------------------------------------------------------------------------------ | |

-- -- | |

-- GNAT COMPILER COMPONENTS -- | |

-- -- | |

-- S Y S T E M . V A L _ U N S -- | |

-- -- | |

-- B o d y -- | |

-- -- | |

-- 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- -- | |

-- 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 -- | |

-- 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 -- | |

-- 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. -- | |

-- -- | |

-- GNAT was originally developed by the GNAT team at New York University. -- | |

-- Extensive contributions were provided by Ada Core Technologies Inc. -- | |

-- -- | |

------------------------------------------------------------------------------ | |

with System.Unsigned_Types; use System.Unsigned_Types; | |

with System.Val_Util; use System.Val_Util; | |

package body System.Val_Uns is | |

------------------- | |

-- Scan_Unsigned -- | |

------------------- | |

function Scan_Unsigned | |

(Str : String; | |

Ptr : access Integer; | |

Max : Integer) | |

return Unsigned | |

is | |

P : Integer; | |

-- Local copy of the pointer | |

Uval : Unsigned; | |

-- Accumulated unsigned integer result | |

Expon : Integer; | |

-- Exponent value | |

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. | |

Overflow : Boolean := False; | |

-- Set True if overflow is detected at any point | |

Start : Positive; | |

-- Save location of first non-blank character | |

Base_Char : Character; | |

-- Base character (# or :) in based case | |

Base : Unsigned := 10; | |

-- Base value (reset in based case) | |

Digit : Unsigned; | |

-- Digit value | |

begin | |

Scan_Sign (Str, Ptr, Max, Minus, Start); | |

if Str (Ptr.all) not in '0' .. '9' then | |

Ptr.all := Start; | |

raise Constraint_Error; | |

end if; | |

P := Ptr.all; | |

Uval := Character'Pos (Str (P)) - Character'Pos ('0'); | |

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. | |

declare | |

Umax : constant := (Unsigned'Last - 9) / 10; | |

-- Max value which cannot overflow on accumulating next digit | |

Umax10 : constant := Unsigned'Last / 10; | |

-- Numbers bigger than Umax10 overflow if multiplied by 10 | |

begin | |

-- Loop through decimal digits | |

loop | |

exit when P > Max; | |

Digit := Character'Pos (Str (P)) - Character'Pos ('0'); | |

-- Non-digit encountered | |

if Digit > 9 then | |

if Str (P) = '_' then | |

Scan_Underscore (Str, P, Ptr, Max, False); | |

else | |

exit; | |

end if; | |

-- Accumulate result, checking for overflow | |

else | |

if Uval <= Umax then | |

Uval := 10 * Uval + Digit; | |

elsif Uval > Umax10 then | |

Overflow := True; | |

else | |

Uval := 10 * Uval + Digit; | |

if Uval < Umax10 then | |

Overflow := True; | |

end if; | |

end if; | |

P := P + 1; | |

end if; | |

end loop; | |

end; | |

Ptr.all := P; | |

-- Deal with based case | |

if P < Max and then (Str (P) = ':' or else Str (P) = '#') then | |

Base_Char := Str (P); | |

P := P + 1; | |

Base := Uval; | |

Uval := 0; | |

-- 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. | |

if Base not in 2 .. 16 then | |

Overflow := True; | |

Base := 16; | |

end if; | |

-- Scan out based integer | |

declare | |

Umax : constant Unsigned := (Unsigned'Last - Base + 1) / Base; | |

-- Max value which cannot overflow on accumulating next digit | |

UmaxB : constant Unsigned := Unsigned'Last / Base; | |

-- Numbers bigger than UmaxB overflow if multiplied by base | |

begin | |

-- Loop to scan out based integer value | |

loop | |

-- We require a digit at this stage | |

if Str (P) in '0' .. '9' then | |

Digit := Character'Pos (Str (P)) - Character'Pos ('0'); | |

elsif Str (P) in 'A' .. 'F' then | |

Digit := | |

Character'Pos (Str (P)) - (Character'Pos ('A') - 10); | |

elsif Str (P) in 'a' .. 'f' then | |

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 | |

-- (now in Base), and the pointer to the base character was | |

-- already stored in Ptr.all. | |

else | |

Uval := Base; | |

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 | |

-- syntactically valid, even if we have detected overflow | |

if Digit >= Base then | |

Overflow := True; | |

-- Here we accumulate the value, checking overflow | |

elsif Uval <= Umax then | |

Uval := Base * Uval + Digit; | |

elsif Uval > UmaxB then | |

Overflow := True; | |

else | |

Uval := Base * Uval + Digit; | |

if Uval < UmaxB then | |

Overflow := True; | |

end if; | |

end if; | |

-- 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. | |

P := P + 1; | |

if P > Max then | |

Ptr.all := P; | |

raise Constraint_Error; | |

end if; | |

-- If terminating base character, we are done with loop | |

if Str (P) = Base_Char then | |

Ptr.all := P + 1; | |

exit; | |

-- Deal with underscore | |

elsif Str (P) = '_' then | |

Scan_Underscore (Str, P, Ptr, Max, True); | |

end if; | |

end loop; | |

end; | |

end if; | |

-- Come here with scanned unsigned value in Uval. The only remaining | |

-- 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 | |

-- 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. | |

declare | |

UmaxB : constant Unsigned := Unsigned'Last / Base; | |

-- Numbers bigger than UmaxB overflow if multiplied by base | |

begin | |

for J in 1 .. Expon loop | |

if Uval > UmaxB then | |

Overflow := True; | |

exit; | |

end if; | |

Uval := Uval * Base; | |

end loop; | |

end; | |

end if; | |

-- Return result, dealing with sign and overflow | |

if Overflow or else (Minus and then Uval /= 0) then | |

raise Constraint_Error; | |

else | |

return Uval; | |

end if; | |

end Scan_Unsigned; | |

-------------------- | |

-- Value_Unsigned -- | |

-------------------- | |

function Value_Unsigned (Str : String) return Unsigned is | |

V : Unsigned; | |

P : aliased Integer := Str'First; | |

begin | |

V := Scan_Unsigned (Str, P'Access, Str'Last); | |

Scan_Trailing_Blanks (Str, P); | |

return V; | |

end Value_Unsigned; | |

end System.Val_Uns; |