nuttx/net/utils/net_ipv6_pref2mask.c
Alin Jerpelea 08e5378b11 NuttX: Gregory Nutt: update licenses to Apache
Several licenses were missed in the initial work

David Sidrane has submitted the ICLA and we can migrate the licenses
 to Apache.

Gregory Nutt has submitted the SGA and we can migrate the licenses
 to Apache.

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2021-04-03 04:20:31 -07:00

107 lines
3.3 KiB
C

/****************************************************************************
* net/utils/net_ipv6_pref2mask.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 <nuttx/net/ip.h>
#include "utils/utils.h"
#ifdef CONFIG_NET_IPv6
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: net_ipv6_pref2mask
*
* Description:
* Convert a IPv6 prefix length to a network mask. The prefix length
* specifies the number of MS bits under mask (0-128)
*
* Input Parameters:
* preflen - Determines the width of the netmask (in bits). Range 0-128
* mask - The location to return the netmask.
*
* Returned Value:
* None
*
****************************************************************************/
void net_ipv6_pref2mask(uint8_t preflen, net_ipv6addr_t mask)
{
unsigned int bit;
unsigned int i;
/* Set the network mask. preflen is the number of MS bits under the mask.
*
* Eg. preflen = 38
* NETMASK: ffff ffff fc00 0000 0000 0000 0000 0000
* bit: 1 1..1
* 1 1..3 3..4 4..6 6..7 8..9 9..1 1..2
* 0..5 6..1 2..7 8..3 4..9 0..5 6..1 2..7
* preflen: 1 1..1
* 1 1..3 3..4 4..6 6..8 8..9 9..1 1..2
* 1..6 7..2 3..8 9..4 5..0 1..6 7..2 3..8
*/
for (i = 0; i < 8; i++)
{
/* bit = {0, 16, 32, 48, 64, 80, 96, 112} */
bit = i << 4;
if (preflen > bit)
{
/* Eg. preflen = 38, bit = {0, 16, 32} */
if (preflen >= (bit + 16))
{
/* Eg. preflen = 38, bit = {0, 16} */
mask[i] = 0xffff;
}
else
{
/* Eg. preflen = 38, bit = {32}
* preflen - bit = 6
* mask = 0xffff << (16-6)
* = 0xfc00
*/
mask[i] = 0xffff << (16 - (preflen - bit));
}
}
else
{
/* Eg. preflen=38, bit= {48, 64, 80, 96, 112} */
mask[i] = 0x0000;
}
}
}
#endif /* CONFIG_NET_IPv6 */