| Norman James | 6a58a27 | 2015-10-07 14:34:16 -0500 | [diff] [blame^] | 1 | /* CC0 (Public domain) - see LICENSE file for details */
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| 2 | #ifndef CCAN_ARRAY_SIZE_H
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| 3 | #define CCAN_ARRAY_SIZE_H
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| 4 | #include "config.h"
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| 5 | #include <ccan/build_assert/build_assert.h>
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| 6 |
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| 7 | /**
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| 8 | * ARRAY_SIZE - get the number of elements in a visible array
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| 9 | * @arr: the array whose size you want.
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| 10 | *
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| 11 | * This does not work on pointers, or arrays declared as [], or
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| 12 | * function parameters. With correct compiler support, such usage
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| 13 | * will cause a build error (see build_assert).
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| 14 | */
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| 15 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + _array_size_chk(arr))
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| 16 |
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| 17 | #if HAVE_BUILTIN_TYPES_COMPATIBLE_P && HAVE_TYPEOF
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| 18 | /* Two gcc extensions.
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| 19 | * &a[0] degrades to a pointer: a different type from an array */
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| 20 | #define _array_size_chk(arr) \
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| 21 | BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(typeof(arr), \
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| 22 | typeof(&(arr)[0])))
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| 23 | #else
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| 24 | #define _array_size_chk(arr) 0
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| 25 | #endif
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| 26 | #endif /* CCAN_ALIGNOF_H */
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