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