#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>
#include <string.h>

#define OPT 1

#define __get_user_x(size, ret, x, ptr)				      \
	asm volatile("call __get_user_" #size			      \
		     : "=c" (ret), "=a" (x)			      \
		     : "0" (ptr))


#ifdef AMD64
#define __get_user_8(__ret_gu, __val_gu, ptr)                           \
	__get_user_x(8, __ret_gu, __val_gu, ptr)
#else
#define __get_user_8(ret, x, ptr)					\
	asm volatile("call __get_user_8_32"				\
		     : "=c" (ret), "=A" (x)				\
		     : "0" (ptr))
#endif

#if OPT == 1
#define get_user(x, ptr)						\
({									\
	int __ret_gu;							\
	unsigned long __val_gu;						\
	unsigned long long __val_gu8;					\
	switch (sizeof(*(ptr))) {					\
	case 1:                                                         \
		__get_user_x(1, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 2:								\
		__get_user_x(2, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 4:								\
		__get_user_x(4, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 8:								\
		__get_user_8(__ret_gu, __val_gu8, ptr);			\
		break;							\
	default:							\
		__get_user_x(X, __ret_gu, __val_gu, ptr);		\
		break;							\
	}								\
	if (sizeof(*(ptr)) == 8)					\
		(x) = (typeof(*(ptr)))__val_gu8;			\
	else								\
		(x) = (typeof(*(ptr)))__val_gu;				\
	__ret_gu;							\
})
#endif

#if OPT == 2
#define get_user(x, ptr)						\
({									\
	int __ret_gu;							\
	register typeof(x) __val_gu asm("eax");				\
	switch (sizeof(*(ptr))) {					\
	case 1:                                                         \
		__get_user_x(1, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 2:								\
		__get_user_x(2, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 4:								\
		__get_user_x(4, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 8:								\
		__get_user_8(__ret_gu, __val_gu, ptr);			\
		break;							\
	default:							\
		__get_user_x(X, __ret_gu, __val_gu, ptr);		\
		break;							\
	}								\
	(x) = (typeof(*(ptr)))__val_gu;					\
	__ret_gu;							\
})
#endif

#if OPT == 3
#define get_user(x, ptr)						\
({									\
	int __ret_gu;							\
	typeof(x) __val_gu;						\
	switch (sizeof(*(ptr))) {					\
	case 1:                                                         \
		__get_user_x(1, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 2:								\
		__get_user_x(2, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 4:								\
		__get_user_x(4, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 8:								\
		__get_user_8(__ret_gu, __val_gu, ptr);			\
		break;							\
	default:							\
		__get_user_x(X, __ret_gu, __val_gu, ptr);		\
		break;							\
	}								\
	(x) = (typeof(*(ptr)))__val_gu;					\
	__ret_gu;							\
})
#endif

int main(void)
{
	uint64_t foo = 0x89abcdef76543210;

	printf(" foo: %"PRIx64"\n", foo);

	struct {
		uint8_t sika1;
		uint16_t sika2;
		uint32_t sika4;
		uint64_t sika8;
	} __attribute__((__packed__)) x;

	if (get_user(x.sika8, (const uint64_t*)&foo)) return 1;
	if (get_user(x.sika4, (const uint64_t*)&foo)) return 1;
	if (get_user(x.sika2, (const uint64_t*)&foo)) return 1;
	if (get_user(x.sika1, (const uint64_t*)&foo)) return 1;
	printf("sika8: %"PRIx64"\n", x.sika8);
	printf("sika4: %x\n", x.sika4);
	printf("sika2: %x\n", x.sika2);
	printf("sika1: %x\n", x.sika1);

	//memset(&x, 0, sizeof(x));

	if (get_user(x.sika1, (const uint64_t*)&foo)) return 1;
	if (get_user(x.sika2, (const uint64_t*)&foo)) return 1;
	if (get_user(x.sika4, (const uint64_t*)&foo)) return 1;
	if (get_user(x.sika8, (const uint64_t*)&foo)) return 1;
	printf("sika8: %"PRIx64"\n", x.sika8);
	printf("sika4: %x\n", x.sika4);
	printf("sika2: %x\n", x.sika2);
	printf("sika1: %x\n", x.sika1);

	return 0;
}