blob: 9997ad20eff11d04906882b0a8da3c7c47ac4f76 [file] [log] [blame]
Harvey Harrisonaf8e24e2009-01-06 14:56:30 -08001/*
2 * arch/arm/include/asm/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_SWAB_H
16#define __ASM_ARM_SWAB_H
17
18#include <linux/compiler.h>
Jaswinder Singh Rajpute42ec242009-01-31 10:43:44 +053019#include <linux/types.h>
Harvey Harrisonaf8e24e2009-01-06 14:56:30 -080020
21#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
22# define __SWAB_64_THRU_32__
23#endif
24
Rabin Vincent40f5b072009-10-25 16:55:33 +010025#if defined(__KERNEL__) && __LINUX_ARM_ARCH__ >= 6
26
27static inline __attribute_const__ __u16 __arch_swab16(__u16 x)
28{
29 __asm__ ("rev16 %0, %1" : "=r" (x) : "r" (x));
30 return x;
31}
32#define __arch_swab16 __arch_swab16
33
34static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
35{
36 __asm__ ("rev %0, %1" : "=r" (x) : "r" (x));
37 return x;
38}
39#define __arch_swab32 __arch_swab32
40
41#else
42
Harvey Harrisonaf8e24e2009-01-06 14:56:30 -080043static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
44{
45 __u32 t;
46
47#ifndef __thumb__
48 if (!__builtin_constant_p(x)) {
49 /*
50 * The compiler needs a bit of a hint here to always do the
51 * right thing and not screw it up to different degrees
52 * depending on the gcc version.
53 */
54 asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
55 } else
56#endif
57 t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */
58
59 x = (x << 24) | (x >> 8); /* mov r0,r0,ror #8 */
60 t &= ~0x00FF0000; /* bic r1,r1,#0x00FF0000 */
61 x ^= (t >> 8); /* eor r0,r0,r1,lsr #8 */
62
63 return x;
64}
65#define __arch_swab32 __arch_swab32
66
67#endif
68
Rabin Vincent40f5b072009-10-25 16:55:33 +010069#endif