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Diffstat (limited to 'gcc/ada/s-strcom.adb')
| -rw-r--r-- | gcc/ada/s-strcom.adb | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/gcc/ada/s-strcom.adb b/gcc/ada/s-strcom.adb new file mode 100644 index 00000000000..bc72db5e3eb --- /dev/null +++ b/gcc/ada/s-strcom.adb @@ -0,0 +1,140 @@ +------------------------------------------------------------------------------ +-- -- +-- GNU ADA RUNTIME LIBRARY COMPONENTS -- +-- -- +-- S Y S T E M . S T R I N G _ C O M P A R E -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 2002 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 Unchecked_Conversion; + +package body System.String_Compare is + + type Word is mod 2 ** 32; + -- Used to process operands by words + + type Big_Words is array (Natural) of Word; + type Big_Words_Ptr is access Big_Words; + -- Array type used to access by words + + type Byte is mod 2 ** 8; + -- Used to process operands by bytes + + type Big_Bytes is array (Natural) of Byte; + type Big_Bytes_Ptr is access Big_Bytes; + -- Array type used to access by bytes + + function To_Big_Words is new + Unchecked_Conversion (System.Address, Big_Words_Ptr); + + function To_Big_Bytes is new + Unchecked_Conversion (System.Address, Big_Bytes_Ptr); + + ----------------- + -- Str_Compare -- + ----------------- + + function Str_Compare + (Left : System.Address; + Right : System.Address; + Left_Len : Natural; + Right_Len : Natural) + return Integer + is + Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len); + + begin + -- If operands are non-aligned, or length is too short, go by bytes + + if (((Left or Right) and 2#11#) /= 0) or else Compare_Len < 4 then + return Str_Compare_Bytes (Left, Right, Left_Len, Right_Len); + end if; + + -- Here we can go by words + + declare + LeftP : constant Big_Words_Ptr := To_Big_Words (Left); + RightP : constant Big_Words_Ptr := To_Big_Words (Right); + Clen4 : constant Natural := Compare_Len / 4 - 1; + Clen4F : constant Natural := Clen4 * 4; + + begin + for J in 0 .. Clen4 loop + if LeftP (J) /= RightP (J) then + return Str_Compare_Bytes + (Left + Address (4 * J), + Right + Address (4 * J), + 4, 4); + end if; + end loop; + + return Str_Compare_Bytes + (Left + Address (Clen4F), + Right + Address (Clen4F), + Left_Len - Clen4F, + Right_Len - Clen4F); + end; + end Str_Compare; + + ----------------------- + -- Str_Compare_Bytes -- + ----------------------- + + function Str_Compare_Bytes + (Left : System.Address; + Right : System.Address; + Left_Len : Natural; + Right_Len : Natural) + return Integer + is + Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len); + + LeftP : constant Big_Bytes_Ptr := To_Big_Bytes (Left); + RightP : constant Big_Bytes_Ptr := To_Big_Bytes (Right); + + begin + for J in 0 .. Compare_Len - 1 loop + if LeftP (J) /= RightP (J) then + if LeftP (J) > RightP (J) then + return +1; + else + return -1; + end if; + end if; + end loop; + + if Left_Len = Right_Len then + return 0; + elsif Left_Len > Right_Len then + return +1; + else + return -1; + end if; + end Str_Compare_Bytes; + +end System.String_Compare; |