endianness.h

Go to the documentation of this file.

/* This file is part of Netsukuku
 * (c) Copyright 2005 Andrea Lo Pumo aka AlpT <alpt@freaknet.org>
 *
 * This source code is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * This source code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * Please refer to the GNU Public License for more details.
 *
 * You should have received a copy of the GNU Public License along with
 * this source code; if not, write to:
 * Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifndef ENDIANNESS_H
#define ENDIANNESS_H

#define MAX_INTS_PER_STRUCT 8       /* The maximum number of short/int variables 
                           present in a struct */

#define IINFO_DYNAMIC_VALUE -1      /* This define is used to fill part in a 
                           int_info struct that must be set each time. 
                           If that part is not set, -1 will remain, and
                           the int_info functions will call fatal(). 
                           Therefore this is useful to track bugs. */


/* flags for int_info.int_type */
#define INT_TYPE_VOID       0       /* Emptiness is loneliness, and loneliness is 
                           cleanliness */
#define INT_TYPE_32BIT      1       /* The int var is of 32 bits */
#define INT_TYPE_16BIT      (1<<1)      /* The int var is of 16 bits */
#define INT_TYPE_WORDS      (1<<2)      /* The int var is composed by an array of ints,
                           like the ipv6 ip (struct in6_addr) */
#define INT_TYPE_NETWORK    (1<<3)      /* The int var is stored in network order */

/*
 * int_info: this struct is used to keep the information about the int/short
 * variables present in a struct. It is useful to convert all the int/short
 * vars in another endian format with a simple function. 
 * WARNING: There is a drawback: the struct must have the __packed__
 * attribute (but since we are using this for packet structs we don't care).
 *
 * Here there is an example which show how to use this int_info:
 *  
 * given the struct s:
 *  struct 
 *  {
 *      u_char a;
 *      int b;
 *      short c;
 *      char d[23];
 *      int e[4];
 *  }__attribute__ ((__packed__)) s;
 *
 * its int_info struct should be filled in this way:
 * 
 * int_info s_int_info = { 3,
 *                 {INT_TYPE_32BIT, INT_TYPE_16BIT, INT_TYPE_32BIT}, 
 *             { sizeof(char), sizeof(char)+sizeof(int), 
 *              sizeof(char)+sizeof(int)+sizeof(short)+sizeof(char)*23},
 *                 { 1, 1, 4 }
 *           };
 */
typedef struct
{
    /* The total int/short vars present in the struct */
    int     total_ints;             

    /* Each member in the int_type array corresponds to a int/short var
     * and it is set using the above INT_TYPE_ flags */
    char    int_type[MAX_INTS_PER_STRUCT];

    /* Each member in the int_offset array specifies the amount of bytes
     * to be added at the end of the struct to get the relative int/short
     * var. */
    size_t  int_offset[MAX_INTS_PER_STRUCT];

    /* int_nmemb[x] is equal to the number of consecutive ints/shorts var,
     * which start at the int_offset[x] offset. */
    size_t  int_nmemb[MAX_INTS_PER_STRUCT];

} int_info;

/* Useful to declare constant static int_info structs in .h files */
#define INT_INFO const static int_info

#if BYTE_ORDER == LITTLE_ENDIAN
#include <linux/byteorder/little_endian.h>
#else
#include <linux/byteorder/big_endian.h>
#endif


/* * * Functions declaration * * */
void *int_info_copy(int_info *dst, const int_info *src);
void ints_array_htons(short *netshort, int nmemb);
void ints_array_ntohs(short *hostshort, int nmemb);
void ints_array_htonl(int *netlong, int nmemb);
void ints_array_ntohl(int *hostlong, int nmemb);
void ints_network_to_host(void *s, int_info iinfo);
void ints_host_to_network(void *s, int_info iinfo);
void ints_printf(void *s, int_info iinfo, void(*print_func(const char *, ...)));

#endif /*ENDIANNESS_H*/