1/*
2 *  linux/include/asm-arm/byteorder.h
3 *
4 * ARM Endian-ness.  In little endian mode, the data bus is connected such
5 * that byte accesses appear as:
6 *  0 = d0...d7, 1 = d8...d15, 2 = d16...d23, 3 = d24...d31
7 * and word accesses (data or instruction) appear as:
8 *  d0...d31
9 *
10 * When in big endian mode, byte accesses appear as:
11 *  0 = d24...d31, 1 = d16...d23, 2 = d8...d15, 3 = d0...d7
12 * and word accesses (data or instruction) appear as:
13 *  d0...d31
14 */
15#ifndef __ASM_ARM_BYTEORDER_H
16#define __ASM_ARM_BYTEORDER_H
17
18#include <linux/compiler.h>
19#include <asm/types.h>
20
21static inline __attribute_const__ __u32 ___arch__swab32(__u32 x)
22{
23	__u32 t;
24
25#ifndef __thumb__
26	if (!__builtin_constant_p(x)) {
27		/*
28		 * The compiler needs a bit of a hint here to always do the
29		 * right thing and not screw it up to different degrees
30		 * depending on the gcc version.
31		 */
32		asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
33	} else
34#endif
35		t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */
36
37	x = (x << 24) | (x >> 8);		/* mov r0,r0,ror #8      */
38	t &= ~0x00FF0000;			/* bic r1,r1,#0x00FF0000 */
39	x ^= (t >> 8);				/* eor r0,r0,r1,lsr #8   */
40
41	return x;
42}
43
44#define __arch__swab32(x) ___arch__swab32(x)
45
46#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
47#  define __BYTEORDER_HAS_U64__
48#  define __SWAB_64_THRU_32__
49#endif
50
51#ifdef __ARMEB__
52#include <linux/byteorder/big_endian.h>
53#else
54#include <linux/byteorder/little_endian.h>
55#endif
56
57#endif
58