Mercurial > hg > xemacs-beta
diff src/strcmp.c @ 428:3ecd8885ac67 r21-2-22
Import from CVS: tag r21-2-22
author | cvs |
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date | Mon, 13 Aug 2007 11:28:15 +0200 |
parents | |
children | abe6d1db359e |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/strcmp.c Mon Aug 13 11:28:15 2007 +0200 @@ -0,0 +1,151 @@ +/* This file is part of XEmacs. + +XEmacs 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 2, or (at your option) any +later version. + +XEmacs 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 General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with XEmacs; see the file COPYING. If not, write to +the Free Software Foundation, Inc., 59 Temple Place - Suite 330, +Boston, MA 02111-1307, USA. */ + +/* Synched up with: Not in FSF. */ + +/* In SunOS 4.1.1 the strcmp and strncmp functions reference memory + past the last byte of the string! This will core dump if the memory + following the last byte is not mapped. + + Here are correct versions by hbs@lucid.com. +*/ + +# include <config.h> +# ifndef REGISTER /* Strictly enforced in 20.3 */ +# define REGISTER +# endif + +#include <string.h> +#define ALIGNED(x) (!(((unsigned long) (x)) & (sizeof (unsigned long) - 1))) + +#define MAGIC 0x7efefeff +#define HIGH_BIT_P(c) ((c) & hi_bit) +#define HAS_ZERO(c) (((((c) + magic) ^ (c)) & not_magic) != not_magic) + +/* CONST IS LOSING, but const is part of the interface of strcmp */ +int +strcmp (const char *x, const char *y) +{ + if (x == y) + return 0; + else if (ALIGNED (x) && ALIGNED (y)) + { + CONST unsigned long *x1 = (CONST unsigned long *) x; + CONST unsigned long *y1 = (CONST unsigned long *) y; + unsigned long c; + unsigned long magic = MAGIC; + unsigned long not_magic = ~magic; + unsigned long hi_bit = 0x80000000; + + while ((c = *x1) == *y1) + { + if (HAS_ZERO(c)) + { + if (!HIGH_BIT_P (c)) + return 0; + else + { + x = (CONST char *) x1; + y = (CONST char *) y1; + goto slow_loop; + } + } + + x1++; + y1++; + } + + x = (CONST char *) x1; + y = (CONST char *) y1; + goto slow_loop; + } + else + { + char c; + + slow_loop: + + while ((c = *x) == *y) + { + if (c == (char) 0) return 0; + x++; + y++; + } + return (*x - *y); + } +} + + +int +strncmp (CONST char *x, CONST char *y, size_t n) +{ + if ((x == y) || (n <= 0)) + return 0; + else if (ALIGNED (x) && ALIGNED (y)) + { + CONST unsigned long *x1 = (CONST unsigned long *) x; + CONST unsigned long *y1 = (CONST unsigned long *) y; + unsigned long c; + unsigned long magic = MAGIC; + unsigned long not_magic = ~magic; + unsigned long hi_bit = 0x80000000; + + while ((c = *x1) == *y1) + { + n -= sizeof (unsigned long); + if (n <= 0) + return 0; + + if (HAS_ZERO(c)) + { + if (!HIGH_BIT_P (c)) + return 0; + else + { + x = (CONST char *) x1; + y = (CONST char *) y1; + goto slow_loop; + } + } + + x1++; + y1++; + } + + x = (CONST char *) x1; + y = (CONST char *) y1; + goto slow_loop; + } + else + { + char c; + + slow_loop: + + while ((c = *x) == *y) + { + n--; + if (n <= 0) + return 0; + if (c == (char) 0) + return 0; + x++; + y++; + } + return (*x - *y); + } +}