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

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

ENTRY(strcmp)
        mov     a3, a0
        /* Check if the s1 addr is aligned.  */
        xor     a2, a3, a1
        andi    a2, 0x3
        bnez    a2, 7f
        andi    t1, a0, 0x3
        bnez    t1, 5f

1:
        /* If aligned, load word each time.  */
        ldw     t0, (a3, 0)
        ldw     t1, (a1, 0)
        /* If s1[i] != s2[i], goto 2f.  */
        cmpne   t0, t1
        bt      2f
        /* If s1[i] == s2[i], check if s1 or s2 is at the end.  */
        tstnbz  t0
        /* If at the end, goto 3f (finish comparing).  */
        bf      3f

        ldw     t0, (a3, 4)
        ldw     t1, (a1, 4)
        cmpne   t0, t1
        bt      2f
        tstnbz  t0
        bf      3f

        ldw     t0, (a3, 8)
        ldw     t1, (a1, 8)
        cmpne   t0, t1
        bt      2f
        tstnbz  t0
        bf      3f

        ldw     t0, (a3, 12)
        ldw     t1, (a1, 12)
        cmpne   t0, t1
        bt      2f
        tstnbz  t0
        bf      3f

        ldw     t0, (a3, 16)
        ldw     t1, (a1, 16)
        cmpne   t0, t1
        bt      2f
        tstnbz  t0
        bf      3f

        ldw     t0, (a3, 20)
        ldw     t1, (a1, 20)
        cmpne   t0, t1
        bt      2f
        tstnbz  t0
        bf      3f

        ldw     t0, (a3, 24)
        ldw     t1, (a1, 24)
        cmpne   t0, t1
        bt      2f
        tstnbz  t0
        bf      3f

        ldw     t0, (a3, 28)
        ldw     t1, (a1, 28)
        cmpne   t0, t1
        bt      2f
        tstnbz  t0
        bf      3f

        addi    a3, 32
        addi    a1, 32

        br      1b

# ifdef __CSKYBE__
        /* d[i] != s[i] in word, so we check byte 0.  */
2:
        xtrb0   a0, t0
        xtrb0   a2, t1
        subu    a0, a2
        bez     a2, 4f
        bnez    a0, 4f

        /* check byte 1 */
        xtrb1   a0, t0
        xtrb1   a2, t1
        subu    a0, a2
        bez     a2, 4f
        bnez    a0, 4f

        /* check byte 2 */
        xtrb2   a0, t0
        xtrb2   a2, t1
        subu    a0, a2
        bez     a2, 4f
        bnez    a0, 4f

        /* check byte 3 */
        xtrb3   a0, t0
        xtrb3   a2, t1
        subu    a0, a2
# else
        /* s1[i] != s2[i] in word, so we check byte 3.  */
2:
        xtrb3   a0, t0
        xtrb3   a2, t1
        subu    a0, a2
        bez     a2, 4f
        bnez    a0, 4f

        /* check byte 2 */
        xtrb2   a0, t0
        xtrb2   a2, t1
        subu    a0, a2
        bez     a2, 4f
        bnez    a0, 4f

        /* check byte 1 */
        xtrb1   a0, t0
        xtrb1   a2, t1
        subu    a0, a2
        bez     a2, 4f
        bnez    a0, 4f

        /* check byte 0 */
        xtrb0   a0, t0
        xtrb0   a2, t1
        subu    a0, a2

# endif /* !__CSKYBE__ */
        jmp     lr
3:
        movi    a0, 0
4:
        jmp     lr

        /* Compare when s1 or s2 is not aligned.  */
5:
        subi    t1, 4
6:
        ldb     a0, (a3, 0)
        ldb     a2, (a1, 0)
        subu    a0, a2
        bez     a2, 4b
        bnez    a0, 4b
        addi    t1, 1
        addi    a1, 1
        addi    a3, 1
        bnez    t1, 6b
        br      1b

7:
        ldb     a0, (a3, 0)
        addi    a3, 1
        ldb     a2, (a1, 0)
        addi    a1, 1
        subu    a0, a2
        bnez    a0, 4b
        bnez    a2, 7b
        jmp     r15
ENDPROC(strcmp)