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/* Copyright (c) 2002 Jeff Johnston <jjohnstn@redhat.com> */
/*
FUNCTION
<<memccpy>>---copy memory regions with end-token check
SYNOPSIS
#include <string.h>
void* memccpy(void *restrict <[out]>, const void *restrict <[in]>,
int <[endchar]>, size_t <[n]>);
DESCRIPTION
This function copies up to <[n]> bytes from the memory region
pointed to by <[in]> to the memory region pointed to by
<[out]>. If a byte matching the <[endchar]> is encountered,
the byte is copied and copying stops.
If the regions overlap, the behavior is undefined.
RETURNS
<<memccpy>> returns a pointer to the first byte following the
<[endchar]> in the <[out]> region. If no byte matching
<[endchar]> was copied, then <<NULL>> is returned.
PORTABILITY
<<memccpy>> is a GNU extension.
<<memccpy>> requires no supporting OS subroutines.
*/
#define _DEFAULT_SOURCE
#include <stddef.h>
#include <string.h>
#include <limits.h>
#include "local.h"
void *
memccpy(void * __restrict dst0, const void * __restrict src0, int endchar0, size_t len0)
{
#if defined(__PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) \
|| defined(_PICOLIBC_NO_OUT_OF_BOUNDS_READS)
void *ptr = NULL;
char *dst = (char *)dst0;
char *src = (char *)src0;
char endchar = endchar0 & 0xff;
while (len0--) {
if ((*dst++ = *src++) == endchar) {
ptr = dst;
break;
}
}
return ptr;
#else
void *ptr = NULL;
unsigned char *dst = dst0;
const unsigned char *src = src0;
long *aligned_dst;
const long *aligned_src;
unsigned char endchar = endchar0 & 0xff;
/* If the size is small, or either SRC or DST is unaligned,
then punt into the byte copy loop. This should be rare. */
if (!TOO_SMALL_LITTLE_BLOCK(len0) && !UNALIGNED_X_Y(src, dst)) {
unsigned int i;
unsigned long mask;
aligned_dst = (long *)dst;
aligned_src = (long *)src;
/* The fast code reads the ASCII 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 NULL in the
result. */
mask = endchar << 8 | endchar;
mask = mask << 16 | mask;
for (i = 32; i < sizeof(mask) * 8; i <<= 1)
mask = (mask << i) | mask;
/* Copy one long word at a time if possible. */
while (!TOO_SMALL_LITTLE_BLOCK(len0)) {
unsigned long buffer = (unsigned long)(*aligned_src);
buffer ^= mask;
if (DETECT_NULL(buffer))
break; /* endchar is found, go byte by byte from here */
*aligned_dst++ = *aligned_src++;
len0 -= LITTLE_BLOCK_SIZE;
}
/* Pick up any residual with a byte copier. */
dst = (unsigned char *)aligned_dst;
src = (unsigned char *)aligned_src;
}
while (len0--) {
if ((*dst++ = *src++) == endchar) {
ptr = dst;
break;
}
}
return ptr;
#endif /* not __PREFER_SIZE_OVER_SPEED */
}
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