/* SPDX-License-Identifier: GPL-2.0 */
#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/bitops.h>
#include <linux/wordpart.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;
}

#define zero_bytemask(mask) (mask)

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

#ifdef CONFIG_DCACHE_WORD_ACCESS

/*
 * 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, tmp;

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

        return ret;
}

#endif  /* DCACHE_WORD_ACCESS */
#endif /* __ASM_ARM_WORD_AT_A_TIME_H */