string2.h

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/* Machine-independant string function optimizations.
   Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <[e-mail]>, 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, 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

#if !defined __NO_STRING_INLINES && !defined __BOUNDED_POINTERS__

/* 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 latter.  */

#ifndef __STRING_INLINE
# ifdef __cplusplus
#  define __STRING_INLINE inline
# else
#  define __STRING_INLINE extern __inline
# endif
#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);
__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.  */
#ifndef _HAVE_STRING_ARCH_memset
# if _STRING_ARCH_unaligned
#  define memset(s, c, n) \
  (__extension__ (__builtin_constant_p (n) && (n) <= 16			      \
		  ? ((n) == 1						      \
		     ? __memset_1 (s, c)				      \
		     : __memset_gc (s, c, n))				      \
		  : (__builtin_constant_p (c) && (c) == '\0'		      \
		     ? ({ void *__s = (s); __bzero (__s, n); __s; })	      \
		     : memset (s, c, n))))

#  define __memset_1(s, c) ({ void *__s = (s);				      \
			    *((__uint8_t *) __s) = (__uint8_t) c; __s; })

#  define __memset_gc(s, c, n) \
  ({ void *__s = (s);							      \
     union {								      \
       unsigned int __ui;						      \
       unsigned short int __usi;					      \
       unsigned char __uc;						      \
     } *__u = __s;							      \
     __uint8_t __c = (__uint8_t) (c);					      \
									      \
     /* This `switch' statement will be removed at compile-time.  */	      \
     switch ((unsigned int) (n))					      \
       {								      \
       case 15:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 11:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 7:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 3:								      \
	 __u->__usi = (unsigned short int) __c * 0x0101;		      \
	 __u = __extension__ (void *)((char *) __u + 2);		      \
	 __u->__uc = (unsigned char) __c;				      \
	 break;								      \
									      \
       case 14:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 10:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 6:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 2:								      \
	 __u->__usi = (unsigned short int) __c * 0x0101;		      \
	 break;								      \
									      \
       case 13:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 9:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 5:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 1:								      \
	 __u->__uc = (unsigned char) __c;				      \
	 break;								      \
									      \
       case 16:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 12:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 8:								      \
	 __u->__ui = __c * 0x01010101;					      \
	 __u = __extension__ (void *)((char *) __u + 4);		      \
       case 4:								      \
	 __u->__ui = __c * 0x01010101;					      \
       case 0:								      \
	 break;								      \
       }								      \
									      \
     __s; })
# else
#  define memset(s, c, n) \
  (__extension__ (__builtin_constant_p (c) && (c) == '\0'		      \
		  ? ({ void *__s = (s); __bzero (__s, n); __s; })	      \
		  : memset (s, c, n)))
# endif

/* GCC optimizes memset(s, 0, n) but not bzero(s, n).
   The optimization is broken before EGCS 1.1.  */
# if __GNUC_PREREQ (2, 91)
#  define __bzero(s, n) __builtin_memset (s, '\0', n)
# endif

#endif


/* Copy N bytes from SRC to DEST, returning pointer to byte following the
   last copied.  */
#ifdef __USE_GNU
# ifndef _HAVE_STRING_ARCH_mempcpy
#  define __mempcpy(dest, src, n) \
  (__extension__ (__builtin_constant_p (src) && __builtin_constant_p (n)      \
		  && __string2_1bptr_p (src) && n <= 8			      \
		  ? __mempcpy_small (dest, __mempcpy_args (src), n)	      \
		  : __mempcpy (dest, src, n)))
/* In glibc we use this function frequently but for namespace reasons
   we have to use the name `__mempcpy'.  */
#  define mempcpy(dest, src, n) __mempcpy (dest, src, n)

