1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S Y S T E M . V A L U E _ D -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 2020, Free Software Foundation, Inc. -- 10-- -- 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 3, 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. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26-- -- 27-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32-- This package contains the routines for supporting the Value attribute for 33-- decimal fixed point types, and also for conversion operations required in 34-- Text_IO.Decimal_IO for such types. 35 36generic 37 38 type Int is range <>; 39 40 type Uns is mod <>; 41 42 with procedure Scaled_Divide 43 (X, Y, Z : Int; 44 Q, R : out Int; 45 Round : Boolean); 46 47package System.Value_D is 48 pragma Preelaborate; 49 50 function Scan_Decimal 51 (Str : String; 52 Ptr : not null access Integer; 53 Max : Integer; 54 Scale : Integer) return Int; 55 -- This function scans the string starting at Str (Ptr.all) for a valid 56 -- real literal according to the syntax described in (RM 3.5(43)). The 57 -- substring scanned extends no further than Str (Max). There are three 58 -- cases for the return: 59 -- 60 -- If a valid real literal is found after scanning past any initial spaces, 61 -- then Ptr.all is updated past the last character of the literal (but 62 -- trailing spaces are not scanned out). The value returned is the value 63 -- Int'Integer_Value (decimal-literal-value), using the given Scale to 64 -- determine this value. 65 -- 66 -- If no valid real literal is found, then Ptr.all points either to an 67 -- initial non-digit character, or to Max + 1 if the field is all spaces 68 -- and the exception Constraint_Error is raised. 69 -- 70 -- If a syntactically valid integer is scanned, but the value is out of 71 -- range, or, in the based case, the base value is out of range or there 72 -- is an out of range digit, then Ptr.all points past the integer, and 73 -- Constraint_Error is raised. 74 -- 75 -- Note: these rules correspond to the requirements for leaving the 76 -- pointer positioned in Text_Io.Get 77 -- 78 -- Note: if Str is null, i.e. if Max is less than Ptr, then this is a 79 -- special case of an all-blank string, and Ptr is unchanged, and hence 80 -- is greater than Max as required in this case. 81 82 function Value_Decimal (Str : String; Scale : Integer) return Int; 83 -- Used in computing X'Value (Str) where X is a decimal fixed-point type. 84 -- Str is the string argument of the attribute. Constraint_Error is raised 85 -- if the string is malformed or if the value is out of range of Int (not 86 -- the range of the fixed-point type, which must be done by the caller). 87 -- Otherwise the value returned is the value Int'Integer_Value 88 -- (decimal-literal-value), using Scale to determine this value. 89 90end System.Value_D; 91