source: mainline/boot/generic/src/memstr.c@ 39916d6

/*
 * SPDX-FileCopyrightText: 2010 Jiri Svoboda
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <memstr.h>
#include <stddef.h>
#include <stdint.h>

/** Move memory block without overlapping.
 *
 * Copy cnt bytes from src address to dst address. The source
 * and destination memory areas cannot overlap.
 *
 * @param dst Destination address to copy to.
 * @param src Source address to copy from.
 * @param cnt Number of bytes to copy.
 *
 * @return Destination address.
 *
 */
void *memcpy(void *dst, const void *src, size_t cnt)
{
        uint8_t *dp = (uint8_t *) dst;
        const uint8_t *sp = (uint8_t *) src;

        while (cnt-- != 0)
                *dp++ = *sp++;

        return dst;
}

/** Fill block of memory.
 *
 * Fill cnt bytes at dst address with the value val.
 *
 * @param dst Destination address to fill.
 * @param val Value to fill.
 * @param cnt Number of bytes to fill.
 *
 * @return Destination address.
 *
 */
void *memset(void *dst, int val, size_t cnt)
{
        uint8_t *dp = (uint8_t *) dst;

        while (cnt-- != 0)
                *dp++ = val;

        return dst;
}

/** Move memory block with possible overlapping.
 *
 * Copy cnt bytes from src address to dst address. The source
 * and destination memory areas may overlap.
 *
 * @param dst Destination address to copy to.
 * @param src Source address to copy from.
 * @param cnt Number of bytes to copy.
 *
 * @return Destination address.
 *
 */
void *memmove(void *dst, const void *src, size_t cnt)
{
        /* Nothing to do? */
        if (src == dst)
                return dst;

        /* Non-overlapping? */
        if ((dst >= src + cnt) || (src >= dst + cnt))
                return memcpy(dst, src, cnt);

        uint8_t *dp;
        const uint8_t *sp;

        /* Which direction? */
        if (src > dst) {
                /* Forwards. */
                dp = dst;
                sp = src;

                while (cnt-- != 0)
                        *dp++ = *sp++;
        } else {
                /* Backwards. */
                dp = dst + (cnt - 1);
                sp = src + (cnt - 1);

                while (cnt-- != 0)
                        *dp-- = *sp--;
        }

        return dst;
}

/** @}
 */