incubator-nuttx/wireless/ieee802154/mac802154_get_mhrlen.c

132 lines
4.1 KiB
C

/****************************************************************************
* wireless/ieee802154/mac802154_get_mhrlen.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 <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <string.h>
#include "mac802154.h"
#include "mac802154_internal.h"
#include <nuttx/wireless/ieee802154/ieee802154_mac.h>
/****************************************************************************
* Private Data
****************************************************************************/
/* Map between ieee802154_addrmode_e enum and actual address length */
static const uint8_t mac802154_addr_length[4] =
{
0, 0, 2, 8
};
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mac802154_get_mhrlen
*
* Description:
* Calculate the MAC header length given the frame meta-data.
*
****************************************************************************/
int mac802154_get_mhrlen(MACHANDLE mac,
FAR const struct ieee802154_frame_meta_s *meta)
{
FAR struct ieee802154_privmac_s *priv =
(FAR struct ieee802154_privmac_s *)mac;
int ret = 3; /* Always frame control (2 bytes) and seq. num (1 byte) */
/* Check to make sure both the dest address and the source address are not
* set to NONE
*/
if (meta->destaddr.mode == IEEE802154_ADDRMODE_NONE &&
meta->srcmode == IEEE802154_ADDRMODE_NONE)
{
return -EINVAL;
}
/* The source address can only be set to NONE
* if the device is the PAN coord
*/
if (meta->srcmode == IEEE802154_ADDRMODE_NONE &&
priv->devmode != IEEE802154_DEVMODE_PANCOORD)
{
return -EINVAL;
}
/* Add the destination address length */
ret += mac802154_addr_length[meta->destaddr.mode];
/* Add the source address length */
ret += mac802154_addr_length[meta->srcmode];
/* If both destination and source addressing information is present, the
* MAC sublayer shall compare the destination and source PAN identifiers.
* [1] pg. 41.
*/
if (meta->srcmode != IEEE802154_ADDRMODE_NONE &&
meta->destaddr.mode != IEEE802154_ADDRMODE_NONE)
{
/* If the PAN identifiers are identical, the PAN ID Compression field
* shall be set to one, and the source PAN identifier shall be omitted
* from the transmitted frame. [1] pg. 41.
*/
if (IEEE802154_PANIDCMP(meta->destaddr.panid, priv->addr.panid))
{
ret += 2; /* 2 bytes for destination PAN ID */
return ret;
}
}
/* If we are here, PAN ID compression is off, so include the dest and
* source PAN ID if the respective address is included
*/
if (meta->srcmode != IEEE802154_ADDRMODE_NONE)
{
ret += 2; /* 2 bytes for source PAN ID */
}
if (meta->destaddr.mode != IEEE802154_ADDRMODE_NONE)
{
ret += 2; /* 2 bytes for destination PAN ID */
}
return ret;
}