word-at-a-time.h

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#ifndef __ASM_ARM_WORD_AT_A_TIME_H
#define __ASM_ARM_WORD_AT_A_TIME_H

#ifndef __ARMEB__

/*
 * Little-endian word-at-a-time zero byte handling.
 * Heavily based on the x86 algorithm.
 */
#include <linux/kernel.h>

struct word_at_a_time {
    const unsigned long one_bits, high_bits;
};

#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }

static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
                     const struct word_at_a_time *c)
{
    unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
    *bits = mask;
    return mask;
}

#define prep_zero_mask(a, bits, c) (bits)

static inline unsigned long create_zero_mask(unsigned long bits)
{
    bits = (bits - 1) & ~bits;
    return bits >> 7;
}

static inline unsigned long find_zero(unsigned long mask)
{
    unsigned long ret;

#if __LINUX_ARM_ARCH__ >= 5
    /* We have clz available. */
    ret = fls(mask) >> 3;
#else
    /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
    ret = (0x0ff0001 + mask) >> 23;
    /* Fix the 1 for 00 case */
    ret &= mask;
#endif

    return ret;
}

#ifdef CONFIG_DCACHE_WORD_ACCESS

#define zero_bytemask(mask) (mask)

/*
 * Load an unaligned word from kernel space.
 *
 * In the (very unlikely) case of the word being a page-crosser
 * and the next page not being mapped, take the exception and
 * return zeroes in the non-existing part.
 */
static inline unsigned long load_unaligned_zeropad(const void *addr)
{
    unsigned long ret, offset;

    /* Load word from unaligned pointer addr */
    asm(
    "1: ldr %0, [%2]\n"
    "2:\n"
    "   .pushsection .fixup,\"ax\"\n"
    "   .align 2\n"
    "3: and %1, %2, #0x3\n"
    "   bic %2, %2, #0x3\n"
    "   ldr %0, [%2]\n"
    "   lsl %1, %1, #0x3\n"
    "   lsr %0, %0, %1\n"
    "   b   2b\n"
    "   .popsection\n"
    "   .pushsection __ex_table,\"a\"\n"
    "   .align  3\n"
    "   .long   1b, 3b\n"
    "   .popsection"
    : "=&r" (ret), "=&r" (offset)
    : "r" (addr), "Qo" (*(unsigned long *)addr));

    return ret;
}


#endif  /* DCACHE_WORD_ACCESS */

#else   /* __ARMEB__ */
#include <asm-generic/word-at-a-time.h>
#endif

#endif /* __ASM_ARM_WORD_AT_A_TIME_H */