text: /****************************************************************************
   * net/utils/utils.h
   *
   *   Copyright (C) 2014-2015 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * 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 NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * 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.
   *
   ****************************************************************************/
  
  #ifndef __NET_UTILS_UTILS_H
  #define __NET_UTILS_UTILS_H
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  #include <nuttx/net/net.h>
  #include <nuttx/net/ip.h>
  
  /****************************************************************************
   * Public Types
   ****************************************************************************/
  
  /* These values control the behavior of net_timeval2desc */
  
  enum tv2ds_remainder_e
  {
    TV2DS_TRUNC = 0, /* Truncate microsecond remainder */
    TV2DS_ROUND,     /* Round to the nearest full decisecond */
    TV2DS_CEIL       /* Force to next larger full decisecond */
  };
  
  /****************************************************************************
   * Public Data
   ****************************************************************************/
  
  #ifdef __cplusplus
  #define EXTERN extern "C"
  extern "C"
  {
  #else
  #define EXTERN extern
  #endif
  
  /****************************************************************************
   * Public Function Prototypes
   ****************************************************************************/
  
  struct net_driver_s;      /* Forward reference */
  struct timeval;           /* Forward reference */
  
  /****************************************************************************
   * Function: net_lockinitialize
   *
   * Description:
   *   Initialize the locking facility
   *
   ****************************************************************************/
  
  #ifdef CONFIG_NET_NOINTS
  void net_lockinitialize(void);
  #else
  #  define net_lockinitialize()
  #endif
  
  /****************************************************************************
   * Function: net_dsec2timeval
   *
   * Description:
   *   Convert a decisecond value to a struct timeval.  Needed by getsockopt()
   *   to report timeout values.
   *
   * Parameters:
   *   dsec The decisecond value to convert
   *   tv   The struct timeval to receive the converted value
   *
   * Returned Value:
   *   None
   *
   * Assumptions:
   *
   ****************************************************************************/
  
  void net_dsec2timeval(uint16_t dsec, FAR struct timeval *tv);
  
  /****************************************************************************
   * Function: net_dsec2tick
   *
   * Description:
   *   Convert a decisecond value to a system clock ticks.  Used by IGMP logic.
   *
   * Parameters:
   *   dsec The decisecond value to convert
   *
   * Returned Value:
   *   The decisecond value expressed as system clock ticks
   *
   ****************************************************************************/
  
  unsigned int net_dsec2tick(int dsec);
  
  /****************************************************************************
   * Function: net_timeval2dsec
   *
   * Description:
   *   Convert a struct timeval to deciseconds.  Needed by setsockopt() to
   *   save new timeout values.
   *
   * Parameters:
   *   tv        - The struct timeval to convert
   *   remainder - Determines how to handler the microsecond remainder
   *
   * Returned Value:
   *   The converted value
   *
   * Assumptions:
   *
   ****************************************************************************/
  
  unsigned int net_timeval2dsec(FAR struct timeval *tv,
                                enum tv2ds_remainder_e remainder);
  
  /****************************************************************************
   * Name: net_ipv6_mask2pref
   *
   * Description:
   *   Convert a 128-bit netmask to a prefix length.  The Nuttx IPv6
   *   networking uses 128-bit network masks internally.  This function
   *   converts the IPv6 netmask to a prefix length.
   *
   *   The prefix length is the number of MS '1' bits on in the netmask.
   *   This, of course, assumes that all MS bits are '1' and all LS bits are
   *   '0' with no intermixed 1's and 0's.  This function searches from the MS
   *   bit until the first '0' is found (this does not necessary mean that
   *   there might not be additional '1' bits following the firs '0', but that
   *   will be a malformed netmask.
   *
   * Parameters:
   *   mask   Points to an IPv6 netmask in the form of uint16_t[8]
   *
   * Return:
   *   The prefix length, range 0-128 on success;  This function will not
   *   fail.
   *
   ****************************************************************************/
  
