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/*-
* 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.
*
* $FreeBSD$
*/
#include <machine/asm.h>
__FBSDID("$FreeBSD$");
/*
* 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 */
#ifdef BCMP
ENTRY(bcmp)
#else
ENTRY(memcmp)
#endif
xorl %eax,%eax
10:
cmpq $16,%rdx
ja 101632f
cmpb $8,%dl
jg 100816f
cmpb $4,%dl
jg 100408f
cmpb $2,%dl
jge 100204f
cmpb $1,%dl
jl 100000f
movzbl (%rdi),%eax
movzbl (%rsi),%r8d
subl %r8d,%eax
100000:
ret
ALIGN_TEXT
100816:
movq (%rdi),%r8
movq (%rsi),%r9
cmpq %r8,%r9
jne 80f
movq -8(%rdi,%rdx),%r8
movq -8(%rsi,%rdx),%r9
cmpq %r8,%r9
jne 10081608f
ret
ALIGN_TEXT
100408:
movl (%rdi),%r8d
movl (%rsi),%r9d
cmpl %r8d,%r9d
jne 80f
movl -4(%rdi,%rdx),%r8d
movl -4(%rsi,%rdx),%r9d
cmpl %r8d,%r9d
jne 10040804f
ret
ALIGN_TEXT
100204:
movzwl (%rdi),%r8d
movzwl (%rsi),%r9d
cmpl %r8d,%r9d
jne 1f
movzwl -2(%rdi,%rdx),%r8d
movzwl -2(%rsi,%rdx),%r9d
cmpl %r8d,%r9d
jne 1f
ret
ALIGN_TEXT
101632:
cmpq $32,%rdx
ja 103200f
movq (%rdi),%r8
movq (%rsi),%r9
cmpq %r8,%r9
jne 80f
movq 8(%rdi),%r8
movq 8(%rsi),%r9
cmpq %r8,%r9
jne 10163208f
movq -16(%rdi,%rdx),%r8
movq -16(%rsi,%rdx),%r9
cmpq %r8,%r9
jne 10163216f
movq -8(%rdi,%rdx),%r8
movq -8(%rsi,%rdx),%r9
cmpq %r8,%r9
jne 10163224f
ret
ALIGN_TEXT
103200:
movq (%rdi),%r8
movq 8(%rdi),%r9
subq (%rsi),%r8
subq 8(%rsi),%r9
orq %r8,%r9
jnz 10320000f
movq 16(%rdi),%r8
movq 24(%rdi),%r9
subq 16(%rsi),%r8
subq 24(%rsi),%r9
orq %r8,%r9
jnz 10320016f
leaq 32(%rdi),%rdi
leaq 32(%rsi),%rsi
subq $32,%rdx
cmpq $32,%rdx
jae 103200b
cmpb $0,%dl
jne 10b
ret
/*
* Mismatch was found.
*/
#ifdef BCMP
ALIGN_TEXT
10320016:
10320000:
10081608:
10163224:
10163216:
10163208:
10040804:
80:
1:
leal 1(%eax),%eax
ret
END(bcmp)
#else
/*
* We need to compute the difference between strings.
* Start with narrowing the range down (16 -> 8 -> 4 bytes).
*/
ALIGN_TEXT
10320016:
leaq 16(%rdi),%rdi
leaq 16(%rsi),%rsi
10320000:
movq (%rdi),%r8
movq (%rsi),%r9
cmpq %r8,%r9
jne 80f
leaq 8(%rdi),%rdi
leaq 8(%rsi),%rsi
jmp 80f
ALIGN_TEXT
10081608:
10163224:
leaq -8(%rdi,%rdx),%rdi
leaq -8(%rsi,%rdx),%rsi
jmp 80f
ALIGN_TEXT
10163216:
leaq -16(%rdi,%rdx),%rdi
leaq -16(%rsi,%rdx),%rsi
jmp 80f
ALIGN_TEXT
10163208:
leaq 8(%rdi),%rdi
leaq 8(%rsi),%rsi
jmp 80f
ALIGN_TEXT
10040804:
leaq -4(%rdi,%rdx),%rdi
leaq -4(%rsi,%rdx),%rsi
jmp 1f
ALIGN_TEXT
80:
movl (%rdi),%r8d
movl (%rsi),%r9d
cmpl %r8d,%r9d
jne 1f
leaq 4(%rdi),%rdi
leaq 4(%rsi),%rsi
/*
* We have up to 4 bytes to inspect.
*/
1:
movzbl (%rdi),%eax
movzbl (%rsi),%r8d
cmpb %r8b,%al
jne 2f
movzbl 1(%rdi),%eax
movzbl 1(%rsi),%r8d
cmpb %r8b,%al
jne 2f
movzbl 2(%rdi),%eax
movzbl 2(%rsi),%r8d
cmpb %r8b,%al
jne 2f
movzbl 3(%rdi),%eax
movzbl 3(%rsi),%r8d
2:
subl %r8d,%eax
ret
END(memcmp)
#endif
.section .note.GNU-stack,"",%progbits
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