cf99fb40c9
Squashed commit of the following:
libs/libxx: Fix some confusing in naming. If the directory is called libxx, then the library must be libxx.a (unless perhaps LIBCXX is selected).
libs/: Fix paths in moved library directories.
libs: Brute force move of libc, libnx, and libxx to libs. Cannot yet build it in that configuration.
100 lines
3.6 KiB
C
100 lines
3.6 KiB
C
/****************************************************************************
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* libs/libc/unistd/lib_swab.c
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*
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* Copyright (C) 2017 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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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* 1. 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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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <unistd.h>
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#include <assert.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: strncpy
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*
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* Description:
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* The swab() function will copy nbytes bytes, which are pointed to by
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* 'src', to the object pointed to by 'dest', exchanging adjacent bytes.
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* The 'nbytes' argument should be even. If 'nbytes' is odd, swab() copies
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* and exchanges 'nbytes'-1 bytes and the disposition of the last byte is
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* unspecified. If copying takes place between objects that overlap, the
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* behavior is undefined. If nbytes is negative, swab() does nothing.
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void swab(FAR const void *src, FAR void *dest, ssize_t nbytes)
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{
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FAR const uint8_t *src8 = (FAR const uint8_t *)src;
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FAR uint8_t *dest8 = (FAR uint8_t *)dest;
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FAR uint8_t *end8;
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DEBUGASSERT(src != NULL && dest != NULL);
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/* Do nother if nbytes is negative or it there are few then 2 bytes to be
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* transferred.
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*/
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if (nbytes > 1)
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{
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/* The end of dest buffer + 1 byte (skipping any odd numbered byte at
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* the end of the buffer.
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*/
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end8 = dest8 + (nbytes & ~1);
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/* Loop until the destination is equal to the end + 1 address */
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while (dest8 != end8)
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{
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register uint8_t tmp;
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/* Transfer the bytes, swapping the order */
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tmp = *src8++;
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*dest8++ = *src8++;
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*dest8++ = tmp;
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}
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}
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}
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