View of xos/include/util.h

/* Copyright (C) 2008  Emmanuel Varoquaux
 
   This file is part of XOS.
 
   This program 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 3 of the License, or
   (at your option) any later version.
 
   This program 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.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
#ifndef _UTIL_H
#define _UTIL_H
 
#include <stddef.h>
 
#define downcast(type, member, ptr) ({ \
  typeof (ptr) _ptr = (ptr); \
  ((type *)(_ptr ? (void *)_ptr - offsetof(type, member) : 0)); \
})
 
#define min(a, b) ({ \
  typeof (a) _a = (a); \
  typeof (b) _b = (b); \
  _a < _b ? _a : _b; \
})
 
#define max(a, b) ({ \
  typeof (a) _a = (a); \
  typeof (b) _b = (b); \
  _a > _b ? _a : _b; \
})
 
#define set_if_lower(var, val) ({ \
  typeof (var) *_pvar = &(var); \
  typeof (val) _val = (val); \
  if (*_pvar < _val) \
    *_pvar = _val; \
})
 
#define set_if_upper(var, val) ({ \
  typeof (var) *_pvar = &(var); \
  typeof (val) _val = (val); \
  if (*_pvar > _val) \
    *_pvar = _val; \
})
 
#endif