#  if _STRING_ARCH_unaligned
#   define __mempcpy_args(src) \
     ((__const char *) (src))[0], ((__const char *) (src))[2],		      \
     ((__const char *) (src))[4], ((__const char *) (src))[6],		      \
     __extension__ __STRING2_SMALL_GET16 (src, 0),			      \
     __extension__ __STRING2_SMALL_GET16 (src, 4),			      \
     __extension__ __STRING2_SMALL_GET32 (src, 0),			      \
     __extension__ __STRING2_SMALL_GET32 (src, 4)
__STRING_INLINE void *__mempcpy_small (void *, char, char, char, char,
				       __uint16_t, __uint16_t, __uint32_t,
				       __uint32_t, size_t);
__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 *)((char *) __u + 1);
      break;
    case 2:
      __u->__usi = __src0_2;
      __u = __extension__ (void *)((char *) __u + 2);
      break;
    case 3:
      __u->__usi = __src0_2;
      __u = __extension__ (void *)((char *) __u + 2);
      __u->__c = __src2_1;
      __u = __extension__ (void *)((char *) __u + 1);
      break;
    case 4:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      break;
    case 5:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__c = __src4_1;
      __u = __extension__ (void *)((char *) __u + 1);
      break;
    case 6:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__usi = __src4_2;
      __u = __extension__ (void *)((char *) __u + 2);
      break;
    case 7:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__usi = __src4_2;
      __u = __extension__ (void *)((char *) __u + 2);
      __u->__c = __src6_1;
      __u = __extension__ (void *)((char *) __u + 1);
      break;
    case 8:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__ui = __src4_4;
      __u = __extension__ (void *)((char *) __u + 4);
      break;
    }
  return (void *) __u;
}
#  else
#   define __mempcpy_args(src) \
     ((__const char *) (src))[0],					      \
     __extension__ ((__STRING2_COPY_ARR2)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1] } }),      \
     __extension__ ((__STRING2_COPY_ARR3)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2] } }),				      \
     __extension__ ((__STRING2_COPY_ARR4)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3] } }),      \
     __extension__ ((__STRING2_COPY_ARR5)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4] } }),				      \
     __extension__ ((__STRING2_COPY_ARR6)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], ((__const char *) (src))[5] } }),      \
     __extension__ ((__STRING2_COPY_ARR7)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], ((__const char *) (src))[5],	      \
	  ((__const char *) (src))[6] } }),				      \
     __extension__ ((__STRING2_COPY_ARR8)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], ((__const char *) (src))[5],	      \
	  ((__const char *) (src))[6], ((__const char *) (src))[7] } })
__STRING_INLINE void *__mempcpy_small (void *, char, __STRING2_COPY_ARR2,
				       __STRING2_COPY_ARR3,
				       __STRING2_COPY_ARR4,
				       __STRING2_COPY_ARR5,
				       __STRING2_COPY_ARR6,
				       __STRING2_COPY_ARR7,
				       __STRING2_COPY_ARR8, size_t);
__STRING_INLINE void *
__mempcpy_small (void *__dest, char __src1,
		 __STRING2_COPY_ARR2 __src2, __STRING2_COPY_ARR3 __src3,
		 __STRING2_COPY_ARR4 __src4, __STRING2_COPY_ARR5 __src5,
		 __STRING2_COPY_ARR6 __src6, __STRING2_COPY_ARR7 __src7,
		 __STRING2_COPY_ARR8 __src8, size_t __srclen)
{
  union {
    char __c;
    __STRING2_COPY_ARR2 __sca2;
    __STRING2_COPY_ARR3 __sca3;
    __STRING2_COPY_ARR4 __sca4;
    __STRING2_COPY_ARR5 __sca5;
    __STRING2_COPY_ARR6 __sca6;
    __STRING2_COPY_ARR7 __sca7;
    __STRING2_COPY_ARR8 __sca8;
  } *__u = __dest;
  switch ((unsigned int) __srclen)
    {
    case 1:
      __u->__c = __src1;
      break;
    case 2:
      __extension__ __u->__sca2 = __src2;
      break;
    case 3:
      __extension__ __u->__sca3 = __src3;
      break;
    case 4:
      __extension__ __u->__sca4 = __src4;
      break;
    case 5:
      __extension__ __u->__sca5 = __src5;
      break;
    case 6:
      __extension__ __u->__sca6 = __src6;
      break;
    case 7:
      __extension__ __u->__sca7 = __src7;
      break;
    case 8:
      __extension__ __u->__sca8 = __src8;
      break;
    }
  return __extension__ (void *)((char *) __u + __srclen);
}
#  endif
# endif
#endif


/* Return pointer to C in S.  */
#ifndef _HAVE_STRING_ARCH_strchr
extern void *__rawmemchr (const void *__s, int __c);
# define strchr(s, c) \
  (__extension__ (__builtin_constant_p (c) && (c) == '\0'		      \
		  ? (char *) __rawmemchr (s, c)				      \
		  : strchr (s, c)))
#endif


/* Copy SRC to DEST.  */
#ifndef _HAVE_STRING_ARCH_strcpy
# define strcpy(dest, src) \
  (__extension__ (__builtin_constant_p (src)				      \
		  ? (__string2_1bptr_p (src) && strlen (src) + 1 <= 8	      \
		     ? __strcpy_small (dest, __strcpy_args (src),	      \
				       strlen (src) + 1)		      \
		     : (char *) memcpy (dest, src, strlen (src) + 1))	      \
		  : strcpy (dest, src)))

# if _STRING_ARCH_unaligned
#  define __strcpy_args(src) \
     __extension__ __STRING2_SMALL_GET16 (src, 0),			      \
     __extension__ __STRING2_SMALL_GET16 (src, 4),			      \
     __extension__ __STRING2_SMALL_GET32 (src, 0),			      \
     __extension__ __STRING2_SMALL_GET32 (src, 4)
__STRING_INLINE char *__strcpy_small (char *, __uint16_t, __uint16_t,
				      __uint32_t, __uint32_t, size_t);
__STRING_INLINE char *
__strcpy_small (char *__dest,
		__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;
  } *__u = (void *) __dest;
  switch ((unsigned int) __srclen)
    {
    case 1:
      __u->__uc = '\0';
      break;
    case 2:
      __u->__usi = __src0_2;
      break;