incubator-nuttx/net/utils/net_incr32.c

100 lines
3.0 KiB
C

/****************************************************************************
* net/utils/net_incr32.c
*
* SPDX-License-Identifier: Apache-2.0
*
* 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 <nuttx/net/netdev.h>
#ifndef CONFIG_NET_ARCH_INCR32
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: net_carry32
*
* Description:
* Calculate the Internet checksum over a buffer.
*
****************************************************************************/
static inline void net_carry32(FAR uint8_t *sum, uint16_t op16)
{
if (sum[2] < (op16 >> 8))
{
++sum[1];
if (sum[1] == 0)
{
++sum[0];
}
}
if (sum[3] < (op16 & 0xff))
{
++sum[2];
if (sum[2] == 0)
{
++sum[1];
if (sum[1] == 0)
{
++sum[0];
}
}
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: net_incr32
*
* Description:
*
* Carry out a 32-bit addition.
*
* By defining CONFIG_NET_ARCH_INCR32, the architecture can replace
* net_incr32 with hardware assisted solutions.
*
* Input Parameters:
* op32 - A pointer to a 4-byte array representing a 32-bit integer in
* network byte order (big endian). This value may not be word
* aligned. The value pointed to by op32 is modified in place
*
* op16 - A 16-bit integer in host byte order.
*
****************************************************************************/
void net_incr32(FAR uint8_t *op32, uint16_t op16)
{
op32[3] += (op16 & 0xff);
op32[2] += (op16 >> 8);
net_carry32(op32, op16);
}
#endif /* CONFIG_NET_ARCH_INCR32 */