) - (Character'Pos ('a') - 10);
-- If we don't have a digit, then this is not a based number
-- after all, so we use the value we scanned out as the base
190 -- (now in Base), and the pointer to the base character was
-- already stored in Ptr.all.
else
Uval := Base;
195 exit;
end if;
-- If digit is too large, just signal overflow and continue.
-- The idea here is to keep scanning as long as the input is
200 -- syntactically valid, even if we have detected overflow
if Digit >= Base then
Overflow := True;
205 -- Here we accumulate the value, checking overflow
elsif Uval <= Umax then
Uval := Base * Uval + Digit;
210 elsif Uval > UmaxB then
Overflow := True;
else
Uval := Base * Uval + Digit;
215
if Uval < UmaxB then
Overflow := True;
end if;
end if;
220
-- If at end of string with no base char, not a based number
-- but we signal Constraint_Error and set the pointer past
-- the end of the field, since this is what the ACVC tests
-- seem to require, see CE3704N, line 204.
225
P := P + 1;
if P > Max then
Ptr.all := P;
230 raise Constraint_Error;
end if;
-- If terminating base character, we are done with loop
235 if Str (P) = Base_Char then
Ptr.all := P + 1;
exit;
-- Deal with underscore
240
elsif Str (P) = '_' then
Scan_Underscore (Str, P, Ptr, Max, True);
end if;
245 end loop;
end;
end if;
-- Come here with scanned unsigned value in Uval. The only remaining
250 -- required step is to deal with exponent if one is present.
Expon := Scan_Exponent (Str, Ptr, Max);
if Expon /= 0 and then Uval /= 0 then
255
-- For non-zero value, scale by exponent value. No need to do this
-- efficiently, since use of exponent in integer literals is rare,
-- and in any case the exponent cannot be very large.
260 declare
UmaxB : constant Long_Long_Unsigned :=
Long_Long_Unsigned'Last / Base;
-- Numbers bigger than UmaxB overflow if multiplied by base
265 begin
for J in 1 .. Expon loop
if Uval > UmaxB then
Overflow := True;
exit;
270 end if;
Uval := Uval * Base;
end loop;
end;
275 end if;
-- Return result, dealing with sign and overflow
if Overflow or else (Minus and then Uval /= 0) then
280 raise Constraint_Error;
else
return Uval;
end if;
end Scan_Long_Long_Unsigned;
285
------------------------------
-- Value_Long_Long_Unsigned --
------------------------------
290 function Value_Long_Long_Unsigned
(Str : String)
return Long_Long_Unsigned
is
V : Long_Long_Unsigned;
295 P : aliased Integer := Str'First;
begin
V := Scan_Long_Long_Unsigned (Str, P'Access, Str'Last);
Scan_Trailing_Blanks (Str, P);
300 return V;
end Value_Long_Long_Unsigned;
end System.Val_LLU;