270 lines
7.4 KiB
C
270 lines
7.4 KiB
C
/****************************************************************************
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* net/utils/net_chksum.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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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#ifdef CONFIG_NET
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#include "utils/utils.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: chksum
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*
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* Description:
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* Calculate the raw change sum over the memory region described by
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* data and len.
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*
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* Input Parameters:
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* sum - Partial calculations carried over from a previous call to
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* chksum(). This should be zero on the first time that check
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* sum is called.
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* data - Beginning of the data to include in the checksum.
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* len - Length of the data to include in the checksum.
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*
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* Returned Value:
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* The updated checksum value.
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*
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****************************************************************************/
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#ifndef CONFIG_NET_ARCH_CHKSUM
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uint16_t chksum(uint16_t sum, FAR const uint8_t *data, uint16_t len)
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{
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FAR const uint8_t *dataptr;
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FAR const uint8_t *last_byte;
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uint16_t t;
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dataptr = data;
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last_byte = data + len - 1;
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while (dataptr < last_byte)
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{
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/* At least two more bytes */
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t = ((uint16_t)dataptr[0] << 8) + dataptr[1];
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sum += t;
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if (sum < t)
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{
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sum++; /* carry */
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}
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dataptr += 2;
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}
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if (dataptr == last_byte)
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{
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t = (dataptr[0] << 8) + 0;
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sum += t;
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if (sum < t)
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{
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sum++; /* carry */
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}
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}
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/* Return sum in host byte order. */
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return sum;
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}
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#endif /* CONFIG_NET_ARCH_CHKSUM */
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/****************************************************************************
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* Name: chksum_iob
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*
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* Description:
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* Calculate the Internet checksum over an iob chain buffer.
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*
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* Input Parameters:
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* sum - Partial calculations carried over from a previous call to
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* chksum(). This should be zero on the first time that check
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* sum is called.
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* iob - An iob chain buffer over which the checksum is to be computed.
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* offset - Specifies the byte offset of the start of valid data.
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*
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* Returned Value:
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* The updated checksum value.
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*
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****************************************************************************/
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#ifdef CONFIG_MM_IOB
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uint16_t chksum_iob(uint16_t sum, FAR struct iob_s *iob, uint16_t offset)
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{
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/* Skip to the I/O buffer containing the data offset */
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while (iob != NULL && offset > iob->io_len)
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{
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offset -= iob->io_len;
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iob = iob->io_flink;
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}
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/* If the link pointer is not empty, loop to walk through all I/O buffer
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* and accumulate the sum
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*/
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while (iob != NULL)
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{
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sum = chksum(sum, iob->io_data + iob->io_offset + offset,
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iob->io_len - offset);
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iob = iob->io_flink;
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offset = 0;
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}
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return sum;
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}
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#endif /* CONFIG_MM_IOB */
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/****************************************************************************
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* Name: net_chksum
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*
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* Description:
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* Calculate the Internet checksum over a buffer.
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*
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* The Internet checksum is the one's complement of the one's complement
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* sum of all 16-bit words in the buffer.
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*
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* See RFC1071.
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*
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* If CONFIG_NET_ARCH_CHKSUM is defined, then this function must be
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* provided by architecture-specific logic.
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*
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* Input Parameters:
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*
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* buf - A pointer to the buffer over which the checksum is to be computed.
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*
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* len - The length of the buffer over which the checksum is to be
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* computed.
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*
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* Returned Value:
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* The Internet checksum of the buffer.
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*
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****************************************************************************/
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#ifndef CONFIG_NET_ARCH_CHKSUM
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uint16_t net_chksum(FAR uint16_t *data, uint16_t len)
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{
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return HTONS(chksum(0, (uint8_t *)data, len));
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}
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#endif /* CONFIG_NET_ARCH_CHKSUM */
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/****************************************************************************
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* Name: net_chksum_iob
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*
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* Description:
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* Calculate the Internet checksum over an iob chain buffer.
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*
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* The Internet checksum is the one's complement of the one's complement
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* sum of all 16-bit words in the buffer.
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*
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* See RFC1071.
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*
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* If CONFIG_NET_ARCH_CHKSUM is defined, then this function must be
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* provided by architecture-specific logic.
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*
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* Input Parameters:
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* sum - Partial calculations carried over from a previous call to
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* chksum(). This should be zero on the first time that check
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* sum is called.
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* iob - An iob chain buffer over which the checksum is to be computed.
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* offset - Specifies the byte offset of the start of valid data.
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*
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* Returned Value:
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* The Internet checksum of the given iob chain buffer.
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*
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****************************************************************************/
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#ifdef CONFIG_MM_IOB
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uint16_t net_chksum_iob(uint16_t sum, FAR struct iob_s *iob, uint16_t offset)
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{
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return HTONS(chksum_iob(sum, iob, offset));
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}
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#endif /* CONFIG_MM_IOB */
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/****************************************************************************
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* Name: net_chksum_adjust
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*
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* Description:
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* Adjusts the checksum of a packet without having to completely
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* recalculate it, as described in RFC 3022, Section 4.2, Page 9.
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*
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* Input Parameters:
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* chksum - points to the chksum in the packet
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* optr - points to the old data in the packet
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* olen - length of old data
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* nptr - points to the new data in the packet
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* nlen - length of new data
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*
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* Limitations:
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* The algorithm is applicable only for even offsets and even lengths.
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****************************************************************************/
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void net_chksum_adjust(FAR uint16_t *chksum,
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FAR const uint16_t *optr, ssize_t olen,
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FAR const uint16_t *nptr, ssize_t nlen)
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{
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#ifdef CONFIG_ENDIAN_BIG
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# warning "Not verified on big-endian yet."
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#endif
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int32_t x;
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int32_t oldval;
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int32_t newval;
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x = NTOHS(*chksum);
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x = ~x & 0xffff;
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while (olen > 0)
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{
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oldval = NTOHS(*optr);
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x -= oldval & 0xffff;
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if (x <= 0)
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{
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x--;
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x &= 0xffff;
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}
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optr++;
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olen -= 2;
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}
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while (nlen > 0)
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{
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newval = NTOHS(*nptr);
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x += newval & 0xffff;
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if ((x & 0x10000) != 0)
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{
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x++;
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x &= 0xffff;
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}
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nptr++;
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nlen -= 2;
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}
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x = ~x & 0xffff;
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*chksum = HTONS(x);
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}
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#endif /* CONFIG_NET */
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