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/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2024 Getz Mikalsen <getz@FreeBSD.org>
*/
#include <machine/asm.h>
.weak strlen
.set strlen, __strlen
.text
ENTRY(__strlen)
bic x10, x0, #0xf // aligned src
and x9, x0, #0xf
ldr q0, [x10]
cmeq v0.16b, v0.16b, #0
shrn v0.8b, v0.8h, #4
fmov x1, d0
cbz x9, .Laligned
lsl x2, x0, #2 // get the byte offset
lsr x1, x1, x2 // shift by offset index
cbz x1, .Lloop
rbit x1, x1
clz x0, x1
lsr x0, x0, #2
ret
.Laligned:
cbnz x1, .Ldone
.Lloop:
ldr q0, [x10, #16]!
cmeq v0.16b, v0.16b, #0
shrn v0.8b, v0.8h, #4 // reduce to fit mask in GPR
fmov x1, d0
cbz x1, .Lloop
.Ldone:
sub x0, x10, x0
rbit x1, x1 // reverse bits as NEON has no ctz
clz x3, x1
lsr x3, x3, #2
add x0, x0, x3
ret
END(__strlen)
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