39 lines
1.1 KiB
C
39 lines
1.1 KiB
C
#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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