110 lines
3.4 KiB
C
110 lines
3.4 KiB
C
/****************************************************************************
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* libs/libc/string/lib_bsdmemcpy.c
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*
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* Copyright (c) 1994-2009 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the BSD License. This program is distributed in the hope that
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* it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
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* including the implied warranties of MERCHANTABILITY or FITNESS FOR
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* A PARTICULAR PURPOSE. A copy of this license is available at
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* http://www.opensource.org/licenses. Any Red Hat trademarks that are
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* incorporated in the source code or documentation are not subject to
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* the BSD License and may only be used or replicated with the express
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* permission of Red Hat, Inc.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <string.h>
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#include "libc.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Nonzero if either x or y is not aligned on a "long" boundary. */
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#define UNALIGNED(x, y) \
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(((long)(uintptr_t)(x) & (sizeof(long) - 1)) | ((long)(uintptr_t)(y) & (sizeof(long) - 1)))
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/* How many bytes are copied each iteration of the 4X unrolled loop. */
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#define BIGBLOCKSIZE (sizeof(long) << 2)
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/* How many bytes are copied each iteration of the word copy loop. */
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#define LITTLEBLOCKSIZE (sizeof(long))
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/* Threshhold for punting to the byte copier. */
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#define TOO_SMALL(len) ((len) < BIGBLOCKSIZE)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: memcpy
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****************************************************************************/
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#if !defined(CONFIG_LIBC_ARCH_MEMCPY) && defined(LIBC_BUILD_MEMCPY)
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#undef memcpy /* See mm/README.txt */
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no_builtin("memcpy")
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FAR void *memcpy(FAR void *dest, FAR const void *src, size_t n)
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{
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FAR char *pout = dest;
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FAR const char *pin = src;
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FAR long *paligned_out;
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FAR const long *paligned_in;
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/* If the size is small, or either pin or pout is unaligned,
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* then punt into the byte copy loop. This should be rare.
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*/
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if (!TOO_SMALL(n) && !UNALIGNED(pin, pout))
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{
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paligned_out = (FAR long *)pout;
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paligned_in = (FAR long *)pin;
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/* Copy 4X long words at a time if possible. */
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while (n >= BIGBLOCKSIZE)
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{
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*paligned_out++ = *paligned_in++;
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*paligned_out++ = *paligned_in++;
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*paligned_out++ = *paligned_in++;
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*paligned_out++ = *paligned_in++;
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n -= BIGBLOCKSIZE;
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}
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/* Copy one long word at a time if possible. */
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while (n >= LITTLEBLOCKSIZE)
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{
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*paligned_out++ = *paligned_in++;
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n -= LITTLEBLOCKSIZE;
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}
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/* Pick up any residual with a byte copier. */
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pout = (FAR char *)paligned_out;
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pin = (FAR char *)paligned_in;
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}
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while (n--)
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{
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*pout++ = *pin++;
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}
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return dest;
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}
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#endif
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