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 59