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cd8446f081
We get structeq and htable updates we don't need for free. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
47 lines
1.7 KiB
C
47 lines
1.7 KiB
C
/* MIT (BSD) license - see LICENSE file for details */
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#ifndef CCAN_STRUCTEQ_H
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#define CCAN_STRUCTEQ_H
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#include <ccan/build_assert/build_assert.h>
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#include <ccan/cppmagic/cppmagic.h>
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#include <string.h>
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#include <stdbool.h>
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/**
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* STRUCTEQ_DEF - define an ..._eq function to compare two structures.
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* @sname: name of the structure, and function (<sname>_eq) to define.
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* @padbytes: number of bytes of expected padding, or negative "max".
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* @...: name of every member of the structure.
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*
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* This generates a single memcmp() call in the common case where the
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* structure contains no padding. Since it can't tell the difference between
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* padding and a missing member, @padbytes can be used to assert that
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* there isn't any, or how many we expect. A negative number means
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* "up to or equal to that amount of padding", as padding can be
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* platform dependent.
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*/
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#define STRUCTEQ_DEF(sname, padbytes, ...) \
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static inline bool CPPMAGIC_GLUE2(sname, _eq)(const struct sname *_a, \
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const struct sname *_b) \
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{ \
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BUILD_ASSERT(((padbytes) < 0 && \
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CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \
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__VA_ARGS__)) \
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- (padbytes) >= sizeof(*_a)) \
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|| CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, \
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__VA_ARGS__)) \
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+ (padbytes) == sizeof(*_a)); \
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if (CPPMAGIC_JOIN(+, CPPMAGIC_MAP(STRUCTEQ_MEMBER_SIZE_, __VA_ARGS__)) \
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== sizeof(*_a)) \
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return memcmp(_a, _b, sizeof(*_a)) == 0; \
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else \
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return CPPMAGIC_JOIN(&&, \
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CPPMAGIC_MAP(STRUCTEQ_MEMBER_CMP_, \
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__VA_ARGS__)); \
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}
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/* Helpers */
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#define STRUCTEQ_MEMBER_SIZE_(m) sizeof((_a)->m)
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#define STRUCTEQ_MEMBER_CMP_(m) memcmp(&_a->m, &_b->m, sizeof(_a->m)) == 0
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#endif /* CCAN_STRUCTEQ_H */
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