compiler.h

/*
 * Copyright 2008-2013 Various Authors
 * Copyright 2005 Timo Hirvonen
 *
 * 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 2 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 CMUS_COMPILER_H
#define CMUS_COMPILER_H

#include <stddef.h>

/*
 * GCC 2.96 or compatible required
 */
#if defined(__GNUC__)

#if __GNUC__ > 3
#undef offsetof
#define offsetof(type, member) __builtin_offsetof(type, member)
#endif

/* Optimization: Condition @x is likely */
#define likely(x)	__builtin_expect(!!(x), 1)

/* Optimization: Condition @x is unlikely */
#define unlikely(x)	__builtin_expect(!!(x), 0)

#ifndef UNUSED
#define UNUSED __attribute__((unused))
#endif

#else

#define likely(x)	(x)
#define unlikely(x)	(x)
#define UNUSED

#endif

/* Optimization: Function never returns */
#define CMUS_NORETURN	__attribute__((__noreturn__))

/* Argument at index @fmt_idx is printf compatible format string and
 * argument at index @first_idx is the first format argument */
#define CMUS_FORMAT(fmt_idx, first_idx) __attribute__((format(printf, (fmt_idx), (first_idx))))

#if defined(__GNUC__) && (__GNUC__ >= 3)

/* Optimization: Pointer returned can't alias other pointers */
#define CMUS_MALLOC	__attribute__((__malloc__))

#else

#define CMUS_MALLOC

#endif


/**
 * container_of - cast a member of a structure out to the containing structure
 *
 * @ptr:	the pointer to the member.
 * @type:	the type of the container struct this is embedded in.
 * @member:	the name of the member within the struct.
 *
 */
#define container_of_portable(ptr, type, member) \
	((type *)(void *)( (char *)(ptr) - offsetof(type,member)))
#undef container_of
#if defined(__GNUC__)
#define container_of(ptr, type, member) __extension__ ({		\
	const __typeof__( ((type *)0)->member) *_mptr = (ptr);	\
	container_of_portable(_mptr, type, member);})
#else
#define container_of(ptr, type, member) container_of_portable(ptr, type, member)
#endif

#endif