94 lines
5.4 KiB
Ada
94 lines
5.4 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- S Y S T E M . S C A L A R _ V A L U E S --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2001-2009, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package defines the constants used for initializing scalar values
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-- when pragma Initialize_Scalars is used. The actual values are defined
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-- in the binder generated file. This package contains the Ada names that
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-- are used by the generated code, which are linked to the actual values
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-- by the use of pragma Import.
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package System.Scalar_Values is
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-- Note: logically this package should be Pure since it can be accessed
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-- from pure units, but the IS_xxx variables below get set at run time,
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-- so they have to be library level variables. In fact we only ever
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-- access this from generated code, and the compiler knows that it is
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-- OK to access this unit from generated code.
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type Byte1 is mod 2 ** 8;
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type Byte2 is mod 2 ** 16;
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type Byte4 is mod 2 ** 32;
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type Byte8 is mod 2 ** 64;
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-- The explicit initializations here are not really required, since these
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-- variables are always set by System.Scalar_Values.Initialize.
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IS_Is1 : Byte1 := 0; -- Initialize 1 byte signed
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IS_Is2 : Byte2 := 0; -- Initialize 2 byte signed
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IS_Is4 : Byte4 := 0; -- Initialize 4 byte signed
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IS_Is8 : Byte8 := 0; -- Initialize 8 byte signed
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-- For the above cases, the undefined value (set by the binder -Sin switch)
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-- is the largest negative number (1 followed by all zero bits).
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IS_Iu1 : Byte1 := 0; -- Initialize 1 byte unsigned
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IS_Iu2 : Byte2 := 0; -- Initialize 2 byte unsigned
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IS_Iu4 : Byte4 := 0; -- Initialize 4 byte unsigned
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IS_Iu8 : Byte8 := 0; -- Initialize 8 byte unsigned
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-- For the above cases, the undefined value (set by the binder -Sin switch)
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-- is the largest unsigned number (all 1 bits).
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IS_Iz1 : Byte1 := 0; -- Initialize 1 byte zeroes
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IS_Iz2 : Byte2 := 0; -- Initialize 2 byte zeroes
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IS_Iz4 : Byte4 := 0; -- Initialize 4 byte zeroes
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IS_Iz8 : Byte8 := 0; -- Initialize 8 byte zeroes
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-- For the above cases, the undefined value (set by the binder -Sin switch)
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-- is the zero (all 0 bits). This is used when zero is known to be an
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-- invalid value.
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-- The float definitions are aliased, because we use overlays to set them
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IS_Isf : aliased Short_Float := 0.0; -- Initialize short float
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IS_Ifl : aliased Float := 0.0; -- Initialize float
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IS_Ilf : aliased Long_Float := 0.0; -- Initialize long float
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IS_Ill : aliased Long_Long_Float := 0.0; -- Initialize long long float
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procedure Initialize (Mode1 : Character; Mode2 : Character);
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-- This procedure is called from the binder when Initialize_Scalars mode
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-- is active. The arguments are the two characters from the -S switch,
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-- with letters forced upper case. So for example if -S5a is given, then
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-- Mode1 will be '5' and Mode2 will be 'A'. If the parameters are EV,
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-- then this routine reads the environment variable GNAT_INIT_SCALARS.
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-- The possible settings are the same as those for the -S switch (except
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-- for EV), i.e. IN/LO/HO/xx, xx = 2 hex digits. If no -S switch is given
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-- then the default of IN (invalid values) is passed on the call.
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end System.Scalar_Values;
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