+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNU ADA RUNTIME LIBRARY (GNARL) COMPONENTS --
--- --
--- S Y S T E M . B I T _ O P S --
--- --
--- B o d y --
--- --
--- $Revision: 1.1.16.1 $
--- --
--- Copyright (C) 1996-2000 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, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, 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. --
--- --
-------------------------------------------------------------------------------
-
-with GNAT.Exceptions; use GNAT.Exceptions;
-with System; use System;
-with System.Unsigned_Types; use System.Unsigned_Types;
-with Unchecked_Conversion;
-
-package body System.Bit_Ops is
-
- subtype Bits_Array is System.Unsigned_Types.Packed_Bytes1 (Positive);
- -- Unconstrained array used to interprete the address values. We use the
- -- unaligned version always, since this will handle both the aligned and
- -- unaligned cases, and we always do these operations by bytes anyway.
- -- Note: we use a ones origin array here so that the computations of the
- -- length in bytes work correctly (give a non-negative value) for the
- -- case of zero length bit strings).
-
- type Bits is access Bits_Array;
- -- This is the actual type into which address values are converted
-
- function To_Bits is new Unchecked_Conversion (Address, Bits);
-
- LE : constant := Standard'Default_Bit_Order;
- -- Static constant set to 0 for big-endian, 1 for little-endian
-
- -- The following is an array of masks used to mask the final byte, either
- -- at the high end (big-endian case) or the low end (little-endian case).
-
- Masks : constant array (1 .. 7) of Packed_Byte := (
- (1 - LE) * 2#1000_0000# + LE * 2#0000_0001#,
- (1 - LE) * 2#1100_0000# + LE * 2#0000_0011#,
- (1 - LE) * 2#1110_0000# + LE * 2#0000_0111#,
- (1 - LE) * 2#1111_0000# + LE * 2#0000_1111#,
- (1 - LE) * 2#1111_1000# + LE * 2#0001_1111#,
- (1 - LE) * 2#1111_1100# + LE * 2#0011_1111#,
- (1 - LE) * 2#1111_1110# + LE * 2#0111_1111#);
-
-
- -----------------------
- -- Local Subprograms --
- -----------------------
-
- procedure Raise_Error;
- -- Raise Constraint_Error, complaining about unequal lengths
-
- -------------
- -- Bit_And --
- -------------
-
- procedure Bit_And
- (Left : Address;
- Llen : Natural;
- Right : Address;
- Rlen : Natural;
- Result : Address)
- is
- LeftB : constant Bits := To_Bits (Left);
- RightB : constant Bits := To_Bits (Right);
- ResultB : constant Bits := To_Bits (Result);
-
- begin
- if Llen /= Rlen then
- Raise_Error;
- end if;
-
- for J in 1 .. (Rlen + 7) / 8 loop
- ResultB (J) := LeftB (J) and RightB (J);
- end loop;
- end Bit_And;
-
- ------------
- -- Bit_Eq --
- ------------
-
- function Bit_Eq
- (Left : Address;
- Llen : Natural;
- Right : Address;
- Rlen : Natural)
- return Boolean
- is
- LeftB : constant Bits := To_Bits (Left);
- RightB : constant Bits := To_Bits (Right);
-
- begin
- if Llen /= Rlen then
- return False;
-
- else
- declare
- BLen : constant Natural := Llen / 8;
- Bitc : constant Natural := Llen mod 8;
-
- begin
- if Llen /= Rlen then
- return False;
-
- elsif LeftB (1 .. BLen) /= RightB (1 .. BLen) then
- return False;
-
- elsif Bitc /= 0 then
- return
- ((LeftB (BLen + 1) xor RightB (BLen + 1))
- and Masks (Bitc)) = 0;
-
- else -- Bitc = 0
- return True;
- end if;
- end;
- end if;
- end Bit_Eq;
-
- -------------
- -- Bit_Not --
- -------------
-
- procedure Bit_Not
- (Opnd : System.Address;
- Len : Natural;
- Result : System.Address)
- is
- OpndB : constant Bits := To_Bits (Opnd);
- ResultB : constant Bits := To_Bits (Result);
-
- begin
- for J in 1 .. (Len + 7) / 8 loop
- ResultB (J) := not OpndB (J);
- end loop;
- end Bit_Not;
-
- ------------
- -- Bit_Or --
- ------------
-
- procedure Bit_Or
- (Left : Address;
- Llen : Natural;
- Right : Address;
- Rlen : Natural;
- Result : Address)
- is
- LeftB : constant Bits := To_Bits (Left);
- RightB : constant Bits := To_Bits (Right);
- ResultB : constant Bits := To_Bits (Result);
-
- begin
- if Llen /= Rlen then
- Raise_Error;
- end if;
-
- for J in 1 .. (Rlen + 7) / 8 loop
- ResultB (J) := LeftB (J) or RightB (J);
- end loop;
- end Bit_Or;
-
- -------------
- -- Bit_Xor --
- -------------
-
- procedure Bit_Xor
- (Left : Address;
- Llen : Natural;
- Right : Address;
- Rlen : Natural;
- Result : Address)
- is
- LeftB : constant Bits := To_Bits (Left);
- RightB : constant Bits := To_Bits (Right);
- ResultB : constant Bits := To_Bits (Result);
-
- begin
- if Llen /= Rlen then
- Raise_Error;
- end if;
-
- for J in 1 .. (Rlen + 7) / 8 loop
- ResultB (J) := LeftB (J) xor RightB (J);
- end loop;
- end Bit_Xor;
-
- -----------------
- -- Raise_Error --
- -----------------
-
- procedure Raise_Error is
- begin
- Raise_Exception (CE, "unequal lengths in logical operation");
- end Raise_Error;
-
-end System.Bit_Ops;
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