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canframelen.h
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canframelen.h
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/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
/*
* canframelen.h
*
* Copyright (c) 2013, 2014 Czech Technical University in Prague
*
* Author: Michal Sojka <sojkam1@fel.cvut.cz>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Czech Technical University in Prague nor the
* names of its contributors may be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* The provided data structures and external interfaces from this code
* are not restricted to be used by modules with a GPL compatible license.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* Send feedback to <linux-can@vger.kernel.org>
*
*/
#ifndef CANFRAMELEN_H
#define CANFRAMELEN_H
#include <linux/can.h>
/**
* Frame length calculation modes.
*
* CFL_WORSTCASE corresponds to *worst* case calculation for
* stuff-bits - see (1)-(3) in [1]. The worst case number of bits on
* the wire can be calculated as:
*
* (34 + 8n - 1)/4 + 34 + 8n + 13 for SFF frames (11 bit CAN-ID) => 55 + 10n
* (54 + 8n - 1)/4 + 54 + 8n + 13 for EFF frames (29 bit CAN-ID) => 80 + 10n
*
* while 'n' is the data length code (number of payload bytes)
*
* [1] "Controller Area Network (CAN) schedulability analysis:
* Refuted, revisited and revised", Real-Time Syst (2007)
* 35:239-272.
*
*/
enum cfl_mode {
CFL_NO_BITSTUFFING, /* plain bit calculation without bitstuffing */
CFL_WORSTCASE, /* worst case estimation - see above */
CFL_EXACT, /* exact calculation of stuffed bits based on frame
* content and CRC */
};
/**
* Calculates the number of bits a frame needs on the wire (including
* inter frame space).
*
* Mode determines how to deal with stuffed bits.
*/
unsigned can_frame_length(struct canfd_frame *frame, enum cfl_mode mode, int mtu);
unsigned can_frame_dbitrate_length(struct canfd_frame *frame, enum cfl_mode mode, int mtu);
#endif