ltt/compiler.h

   1 /* This file is part of the Linux Trace Toolkit trace reading library
   2  * Copyright (C) 2003-2004 Mathieu Desnoyers
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License Version 2.1 as published by the Free Software Foundation.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 02111-1307, USA.
  17  */
  18
  19 #ifndef COMPILER_H
  20 #define COMPILER_H
  21
  22 /* Fast prediction if likely branches */
  23 #define likely(x) __builtin_expect(!!(x), 1)
  24 #define unlikely(x) __builtin_expect(!!(x), 0)
  25
  26
  27 /*
  28  * Check at compile time that something is of a particular type.
  29  * Always evaluates to 1 so you may use it easily in comparisons.
  30  */
  31 #define typecheck(type,x) \
  32 ({  type __dummy; \
  33   typeof(x) __dummy2; \
  34   (void)(&__dummy == &__dummy2); \
  35   1; \
  36 })
  37
  38 /* Deal with 32 wrap correctly */
  39 #define guint32_after(a,b) \
  40   (typecheck(guint32, a) && \
  41    typecheck(guint32, b) && \
  42    ((gint32)(b) - (gint32)(a) < 0))
  43 #define guint32_before(a,b)  guint32_after(b,a)
  44
  45 #define guint32_after_eq(a,b) \
  46   (typecheck(guint32, a) && \
  47    typecheck(guint32, b) && \
  48    ((gint32)(b) - (gint32)(a) <= 0))
  49 #define guint32_before_eq(a,b)  guint32_after_eq(b,a)
  50
  51 #define __EXPORT __attribute__ ((visibility ("default")))
  52
  53 #endif //COMPILER_H