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Diffstat (limited to 'gcc/ada/s-bitops.adb')
| -rw-r--r-- | gcc/ada/s-bitops.adb | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/gcc/ada/s-bitops.adb b/gcc/ada/s-bitops.adb new file mode 100644 index 00000000000..6b5538c30d4 --- /dev/null +++ b/gcc/ada/s-bitops.adb @@ -0,0 +1,223 @@ +------------------------------------------------------------------------------ +-- -- +-- GNU ADA RUNTIME LIBRARY (GNARL) COMPONENTS -- +-- -- +-- S Y S T E M . B I T _ O P S -- +-- -- +-- B o d y -- +-- -- +-- $Revision: 1.10 $ +-- -- +-- 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. -- +-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). -- +-- -- +------------------------------------------------------------------------------ + +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; |