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