  #ifdef CONFIG_NET_IPv6
  uint8_t net_ipv6_mask2pref(FAR const uint16_t *mask);
  #endif
  
  /****************************************************************************
   * Function: net_ipv6_pref2mask
   *
   * Description:
   *   Convert a IPv6 prefix length to a network mask.  The prefix length
   *   specifies the number of MS bits under mask (0-128)
   *
   * Parameters:
   *   preflen  - Determines the width of the netmask (in bits).  Range 0-128
   *   mask  - The location to return the netmask.
   *
   * Returned Value:
   *   None
   *
   ****************************************************************************/
  
  #ifdef CONFIG_NET_IPv6
  void net_ipv6_pref2mask(uint8_t preflen, net_ipv6addr_t mask);
  #endif
  
  /****************************************************************************
   * Name: tcp_chksum, tcp_ipv4_chksum, and tcp_ipv6_chksum
   *
   * Description:
   *   Calculate the TCP checksum of the packet in d_buf and d_appdata.
   *
   *   The TCP checksum is the Internet checksum of data contents of the
   *   TCP segment, and a pseudo-header as defined in RFC793.
   *
   *   Note: The d_appdata pointer that points to the packet data may
   *   point anywhere in memory, so it is not possible to simply calculate
   *   the Internet checksum of the contents of the d_buf buffer.
   *
   * Returned Value:
   *   The TCP checksum of the TCP segment in d_buf and pointed to by
   *   d_appdata.
   *
   ****************************************************************************/
  
  #ifdef CONFIG_NET_IPv4
  uint16_t tcp_ipv4_chksum(FAR struct net_driver_s *dev);
  #endif
  
  #ifdef CONFIG_NET_IPv6
  /* REVIST: Is this used? */
  uint16_t tcp_ipv6_chksum(FAR struct net_driver_s *dev);
  #endif
  
  #if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
  uint16_t tcp_chksum(FAR struct net_driver_s *dev);
  #elif defined(CONFIG_NET_IPv4)
  #  define tcp_chksum(d) tcp_ipv4_chksum(d)
  #else /* if defined(CONFIG_NET_IPv6) */
  #  define tcp_chksum(d) tcp_ipv6_chksum(d)
  #endif
  
  /****************************************************************************
   * Name: udp_ipv4_chksum
   *
   * Description:
   *   Calculate the UDP/IPv4 checksum of the packet in d_buf and d_appdata.
   *
   ****************************************************************************/
  
  #if defined(CONFIG_NET_UDP_CHECKSUMS) && defined(CONFIG_NET_IPv4)
  uint16_t udp_ipv4_chksum(FAR struct net_driver_s *dev);
  #endif
  
  /****************************************************************************
   * Name: udp_ipv6_chksum
   *
   * Description:
   *   Calculate the UDP/IPv6 checksum of the packet in d_buf and d_appdata.
   *
   ****************************************************************************/
  
  #if defined(CONFIG_NET_UDP_CHECKSUMS) && defined(CONFIG_NET_IPv6)
  uint16_t udp_ipv6_chksum(FAR struct net_driver_s *dev);
  #endif
  
  /****************************************************************************
   * Name: icmp_chksum
   *
   * Description:
   *   Calculate the checksum of the IPv4 ICMP message
   *
   ****************************************************************************/
  
  #if defined(CONFIG_NET_ICMP) && defined(CONFIG_NET_ICMP_PING)
  uint16_t icmp_chksum(FAR struct net_driver_s *dev, int len);
  #endif
  
  /****************************************************************************
   * Name: icmpv6_chksum
   *
   * Description:
   *   Calculate the checksum of the ICMPv6 message
   *
   ****************************************************************************/
  
  #ifdef CONFIG_NET_ICMPv6
  uint16_t icmpv6_chksum(FAR struct net_driver_s *dev);
  #endif
  
  #undef EXTERN
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* __NET_UTILS_UTILS_H */
  