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Diffstat (limited to 'gcc/ada/libgnat/s-valuer.ads')
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1 files changed, 99 insertions, 0 deletions
diff --git a/gcc/ada/libgnat/s-valuer.ads b/gcc/ada/libgnat/s-valuer.ads new file mode 100644 index 00000000000..8d2f3fde11a --- /dev/null +++ b/gcc/ada/libgnat/s-valuer.ads @@ -0,0 +1,99 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S Y S T E M . V A L U E _ R -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 2020, 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 3, 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. -- +-- -- +-- As a special exception under Section 7 of GPL version 3, you are granted -- +-- additional permissions described in the GCC Runtime Library Exception, -- +-- version 3.1, as published by the Free Software Foundation. -- +-- -- +-- You should have received a copy of the GNU General Public License and -- +-- a copy of the GCC Runtime Library Exception along with this program; -- +-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- +-- <http://www.gnu.org/licenses/>. -- +-- -- +-- GNAT was originally developed by the GNAT team at New York University. -- +-- Extensive contributions were provided by Ada Core Technologies Inc. -- +-- -- +------------------------------------------------------------------------------ + +-- This package contains routines for scanning real values for use in +-- Text_IO.Decimal_IO, Fixed_IO, Float_IO and the Value attribute. + +with System.Unsigned_Types; use System.Unsigned_Types; + +generic + + type Uns is mod <>; + + Floating : Boolean; + +package System.Value_R is + pragma Preelaborate; + + function Scan_Raw_Real + (Str : String; + Ptr : not null access Integer; + Max : Integer; + Base : out Unsigned; + Scale : out Integer; + Extra : out Unsigned; + Minus : out Boolean) return Uns; + -- This function scans the string starting at Str (Ptr.all) for a valid + -- real literal according to the syntax described in (RM 3.5(43)). The + -- substring scanned extends no further than Str (Max). There are three + -- cases for the return: + -- + -- If a valid real is found after scanning past any initial spaces, then + -- Ptr.all is updated past the last character of the real (but trailing + -- spaces are not scanned out) and the Base, Scale, Extra and Minus out + -- parameters are set; if Val is the result of the call, then the real + -- represented by the literal is equal to + -- + -- (Val * Base + Extra) * (Base ** (Scale - 1)) + -- + -- with the negative sign if Minus is true. + -- + -- If no valid real is found, then Ptr.all points either to an initial + -- non-blank character, or to Max + 1 if the field is all spaces and the + -- exception Constraint_Error is raised. + -- + -- If a syntactically valid real is scanned, but the value is out of + -- range, or, in the based case, the base value is out of range or there + -- is an out of range digit, then Ptr.all points past the real literal, + -- and Constraint_Error is raised. + -- + -- Note: these rules correspond to the requirements for leaving the + -- pointer positioned in Text_Io.Get + -- + -- Note: if Str is null, i.e. if Max is less than Ptr, then this is a + -- special case of an all-blank string, and Ptr is unchanged, and hence + -- is greater than Max as required in this case. + -- + -- Note: this routine should not be called with Str'Last = Positive'Last. + -- If this occurs Program_Error is raised with a message noting that this + -- case is not supported. Most such cases are eliminated by the caller. + + function Value_Raw_Real + (Str : String; + Base : out Unsigned; + Scale : out Integer; + Extra : out Unsigned; + Minus : out Boolean) return Uns; + -- Used in computing X'Value (Str) where X is a real type. Str is the + -- string argument of the attribute. Constraint_Error is raised if the + -- string is malformed. + +end System.Value_R; |