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4377 svoboda 1
/*
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 * Copyright (c) 2005 Martin Decky
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 * Copyright (c) 2008 Jiri Svoboda
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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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 *
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 * - 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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 * - 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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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup libc
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 * @{
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 */
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/** @file
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 */
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#include <mem.h>
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#include <stdlib.h>
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#include <sys/types.h>
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/** Fill memory block with a constant value. */
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void *memset(void *dest, int b, size_t n)
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{
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    char *pb;
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    unsigned long *pw;
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    size_t word_size;
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    size_t n_words;
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    unsigned long pattern;
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    size_t i;
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    size_t fill;
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    /* Fill initial segment. */
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    word_size = sizeof(unsigned long);
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    fill = word_size - ((uintptr_t) dest & (word_size - 1));
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    if (fill > n) fill = n;
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    pb = dest;
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    i = fill;
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    while (i-- != 0)
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        *pb++ = b;
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    /* Compute remaining size. */
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    n -= fill;
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    if (n == 0) return dest;
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    n_words = n / word_size;
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    n = n % word_size;
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    pw = (unsigned long *) pb;
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    /* Create word-sized pattern for aligned segment. */
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    pattern = 0;
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    i = word_size;
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    while (i-- != 0)
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        pattern = (pattern << 8) | (uint8_t) b;
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    /* Fill aligned segment. */
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    i = n_words;
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    while (i-- != 0)
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        *pw++ = pattern;
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    pb = (char *) pw;
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    /* Fill final segment. */
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    i = n;
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    while (i-- != 0)
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        *pb++ = b;
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    return dest;
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}
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struct along {
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    unsigned long n;
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} __attribute__ ((packed));
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static void *unaligned_memcpy(void *dst, const void *src, size_t n)
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{
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    size_t i, j;
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    struct along *adst = dst;
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    const struct along *asrc = src;
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    for (i = 0; i < n / sizeof(unsigned long); i++)
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        adst[i].n = asrc[i].n;
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    for (j = 0; j < n % sizeof(unsigned long); j++)
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        ((unsigned char *) (((unsigned long *) dst) + i))[j] =
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            ((unsigned char *) (((unsigned long *) src) + i))[j];
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    return (char *) dst;
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}
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/** Copy memory block. */
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void *memcpy(void *dst, const void *src, size_t n)
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{
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    size_t i;
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    size_t mod, fill;
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    size_t word_size;
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    size_t n_words;
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    const unsigned long *srcw;
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    unsigned long *dstw;
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    const uint8_t *srcb;
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    uint8_t *dstb;
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    word_size = sizeof(unsigned long);
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    /*
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     * Are source and destination addresses congruent modulo word_size?
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     * If not, use unaligned_memcpy().
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     */
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    if (((uintptr_t) dst & (word_size - 1)) !=
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        ((uintptr_t) src & (word_size - 1)))
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        return unaligned_memcpy(dst, src, n);
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    /*
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     * mod is the address modulo word size. fill is the length of the
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     * initial buffer segment before the first word boundary.
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     * If the buffer is very short, use unaligned_memcpy(), too.
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     */
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    mod = (uintptr_t) dst & (word_size - 1);
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    fill = word_size - mod;
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    if (fill > n) fill = n;
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    /* Copy the initial segment. */
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    srcb = src;
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    dstb = dst;
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    i = fill;
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    while (i-- != 0)
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        *dstb++ = *srcb++;
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    /* Compute remaining length. */
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    n -= fill;
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    if (n == 0) return dst;
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    /* Pointers to aligned segment. */
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    dstw = (unsigned long *) dstb;
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    srcw = (const unsigned long *) srcb;
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    n_words = n / word_size;    /* Number of whole words to copy. */
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    n -= n_words * word_size;   /* Remaining bytes at the end. */
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    /* "Fast" copy. */
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    i = n_words;
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    while (i-- != 0)
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        *dstw++ = *srcw++;
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    /*
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     * Copy the rest.
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     */
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    srcb = (const uint8_t *) srcw;
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    dstb = (uint8_t *) dstw;
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    i = n;
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    while (i-- != 0)
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        *dstb++ = *srcb++;
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    return dst;
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}
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/** Move memory block with possible overlapping. */
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void *memmove(void *dst, const void *src, size_t n)
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{
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    const uint8_t *sp;
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    uint8_t *dp;
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    /* Nothing to do? */
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    if (src == dst)
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        return dst;
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    /* Non-overlapping? */
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    if (dst >= src + n || src >= dst + n) {
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        return memcpy(dst, src, n);
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    }
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    /* Which direction? */
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    if (src > dst) {
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        /* Forwards. */
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        sp = src;
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        dp = dst;
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        while (n-- != 0)
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            *dp++ = *sp++;
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    } else {
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        /* Backwards. */
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        sp = src + (n - 1);
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        dp = dst + (n - 1);
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        while (n-- != 0)
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            *dp-- = *sp--;
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    }
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    return dst;
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}
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/** Compare two memory areas.
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 *
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 * @param s1        Pointer to the first area to compare.
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 * @param s2        Pointer to the second area to compare.
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 * @param len       Size of the first area in bytes. Both areas must have
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 *          the same length.
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 * @return      If len is 0, return zero. If the areas match, return
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 *          zero. Otherwise return non-zero.
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 */
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int bcmp(const char *s1, const char *s2, size_t len)
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{
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    for (; len && *s1++ == *s2++; len--)
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        ;
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    return len;
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}
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/** @}
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 */