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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- S Y S T E M . S C A L A R _ V A L U E S --
-- --
-- S p e c --
-- --
-- Copyright (C) 2001-2005, 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, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, 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. --
-- --
------------------------------------------------------------------------------
-- This package defines the constants used for initializing scalar values
-- when pragma Initialize_Scalars is used. The actual values are defined
-- in the binder generated file. This package contains the Ada names that
-- are used by the generated code, which are linked to the actual values
-- by the use of pragma Import.
package System.Scalar_Values is
-- Note: logically this package should be Pure since it can be accessed
-- from pure units, but the IS_xxx variables below get set at run time,
-- so they have to be library level variables. In fact we only ever
-- access this from generated code, and the compiler knows that it is
-- OK to access this unit from generated code.
type Byte1 is mod 2 ** 8;
type Byte2 is mod 2 ** 16;
type Byte4 is mod 2 ** 32;
type Byte8 is mod 2 ** 64;
-- The explicit initializations here are not really required, since these
-- variables are always set by System.Scalar_Values.Initialize.
IS_Is1 : Byte1 := 0; -- Initialize 1 byte signed
IS_Is2 : Byte2 := 0; -- Initialize 2 byte signed
IS_Is4 : Byte4 := 0; -- Initialize 4 byte signed
IS_Is8 : Byte8 := 0; -- Initialize 8 byte signed
-- For the above cases, the undefined value (set by the binder -Sin switch)
-- is the largest negative number (1 followed by all zero bits).
IS_Iu1 : Byte1 := 0; -- Initialize 1 byte unsigned
IS_Iu2 : Byte2 := 0; -- Initialize 2 byte unsigned
IS_Iu4 : Byte4 := 0; -- Initialize 4 byte unsigned
IS_Iu8 : Byte8 := 0; -- Initialize 8 byte unsigned
-- For the above cases, the undefined value (set by the binder -Sin switch)
-- is the largest unsigned number (all 1 bits).
IS_Iz1 : Byte1 := 0; -- Initialize 1 byte zeroes
IS_Iz2 : Byte2 := 0; -- Initialize 2 byte zeroes
IS_Iz4 : Byte4 := 0; -- Initialize 4 byte zeroes
IS_Iz8 : Byte8 := 0; -- Initialize 8 byte zeroes
-- For the above cases, the undefined value (set by the binder -Sin switch)
-- is the zero (all 0 bits). This is used when zero is known to be an
-- invalid value.
-- The float definitions are aliased, because we use overlays to set them
IS_Isf : aliased Short_Float := 0.0; -- Initialize short float
IS_Ifl : aliased Float := 0.0; -- Initialize float
IS_Ilf : aliased Long_Float := 0.0; -- Initialize long float
IS_Ill : aliased Long_Long_Float := 0.0; -- Initialize long long float
procedure Initialize (Mode1 : Character; Mode2 : Character);
-- This procedure is called from the binder when Initialize_Scalars mode
-- is active. The arguments are the two characters from the -S switch,
-- with letters forced upper case. So for example if -S5a is given, then
-- Mode1 will be '5' and Mode2 will be 'A'. If the parameters are EV,
-- then this routine reads the environment variable GNAT_INIT_SCALARS.
-- The possible settings are the same as those for the -S switch (except
-- for EV), i.e. IN/LO/HO/xx, xx = 2 hex digits. If no -S switch is given
-- then the default of IN (invalid values) is passed on the call.
end System.Scalar_Values;
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