X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fmemchr.c;h=3c5ecfd0e10b1dcc32f149fe0a92d4194dedfd35;hb=f84215faa43d2933011459dd42ba518df63e34c4;hp=ac2f9ddca07e6a1ef999ef722add21031d96997a;hpb=d349992d82f97d614404565ff66e3f8a47b4a568;p=gnulib.git diff --git a/lib/memchr.c b/lib/memchr.c index ac2f9ddca..3c5ecfd0e 100644 --- a/lib/memchr.c +++ b/lib/memchr.c @@ -1,4 +1,6 @@ -/* Copyright (C) 1991, 1993, 1997, 1999, 2000 Free Software Foundation, Inc. +/* Copyright (C) 1991, 1993, 1996, 1997, 1999, 2000, 2003, 2004 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); @@ -19,65 +21,58 @@ 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 -along with this program; if not, write to the Free Software -Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, -USA. */ +along with this program; if not, write to the Free Software Foundation, +Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #ifdef HAVE_CONFIG_H # include #endif -#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. */ +#include -#if defined (_LIBC) -# include -#endif +#include -#if defined (HAVE_LIMITS_H) || defined (_LIBC) -# include +#if defined _LIBC +# include +#else +# define reg_char char #endif -#define LONG_MAX_32_BITS 2147483647 +#include -#ifndef LONG_MAX -# define LONG_MAX LONG_MAX_32_BITS +#if HAVE_BP_SYM_H || defined _LIBC +# include +#else +# define BP_SYM(sym) sym #endif -#include - +#undef memchr +#undef __memchr /* Search no more than N bytes of S for C. */ - -__ptr_t -memchr (s, c, n) - const __ptr_t s; - int c; - size_t n; +void * +__memchr (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; + c = (unsigned char) c_in; /* Handle the first 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 > 0 && ((unsigned long int) char_ptr - & (sizeof (longword) - 1)) != 0; + n > 0 && (size_t) char_ptr % sizeof longword != 0; --n, ++char_ptr) 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 @@ -89,26 +84,28 @@ memchr (s, c, n) 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. @@ -163,26 +160,28 @@ memchr (s, c, n) const unsigned char *cp = (const unsigned char *) (longword_ptr - 1); if (cp[0] == c) - return (__ptr_t) cp; + return (void *) cp; if (cp[1] == c) - return (__ptr_t) &cp[1]; + return (void *) &cp[1]; if (cp[2] == c) - return (__ptr_t) &cp[2]; + return (void *) &cp[2]; if (cp[3] == c) - return (__ptr_t) &cp[3]; -#if LONG_MAX > 2147483647 - if (cp[4] == c) - return (__ptr_t) &cp[4]; - if (cp[5] == c) - return (__ptr_t) &cp[5]; - if (cp[6] == c) - return (__ptr_t) &cp[6]; - if (cp[7] == c) - return (__ptr_t) &cp[7]; -#endif + return (void *) &cp[3]; + if (4 < sizeof longword && cp[4] == c) + return (void *) &cp[4]; + if (5 < sizeof longword && cp[5] == c) + return (void *) &cp[5]; + if (6 < sizeof longword && cp[6] == c) + return (void *) &cp[6]; + if (7 < sizeof longword && cp[7] == c) + return (void *) &cp[7]; + if (8 < sizeof longword) + for (i = 8; i < sizeof longword; i++) + if (cp[i] == c) + return (void *) &cp[i]; } - n -= sizeof (longword); + n -= sizeof longword; } char_ptr = (const unsigned char *) longword_ptr; @@ -190,10 +189,13 @@ memchr (s, c, n) while (n-- > 0) { if (*char_ptr == c) - return (__ptr_t) char_ptr; + return (void *) char_ptr; else ++char_ptr; } return 0; } +#ifdef weak_alias +weak_alias (__memchr, BP_SYM (memchr)) +#endif