1*90b052abSAntonio Huete Jimenez /*-
2*90b052abSAntonio Huete Jimenez * Copyright (c) 2012 Ed Schouten <ed@FreeBSD.org>
3*90b052abSAntonio Huete Jimenez * All rights reserved.
4*90b052abSAntonio Huete Jimenez *
5*90b052abSAntonio Huete Jimenez * Redistribution and use in source and binary forms, with or without
6*90b052abSAntonio Huete Jimenez * modification, are permitted provided that the following conditions
7*90b052abSAntonio Huete Jimenez * are met:
8*90b052abSAntonio Huete Jimenez * 1. Redistributions of source code must retain the above copyright
9*90b052abSAntonio Huete Jimenez * notice, this list of conditions and the following disclaimer.
10*90b052abSAntonio Huete Jimenez * 2. Redistributions in binary form must reproduce the above copyright
11*90b052abSAntonio Huete Jimenez * notice, this list of conditions and the following disclaimer in the
12*90b052abSAntonio Huete Jimenez * documentation and/or other materials provided with the distribution.
13*90b052abSAntonio Huete Jimenez *
14*90b052abSAntonio Huete Jimenez * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15*90b052abSAntonio Huete Jimenez * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16*90b052abSAntonio Huete Jimenez * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17*90b052abSAntonio Huete Jimenez * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18*90b052abSAntonio Huete Jimenez * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19*90b052abSAntonio Huete Jimenez * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20*90b052abSAntonio Huete Jimenez * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21*90b052abSAntonio Huete Jimenez * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22*90b052abSAntonio Huete Jimenez * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23*90b052abSAntonio Huete Jimenez * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24*90b052abSAntonio Huete Jimenez * SUCH DAMAGE.
25*90b052abSAntonio Huete Jimenez *
26*90b052abSAntonio Huete Jimenez * $FreeBSD: src/sys/libkern/memcchr.c,v 1.1 2012/01/01 20:26:11 ed Exp $
27*90b052abSAntonio Huete Jimenez *
28*90b052abSAntonio Huete Jimenez */
29*90b052abSAntonio Huete Jimenez
30*90b052abSAntonio Huete Jimenez #include <sys/cdefs.h>
31*90b052abSAntonio Huete Jimenez
32*90b052abSAntonio Huete Jimenez #include <sys/libkern.h>
33*90b052abSAntonio Huete Jimenez #include <sys/limits.h>
34*90b052abSAntonio Huete Jimenez #include <sys/param.h>
35*90b052abSAntonio Huete Jimenez
36*90b052abSAntonio Huete Jimenez /*
37*90b052abSAntonio Huete Jimenez * memcchr(): find first character in buffer not matching `c'.
38*90b052abSAntonio Huete Jimenez *
39*90b052abSAntonio Huete Jimenez * This function performs the complement of memchr(). To provide decent
40*90b052abSAntonio Huete Jimenez * performance, this function compares data from the buffer one word at
41*90b052abSAntonio Huete Jimenez * a time.
42*90b052abSAntonio Huete Jimenez *
43*90b052abSAntonio Huete Jimenez * This code is inspired by libc's strlen(), written by Xin Li.
