swab.h

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/*
 *  arch/arm/include/asm/byteorder.h
 *
 * ARM Endian-ness.  In little endian mode, the data bus is connected such
 * that byte accesses appear as:
 *  0 = d0...d7, 1 = d8...d15, 2 = d16...d23, 3 = d24...d31
 * and word accesses (data or instruction) appear as:
 *  d0...d31
 *
 * When in big endian mode, byte accesses appear as:
 *  0 = d24...d31, 1 = d16...d23, 2 = d8...d15, 3 = d0...d7
 * and word accesses (data or instruction) appear as:
 *  d0...d31
 */
#ifndef _UAPI__ASM_ARM_SWAB_H
#define _UAPI__ASM_ARM_SWAB_H

#include <linux/compiler.h>
#include <linux/types.h>

#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
#  define __SWAB_64_THRU_32__
#endif


#if !defined(__KERNEL__) || __LINUX_ARM_ARCH__ < 6
static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
{
    __u32 t;

#ifndef __thumb__
    if (!__builtin_constant_p(x)) {
        /*
         * The compiler needs a bit of a hint here to always do the
         * right thing and not screw it up to different degrees
         * depending on the gcc version.
         */
        asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
    } else
#endif
        t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */

    x = (x << 24) | (x >> 8);       /* mov r0,r0,ror #8      */
    t &= ~0x00FF0000;           /* bic r1,r1,#0x00FF0000 */
    x ^= (t >> 8);              /* eor r0,r0,r1,lsr #8   */

    return x;
}
#define __arch_swab32 __arch_swab32

#endif

#endif /* _UAPI__ASM_ARM_SWAB_H */