/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
 */

#include <linux/export.h>
#include <asm/alternative-asm.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/cpu.h>
#include <asm/regdef.h>
#include <asm/unwind_hints.h>

.macro fill_to_64 r0
        bstrins.d \r0, \r0, 15, 8
        bstrins.d \r0, \r0, 31, 16
        bstrins.d \r0, \r0, 63, 32
.endm

.section .noinstr.text, "ax"

SYM_FUNC_START(memset)
        /*
         * Some CPUs support hardware unaligned access
         */
        ALTERNATIVE     "b __memset_generic", \
                        "b __memset_fast", CPU_FEATURE_UAL
SYM_FUNC_END(memset)
SYM_FUNC_ALIAS(__memset, memset)

EXPORT_SYMBOL(memset)
EXPORT_SYMBOL(__memset)

_ASM_NOKPROBE(memset)
_ASM_NOKPROBE(__memset)

/*
 * void *__memset_generic(void *s, int c, size_t n)
 *
 * a0: s
 * a1: c
 * a2: n
 */
SYM_FUNC_START(__memset_generic)
        move    a3, a0
        beqz    a2, 2f

1:      st.b    a1, a0, 0
        addi.d  a0, a0, 1
        addi.d  a2, a2, -1
        bgt     a2, zero, 1b

2:      move    a0, a3
        jr      ra
SYM_FUNC_END(__memset_generic)
_ASM_NOKPROBE(__memset_generic)

/*
 * void *__memset_fast(void *s, int c, size_t n)
 *
 * a0: s
 * a1: c
 * a2: n
 */
SYM_FUNC_START(__memset_fast)
        /* fill a1 to 64 bits */
        fill_to_64 a1

        sltui   t0, a2, 9
        bnez    t0, .Lsmall

        add.d   a2, a0, a2
        st.d    a1, a0, 0

        /* align up address */
        addi.d  a3, a0, 8
        bstrins.d       a3, zero, 2, 0

        addi.d  a4, a2, -64
        bgeu    a3, a4, .Llt64

        /* set 64 bytes at a time */
.Lloop64:
        st.d    a1, a3, 0
        st.d    a1, a3, 8
        st.d    a1, a3, 16
        st.d    a1, a3, 24
        st.d    a1, a3, 32
        st.d    a1, a3, 40
        st.d    a1, a3, 48
        st.d    a1, a3, 56
        addi.d  a3, a3, 64
        bltu    a3, a4, .Lloop64

        /* set the remaining bytes */
.Llt64:
        addi.d  a4, a2, -32
        bgeu    a3, a4, .Llt32
        st.d    a1, a3, 0
        st.d    a1, a3, 8
        st.d    a1, a3, 16
        st.d    a1, a3, 24
        addi.d  a3, a3, 32

.Llt32:
        addi.d  a4, a2, -16
        bgeu    a3, a4, .Llt16
        st.d    a1, a3, 0
        st.d    a1, a3, 8
        addi.d  a3, a3, 16

.Llt16:
        addi.d  a4, a2, -8
        bgeu    a3, a4, .Llt8
        st.d    a1, a3, 0

.Llt8:
        st.d    a1, a2, -8

        /* return */
        jr      ra

        .align  4
.Lsmall:
        pcaddi  t0, 4
        slli.d  a2, a2, 4
        add.d   t0, t0, a2
        jr      t0

        .align  4
0:      jr      ra

        .align  4
1:      st.b    a1, a0, 0
        jr      ra

        .align  4
2:      st.h    a1, a0, 0
        jr      ra

        .align  4
3:      st.h    a1, a0, 0
        st.b    a1, a0, 2
        jr      ra

        .align  4
4:      st.w    a1, a0, 0
        jr      ra

        .align  4
5:      st.w    a1, a0, 0
        st.b    a1, a0, 4
        jr      ra

        .align  4
6:      st.w    a1, a0, 0
        st.h    a1, a0, 4
        jr      ra

        .align  4
7:      st.w    a1, a0, 0
        st.w    a1, a0, 3
        jr      ra

        .align  4
8:      st.d    a1, a0, 0
        jr      ra
SYM_FUNC_END(__memset_fast)
_ASM_NOKPROBE(__memset_fast)

STACK_FRAME_NON_STANDARD __memset_fast