path: root/string/bits/string2.h

/* Machine-independant string function optimizations.
   Copyright (C) 1997-2016 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#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 GCC'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 latter.  */

#ifndef __STRING_INLINE
# ifdef __cplusplus
#  define __STRING_INLINE inline
# else
#  define __STRING_INLINE __extern_inline
# endif
#endif

#if _STRING_INLINE_unaligned
# include <bits/types.h>
#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]; }				      \
    __attribute__ ((__packed__)) __STRING2_COPY_ARR##N
__STRING2_COPY_TYPE (2);
__STRING2_COPY_TYPE (3);
__STRING2_COPY_TYPE (4);
__STRING2_COPY_TYPE (5);
__STRING2_COPY_TYPE (6);
__STRING2_COPY_TYPE (7);
__STRING2_COPY_TYPE (8);
# undef __STRING2_COPY_TYPE
#endif

/* Dereferencing a pointer arg to run sizeof on it fails for the void
   pointer case, so we use this instead.
   Note that __x is evaluated twice. */
#define __string2_1bptr_p(__x) \
  ((size_t)(const void *)((__x) + 1) - (size_t)(const void *)(__x) == 1)

/* Set N bytes of S to C.  */
#if !defined _HAVE_STRING_ARCH_memset
# define __bzero(s, n) __builtin_memset (s, '\0', n)
#endif

# if defined _FORCE_INLINES
#  if _STRING_INLINE_unaligned
__STRING_INLINE void *
__mempcpy_small (void *__dest1,
		 char __src0_1, char __src2_1, char __src4_1, char __src6_1,
		 __uint16_t __src0_2, __uint16_t __src4_2,
		 __uint32_t __src0_4, __uint32_t __src4_4,
		 size_t __srclen)
{
  union {
    __uint32_t __ui;
    __uint16_t __usi;
    unsigned char __uc;
    unsigned char __c;
  } *__u = __dest1;
  switch ((unsigned int) __srclen)
    {
    case 1:
      __u->__c = __src0_1;
      __u = __extension__ ((void *) __u + 1);
      break;
    case 2:
      __u->__usi = __src0_2;
      __u = __extension__ ((void *) __u + 2);
      break;
    case 3:
      __u->__usi = __src0_2;
      __u = __extension__ ((void *) __u + 2);
      __u->__c = __src2_1;
      __u = __extension__ ((void *) __u + 1);
      break;
    case 4:
      __u->__ui = __src0_4;
      __u = __extension__ ((void