source: vendor/FreeBSD-libc/5.1/stdlib/lsearch.c

/*
 * Initial implementation:
 * Copyright (c) 2002 Robert Drehmel
 * All rights reserved.
 *
 * As long as the above copyright statement and this notice remain
 * unchanged, you can do what ever you want with this file. 
 */
#include <sys/types.h>
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/stdlib/lsearch.c,v 1.1 2002/10/16 14:29:22 robert Exp $");

#define _SEARCH_PRIVATE
#include <search.h>
#include <stdint.h>     /* for uint8_t */
#include <stdlib.h>     /* for NULL */
#include <string.h>     /* for memcpy() prototype */

static void *lwork(const void *, const void *, size_t *, size_t,
    int (*)(const void *, const void *), int);

void *lsearch(const void *key, void *base, size_t *nelp, size_t width,
    int (*compar)(const void *, const void *))
{

        return (lwork(key, base, nelp, width, compar, 1));
}

void *lfind(const void *key, const void *base, size_t *nelp, size_t width,
    int (*compar)(const void *, const void *))
{

        return (lwork(key, base, nelp, width, compar, 0));
}

static void *
lwork(const void *key, const void *base, size_t *nelp, size_t width,
    int (*compar)(const void *, const void *), int addelem)
{
        uint8_t *ep, *endp;

        /*
         * Cast to an integer value first to avoid the warning for removing
         * 'const' via a cast.
         */
        ep = (uint8_t *)(uintptr_t)base;
        for (endp = (uint8_t *)(ep + width * *nelp); ep < endp; ep += width) {
                if (compar(key, ep) == 0)
                        return (ep);
        }

        /* lfind() shall return when the key was not found. */
        if (!addelem)
                return (NULL);

        /*
         * lsearch() adds the key to the end of the table and increments
         * the number of elements.
         */
        memcpy(endp, key, width);
        ++*nelp;

        return (endp);
}