linux/arch/x86/include/uapi/asm/swab.h

#ifndef _ASM_X86_SWAB_H
#define _ASM_X86_SWAB_H

#include <linux/types.h>
#include <linux/compiler.h>

static inline __attribute_const__ __u32 __arch_swab32(__u32 val)
{
	asm("bswapl %0" : "=r" (val) : "0" (val));
	return val;
}
#define __arch_swab32 __arch_swab32

static inline __attribute_const__ __u64 __arch_swab64(__u64 val)
{
#ifdef __i386__
	union {
		struct {
			__u32 a;
			__u32 b;
		} s;
		__u64 u;
	} v;
	v.u = val;
	asm("bswapl %0 ; bswapl %1 ; xchgl %0,%1"
	    : "=r" (v.s.a), "=r" (v.s.b)
	    : "0" (v.s.a), "1" (v.s.b));
	return v.u;
#else /* __i386__ */
	asm("bswapq %0" : "=r" (val) : "0" (val));
	return val;
#endif
}
#define __arch_swab64 __arch_swab64

#endif /* _ASM_X86_SWAB_H */