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1 | /* |
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> | |
19 | #include <asm/types.h> | |
20 | ||
21 | #if !defined(__STRICT_ANSI__) || defined(__KERNEL__) | |
22 | # define __SWAB_64_THRU_32__ | |
23 | #endif | |
24 | ||
25 | static inline __attribute_const__ __u32 __arch_swab32(__u32 x) | |
26 | { | |
27 | __u32 t; | |
28 | ||
29 | #ifndef __thumb__ | |
30 | if (!__builtin_constant_p(x)) { | |
31 | /* | |
32 | * The compiler needs a bit of a hint here to always do the | |
33 | * right thing and not screw it up to different degrees | |
34 | * depending on the gcc version. | |
35 | */ | |
36 | asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x)); | |
37 | } else | |
38 | #endif | |
39 | t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */ | |
40 | ||
41 | x = (x << 24) | (x >> 8); /* mov r0,r0,ror #8 */ | |
42 | t &= ~0x00FF0000; /* bic r1,r1,#0x00FF0000 */ | |
43 | x ^= (t >> 8); /* eor r0,r0,r1,lsr #8 */ | |
44 | ||
45 | return x; | |
46 | } | |
47 | #define __arch_swab32 __arch_swab32 | |
48 | ||
49 | #endif | |
50 |