x15/kern/macros.h

/*
 * Copyright (c) 2009-2018 Richard Braun.
 *
 * 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/>.
 *
 * Upstream site with license notes :
 * http://git.sceen.net/rbraun/librbraun.git/
 *
 *
 * Helper macros.
 *
 * This file is a top header in the inclusion hierarchy, and shouldn't include
 * other headers that may cause circular dependencies.
 *
 * TODO Improve documentation.
 */

#ifndef KERN_MACROS_H
#define KERN_MACROS_H

#if !defined(__GNUC__) || (__GNUC__ < 4)
  #error "GCC 4+ required"
#endif

#ifndef __ASSEMBLER__
  #include <stdbool.h>
  #include <stddef.h>
#endif

// Attributes for variables that are mostly read and seldom changed.
#define __read_mostly       __section (".data.read_mostly")

#define MACRO_BEGIN         ({
#define MACRO_END           })

#define __QUOTE(x)          #x
#define QUOTE(x)            __QUOTE(x)

#define CONCAT_(x, y)       x ## y
#define CONCAT(x, y)        CONCAT_ (x, y)

#ifdef __ASSEMBLER__
  #define DECL_CONST(x, s)    x
#else
  #define DECL_CONST(x, s)    CONCAT (x, s)
#endif

#define STRLEN(x)           (sizeof (x) - 1)
#define ARRAY_SIZE(x)       (sizeof (x) / sizeof ((x)[0]))

#define MIN(a, b)   ((a) < (b) ? (a) : (b))
#define MAX(a, b)   ((a) > (b) ? (a) : (b))

#define SWAP(a, b)   \
  do   \
    {   \
      _Auto a_ = *(a);   \
      *(a) = *(b);   \
      *(b) = a_;   \
    }   \
  while (0)

#define DIV_CEIL(n, d)   (((n) + (d) - 1) / (d))

#define P2ALIGNED(x, a)     (((x) & ((a) - 1)) == 0)
#define ISP2(x)             P2ALIGNED (x, x)
#define P2ALIGN(x, a)       ((x) & -(a))        // decreases if not aligned
#define P2ROUND(x, a)       (-(-(x) & -(a)))    // increases if not aligned
#define P2END(x, a)         (-(~(x) & -(a)))    // always increases

#define structof(ptr, type, member)   \
  ((type *)((char *)(ptr) - offsetof (type, member)))

#define likely(expr)        __builtin_expect (!!(expr), 1)
#define unlikely(expr)      __builtin_expect (!!(expr), 0)

#define barrier()           asm volatile ("" : : : "memory")

// Allocate memory from the stack.
#define alloca   __builtin_alloca

// The following macros may be provided by the C environment.

#ifndef __noinline
  #define __noinline          __attribute__ ((noinline))
#endif

#ifndef __always_inline
  #define __always_inline     inline __attribute__ ((always_inline))
#endif

#ifndef __section
  #define __section(x)        __attribute__ ((section(x)))
#endif

#ifndef __packed
  #define __packed            __attribute__ ((packed))
#endif

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

#ifndef __used
  #define __used              __attribute__ ((used))
#endif

#ifndef __weak
  #define __weak              __attribute__ ((weak))
#endif

#ifndef __fallthrough
  #if __GNUC__ >= 7
    #define __fallthrough       __attribute__ ((fallthrough))
  #else
    #define __fallthrough
  #endif
#endif

// Standard offsetof.
#define OFFSETOF   __builtin_offsetof

// Type inference.
#define _Auto   __auto_type

// Unique identifiers.
#define UNIQ(prefix)   CONCAT (prefix, __COUNTER__)

// Cleanup functions.
#define CLEANUP(fct)   __attribute__ ((cleanup (fct)))

#endif