/* SPDX-License-Identifier: GPL-2.0 */
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/linkage.h>
#include "sysdep.h"

ENTRY(__memcpy)
ENTRY(memcpy)
        /* Test if len less than 4 bytes.  */
        mov     r12, r0
        cmplti  r2, 4
        bt      .L_copy_by_byte

        andi    r13, r0, 3
        movi    r19, 4
        /* Test if dest is not 4 bytes aligned.  */
        bnez    r13, .L_dest_not_aligned

/* Hardware can handle unaligned access directly.  */
.L_dest_aligned:
        /* If dest is aligned, then copy.  */
        zext    r18, r2, 31, 4

        /* Test if len less than 16 bytes.  */
        bez     r18, .L_len_less_16bytes
        movi    r19, 0

        LABLE_ALIGN
.L_len_larger_16bytes:
#if defined(__CK860__)
        ldw     r3, (r1, 0)
        stw     r3, (r0, 0)
        ldw     r3, (r1, 4)
        stw     r3, (r0, 4)
        ldw     r3, (r1, 8)
        stw     r3, (r0, 8)
        ldw     r3, (r1, 12)
        addi    r1, 16
        stw     r3, (r0, 12)
        addi    r0, 16
#else
        ldw     r20, (r1, 0)
        ldw     r21, (r1, 4)
        ldw     r22, (r1, 8)
        ldw     r23, (r1, 12)
        stw     r20, (r0, 0)
        stw     r21, (r0, 4)
        stw     r22, (r0, 8)
        stw     r23, (r0, 12)
        PRE_BNEZAD (r18)
        addi    r1, 16
        addi    r0, 16
#endif
        BNEZAD (r18, .L_len_larger_16bytes)

.L_len_less_16bytes:
        zext    r18, r2, 3, 2
        bez     r18, .L_copy_by_byte
.L_len_less_16bytes_loop:
        ldw     r3, (r1, 0)
        PRE_BNEZAD (r18)
        addi    r1, 4
        stw     r3, (r0, 0)
        addi    r0, 4
        BNEZAD (r18, .L_len_less_16bytes_loop)

/* Test if len less than 4 bytes.  */
.L_copy_by_byte:
        zext    r18, r2, 1, 0
        bez     r18, .L_return
.L_copy_by_byte_loop:
        ldb     r3, (r1, 0)
        PRE_BNEZAD (r18)
        addi    r1, 1
        stb     r3, (r0, 0)
        addi    r0, 1
        BNEZAD (r18, .L_copy_by_byte_loop)

.L_return:
        mov     r0, r12
        rts

/*
 * If dest is not aligned, just copying some bytes makes the
 * dest align.
 */
.L_dest_not_aligned:
        sub     r13, r19, r13
        sub     r2, r13

/* Makes the dest align.  */
.L_dest_not_aligned_loop:
        ldb     r3, (r1, 0)
        PRE_BNEZAD (r13)
        addi    r1, 1
        stb     r3, (r0, 0)
        addi    r0, 1
        BNEZAD (r13, .L_dest_not_aligned_loop)
        cmplti  r2, 4
        bt      .L_copy_by_byte

        /* Check whether the src is aligned.  */
        jbr     .L_dest_aligned
ENDPROC(__memcpy)