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Wrap

Text File | 1995-10-17 | 8.3 KB | 254 lines

------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S Y S T E M . V A L _ L L U -- -- -- -- S p e c -- -- -- -- $Revision: 1.7 $ -- -- -- -- Copyright (c) 1992,1993,1994 NYU, All Rights Reserved -- -- -- -- The GNAT library is free software; you can redistribute it and/or modify -- -- it under terms of the GNU Library General Public License as published by -- -- the Free Software Foundation; either version 2, or (at your option) any -- -- later version. The GNAT library 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 -- -- Library General Public License for more details. You should have -- -- received a copy of the GNU Library General Public License along with -- -- the GNAT library; see the file COPYING.LIB. If not, write to the Free -- -- Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. -- -- -- ------------------------------------------------------------------------------ with System.Unsigned_Types; use System.Unsigned_Types; with System.Val_Util; use System.Val_Util; package body System.Val_LLU is ----------------------------- -- Scan_Long_Long_Unsigned -- ----------------------------- function Scan_Long_Long_Unsigned (Str : String; Ptr : access Positive'Base; Max : Positive'Base) return Long_Long_Unsigned is P : Positive'Base; -- Local copy of the pointer Uval : Long_Long_Unsigned; -- Accumulated unsigned integer result (in the loop to scan out based -- numbers, this is the value of the base, scanned on entry) Bval : Long_Long_Unsigned; -- Value of based number accumulated New_Val : Long_Long_Unsigned; -- Used in checking overflow during accumulation of 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, not used for this case Base_Char : Character; -- Base character (# or :) in based case Base : Long_Long_Unsigned := 10; -- Base value (reset in based case) Digit : Long_Long_Unsigned; -- Digit value (0..15) in based case 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; -- Loop to scan out digits of what is either the number or the base loop exit when P > Max; -- Non-digit encountered if Str (P) not in '0' .. '9' then if Str (P) = '_' then Scan_Underscore (Str, P, Ptr, Max, False); else exit; end if; -- Accumulate result unless we have overflow. Overflow is detected -- by the wrap around, which results in the a smaller value. else New_Val := 10 * Uval + Character'Pos (Str (P)) - Character'Pos ('0'); if New_Val < Uval then Overflow := True; else Uval := New_Val; end if; P := P + 1; end if; end loop; 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; Bval := 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. if Uval not in 2 .. 16 then Overflow := True; end if; -- Loop to scan out based integer value loop -- We require a digit at this stage. If we don't have one, then -- it isn't a based number after all, so the number we scanned -- out as the base (still in Uval) is the value we wnat. 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); else exit; end if; -- Here we accumulate the value, checking overflow (which -- is detected by wrap around leaving the result smaller) if Digit >= Uval then Overflow := True; else New_Val := Bval * Uval + Digit; if New_Val < Bval then Overflow := True; else Bval := New_Val; 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; Base := Uval; Uval := Bval; exit; -- Deal with underscore elsif Str (P) = '_' then Scan_Underscore (Str, P, Ptr, Max, True); end if; end loop; 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. loop New_Val := Uval * Base; if New_Val < Uval then Overflow := True; else Uval := New_Val; end if; Expon := Expon - 1; exit when Expon = 0; end loop; 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_Long_Long_Unsigned; ------------------------------ -- Value_Long_Long_Unsigned -- ------------------------------ function Value_Long_Long_Unsigned (Str : String) return Long_Long_Unsigned is V : Long_Long_Unsigned; P : aliased Natural := Str'First; begin V := Scan_Long_Long_Unsigned (Str, P'Access, Str'Last); Scan_Trailing_Blanks (Str, P); return V; end Value_Long_Long_Unsigned; end System.Val_LLU;