include/linux/ppp_defs.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * ppp_defs.h - PPP definitions.
   4  *
   5  * Copyright 1994-2000 Paul Mackerras.
   6  */
   7 #ifndef _PPP_DEFS_H_
   8 #define _PPP_DEFS_H_
   9
  10 #include <linux/crc-ccitt.h>
  11 #include <uapi/linux/ppp_defs.h>
  12
  13 #define PPP_FCS(fcs, c) crc_ccitt_byte(fcs, c)
  14
  15 /**
  16  * ppp_proto_is_valid - checks if PPP protocol is valid
  17  * @proto: PPP protocol
  18  *
  19  * Assumes proto is not compressed.
  20  * Protocol is valid if the value is odd and the least significant bit of the
  21  * most significant octet is 0 (see RFC 1661, section 2).
  22  */
  23 static inline bool ppp_proto_is_valid(u16 proto)
  24 {
  25         return !!((proto & 0x0101) == 0x0001);
  26 }
  27
  28 #endif /* _PPP_DEFS_H_ */