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/* Copyright (c) 2013 Yaakov Selkowitz <yselkowi@redhat.com> */
/*
FUNCTION
<<rawmemchr>>---find character in memory
INDEX
rawmemchr
SYNOPSIS
#include <string.h>
void *rawmemchr(const void *<[src]>, int <[c]>);
DESCRIPTION
This function searches memory starting at <<*<[src]>>> for the
character <[c]>. The search only ends with the first occurrence
of <[c]>; in particular, <<NUL>> does not terminate the search.
No bounds checking is performed, so this function should only
be used when it is certain that the character <[c]> will be found.
RETURNS
A pointer to the first occurance of character <[c]>.
PORTABILITY
<<rawmemchr>> is a GNU extension.
<<rawmemchr>> requires no supporting OS subroutines.
QUICKREF
rawmemchr
*/
#define _GNU_SOURCE
#include <string.h>
#include <limits.h>
#include "local.h"
void *
rawmemchr(const void *src_void, int c)
{
const unsigned char *src = (const unsigned char *)src_void;
unsigned char d = c;
#if !defined(__PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) \
&& !defined(_PICOLIBC_NO_OUT_OF_BOUNDS_READS)
unsigned long *asrc;
unsigned long mask;
unsigned int i;
while (UNALIGNED_X(src)) {
if (*src == d)
return (void *)src;
src++;
}
/* If we get this far, we know that src is word-aligned. */
/* The fast code reads the source one word at a time and only
performs the bytewise search on word-sized segments if they
contain the search character, which is detected by XORing
the word-sized segment with a word-sized block of the search
character and then detecting for the presence of NUL in the
result. */
asrc = (unsigned long *)src;
mask = d << 8 | d;
mask = mask << 16 | mask;
for (i = 32; i < sizeof(mask) * 8; i <<= 1)
mask = (mask << i) | mask;
while (1) {
if (DETECT_CHAR(*asrc, mask))
break;
asrc++;
}
/* We have the matching word, now we resort to a bytewise loop. */
src = (unsigned char *)asrc;
#endif /* !__PREFER_SIZE_OVER_SPEED && !__OPTIMIZE_SIZE__ */
while (1) {
if (*src == d)
return (void *)src;
src++;
}
}