nuttx/libs/libc/unistd/lib_swab.c
Alin Jerpelea d6b50a1d3f libs: nxstyle fixes
nxstyle fixes to pass the CI checks

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2021-03-03 18:52:53 -08:00

85 lines
2.9 KiB
C

/****************************************************************************
* libs/libc/unistd/lib_swab.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <unistd.h>
#include <assert.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: strncpy
*
* Description:
* The swab() function will copy nbytes bytes, which are pointed to by
* 'src', to the object pointed to by 'dest', exchanging adjacent bytes.
* The 'nbytes' argument should be even. If 'nbytes' is odd, swab() copies
* and exchanges 'nbytes'-1 bytes and the disposition of the last byte is
* unspecified. If copying takes place between objects that overlap, the
* behavior is undefined. If nbytes is negative, swab() does nothing.
*
* Returned Value:
* None
*
****************************************************************************/
void swab(FAR const void *src, FAR void *dest, ssize_t nbytes)
{
FAR const uint8_t *src8 = (FAR const uint8_t *)src;
FAR uint8_t *dest8 = (FAR uint8_t *)dest;
FAR uint8_t *end8;
DEBUGASSERT(src != NULL && dest != NULL);
/* Do nother if nbytes is negative or it there are few then 2 bytes to be
* transferred.
*/
if (nbytes > 1)
{
/* The end of dest buffer + 1 byte (skipping any odd numbered byte at
* the end of the buffer.
*/
end8 = dest8 + (nbytes & ~1);
/* Loop until the destination is equal to the end + 1 address */
while (dest8 != end8)
{
register uint8_t tmp;
/* Transfer the bytes, swapping the order */
tmp = *src8++;
*dest8++ = *src8++;
*dest8++ = tmp;
}
}
}