path: root/string/bits/string2.h

/* Machine-independant string function optimizations.
   Copyright (C) 1997, 1998 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#ifndef _STRING_H
# error "Never use <bits/string2.h> directly; include <string.h> instead."
#endif

#ifndef __NO_STRING_INLINES

/* Unlike the definitions in the header <bits/string.h> the
   definitions contained here are not optimized down to assembler
   level.  Those optimizations are not always a good idea since this
   means the code size increases a lot.  Instead the definitions here
   optimize some functions in a way which do not dramatically
   increase the code size and which do not use assembler.  The main
   trick is to use GNU CC's `__builtin_constant_p' function.

   Every function XXX which has a defined version in
   <bits/string.h> must be accompanied by a symbol _HAVE_STRING_ARCH_XXX
   to make sure we don't get redefinitions.

   We must use here macros instead of inline functions since the
   trick won't work with the later.  */

#ifdef __cplusplus
# define __STRING_INLINE inline
#else
# define __STRING_INLINE extern __inline
#endif

#if _STRING_ARCH_unaligned
/* If we can do unaligned memory accesses we must know the endianess.  */
# include <endian.h>
# include <bits/types.h>

# if __BYTE_ORDER == __LITTLE_ENDIAN
#  define __STRING2_SMALL_GET16(src, idx) \
     (((__const unsigned char *) (__const char *) (src))[idx + 1] << 8	      \
      | ((__const unsigned char *) (__const char *) (src))[idx])
#  define __STRING2_SMALL_GET32(src, idx) \
     (((((__const unsigned char *) (__const char *) (src))[idx + 3] << 8      \
	| ((__const unsigned char *) (__const char *) (src))[idx + 2]) << 8   \
       | ((__const unsigned char *) (__const char *) (src))[idx + 1]) << 8    \
      | ((__const unsigned char *) (__const char *) (src))[idx])
# else
#  define __STRING2_SMALL_GET16(src, idx) \
     (((__const unsigned char *) (__const char *) (src))[idx] << 8	      \
      | ((__const unsigned char *) (__const char *) (src))[idx + 1])
#  define __STRING2_SMALL_GET32(src, idx) \
     (((((__const unsigned char *) (__const char *) (src))[idx] << 8	      \
	| ((__const unsigned char *) (__const char *) (src))[idx + 1]) << 8   \
       | ((__const unsigned char *) (__const char *) (src))[idx + 2]) << 8    \
      | ((__const unsigned char *) (__const char *) (src))[idx + 3])
# endif
#else
/* These are a few types we need for the optimizations if we cannot
   use unaligned memory accesses.  */
# define __STRING2_COPY_TYPE(N) \
  typedef struct { unsigned char __arr[N]; }				      \
    __STRING2_COPY_ARR##N __attribute__ ((packed))
__STRING2_COPY_TYPE (2);
__STRING2_COPY_TYPE (3);
__STRING2_COPY_TYPE (4);
__STRING2_COPY_TYPE (5