common/include/minmax.h

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
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   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #ifndef NBDKIT_MINMAX_H
  34 #define NBDKIT_MINMAX_H
  35
  36 #include <config.h>
  37
  38 /* Safe MIN and MAX macros.  These evaluate each parameter once.  They
  39  * work for any comparable type.
  40  *
  41  * __auto_type is a GCC extension, added in GCC 4.9 in 2014, and to
  42  * Clang in 2015.  The fallback uses typeof which was added a very
  43  * long time ago.  Note that OpenBSD lacks __auto_type so the fallback
  44  * is required.
  45  */
  46
  47 #include "unique-name.h"
  48
  49 #undef MIN
  50 #define MIN(x, y) \
  51   MIN_1 ((x), (y), NBDKIT_UNIQUE_NAME (_x), NBDKIT_UNIQUE_NAME (_y))
  52 #undef MAX
  53 #define MAX(x, y) \
  54   MAX_1 ((x), (y), NBDKIT_UNIQUE_NAME (_x), NBDKIT_UNIQUE_NAME (_y))
  55
  56 #ifdef HAVE_AUTO_TYPE
  57
  58 #define MIN_1(x, y, _x, _y) ({                 \
  59       __auto_type _x = (x);                    \
  60       __auto_type _y = (y);                    \
  61       _x < _y ? _x : _y;                       \
  62     })
  63 #define MAX_1(x, y, _x, _y) ({                 \
  64       __auto_type _x = (x);                    \
  65       __auto_type _y = (y);                    \
  66       _x > _y ? _x : _y;                       \
  67     })
  68
  69 #else
  70
  71 #define MIN_1(x, y, _x, _y) ({                 \
  72       typeof (x) _x = (x);                     \
  73       typeof (y) _y = (y);                     \
  74       _x < _y ? _x : _y;                       \
  75     })
  76 #define MAX_1(x, y, _x, _y) ({                 \
  77       typeof (x) _x = (x);                     \
  78       typeof (y) _y = (y);                     \
  79       _x > _y ? _x : _y;                       \
  80     })
  81
  82 #endif
  83
  84 #endif /* NBDKIT_MINMAX_H */