44*90b052abSAntonio Huete Jimenez */
45*90b052abSAntonio Huete Jimenez
46*90b052abSAntonio Huete Jimenez #if LONG_BIT != 32 && LONG_BIT != 64
47*90b052abSAntonio Huete Jimenez #error Unsupported word size
48*90b052abSAntonio Huete Jimenez #endif
49*90b052abSAntonio Huete Jimenez
50*90b052abSAntonio Huete Jimenez #define LONGPTR_MASK (sizeof(long) - 1)
51*90b052abSAntonio Huete Jimenez
52*90b052abSAntonio Huete Jimenez #define TESTBYTE \
53*90b052abSAntonio Huete Jimenez do { \
54*90b052abSAntonio Huete Jimenez if (*p != (unsigned char)c) \
55*90b052abSAntonio Huete Jimenez goto done; \
56*90b052abSAntonio Huete Jimenez p++; \
57*90b052abSAntonio Huete Jimenez } while (0)
58*90b052abSAntonio Huete Jimenez
59*90b052abSAntonio Huete Jimenez void *
memcchr(const void * begin,int c,size_t n)60*90b052abSAntonio Huete Jimenez memcchr(const void *begin, int c, size_t n)
61*90b052abSAntonio Huete Jimenez {
62*90b052abSAntonio Huete Jimenez const unsigned long *lp;
63*90b052abSAntonio Huete Jimenez const unsigned char *p, *end;
64*90b052abSAntonio Huete Jimenez unsigned long word;
65*90b052abSAntonio Huete Jimenez
66*90b052abSAntonio Huete Jimenez /* Four or eight repetitions of `c'. */
67*90b052abSAntonio Huete Jimenez word = (unsigned char)c;
68*90b052abSAntonio Huete Jimenez word |= word << 8;
69*90b052abSAntonio Huete Jimenez word |= word << 16;
70*90b052abSAntonio Huete Jimenez #if LONG_BIT >= 64
71*90b052abSAntonio Huete Jimenez word |= word << 32;
72*90b052abSAntonio Huete Jimenez #endif
73*90b052abSAntonio Huete Jimenez
74*90b052abSAntonio Huete Jimenez /* Don't perform memory I/O when passing a zero-length buffer. */
75*90b052abSAntonio Huete Jimenez if (n == 0)
76*90b052abSAntonio Huete Jimenez return (NULL);
77*90b052abSAntonio Huete Jimenez
78*90b052abSAntonio Huete Jimenez /*
79*90b052abSAntonio Huete Jimenez * First determine whether there is a character unequal to `c'
80*90b052abSAntonio Huete Jimenez * in the first word. As this word may contain bytes before
81*90b052abSAntonio Huete Jimenez * `begin', we may execute this loop spuriously.
82*90b052abSAntonio Huete Jimenez */
83*90b052abSAntonio Huete Jimenez lp = (const unsigned long *)((uintptr_t)begin & ~LONGPTR_MASK);
84*90b052abSAntonio Huete Jimenez end = (const unsigned char *)begin + n;
85*90b052abSAntonio Huete Jimenez if (*lp++ != word)
86*90b052abSAntonio Huete Jimenez for (p = begin; p < (const unsigned char *)lp;)
87*90b052abSAntonio Huete Jimenez TESTBYTE;
88*90b052abSAntonio Huete Jimenez
89*90b052abSAntonio Huete Jimenez /* Now compare the data one word at a time. */
90*90b052abSAntonio Huete Jimenez for (; (const unsigned char *)lp < end; lp++) {
91*90b052abSAntonio Huete Jimenez if (*lp != word) {
92*90b052abSAntonio Huete Jimenez p = (const unsigned char *)lp;
93*90b052abSAntonio Huete Jimenez TESTBYTE;
94*90b052abSAntonio Huete Jimenez TESTBYTE;
95*90b052abSAntonio Huete Jimenez TESTBYTE;
96*90b052abSAntonio Huete Jimenez #if LONG_BIT >= 64
97*90b052abSAntonio Huete Jimenez TESTBYTE;
98*90b052abSAntonio Huete Jimenez TESTBYTE;
99*90b052abSAntonio Huete Jimenez TESTBYTE;
100*90b052abSAntonio Huete Jimenez TESTBYTE;
101*90b052abSAntonio Huete Jimenez #endif
102*90b052abSAntonio Huete Jimenez goto done;
103*90b052abSAntonio Huete Jimenez }
104*90b052abSAntonio Huete Jimenez }
105*90b052abSAntonio Huete Jimenez
106*90b052abSAntonio Huete Jimenez return (NULL);
107*90b052abSAntonio Huete Jimenez
108*90b052abSAntonio Huete Jimenez done:
109*90b052abSAntonio Huete Jimenez /*
110*90b052abSAntonio Huete Jimenez * If the end of the buffer is not word aligned, the previous
111*90b052abSAntonio Huete Jimenez * loops may obtain an address that's beyond the end of the
112*90b052abSAntonio Huete Jimenez * buffer.
113*90b052abSAntonio Huete Jimenez */
114*90b052abSAntonio Huete Jimenez if (p < end)
115*90b052abSAntonio Huete Jimenez return (__DECONST(void *, p));
116*90b052abSAntonio Huete Jimenez return (NULL);
117*90b052abSAntonio Huete Jimenez }
118