/* memrchr -- find the last occurrence of a byte in a memory block
- Copyright (C) 1991, 93, 96, 97, 99, 2000 Free Software Foundation, Inc.
+
+ Copyright (C) 1991, 1993, 1996, 1997, 1999, 2000, 2003, 2004, 2005,
+ 2006, 2007 Free Software Foundation, Inc.
+
Based on strlen implementation by Torbjorn Granlund (tege@sics.se),
with help from Dan Sahlin (dan@sics.se) and
commentary by Jim Blandy (jimb@ai.mit.edu);
adaptation to memchr suggested by Dick Karpinski (dick@cca.ucsf.edu),
and implemented by Roland McGrath (roland@ai.mit.edu).
- 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.
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
- The GNU C Library is distributed in the hope that it will be useful,
+ This program 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. */
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
-#include <stdlib.h>
-
-#undef __ptr_t
-#if defined (__cplusplus) || (defined (__STDC__) && __STDC__)
-# define __ptr_t void *
-#else /* Not C++ or ANSI C. */
-# define __ptr_t char *
-#endif /* C++ or ANSI C. */
-
-#if defined (_LIBC)
-# include <string.h>
+#if defined _LIBC
# include <memcopy.h>
#else
+# include <config.h>
# define reg_char char
#endif
-#if defined (HAVE_LIMITS_H) || defined (_LIBC)
-# include <limits.h>
-#endif
-
-#define LONG_MAX_32_BITS 2147483647
-
-#ifndef LONG_MAX
-# define LONG_MAX LONG_MAX_32_BITS
-#endif
-
-#include <sys/types.h>
+#include <string.h>
+#include <limits.h>
#undef __memrchr
#undef memrchr
#endif
/* Search no more than N bytes of S for C. */
-__ptr_t
-__memrchr (s, c_in, n)
- const __ptr_t s;
- int c_in;
- size_t n;
+void *
+__memrchr (void const *s, int c_in, size_t n)
{
const unsigned char *char_ptr;
const unsigned long int *longword_ptr;
unsigned long int longword, magic_bits, charmask;
unsigned reg_char c;
+ int i;
c = (unsigned char) c_in;
/* Handle the last few characters by reading one character at a time.
Do this until CHAR_PTR is aligned on a longword boundary. */
for (char_ptr = (const unsigned char *) s + n;
- n > 0 && ((unsigned long int) char_ptr
- & (sizeof (longword) - 1)) != 0;
+ n > 0 && (size_t) char_ptr % sizeof longword != 0;
--n)
if (*--char_ptr == c)
- return (__ptr_t) char_ptr;
+ return (void *) char_ptr;
/* All these elucidatory comments refer to 4-byte longwords,
- but the theory applies equally well to 8-byte longwords. */
+ but the theory applies equally well to any size longwords. */
- longword_ptr = (unsigned long int *) char_ptr;
+ longword_ptr = (const unsigned long int *) char_ptr;
/* Bits 31, 24, 16, and 8 of this number are zero. Call these bits
the "holes." Note that there is a hole just to the left of
The 1-bits make sure that carries propagate to the next 0-bit.
The 0-bits provide holes for carries to fall into. */
- if (sizeof (longword) != 4 && sizeof (longword) != 8)
- abort ();
+ /* Set MAGIC_BITS to be this pattern of 1 and 0 bits.
+ Set CHARMASK to be a longword, each of whose bytes is C. */
-#if LONG_MAX <= LONG_MAX_32_BITS
- magic_bits = 0x7efefeff;
-#else
- magic_bits = ((unsigned long int) 0x7efefefe << 32) | 0xfefefeff;
-#endif
-
- /* Set up a longword, each of whose bytes is C. */
+ magic_bits = 0xfefefefe;
charmask = c | (c << 8);
charmask |= charmask << 16;
-#if LONG_MAX > LONG_MAX_32_BITS
+#if 0xffffffffU < ULONG_MAX
+ magic_bits |= magic_bits << 32;
charmask |= charmask << 32;
+ if (8 < sizeof longword)
+ for (i = 64; i < sizeof longword * 8; i *= 2)
+ {
+ magic_bits |= magic_bits << i;
+ charmask |= charmask << i;
+ }
#endif
+ magic_bits = (ULONG_MAX >> 1) & (magic_bits | 1);
/* Instead of the traditional loop which tests each character,
we will test a longword at a time. The tricky part is testing
if *any of the four* bytes in the longword in question are zero. */
- while (n >= sizeof (longword))
+ while (n >= sizeof longword)
{
/* We tentatively exit the loop if adding MAGIC_BITS to
LONGWORD fails to change any of the hole bits of LONGWORD.
const unsigned char *cp = (const unsigned char *) longword_ptr;
-#if LONG_MAX > 2147483647
- if (cp[7] == c)
- return (__ptr_t) &cp[7];
- if (cp[6] == c)
- return (__ptr_t) &cp[6];
- if (cp[5] == c)
- return (__ptr_t) &cp[5];
- if (cp[4] == c)
- return (__ptr_t) &cp[4];
-#endif
+ if (8 < sizeof longword)
+ for (i = sizeof longword - 1; 8 <= i; i--)
+ if (cp[i] == c)
+ return (void *) &cp[i];
+ if (7 < sizeof longword && cp[7] == c)
+ return (void *) &cp[7];
+ if (6 < sizeof longword && cp[6] == c)
+ return (void *) &cp[6];
+ if (5 < sizeof longword && cp[5] == c)
+ return (void *) &cp[5];
+ if (4 < sizeof longword && cp[4] == c)
+ return (void *) &cp[4];
if (cp[3] == c)
- return (__ptr_t) &cp[3];
+ return (void *) &cp[3];
if (cp[2] == c)
- return (__ptr_t) &cp[2];
+ return (void *) &cp[2];
if (cp[1] == c)
- return (__ptr_t) &cp[1];
+ return (void *) &cp[1];
if (cp[0] == c)
- return (__ptr_t) cp;
+ return (void *) cp;
}
- n -= sizeof (longword);
+ n -= sizeof longword;
}
char_ptr = (const unsigned char *) longword_ptr;
while (n-- > 0)
{
if (*--char_ptr == c)
- return (__ptr_t) char_ptr;
+ return (void *) char_ptr;
}
return 0;
projects / gnulib.git / blobdiff