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f0ceb98f93
implementations inspired by the ones in DragonFly. Unlike the DragonFly versions, these have a small data cache footprint, and my tests show that they're never slower than the old code except when the charset or the span is 0 or 1 characters. This implementation is generally faster than DragonFly until either the charset or the span gets in the ballpark of 32 to 64 characters.
72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
/*-
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* Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/libkern.h>
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#include <sys/limits.h>
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#include <sys/types.h>
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#define IDX(c) ((u_char)(c) / LONG_BIT)
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#define BIT(c) ((u_long)1 << ((u_char)(c) % LONG_BIT))
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size_t
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strspn(const char *s, const char *charset)
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{
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/*
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* NB: idx and bit are temporaries whose use causes gcc 3.4.2 to
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* generate better code. Without them, gcc gets a little confused.
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*/
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const char *s1;
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u_long bit;
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u_long tbl[(UCHAR_MAX + 1) / LONG_BIT];
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int idx;
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if(*s == '\0')
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return (0);
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#if LONG_BIT == 64 /* always better to unroll on 64-bit architectures */
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tbl[3] = tbl[2] = tbl[1] = tbl[0] = 0;
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#else
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for (idx = 0; idx < sizeof(tbl) / sizeof(tbl[0]); idx++)
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tbl[idx] = 0;
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#endif
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for (; *charset != '\0'; charset++) {
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idx = IDX(*charset);
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bit = BIT(*charset);
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tbl[idx] |= bit;
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}
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for(s1 = s; ; s1++) {
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idx = IDX(*s1);
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bit = BIT(*s1);
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if ((tbl[idx] & bit) == 0)
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break;
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}
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return (s1 - s);
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}
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