source: mainline/kernel/generic/src/lib/memstr.c@ 96b02eb9

/*
 * Copyright (c) 2001-2004 Jakub Jermar
 * Copyright (c) 2008 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup generic 
 * @{
 */

/**
 * @file
 * @brief       Memory string operations.
 *
 * This file provides architecture independent functions to manipulate blocks of
 * memory. These functions are optimized as much as generic functions of this
 * type can be. However, architectures are free to provide even more optimized
 * versions of these functions.
 */

#include <memstr.h>
#include <typedefs.h>
#include <align.h>

/** Copy block of memory.
 *
 * Copy cnt bytes from src address to dst address.  The copying is done
 * word-by-word and then byte-by-byte.  The source and destination memory areas
 * cannot overlap.
 *
 * @param src           Source address to copy from.
 * @param dst           Destination address to copy to.
 * @param cnt           Number of bytes to copy.
 *
 * @return              Destination address.
 */
void *_memcpy(void *dst, const void *src, size_t cnt)
{
        unsigned int i, j;
        
        if (ALIGN_UP((uintptr_t) src, sizeof(sysarg_t)) != (uintptr_t) src ||
            ALIGN_UP((uintptr_t) dst, sizeof(sysarg_t)) != (uintptr_t) dst) {
                for (i = 0; i < cnt; i++)
                        ((uint8_t *) dst)[i] = ((uint8_t *) src)[i];
        } else { 
                for (i = 0; i < cnt / sizeof(sysarg_t); i++)
                        ((sysarg_t *) dst)[i] = ((sysarg_t *) src)[i];
                
                for (j = 0; j < cnt % sizeof(sysarg_t); j++)
                        ((uint8_t *)(((sysarg_t *) dst) + i))[j] =
                            ((uint8_t *)(((sysarg_t *) src) + i))[j];
        }
                
        return (char *) 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 src           Source address to copy from.
 * @param dst           Destination address to copy to.
 * @param cnt           Number of bytes to copy.
 *
 * @return              Destination address.
 */
void *memmove(void *dst, const void *src, size_t n)
{
        const uint8_t *sp;
        uint8_t *dp;

        /* Nothing to do? */
        if (src == dst)
                return dst;

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

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

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

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

        return dst;
}

/** Fill block of memory
 *
 * Fill cnt bytes at dst address with the value x.  The filling is done
 * byte-by-byte.
 *
 * @param dst           Destination address to fill.
 * @param cnt           Number of bytes to fill.
 * @param x             Value to fill.
 *
 */
void _memsetb(void *dst, size_t cnt, uint8_t x)
{
        unsigned int i;
        uint8_t *p = (uint8_t *) dst;
        
        for (i = 0; i < cnt; i++)
                p[i] = x;
}

/** Fill block of memory.
 *
 * Fill cnt words at dst address with the value x.  The filling is done
 * word-by-word.
 *
 * @param dst           Destination address to fill.
 * @param cnt           Number of words to fill.
 * @param x             Value to fill.
 *
 */
void _memsetw(void *dst, size_t cnt, uint16_t x)
{
        unsigned int i;
        uint16_t *p = (uint16_t *) dst;
        
        for (i = 0; i < cnt; i++)
                p[i] = x;       
}

/** @}
 */