// SPDX-License-Identifier: GPL-2.0
#include <linux/string.h>
#include <linux/export.h>

#undef memcpy
#undef memset

__visible void *memcpy(void *to, const void *from, size_t n)
{
#if defined(CONFIG_X86_USE_3DNOW) && !defined(CONFIG_FORTIFY_SOURCE)
        return __memcpy3d(to, from, n);
#else
        return __memcpy(to, from, n);
#endif
}
EXPORT_SYMBOL(memcpy);

__visible void *memset(void *s, int c, size_t count)
{
        return __memset(s, c, count);
}
EXPORT_SYMBOL(memset);

__visible void *memmove(void *dest, const void *src, size_t n)
{
        int d0,d1,d2,d3,d4,d5;
        char *ret = dest;

        __asm__ __volatile__(
                /* Handle more 16 bytes in loop */
                "cmp $0x10, %0\n\t"
                "jb     1f\n\t"

                /* Decide forward/backward copy mode */
                "cmp %2, %1\n\t"
                "jb     2f\n\t"

                /*
                 * movs instruction have many startup latency
                 * so we handle small size by general register.
                 */
                "cmp  $680, %0\n\t"
                "jb 3f\n\t"
                /*
                 * movs instruction is only good for aligned case.
                 */
                "mov %1, %3\n\t"
                "xor %2, %3\n\t"
                "and $0xff, %3\n\t"
                "jz 4f\n\t"
                "3:\n\t"
                "sub $0x10, %0\n\t"

                /*
                 * We gobble 16 bytes forward in each loop.
                 */
                "3:\n\t"
                "sub $0x10, %0\n\t"
                "mov 0*4(%1), %3\n\t"
                "mov 1*4(%1), %4\n\t"
                "mov  %3, 0*4(%2)\n\t"
                "mov  %4, 1*4(%2)\n\t"
                "mov 2*4(%1), %3\n\t"
                "mov 3*4(%1), %4\n\t"
                "mov  %3, 2*4(%2)\n\t"
                "mov  %4, 3*4(%2)\n\t"
                "lea  0x10(%1), %1\n\t"
                "lea  0x10(%2), %2\n\t"
                "jae 3b\n\t"
                "add $0x10, %0\n\t"
                "jmp 1f\n\t"

                /*
                 * Handle data forward by movs.
                 */
                ".p2align 4\n\t"
                "4:\n\t"
                "mov -4(%1, %0), %3\n\t"
                "lea -4(%2, %0), %4\n\t"
                "shr $2, %0\n\t"
                "rep movsl\n\t"
                "mov %3, (%4)\n\t"
                "jmp 11f\n\t"
                /*
                 * Handle data backward by movs.
                 */
                ".p2align 4\n\t"
                "6:\n\t"
                "mov (%1), %3\n\t"
                "mov %2, %4\n\t"
                "lea -4(%1, %0), %1\n\t"
                "lea -4(%2, %0), %2\n\t"
                "shr $2, %0\n\t"
                "std\n\t"
                "rep movsl\n\t"
                "mov %3,(%4)\n\t"
                "cld\n\t"
                "jmp 11f\n\t"

                /*
                 * Start to prepare for backward copy.
                 */
                ".p2align 4\n\t"
                "2:\n\t"
                "cmp  $680, %0\n\t"
                "jb 5f\n\t"
                "mov %1, %3\n\t"
                "xor %2, %3\n\t"
                "and $0xff, %3\n\t"
                "jz 6b\n\t"

                /*
                 * Calculate copy position to tail.
                 */
                "5:\n\t"
                "add %0, %1\n\t"
                "add %0, %2\n\t"
                "sub $0x10, %0\n\t"

                /*
                 * We gobble 16 bytes backward in each loop.
                 */
                "7:\n\t"
                "sub $0x10, %0\n\t"

                "mov -1*4(%1), %3\n\t"
                "mov -2*4(%1), %4\n\t"
                "mov  %3, -1*4(%2)\n\t"
                "mov  %4, -2*4(%2)\n\t"
                "mov -3*4(%1), %3\n\t"
                "mov -4*4(%1), %4\n\t"
                "mov  %3, -3*4(%2)\n\t"
                "mov  %4, -4*4(%2)\n\t"
                "lea  -0x10(%1), %1\n\t"
                "lea  -0x10(%2), %2\n\t"
                "jae 7b\n\t"
                /*
                 * Calculate copy position to head.
                 */
                "add $0x10, %0\n\t"
                "sub %0, %1\n\t"
                "sub %0, %2\n\t"

                /*
                 * Move data from 8 bytes to 15 bytes.
                 */
                ".p2align 4\n\t"
                "1:\n\t"
                "cmp $8, %0\n\t"
                "jb 8f\n\t"
                "mov 0*4(%1), %3\n\t"
                "mov 1*4(%1), %4\n\t"
                "mov -2*4(%1, %0), %5\n\t"
                "mov -1*4(%1, %0), %1\n\t"

                "mov  %3, 0*4(%2)\n\t"
                "mov  %4, 1*4(%2)\n\t"
                "mov  %5, -2*4(%2, %0)\n\t"
                "mov  %1, -1*4(%2, %0)\n\t"
                "jmp 11f\n\t"

                /*
                 * Move data from 4 bytes to 7 bytes.
                 */
                ".p2align 4\n\t"
                "8:\n\t"
                "cmp $4, %0\n\t"
                "jb 9f\n\t"
                "mov 0*4(%1), %3\n\t"
                "mov -1*4(%1, %0), %4\n\t"
                "mov  %3, 0*4(%2)\n\t"
                "mov  %4, -1*4(%2, %0)\n\t"
                "jmp 11f\n\t"

                /*
                 * Move data from 2 bytes to 3 bytes.
                 */
                ".p2align 4\n\t"
                "9:\n\t"
                "cmp $2, %0\n\t"
                "jb 10f\n\t"
                "movw 0*2(%1), %%dx\n\t"
                "movw -1*2(%1, %0), %%bx\n\t"
                "movw %%dx, 0*2(%2)\n\t"
                "movw %%bx, -1*2(%2, %0)\n\t"
                "jmp 11f\n\t"

                /*
                 * Move data for 1 byte.
                 */
                ".p2align 4\n\t"
                "10:\n\t"
                "cmp $1, %0\n\t"
                "jb 11f\n\t"
                "movb (%1), %%cl\n\t"
                "movb %%cl, (%2)\n\t"
                ".p2align 4\n\t"
                "11:"
                : "=&c" (d0), "=&S" (d1), "=&D" (d2),
                  "=r" (d3),"=r" (d4), "=r"(d5)
                :"0" (n),
                 "1" (src),
                 "2" (dest)
                :"memory");

        return ret;

}
EXPORT_SYMBOL(memmove);