src/openvpn/integer.h

   1 /*
   2  *  OpenVPN -- An application to securely tunnel IP networks
   3  *             over a single UDP port, with support for SSL/TLS-based
   4  *             session authentication and key exchange,
   5  *             packet encryption, packet authentication, and
   6  *             packet compression.
   7  *
   8  *  Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@openvpn.net>
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License version 2
  12  *  as published by the Free Software Foundation.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program (see the file COPYING included with this
  21  *  distribution); if not, write to the Free Software Foundation, Inc.,
  22  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  */
  24
  25 #ifndef INTEGER_H
  26 #define INTEGER_H
  27
  28 #include "error.h"
  29
  30 /*
  31  * min/max functions
  32  */
  33
  34 static inline int
  35 max_int (int x, int y)
  36 {
  37   if (x > y)
  38     return x;
  39   else
  40     return y;
  41 }
  42
  43 static inline int
  44 min_int (int x, int y)
  45 {
  46   if (x < y)
  47     return x;
  48   else
  49     return y;
  50 }
  51
  52 static inline int
  53 constrain_int (int x, int min, int max)
  54 {
  55   if (min > max)
  56     return min;
  57   if (x < min)
  58     return min;
  59   else if (x > max)
  60     return max;
  61   else
  62     return x;
  63 }
  64
  65 /*
  66  * Functions used for circular buffer index arithmetic.
  67  */
  68
  69 /*
  70  * Return x - y on a circle of circumference mod by shortest path.
  71  *
  72  * 0 <= x < mod
  73  * 0 <= y < mod
  74  */
  75 static inline int
  76 modulo_subtract(int x, int y, int mod)
  77 {
  78   const int d1 = x - y;
  79   const int d2 = (x > y ? -mod : mod) + d1;
  80   ASSERT (0 <= x && x < mod && 0 <= y && y < mod);
  81   return abs(d1) > abs(d2) ? d2 : d1;
  82 }
  83
  84 /*
  85  * Return x + y on a circle of circumference mod.
  86  *
  87  * 0 <= x < mod
  88  * -mod <= y <= mod
  89  */
  90 static inline int
  91 modulo_add(int x, int y, int mod)
  92 {
  93   int sum = x + y;
  94   ASSERT (0 <= x && x < mod && -mod <= y && y <= mod);
  95   if (sum >= mod)
  96     sum -= mod;
  97   if (sum < 0)
  98     sum += mod;
  99   return sum;
 100 }
 101
 102 static inline int
 103 index_verify (int index, int size, const char *file, int line)
 104 {
 105   if (index < 0 || index >= size)
 106     msg (M_FATAL, "Assertion Failed: Array index=%d out of bounds for array size=%d in %s:%d",
 107          index,
 108          size,
 109          file,
 110          line);
 111   return index;
 112 }
 113
 114 #endif