/*-
 * Copyright (c) 2018 The FreeBSD Foundation
 *
 * This software was developed by Mateusz Guzik <mjg@FreeBSD.org>
 * under sponsorship from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <machine/asm.h>
/*
 * Note: this routine was written with kernel use in mind (read: no simd),
 * it is only present in userspace as a temporary measure until something
 * better gets imported.
 */

#define ALIGN_TEXT      .p2align 4,0x90 /* 16-byte alignment, nop filled */

.macro MEMSET erms
        movq    %rdi,%rax
        movq    %rdx,%rcx
        movzbq  %sil,%r8
        movabs  $0x0101010101010101,%r10
        imulq   %r8,%r10

        cmpq    $32,%rcx
        jbe     101632f

        cmpq    $256,%rcx
        ja      1256f

        ALIGN_TEXT
103200:
        movq    %r10,(%rdi)
        movq    %r10,8(%rdi)
        movq    %r10,16(%rdi)
        movq    %r10,24(%rdi)
        leaq    32(%rdi),%rdi
        subq    $32,%rcx
        cmpq    $32,%rcx
        ja      103200b
        cmpb    $16,%cl
        ja      201632f
        movq    %r10,-16(%rdi,%rcx)
        movq    %r10,-8(%rdi,%rcx)
        ret
        ALIGN_TEXT
101632:
        cmpb    $16,%cl
        jl      100816f
201632:
        movq    %r10,(%rdi)
        movq    %r10,8(%rdi)
        movq    %r10,-16(%rdi,%rcx)
        movq    %r10,-8(%rdi,%rcx)
        ret
        ALIGN_TEXT
100816:
        cmpb    $8,%cl
        jl      100408f
        movq    %r10,(%rdi)
        movq    %r10,-8(%rdi,%rcx)
        ret
        ALIGN_TEXT
100408:
        cmpb    $4,%cl
        jl      100204f
        movl    %r10d,(%rdi)
        movl    %r10d,-4(%rdi,%rcx)
        ret
        ALIGN_TEXT
100204:
        cmpb    $2,%cl
        jl      100001f
        movw    %r10w,(%rdi)
        movw    %r10w,-2(%rdi,%rcx)
        ret
        ALIGN_TEXT
100001:
        cmpb    $0,%cl
        je      100000f
        movb    %r10b,(%rdi)
100000:
        ret
        ALIGN_TEXT
1256:
        movq    %rdi,%r9
        movq    %r10,%rax
        testl   $15,%edi
        jnz     3f
1:
.if \erms == 1
        rep
        stosb
        movq    %r9,%rax
.else
        movq    %rcx,%rdx
        shrq    $3,%rcx
        rep
        stosq
        movq    %r9,%rax
        andl    $7,%edx
        jnz     2f
        ret
2:
        movq    %r10,-8(%rdi,%rdx)
.endif
        ret
        ALIGN_TEXT
3:
        movq    %r10,(%rdi)
        movq    %r10,8(%rdi)
        movq    %rdi,%r8
        andq    $15,%r8
        leaq    -16(%rcx,%r8),%rcx
        neg     %r8
        leaq    16(%rdi,%r8),%rdi
        jmp     1b
.endm


ENTRY(memset)
        MEMSET erms=0
END(memset)

        .section .note.GNU-stack,"",%progbits