inc/hf/decl_offsets.h

#pragma once

#ifdef GEN_OFFSETS

/* When generating offsets, create constants which can be extracted from the
 * generated assembly. */

#define DECL(name, type, field) \
	const size_t DEFINE_OFFSET__##name = offsetof(type, field)

#define DECL_SIZE(name, type) const size_t DEFINE_OFFSET__name = sizeof(type)

#else /* GEN_OFFSETS */

/* When not generating offsets, validate that the extracted values are as
 * expected. */

#include <assert.h>

#define DECL(name, type, field) DECL_1(#name, name, offsetof(type, field))
#define DECL_1(name, actual, expected)                       \
	static_assert((actual) == (expected),                \
		      "Offset " name " should be " #expected \
		      " and not " #actual)

#define DECL_SIZE(name, type) DECL_SIZE_1(#name, name, sizeof(type))
#define DECL_SIZE_1(name, actual, expected)                 \
	static_assert((actual) == (expected),               \
		      "Size " #name " should be " #expected \
		      " and not" #actual)

#endif /* GEN_OFFSETS */