1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 /* 3 * arch/arm/include/asm/byteorder.h 4 * 5 * ARM Endian-ness. In little endian mode, the data bus is connected such 6 * that byte accesses appear as: 7 * 0 = d0...d7, 1 = d8...d15, 2 = d16...d23, 3 = d24...d31 8 * and word accesses (data or instruction) appear as: 9 * d0...d31 10 * 11 * When in big endian mode, byte accesses appear as: 12 * 0 = d24...d31, 1 = d16...d23, 2 = d8...d15, 3 = d0...d7 13 * and word accesses (data or instruction) appear as: 14 * d0...d31 15 */ 16 #ifndef _UAPI__ASM_ARM_SWAB_H 17 #define _UAPI__ASM_ARM_SWAB_H 18 19 #include <linux/compiler.h> 20 #include <linux/types.h> 21 22 #if !defined(__STRICT_ANSI__) || defined(__KERNEL__) 23 # define __SWAB_64_THRU_32__ 24 #endif 25 26 27 #if !defined(__KERNEL__) || __LINUX_ARM_ARCH__ < 6 28 static inline __attribute_const__ __u32 __arch_swab32(__u32 x) 29 { 30 __u32 t; 31 32 #ifndef __thumb__ 33 if (!__builtin_constant_p(x)) { 34 /* 35 * The compiler needs a bit of a hint here to always do the 36 * right thing and not screw it up to different degrees 37 * depending on the gcc version. 38 */ 39 asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x)); 40 } else 41 #endif 42 t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */ 43 44 x = (x << 24) | (x >> 8); /* mov r0,r0,ror #8 */ 45 t &= ~0x00FF0000; /* bic r1,r1,#0x00FF0000 */ 46 x ^= (t >> 8); /* eor r0,r0,r1,lsr #8 */ 47 48 return x; 49 } 50 #define __arch_swab32 __arch_swab32 51 52 #endif 53 54 #endif /* _UAPI__ASM_ARM_SWAB_H */ 55
